Speedometers are seldom right

Don't Trust Your Car's Speedometer

It's not just that speedometers are sometimes wrong. Based on how they work, it's almost impossible for them to ever be right.

By Jason Cammisa, Road & Track, Jun 8, 2020

Back in high school, my best friend managed to get the speedometer needle in his mom’s 1987 Chevrolet Cavalier— we called it the “Lier-Jet”—so far past the end of the scale that it twisted all the way back to zero. That speedo admittedly maxed at just 85 mph, but a wrapped needle meant the front wheels were doing about 125 mph. A grand accomplishment, given that the rest of the car wasn’t actually moving.

Traditional speedometers don’t really measure a car’s speed. They’re just an rpm gauge for the drive wheels, because that’s where they get their information—typically from a drive cable or sensor on the driveline. The way they convert that data to vehicle speed assumes that you are not, in fact, doing an epic burnout in a front-drive Chevy while the car is held stationary by the handbrake. (Guilty.)

That conversion also makes another incorrect but critical assumption — the circumference of your tires. Because that measurement changes continuously, as the tire expands and contracts with use and environment, your speedometer is never accurate.

Circumference is a simple function of a tire’s radius, or the distance between the center of the wheel and ground. Part of that radius is the tire’s flexible sidewall, which deforms under the vehicle’s weight. The amount of deformation is predominantly a function of tire pressure and mass, meaning that, even if your speedometer was accurate on a cold morning, it would be inaccurate later that day, when ambient temperature was higher and tires were warm from use.

Add a few passengers and their weight squishes the sidewall further, causing the speedo to read high. Finally, your tires’ circumference gradually decreases with use, as the rubber wears away—worn tires alone can throw off your speedo accuracy by more than a percent.

To offset all of this, and to help prevent you from getting a speeding ticket, most speedometers are designed to read slightly high. European regulations in particular allow most cars to display 10 percent plus 6 kilometers per hour (3.7 mph) above actual speed, but those same regulations do not allow for the reporting of a speed lower than the car is actually traveling.

The United Kingdom’s regs are similar but even more lenient, allowing 10 percent plus 6.25 mph, which is probably why every Lotus I’ve driven exaggerates its speed like a teenage boy. Volkswagen, a company that’s never lied about anything (right?), tends to have speedometers so close to accurate that they occasionally read low. (I think he should rather state: 10 percent OR 6 / 6.25 mph, but we'll let it go this time - Ed)

This isn’t actually illegal in America; passenger cars aren’t subject to speedometer-accuracy legislation, though some carmakers voluntarily adhere to SAE standards. And in VW’s defense, huge speedo error can be caused by variations in the rolling circumference of different tires. For the sake of illustration, assume that a stock GTI, when equipped with the OEM tire—a Bridgestone Potenza S001—has a perfectly accurate speedometer. Replacing its tires with, say, a Kumho Solus TA71 in the same 225/40-18 size would result in a road speed of 75.6 mph when the GTI’s speedo says 70.

In other words, a potentially big ticket. That nearly eight-percent difference in rolling circumference is calculated from the two tire manufacturers’ published specifications for revolutions per mile. And that brings us back to the fun part: The significant variation between two tires of the same size highlights just how silly it is to calculate speed via wheel rpm.

Decades ago, tech limitations gave carmakers no other choice for measuring velocity. These days, we have plenty of other ways. GPS is a line-of-sight technology, dependent on a relatively clear sky path to satellites, so it doesn’t work in tunnels and can be confused by tall buildings or trees. But since in-car GPS receivers are now widespread, that information could be used for continuous speedometer calibration.

Too bad car companies don’t think this way. If they did, they’d have stopped using drive axles for speedometer information. And modern cars already know exactly how fast they’re going because they have to. Electronic stability control systems, mandated by law, need speed and direction-of-travel information in order to rein in an out-of-control car. To obtain it, those systems use yaw-rate sensors and accelerometers, in conjunction with individual wheel-speed sensors, to continuously calculate a vehicle’s actual velocity. Oddly, that information never makes it to your speedometer.

Unless you’re in a Tesla. The dash in every one of Elon Musk’s EVs shows a calculated speed value, computed using all available inputs (drive-motor speeds, individual wheel speeds, and inertial measurements) and then corrected using physics-based models that include motor and brake torque. Now that’s clever.

It’s also a little sad, because twisting a speedo needle clean off the dial before you’ve even moved is one of life’s great pleasures. Today’s teens might not get a speeding ticket by mistake, but they’ll miss out on something better: the pleasure of 125-mph burnouts.

Jason Cammisa is a Road & Track contributing editor and our resident tire-smoke fanatic. You can find more of his nerdism at @jasoncammisa on Instagram.

Tape is one consumable your seldom think about

Hollywood Hanger, a simple loop created with a piece of rope and a pair of carabiners

A small patch of duct tape could save your day

A wrap of tape provides support

Or just hang it up in the workshop

Wrenchin’ Wednesday: Three duct tape hacks for your tool kit

Phillip Thomas, Hagerty, 03 June 2020

Without our Lord and Saviour, adhesion, the automotive world as we know it would probably not exist. Tape is one of those shop consumables you rarely think about twice unless you’re in dire need of it — or have none of it. Today’s Wrenchin’ Wednesday will show you three hacks to make the most of your adhesive tool kit.

The Hollywood Hanger

The first trick comes from a buddy of mine who works in the special effects industry, in which masking, gaffer’s, and duct tape rule the roost when it comes to set building. His strategy for keeping these reels of adhesive close by gave birth to what I call The Hollywood Hanger, a simple loop created with a piece of rope and a pair of carabiners.

The Hollywood Hanger is great for mobile tool kits, too; it keeps the rolls of tape organised and prevents them from rolling around in a bag or back seat. Plus, the carabiners make the arrangement easy to hang from a workbench or wall hook, and they’re secure enough to hang from your belt if the need arises.

Keychain backup

Okay, so hanging rolls of tape off your hip may not be convenient. Having a small patch of duct tape on hand, though, could still save the day. I’ll never have a use for a 5/32 wrench, but it’s far more likely I’ll need to slap duct tape on a problem. Using a tiny wrench as a keychain isn’t a novel idea, and rewrapping one in duct tape keeps the kitsch factor while promising to save your own bacon one day.

Wobble no more

Wobble (flexible) extensions are essential in some automotive jobs. By acting like a driveshaft’s universal joint, these attachments allow you to spin off-angle bolts. The tricky task is when you need to fish for a bolt hole deep inside the machine and keep the wobble supported so that you can quickly align the threads.

It only takes a wrap or two of tape to give the extension enough support to hold a socket upright while still giving it enough flexibility to wobble or flex.

It isn't always the pump

Troubleshooting a no-start on a car with a mechanical fuel pump

Story and pics by Rob Siegel, Hagerty, 18 May 2020

So, your car ran a few months ago. You take it out of storage after a long snooze, then crank and crank and crank it, but it won’t start. What’s up? If it’s a carburetted car with a mechanical fuel pump, it may have a priming issue.

Nearly all fuel-injected cars have an electric fuel pump. The pumps on early injected cars switch on immediately when you crank the key to ignition. Later ones have a safety interlock that typically requires the presence of air flow into the engine so that they won’t continue to pump fuel if the car is in an accident. But in either case, electric pumps deliver gobs of fuel pressure almost immediately, which is one of the things that helps fuel-injected cars start even if they’ve been sitting for a long time.

In contrast, most carburetted cars have, or originally had, a mechanical fuel pump with a rubber diaphragm inside that’s moved in and out by a lever or a pushrod typically driven off the camshaft. There are several reasons why this often creates a situation where the car is difficult, sometimes impossible, to start after it’s been sitting a long time.

First, electric fuel pumps on fuel-injected cars can easily output 60 psi, often regulated down to 30-ish psi and then the excess fuel dumped back into the tank through a return line. That pressure pushes fuel very quickly. In contrast, the fuel pressure created by mechanical fuel pumps is much less, usually in the 1–4 psi range.

Second, this is important because the fuel system needs to be primed — the lines between the tank and the engine have to be filled with fuel. On a fuel-injected car with an electric fuel pump, this happens in mere seconds, but it’s different in a carburetted car with a mechanical pump whose fuel pressure depends on engine rpm. If there’s still fuel in the float bowl, you can mash the accelerator pedal a few times, and on a carburettor with an accelerator pump, it’ll squirt gas from the float bowl down into the throat of the carb.

That’ll help the engine to start, and once it’s running, the higher rpm will make the fuel pump run faster, making it easier for it to prime the system. But if the car’s been sitting long enough that the fuel in the float bowl has evaporated, the fuel pump will need to fill it. So you can get into a bootstrapping issue where, when the engine is being cranked off the starter, it’s spinning only a fraction as fast as it is when its running, and combined with a weak battery, an old starter, an original mechanical fuel pump in which the rubber diaphragm has gotten old and lost some of its elasticity, it may have trouble priming.

The third issue is that, in addition to the pressure differences between mechanical and electric fuel pumps, they work in different ways. Mechanical fuel pumps suck fuel by creating an oscillating vacuum on the inlet side. In contrast, electric fuel pumps, at least the rotary ones, create a fairly constant fuel pressure, and while they obviously have to draw fuel from the tank, they push more than they suck. This is why mechanical fuel pumps are mounted on the engine whereas electric fuel pumps are mounted at the rear of the car, often in the gas tank itself.

Last is the issue of vacuum leaks in the fuel lines. As rubber fuel hose gets old, it dries out, and it’s possible for air to be drawn through the sides. On various old cars, there’s a short section of rubber fuel line in the trunk that connects the pick-up tube in the task tank to the metal or plastic line that runs the length of the car.

That line could be under a screwed-down trunk panel, so it’s common to find that it’s the original 47-year-old piece and it’s become dry-rotted. If the car ran last winter but won’t fill the float bowl in the spring, this is a prime culprit. If it’s original, replace it. Be certain the hose clamps are tight. If the fuel line is plastic, check the end of it thoroughly for cracks and splits.

Of course, it’s possible that the mechanical fuel pump really has died — that the rubber diaphragm has cracked or torn, or that the little check valve inside is stuck open. So how to you test it?

Obviously, first make sure that the problem actually is fuel and not spark. Take the centre wire out of the distributor and hold it with rubber gloves or insulated pliers one-quarter inch from a good ground while someone cranks the engine. If you see spark, good. Then, if you like, you can hold open the throttle, give a good blast of starting fluid, and try to start the car. If it runs for a few seconds, then dies, you definitely have a fuel delivery problem.

If you have a low-pressure electric fuel pump, or even a pump bulb (like for a small gas boat engine), you can temporarily splice it in and fill up the float bowl. If it won’t fill, then you have some other problem like a fuel line obstruction or a clogged fuel filter. If once the float bowl is full, the car still won’t start and run, you have some other problem in the carb such as plugged jets or accelerator pump nozzle. The irony, though, is that if you prime the system and the car then starts and runs, you’ve made it harder to find the root cause of the inability for the system to prime itself.

DIY pump testing kit

Here’s what I do to test the mechanical fuel pump directly

Undo the gas lines from the fuel pump and unbolt the pump from the engine. A lever of some sort will be located at the base. The one on my Lotus Europa protrudes by several inches and directly contacts the camshaft, but others may use an intermediate pushrod and have a much smaller lever mechanism. It may look like a little lever or it may be a spring around a plunger. It may be recessed inside the base or it may protrude.

If it is recessed, use a wooden or plastic probe to move it. If it’s exposed, you can just push the fuel pump down on it on a block of wood. Listen for a sound vaguely like inhaling and exhaling out of pursed lips. If you hear nothing, the diaphragm could be torn, and the pump is likely bad.

If the pump passes that test, repeat it while putting a finger on both the inlet and outlet fittings. You should feel suction on the former and pressure on the latter. If you don’t, the check valve inside the pump could be stuck open.

Next, test that the pump actually moves liquid. You can do this with water, but because of concern over getting water into the float bowl, I do it with gas (be sure to have a fire extinguisher at the ready). Put a short length of rubber gas line (that you’re certain isn’t porous) on the inlet and outlet sides of the pump. Put the inlet hose into a container of liquid and the outlet hose into a catch container.

Work the lever of the pump back and forth. It usually doesn’t take much effort to move liquid and convince yourself that either the fuel pump actually pumps fuel or it’s dead. If it is dead, whether it’s rebuildable or worth rebuilding varies greatly model to model. Sometimes the diaphragm can be easily replaced, but other pumps have permanently crimped top and bottom sections. As with many vintage car parts, if originality is important to you, there are specialty shops that rebuild fuel pumps.

The standalone liquid test.

If the pump seems healthy, repeat the test with it installed on the engine. That is, mount the pump back onto the engine but continue to feed it gas or water via a hose into a source container, and the output sent into a catch container. It’s easiest to do this with a helper who cranks the engine, or to use a remote start switch hooked to the starter. Be certain to disconnect the wire from the “+” or “15” side of the coil so the engine won’t try to start.

If you like, you can remove the spark plugs to make the starter spin faster. If no liquid pumps when the pump is attached but it did when it was tested alone, you may still have an air leak you haven’t found. If not, the difference could be that loss of elasticity in the diaphragm, or in extreme cases, wear in the pump rod/lever—or even the lobe of the camshaft—has tipped it over the edge to non-functionality.

But if it does pump fuel from a small container, re-install one connection at a time. Try the inlet side — the connection to the fuel tank—first. If it doesn’t pump, trace it down. You’ll likely find a porous rubber gas hose, or a cracked plastic one. Then reconnect the output side. It’s possible that the needle valve in the float bowl is stuck closed.

So, with all that, I can tell my mechanical fuel pump story. I just went through everything above on my 48,000-mile 1973 BMW 2002. It had a hard time starting when I bought it last fall, but that wasn’t surprising since it had sat for a decade. I primed it with an electric fuel pump, and the problem largely went away; after that it started and drove fine. But when I roused it from its winter snooze, I faced the same problem and wanted to solve it once and for all.

I went through the above steps, found that the mechanical fuel pump worked fine both in standalone testing and when reattached to the engine and fed gas from a can, but didn’t work when the gas lines were hooked back up to it. There was a fuel filter on the inlet side of the pump, as there usually is on a BMW 2002. I removed both hoses and the filter and replaced them with a single brand-new section of fuel hose run directly from the plastic fuel pipe coming through the firewall to the fuel pump inlet, and it pumped fine.

What was going on? The problem was the fuel filter. No, it wasn’t clogged. No, it wasn’t leaking.

The cause appears to be that mechanical fuel pumps aren’t really designed to have filters on the inlet side — screens, yes, but not canister filters with any substantial volume to them. I would’ve sworn that this was the stock location for a BMW 2002 fuel filter, but on digging into it, I learned that these cars have a screen at the bottom of the pickup tube in the trunk, and a second one inside the fuel pump, but that, when delivered new, had no external fuel filter. They were added by repair shops and DIYers and became so ubiquitous that I and most other folks assume they’re original.

There’s the school of thought (which I always followed), that the filter should go before the fuel pump because that way it keeps rust and sediment from the gas tank out of the pump. The other argument, by the way, for having the filter on the inlet side of the fuel pump is that if the filter splits or leaks, the pump will just suck air and fuel flow will stop, whereas if it’s on the outlet side, fuel will continue to be pumped into it and it’ll leak in the engine compartment.

While I don’t discount either of these arguments, it turns out that, with a mechanical fuel pump, having the filter on the inlet side can be problem because, if it’s not full of fuel, the fuel filter housing then holds a pocket of air that the oscillating pressure of the fuel pump can’t suck out. As I said above, combine this with an old fuel pump and a weak starter motor and it can be enough that the system won’t prime. This appeared to be the case with my car. Fuel filter on inlet side of pump = no prime. No fuel filter at all or filter on outlet side of pump = prime and start.

For years, when resurrecting long-dead cars with rusty gas tanks, I’ve cleaned the gas tank by throwing a chain into it and shaking the tank, reaching into it (if I can) and scrubbing it with a Scotch-Brite pad, then splicing a canister filter into the gas line in the trunk to catch any residual rust and sediment before it gets into the electric fuel pump and ruins it. However, I now realise that this has been on fuel-injected cars, whose rear-mounted high-pressure electric fuel pumps aren’t as likely to have the priming issue described above.

I’m not saying that every fuel filter mounted in front of a mechanical fuel pump will cause problems. I’m just saying that, if you’re experiencing a priming issue, add it to the list of possibilities.

Go and find your prime suspect.


Disc brakes offer better stopping performance than comparable drums


Posted by Matt Bell in Classics World on 18th December 2018

Disc brakes offer better stopping performance than comparable drums, including resistance to ‘fade’ caused by overheating. We trace the development of this important automotive innovation back to the opening years of the Twentieth Century.

Although Fredrick William Lanchester is generally recognised as being the first UK motor manufacturer to patent a mechanical version of the automotive disc brake in 1902, the Birmingham-based automotive engineer can only really be credited for improving an existing technology. This is because a very basic disc and calliper-type braking system had been fitted to the front wheel of an electrically powered vehicle built in the US by Elmer Ambrose Cleveland back in 1898.

The performance of the disc-based braking system fitted to Lanchester’s cars was severely limited as the braking medium acting on the disc was made from copper. Not only were these copper ‘pads’ noisy in operation, they also wore out quickly due to the dusty conditions that prevailed on the roads at the time. Despite later versions having more efficient asbestos-lined pads, drum-based braking systems proved simpler and cheaper to make and became the preferred choice with vehicle manufactures right up until the mid ‘fifties.

As pre-war American cars were notoriously under braked, several experiments with complex internal and expanding disc-based systems took place in the US during the lead up to the Second World War. The outbreak of war resulted in this research being switched to the development of reliable and efficient hydraulically operated calliper-type disc brakes for aircraft applications.

After the war, UK-based Dunlop became a major producer of aeronautical disc brakes, a factor that led to the company to adapt the technology for use on performance road vehicles.

In 1953, a Jaguar C-type racer caused a sensation when it was fitted with a pair of fade-resistant, Dunlop-made automotive disc brakes for that year’s Mille Miglia time trail in Italy. Citroën followed this up with a pair of powered inboard front discs on its 1955 DS and in 1956, the Triumph TR3 became the first British-built production car to be fitted with front disc brakes as standard.

Disc brakes consist of a cast iron disc that rotates at the same speed as a car’s road wheel. Each disc is partly covered by a calliper containing a pair of cylindrical, hydraulically operated pistons. Activating the car’s brake pedal causes the cylinders to push on a set of steel-backed friction pads and press them against the disc to slow or halt the car. A set of rubber seals around each piston prevents hydraulic fluid escaping from the calliper when pressure is applied, while rubber sealing rings keep dust and dirt out of the housings.

The inner face of the disc not covered by the calliper is protected from road debris and water by a pressed steel splash shield. Each piston is cast in a ‘U’ shape so that the fluid pushes on a flat surface and the minimum amount of material comes into contact with the steel part of the pad. As the calliper covers only part of the disc, the whole assembly is more easily cooled in the slipstream than the linings in an enclosed drum brake.

Heat transfer from the friction surface into the calliper is kept to the minimum on a disc brake, thus preventing brake ‘fade’, a common problem that can severely affect the performance of overheated drum-based systems. Brake fade is when a very hot drum moves away from the shoe assembly slightly, decreasing the vehicle’s braking efficiency. On a disc brake-equipped car the opposite happens as the disc expands slightly when it gets overheated. As an expanded disc moves closer to the pads, braking efficiency is maintained so long as the fluid doesn’t reach boiling point.

Pads are relatively easy to change and are generally held in place by two retaining pins that pass through the calliper. Each retaining pin is kept in place by a special spring clip. A shim plate is usually fitted between the piston and pad to eliminate brake squeal, while some pads incorporate wear indicators. Pads are usually segmental in shape but some can be rectangular, oval or even square. When replacing pads, it’s always advisable to put a smear of special brake grease on each side of the shim as an extra precaution against squeal.

As well as fixed callipers, there are several different types of assembly: the swinging type, the fist type and the sliding-calliper brake. A swinging calliper contains a single direct-acting hydraulic piston that operates on one friction pad. Fluid pressure on the cylinder or piston causes the calliper to operate the other pad in a swinging or sliding motion. Fist-type callipers are designed for compactness and have special V-slots in a fixed housing to prevent jamming. Applying the brake moves the cylindrical part of the ‘fist’ and corresponding pad onto the disc.

The sliding calliper brake works on the principal of two pistons working in a single cylinder. When pressurised fluid acts between them, it forces each piston apart. One piston forces a friction pad onto the disc by direct action, while the other piston forces the calliper in the opposite direction and in doing so brings the companion pad in direct contact with the disc.

Some callipers fitted to high performance cars contain four pistons, two in each calliper. For extra performance, discs can be drilled or have angled grooves milled across their faces. Modern replacement pads don’t contain any dangerous asbestos, but are made of various hard compounds that can sometimes include metal particles. The combination of these different materials can cause the disc to wear out and as such it is expected that new discs are fitted on every second or third pad change.

Changing the differential oil is one of the most-overlooked maintenance tasks

How to Care for Your Car's Differential

You change your engine oil every few thousand miles, but have you ever looked at your differential?

By Ben Wojdyla, Popular Mechanics Apr 18, 2020

Pics by Nick Ferrari/Popular Mechanics

Changing the differential oil is one of the most-overlooked maintenance tasks on non-FWD light trucks, SUVs, and passenger cars. Because the differential is at the rear and under the car, it gets none of the star treatment that the engine up front does.

But if lubrication in the differential fails, you won't be getting very far for very long. Fortunately, you only need to change this oil every 30,000 to 50,000 miles.

As always, check your owner's manual for the exact frequency you should service your differential. Every car is different.

The differential is a component in all cars and is designed to compensate for the difference in distance the inner wheels and outer wheels travel as the car goes around a corner. In a rear-wheel-drive car, the differential has its own housing and lubrication, a thick, dark oil usually heavier than 80 weight.

Front-drivers typically integrate the differential in the transmission housing and share the same fluid. The differential oil lubricates the ring and pinion gears that transfer power from the driveshaft to the wheel axles. If your car is fitted with a limited-slip differential, it also keeps all the moving parts in that assembly healthy.

A differential allows your car to make corners without drama. If both drive wheels rotated together, they'd jump-skitter because the outside tyre travels farther than the inside. There are many variations on the design, but they fall into three categories; open, limited-slip, and torque-vectoring. (See graphics at end of this article - Ed)

Changing this oil is just as important as changing the engine's oil, and for the same reason. Metal-to-metal contact wears down surfaces and creates heat from friction, which inevitably weakens the gears and leads to failure. Checking and changing the differential oil in a light truck is actually pretty easy, and it's only a bit more difficult in a car.

In either case, this small procedure can save you a big headache down the road.

Prep the Area

Loosen the bolt at the very top of the cover, but leave the bolt in place to prevent the cover from falling off completely and drenching the floor—and you—in differential oil.

Depending on the design of your differential, this can be a very messy or a very tidy job. Some differentials have a drain plug; others require you to remove the housing cover. In either case, you'll need a wide catch pan; a plastic drop-cloth beneath that would be good insurance. Drive your vehicle for a few minutes to warm the oil, then change into your grungy clothes — you'll probably get dirty.

Out with the old

It's just changing oil, right? Nothing that complicated, but brace yourself, because old differential oil has the foulest smell in the automotive world. With that warning, remove the fill-hole plug at the top of the diff casing, then unscrew the drain plug. If you don't have a drain plug, unscrew the housing bolts, leaving a couple of bolts on top loosely attached to hold the cover in place.

Using a standard screwdriver, pry open the cover gently or the oil will gush out and cover you in that unholy stink. Be careful not to mar the surface of the differential housing. Let the oil drain completely, then remove the cover.

Clean Everything and Seal It Up

Assume that all the leftover oil in the axle is loaded with metal shavings. If you're an oil-changing Boy Scout, you don't have to worry about this, but the rest of us should take the time to wipe the remaining oil out of the housing, the gears, and the wet side of the housing cover. Make sure to get it all, because there could be some shavings hiding in the nooks and crannies.

A basic degreaser or just a series of shop towels is all that’s necessary to clean out the housing cover. Use gloves you won’t mind throwing away. Once the cover is shiny, run a magnet around the inside to pick up stray metal shavings.

Clean the tip of the fill-hole plug too; most are fitted with a magnet to grab fine metal particles. Don't go crazy with harsh cleaners — you wouldn't want the residue to affect your new oil. Grab a razor scraper or light abrasive pad and clear off the mating surface of both the housing and cover. Wipe down both faces using a lint-free shop towel and brake cleaner.

Some cars have pre-made gaskets. If not, use a liquid gasket product designed for harsh conditions and oil exposure, such as Permatex Ultra Black. Lay a single bead on the mating face of the cover and draw a circle around each mounting hole, then bolt the cover in place with just enough clamping force to flatten the bead. Let it harden according to the instructions, then tighten the bolts to your vehicle's specs with a torque wrench.

Fill to the Brim

Use the highest-quality gear oil you can afford to fill the differential. The weight and capacity will be listed in your owner's manual; your differential will usually hold as much as three (US) quarts (2.84 litres). Be sure to read that manual, though, because some limited-slip differentials require a secondary friction-modifying additive.

Fill the differential directly from the bottle if you've got clearance, but if space is tight, you can get a pump or extension hose to make the job easier. The bottom of the plug hole is the maximum fill line, so when oil starts dripping out, you're finished.

Instal the plug, torque it to spec, and you're good for tens of thousands of miles.

Here are the three main types of differential

Jaguar stopper: Could it be vapour lock?

Vapour lock in a Jag

From Hagerty, 20 April 2020

Pic by Rob Siegel

Jonathan Lentz writes: I have a 1971 Jaguar E-Type six-cylinder that will start and run fine for about 15 to 20 minutes before it begins to sputter. Upon acceleration, it conks out and I am unable to start it up for an hour.

This problem has been ongoing for years. I once fixed it by replacing an overheating ignition switch, and the Jag ran fine for two years. Now the problem is back. The hotter the car is, the faster the problem will surface. The temp gauge reads normal; could it be vapour lock?

Jonathan, it certainly could be vapour lock — fuel turning into vapour before reaching the carburettors — but it also could be a different fuel delivery problem, or even an ignition issue. The best way to check for vapour lock is to temporarily instal a clear fuel hose on the inlet to the carburettors. If, as the car warms up, you see the liquid fuel bubble and vaporise in the hose, you’ve caught it in the act.

On the fuel delivery side, it could also be an issue with the SU fuel pump and its internal contact points (like points in a distributor) or a fuel filter that gets clogged but has the blockage relax when it sits for a while. On the ignition side, it could be that your ignition switch has failed again, or that the coil or condenser are failing.

Lead acid batteries are smashed apart in hammer mills

Recycling two main types of automobile battery

Credits: Battery Solutions and Wikipedia

Lead Acid

The battery is broken apart in a hammer mill, a machine that hammers the battery into pieces. The broken battery pieces are then placed into a vat, where the lead and heavy materials fall to the bottom and the plastic floats. At this point, the polypropylene pieces are scooped away and the liquids are drawn off, leaving the lead and heavy metals. Each of the materials goes into a different recycling “stream”.


Polypropylene pieces are washed, blown dry and sent to a plastic recycler where the pieces are melted together into an almost liquid state. The molten plastic is put through an extruder that produces small plastic pellets of a uniform size. The pellets are put back into manufacturing battery cases and the process begins again.


Lead grids, lead oxide and other lead parts are cleaned and heated within smelting furnaces. The molten melted lead is then poured into ingot moulds. After a few minutes, the impurities float to the top of the still molten lead in the ingot moulds. These impurities are scraped away and the ingots are left to cool. When the ingots are cool, they’re removed from the moulds and sent to battery manufacturers, where they’re re-melted and used in the production of new batteries.

Sulphuric Acid

Old battery acid can be handled in two ways:

1. The acid is neutralised with an industrial compound similar to household baking soda. Neutralisation turns the acid into water. The water is then treated, cleaned, tested in a waste water treatment plant to be sure it meets clean water standards.

2. The acid is processed and converted to sodium sulphate, an odourless white powder that’s used in laundry detergent, glass and textile manufacturing.

Lead acid batteries are closed-loop recycled, meaning each part the the old batteries is recycled into a new battery. It is estimated that 98 percent of all lead acid batteries are recycled.

This Lithium-Ion battery is from a 2014 Chevrolet Spark EV prototype

Lithium Ion

Lithium-ion batteries and lithium iron phosphate (LiFePO4) batteries often contain among other useful metals high-grade copper and aluminium in addition to – depending on the active material – transition metals cobalt and nickel as well as rare earths. To prevent a future shortage of cobalt, nickel, and lithium and to enable a sustainable life cycle of these technologies, recycling processes for lithium batteries are needed.

These processes have to regain not only cobalt, nickel, copper, and aluminium from spent battery cells, but also a significant share of lithium. Other potentially valuable and recoverable materials are graphite and manganese. Recycling processes today recover approximately 25- to 96 percent of the materials of a lithium-ion battery cell, depending on the separation technology.

In order to achieve this goal, several steps are combined into complex process chains, especially considering the task to recover high rates of valuable materials with regard to involved safety issues.

These steps are:

Deactivation or discharging of the battery (especially in case of batteries from electric vehicles)

Disassembly of battery systems (especially in case of batteries from electric vehicles)

Mechanical processes (including crushing, sorting, and sieving processes)

Electrolyte recovery

Hydrometallurgical processes

Pyrometallurgical processes

Specific dangers associated with lithium-ion battery recycling processes are: electrical dangers, chemical dangers, burning reactions, and their potential interactions. A complicating factor is the water sensitivity: lithium hexafluorophosphate, a possible electrolyte material, will react with water to form hydrofluoric acid; cells are often immersed in a solvent to prevent this. Once removed, the jelly rolls are separated and the materials removed by ultrasonic agitation, leaving the electrodes ready for melting down and recycling.

Pouch cells are particularly easier to recycle in this way and some people already do this to salvage the copper despite the safety issues.

As of 2019, the recycling of Li-Ion batteries in most cases does not extract lithium since lithium-ion battery technology continuously changes and processes to recycle these batteries can thus be outdated in a couple of years.

Another reason why it isn't being done on a large scale is because the extraction of lithium from old batteries is five times more expensive than mined lithium. However, it is already being done on a small scale (by some companies), an industry in expectation of large quantities of disused batteries to come.

Energy saving and effective recycling solutions for lithium-ion batteries can reduce the carbon footprint of the production of lithium-ion batteries significantly.

Five and a half workshop hacks you may be able to use


1) Ad-hoc Micrometer

Measuring diameters can be difficult. Sure, it works OK to just measure the end, but if you need accuracy, here's another method.

Take apart one of your combination squares and slide the head to another square so that the straight edges are facing each other.

Set one of the square heads at an even measurement and then slide the other head until both are touching the part you're measuring. Read the measurement right off the ruler.

2) Magnetic Broom

When you spill screws, nuts, washers or other small metal parts on a dusty shop floor, pick them up in seconds, minus the dust.

Screw a 3-in. dia. pot magnet on the end of a wooden dowel to create your 'picker-upper.'

To use this tool, place an inside-out sandwich bag over the magnet and start sweeping the area.

The hardware will leap up to the powerful magnet as you 'sweep' the floor. To unload and bag the metal pieces in one quick step, just pull the bag off the magnet.

3) Pie Plate Dustpan

Create a quick disposable dustpan out of an aluminium pie plate. Use tin snips or heavy-duty scissors to cut the pie plate in half.

Sweep up the mess and toss it in the trash.

4)  Stay-put pvc pipe cutter

Should work with metal tubing too.

Here's a nifty way to cut PVC pipe on the fly. Just make a couple of notches in the top of a 5-gallon bucket.

Set the pipe in the notches and you've got a stable spot for sawing. As a bonus, you can load up the bucket and carry your tools along, too.

5) Is your Square actually square?

Follow these simple steps for ensuring that your square is square: Align the short side of the square with the factory edge of a piece of plywood.

Draw a line along the edge of the long side of the square. Flip over the tool and align the base of the mark with the same edge of the long side of the square.

Draw another line. If the marks do not align perfectly, the square is not square.

5½) How to Fix a Square

Before tossing your off-kilter square and spending money on a new one, try fixing it with this simple process.

Use a centre punch, a hammer and an anvil. If the sides of the square are too close together, punch the inner corner.

If the sides are too far apart, punch the outer corner. Check your progress, and repeat as needed until the square is square.

Doesn't always work, but it if it does, it could save you some time and money.

3D print hard-to-get parts

Could 3D printing really help keep your vintage car on the road?

Hagerty, 30 March 2020

Fabrication techniques had been relatively stagnant for many years until 3D printing came along. The technology has advanced quickly, and now the home fabricator can reasonably use plastic 3D printing to make templates and parts for their own projects. If you are still fuzzy on how this tech could help you with your car, Davin and Matt take a deep dive into just how they’ve made parts for a few of our Redline Rebuild projects.

The concept of 3D printing is sometimes hard to grasp since it is the polar opposite of machining. Rather than starting with a large chunk of material and removing material until it reaches the desired size, it starts with nothing and creates the piece by stacking material up. This technique has its limitations, but solutions have been ironed out to overcome most of those hurdles.

To show the process from start to finish, Davin and Matt talk through their latest venture of creating a spacer to mount an additional pulley to the front of a 1951 Buick straight-eight crankshaft balancer. The rivets holding the balancer together complicated the issue of simply bolting on a new pulley, and rather than clearance the new pulley to fit around those rivets, Davin elected to go with a spacer to give the clearance required.

He designed the spacer in a simple CAD program and then shipped the file over to Matt, who rendered it into a file that his 3D printer could work with. From there the machine took over and artfully melted strands of PLA material into a form that Davin could use to confirm his part would work as he desired.

This method of prototyping saves a significant amount of machine time—especially if the design does not work perfectly the first time, as this situation did for Davin. The design can be easily modified and reprinted with minimal investment and tooling cost. In an era when it is tough to get machinists to take on small projects like this, and when labor rates can be upwards of $80 an hour, this prototyping can keep you in good standing with your machinist.

Davin and Matt talk through the whole process in great detail, and if you are curious about how this technology is going to change the landscape of fabrication, you should absolutely give this livestream a watch from beginning to end.

Heads-up: It is 1 hr and 5 minutes long. Because they waffle a lot.

Keep your shock absorbers in good order

Signs of worn shock absorbers

By rmieditor on January 30, 2020

Shock absorbers are designed to assist the driver in maintaining control of the car by keeping the tyres on the ground. Bad or worn out shocks will make your ride uncomfortable and to some extent unsafe, hence, it is recommended that you regularly service your car and ensure it is properly maintained.

“Signs of worn out shock absorbers include your car veering to one side, uneven tyre wear, delayed stopping when braking, excessive bouncing while driving, and leaking fluid,” explains Barend Smit, Marketing Director of MotorHappy.

Worn or leaking shocks can lead to unsteadiness on the road, like veering to the side or sliding in high winds. You might also hear unusual noises like metal-to-metal and a knocking sound coming from the rear or front wheels.

If the tread on your tyre is uneven it’s an indication that your tyres are not firmly on the road, a sure sign of worn shock absorbers. If you leave this unattended, you have a greater chance of hydroplaning in wet weather and could also more easily get a flat tyre. A slight vibration from the steering wheel and too much bouncing as you drive over a speed bump are both possible signs of worn out shocks.

The broken seals on the shocks could also result in brake fluid leaks. “If your shock absorbers need to be replaced, you will find that your car takes longer to come to a stop when braking,” Smit points out. “The braking distance could be increased by up to 20% which could mean the difference between a safe stop and an accident.”

Keeping your shock absorbers, and all other mechanical parts of your car, in good working order is essential for road safety and the longevity of your car.”

What are the rules for running-in a reconditioned engine when there are no rules?

How to break in a rebuilt engine

By rmieditor on March 26, 2020

What process do you use, when there isn’t a process for breaking in a rebuilt engine?

One process that is often missing from Original Engine Manufacturer’s service publications is how to correctly break in a rebuilt engine, especially without the use of a dynamometer or load bank. Dynamometer or load bank testing are the preferred methods, but realistically it is not always an option. Regardless, breaking in the engine is critical.

If this is not done correctly or completely, then the engine will most likely perform poorly, smoke, and consume oil. Often these symptoms are irreversible over time. The term, ‘breaking in’ an engine refers to the process where combustion temperatures and operating conditions force the rings and cylinder bores to conform to each other sealing the combustion gasses within the cylinders. Idling will not produce the temperatures and forces needed.

Piston rings are designed to apply a certain amount of tangential force outward by themselves, but compression rings rely on greater combustion pressures to force them down against the bottom of the piston ring lands and outward to the cylinder wall. Without this combustion force, these rings may not seat or seal properly.

Oil control rings regulate the amount of oil film left on the cylinder wall to lubricate the compression (top and intermediate) rings, and each compression ring removes some amount of this oil film resulting in proper oil control. It is important that an adequate load be put on the engine to create enough combustion pressure and temperatures to seat the rings. This is most critical within the first few hours of the engine’s new service life. Idling, increasing the RPM, and hauling light loads may not create enough combustion pressure or heat to seat new rings. Under load, you can obtain the pressure and temperatures needed.

Idle time and low load on a freshly rebuilt engine can result in “glazing” of the cylinder walls and prevent the rings from ever sealing correctly. “Glazing” is a condition where hard oil and fuel deposit build-up on the cylinder walls and prevent the rings from sealing properly. Once glazing forms, it can be difficult, if not impossible to remove without disassembling the engine. The ‘old-timers’ reading this are already thinking —“Bon Ami it.” Bon Ami household cleaner was available at their local grocery or hardware stores and was their substitute for Caterpillar’s 7F5225 ‘Break-in Powder’ (other manufacturers possibly offered something similar). Caterpillar’s serviceman’s reference guides gave the instructions for using their 7F5225 powder.

That’s not to say that these miracle powders didn’t have major side effects. Intentionally introducing abrasives into an engine sounds like fingernails on a chalkboard, as well as outdated. With the tighter tolerances, precise surface finishes, and coatings you can only imagine the amount of damage this can do to today’s engines. There is no piston ring manufacturer who would ever suggest using such products for any of the current modern-day engines!

Once an engine is up to temperature and there are no leaks, rebuilders tend to have their own methods for break-in.

These can range from:

“drive it like you stole it”

“run up to the speed limit as fast as possible, and then while still in gear, let off the throttle and let it coast to the stop—repeat as often as needed”

“use the heaviest trailer and steepest hill you can find and drive up it.”

These individuals can be secretive about the processes they’ve worked out from years of experience, but what they have in common is they focus on getting approximately 75% of full load on the engine for three to four hours and keeping idle time to a minimum produces the results they are looking for to seat the rings.

Outside of the operational processes, there are several break-in oils and additives on the market. These need to be considered with some degree of caution since many can only remain in the engine for a set number of hours, and most original engine manufacturers do not approve them. However, much like the individual break-in processes, some rebuilders use them faithfully, and others don’t like them at all.

The focus of this article is not to say every engine must be dyno tested, or that one process or fluid is better than the other. The purpose is to bring attention to a critical part of the entire rebuild process. Consult with your rebuilder, or original engine manufacturers publications (if available) about their recommended break-in procedures and service intervals. The first oil samples on freshly rebuilt engines tend to be high in metals, so they may recommend the oil be changed after a shorter number of hours or miles.

What happens to a freshly rebuilt engine after it is picked up at the shop or driven off the lot can determine how satisfied you are with the service life of the engine.

Written by Steve Scott for Engine Professional.

Tips on cleaning and sanitising your car's interior. Copy and paste this URL into your browser: https://www.roadandtrack.com/car-culture/buying-maintenance/a31900626/how-to-disinfect-your-car-interior/

Keeping your vehicle from overheating requires regular maintenance

How to Flush Your Radiator and Cooling System

Keeping your vehicle from overheating requires regular maintenance of your cooling system. This will extend the life of your vehicle and prevent roadside emergencies.

By Mike Allen, Popular Mechanics, Dec 11, 2019

You take off the cap and look at the coolant. It's a nice shade of green, or maybe red, or maybe even orange. It looks good. Should you leave it in? Unless it's coluored orange, the answer is no, especially if it's been two years or more since the last time you drained it.

Today's engines are loaded with aluminium components: cylinder heads, water pumps, manifolds, even engine blocks. And the two primary heat exchangers–radiator and heater–are also aluminium. Aluminium needs great corrosion protection to survive, and the corrosion protection in green and red antifreeze is used up in about two years. Orange offers longer life, but if your car came with green or red, you can't switch to orange without a fair amount of preparation. And if your car is much more than four years old, a switch is not likely to yield long-term coolant life–you'd still face the usual 2-year drain interval.

Drain the Coolant

First, let's do a proper job of draining the coolant. Start by checking the specs to see how much is in the system. This is important, because capacities vary all over the lot. Some Toyota Fours and V6s, for example, hold only about 5 1/2 quarts (5.2 litres). Other systems hold 14 to 18 quarts (13.25 to 17 litres). This way, you'll know what percentage of the coolant drains out.

Start with a cool engine.

If the pressure cap is on the engine or radiator, look at the overflow reservoir, and if it's easy to disconnect and empty, go ahead. Then, remove the radiator cap and open the radiator drain cock. If the drain cock is in tight quarters, use a special socket available at most auto parts stores.

Let the coolant drain into a pan. Unless your town has a coolant collection setup, pour the old antifreeze into a household drain, clothes-washer pipe or a toilet. That's an environmentally safe approach. Don't pour it on the ground or into a storm sewer. If your car has a copper radiator or heater core, the coolant is contaminated with lead solder. Many municipalities have hazardous-waste disposal facilities that will take it.

Next, move the dashboard temperature lever to hot, so if your car happens to have a heater coolant control valve, it will open. If the pressure cap is on the plastic reservoir, remove the cap, then open the drain cock. No radiator drain cock? Disconnect the lower radiator hose from the radiator. Move the hose clamp back from the radiator neck, slip a thin screwdriver between the hose end and radiator neck to free up the hose, then twist slightly to disconnect the hose.

Draining the radiator alone should normally remove 40 to 45 percent of the coolant. After the first drain, fill the system as well as you can with water, then warm up the engine and let it cool. Drain the radiator again and fill it once more with water. Repeat.

Bleed the System

Now comes the hard part; filling the system. If the system holds 12 quarts (11.36 litres), you want to install 6 quarts (5.7 litres) of undiluted antifreeze, or exactly half of the cooling system's capacity.

The cooling system has lots of nooks and crannies that trap air, making it difficult to fill the system with coolant. The filler cap and neck are supposed to be at the high point of the system to help air bleed out, but often they aren't. And even if they are, you need all the natural help you can get. So jack up the front of the car, which gets the coolant filler neck as high as possible.

Check for air bleeds on the engine.

Sometimes you'll see an obvious air bleed, such as a boltlike item threaded into a hose. If there's an air bleed, open it. If there are several, open them all. If you have access to a factory service manual or PM CD-ROM for your car, check it for a coolant fill procedure.

Slowly pour in the required amount of antifreeze until you see coolant oozing out of the open air bleeds. Then close the bleeds and top-off the system with the remaining antifreeze and then plain water.

If the system has a heater coolant valve, close it by moving the temperature control lever or knob to cold. With the engine running at fast idle and warmed up, have a helper move the lever or knob to hot while you listen at the coolant valve. If after the first rush of coolant you hear a continuous gurgling noise, there's still air in the coolant, and you should be prepared to watch the coolant level in the reservoir over the next few weeks.

Pick the Antifreeze

Most antifreeze is made with a base chemical called ethylene glycol. Green dye is used in most brands, except Toyota, which uses red. Extended-life antifreezes, also with green dye, were on the market until two years ago. But the newest entry is a superlong-life antifreeze with a totally new rust/corrosion inhibitor developed originally for heavy-duty use (such as trucks). The original, from Texaco (used as original equipment by GM), is called Dex-Cool. The latest is Prestone Long Life 5/100. These two are orange.

The rust/corrosion inhibitors vary, but if antifreeze is green, assume that its life in a car with a lot of aluminium components is two years or 30,000 miles – whichever comes first. You can push that to a third year if the engine is all cast-iron. "Toyota Red" is a specific formula, but if you drain it, you can replace it with any known name-brand formula. Here again, the replacement interval is two years or 30,000 miles.

The inhibitors in orange antifreeze are not chemically compatible with what's in green or red. However, if you have at least 5000 miles on the green, the chemical bond with the aluminium components is "solid." So if you want to get extended life with a coolant installation, just do a thorough drain-by-dilution, at least three times. The coolant you drain out should be virtually clear, like the colour of water. If it's still green, you have to repeat the process until it's all out.

With the radiator and reservoir drained, pour in the amount of antifreeze necessary–there should be plenty of room – and then top up with water. Follow the procedures we've discussed to ensure a full system.

What about "pet-friendly" or "safer" antifreezes made with a base of propylene glycol? The name brands will do the same job as ethylene glycol. But they cost a little more and actually require a greater quantity to provide the same freeze protection, and in truth, they're only a bit less hazardous.

They aren't sweet, and consequently aren't as likely to be consumed by toddlers or pets. Don't rely on this, however. Store all unused coolant, low-tox or not, safely. Dispose of all drained coolant in a sanitary sewer and sweep up or rinse away any spillage.

A coolant pump, or water pump, circulates the antifreeze and water mixture between the engine and the radiator. After the coolant circulates through the engine, the pump pushes it out the upper radiator hose into the radiator, a heat exchanger made of metal tubes (aluminium on today's cars) to which fins are attached. The fins draw away heat and dissipate it to the air that is drawn through the radiator by fans and the forward motion of the car. The cooled coolant is drawn from the radiator through the lower radiator hose and back into the engine by the pump, and the cycle starts all over again.

When the engine is cold, coolant circulates only within the engine, so engine heat warms it up faster. At about 195 degrees F (90 degrees C), the coolant heats a temperature-sensitive valve (the thermostat) that opens to allow the coolant to flow through the radiator. The thermostat may be located at the engine outlet, in line with the upper radiator hose, or at the inlet to the water pump (the preferred location on today's cars).

The coolant also flows through hoses into and out of the heater, which, like a miniature radiator, gives up its heat to the surrounding air. In this case, however, the heated air is blown into the passenger compartment.

Raising the cooling system's pressure also raises the coolant's boiling point, so the radiator cap (which also could be on the engine or on the separate reservoir) has a pressure valve to raise the pressure in the cooling system by about 15 psi (1.03 bar). This increases the boiling point of the coolant by about 40 degrees F (4.5 deg. C). So, the boiling point of a 50/50 mix of antifreeze and water in a properly functioning system is about 130 degrees C or higher.

Body repair DIY

Five tips for avoiding body filler repair disaster

by Mike Bumbeck, Hagerty, January 20, 2020

The miraculous blend of polyester resins and cream hardener known as Bondo (a US brand of body filler - ed) can make wavy panels straight and door dings disappear. It can hide a welding seam in seconds but Bondo in the hands of those with calamitous intentions can result in a restoration nightmare.

Along with Band-Aid and Jell-O, Bondo entered the English lexicon with both positive and negative meanings. A well-placed Band-Aid on a minor wound can help prevent infection but a Band-Aid solution means a haphazard repair representing a merely temporary fix. Bondo has a similarly two-sided identity.

Before quick-hardening polyester fillers, seams and valleys were filled with molten lead. Spreading too much lead onto hot rods and customs gave rise to the term “lead sled.” Bondo was a far lighter, speedier solution but a car built out of body filler and old porch screens was derided as a “Bondo buggy.”

Decades of trial and error, along with a few years as a card-carrying member of the set painters’ union, place my experience somewhere in the middle. Follow along for a list of my five Bondo tips and tricks — a guide which, we can only hope, promotes the use of Bondo for the greater good.

A brief qualification: Bondo is a registered trademark of 3M and just one of the myriad brands and types of polyester body fillers. And as much as we appreciate Evercoat Tiger Hair for its tenacious blend of fiberglass strands and super tough resins, one can of regular weight Bondo and one can of lightweight Bondo Gold were used in this five-part journey from rust to repair.

Tools and supplies

Here’s what you’ll need for your Bondo battle kit:

Bondo or your favorite polyester body filler

Mixing board


Putty Knife

Razorblade scraper

Surform or rasp



Disposable gloves

Dust mask

Eye protection

Mixing sticks

Contour gauge

Metal Prep Etch Primer

Prepare for the worst

Find out what’s going on under the paint. The Bondo discovery process rarely goes as planned. A recently tackled door panel looked reasonable but was, not surprisingly, a giant mess. Quick work with a grinder revealed multiple layers of paint, old Bondo, and rust. The goal was to get down to the metal, take a measure, and scuff the repair area back out to 60–80 grit. I found a few low spots with a contour gauge, so out came the pin welder. Anything deeper than 1/4-inch needs fixing, since thick Bondo shrinks over time.

The next question: to prime or not to prime? One school of thought suggests bare metal, then Bondo. The other says primer, then Bondo. Avoid endless forum threads and consult the manufacturer for the definitive answer. There was a uniform layer of rust underneath the old Bondo on this particular door panel so, in this case, it was primer first, Bondo second. Any bare metal was treated with a phosphoric acid metal prep followed by an etch primer.

Sir Mix-a-lot

Gather up the Bondo, spreaders, putty knife, mixing board, the Surform or rasp, and acetone for clean up. A piece of scrap steel works excellent as a mixing board, but don’t use anything porous or absorbent. Disposable gloves are highly recommended.

Plan ahead.

Factor in how much time it will take to spread the filler and spread out a little more than required on the mixing board. Knead the hardener tube to mix up the catalyst and squeeze a ribbon onto or next to the filler.

Hardener and ambient temperature determine cure time. Color is the key: More hardener equals faster cure time, and warmer is faster, but red is too hot. Shoot for that Band-Aid color to prevent a Band-Aid fix.

Fold, but do not stir, the mixture together with the putty knife until the color is uniform. (Stirring introduces unwanted air into the mix.)

Skim and carve

The curing process starts immediately, so load up the spreader and get to work. Multiple thin coats are better than a thick swath. Spread the filler on the repair slightly higher than the depression or contour, and don’t worry about ridges or high spots. First time out? Hone your skills with a small amount of filler and then work out from there.

Stop before the mix hardens. Clean the Bondo off the spreader and mixing board as soon as it gets rubbery and roll it into a ball. Get the rasp or Surform ready and pay attention to the temperature of the ball. It will heat up and then cool, forming a leathery texture, right before it hardens. Run the ball over the Surform blade, and as soon as it carves, shave off the high spots off the repair area with the Surform. This eliminates tons of sanding and giant dust clouds.

Cut and sand

Once the Bondo cures, it’s time to sand. Power sanders are OK to break the surface and knock down any high spots, but hand sanding with the body contour is the best way forward. Cut in with heavier grit sandpaper and work out to about 80 grit to leave a tooth for the following skim coats. Make long sweeps for sanding over the repair.

Run your hand over the repair and feel for depressions or high spots; anything you can feel as wavy will translate through the paint. The lightweight Bondo Gold is far easier to sand than the heavier type, so consider using the good stuff on the way out. Use a tack cloth to remove any dust between coats.

Do it all again

Repeat the clean, mix, spread, carve and sand routine until the repair is flat. Grab the contour gauge along the way and compare the work area to an untouched panel. Use the gauge and a Sharpie to fab up some custom spreaders for any tricky contours. A guide coat can reveal otherwise-hidden low spots. The idea is to spray an extremely light mist of paint on the repair and then block-sand by hand. Any painted areas left behind are low spots.

Guide coat paint isn’t super pricey but a can of quick-dry flat black works in a pinch. No spots? Success! Sand off any leftover guide coat, cue "The Final Countdown" by Europe, and skim in the last coat of Bondo for victory.

See the original article here: https://www.hagerty.com/articles-videos/articles/2020/01/20/tips-for-avoiding-bondo-repair-disaster/

Don't buy an expensive new workshop vice; restore a classic instead

Buy an Old Vice and Bring It Back From the Dead

Everybody needs a machinists' vice and there are plenty of shiny new and expensive ones you could buy. Fortunately, there are also lots of good, "retired" vices available at flea markets, on eBay and at garage sales; just waiting to be bought and restored.

By Roy Berendsohn, Popular Mechanics Pro on Jan 3, 2019

The Tool: Machinist Vice

Why You Want One: A vice is handy for all manner of repairs and projects. Mounted on your workbench, it holds metal firmly in position while you cut it, grind it, file it, or cut threads in it or on it.

Why Buy a Rescue: Old American-made vices and other tools are astonishingly high quality. Workmanship and materials that are considered extraordinary today were standard from the 1930s all the way through the '70s. Then the cost-cutting wrecking ball swung through this society and we’ve been the worse for it ever since. And there’s DIY satisfaction in finding an abused, abandoned piece of iron and saving it.

How to Find a Used One: First, don’t overpay. You can get a perfectly good vice for anywhere from $10 to $50 at flea markets and on eBay, depending on size and age. The vice should preferably have a swivelling base, its handle should be reasonably straight, and it should be plainly visible that it hasn’t been abused.

A chipped anvil, vice jaws that are misaligned, bent handles and a thick coating of rust are all indicators that this is a product you should pass over. On the other hand, there’s lots of good iron out there, as multiple eBay posts attest.

I came upon the Columbian vice here late one afternoon at a flea market in New Jersey. It was sitting on a pile of rusty junk that the owner was about to load back in his van. He wanted $10. I gave him $5. It looked to me to be a late 1950s or early '60s model at the oldest. It swivels nicely and has a grip like a Gila monster.

What You'll Need: Some standard hand tools and materials are all that you need to restore an old vice. In terms of time, total cleanup, disassembly, painting, and reassembly took about an hour and a half. If I wanted it to be pristine, I would have spent twice that amount of time.

The Steps

Step 1: Put the vice on a work surface and wipe off, brush off, and vacuum it so that it’s relatively clean. That gives you the starting point.

Step 2: Disassemble the vice from its base and its jaws from one another. Use a wire brush and a sanding sponge to remove flaking paint, rust, and caked-on dirt. Vacuum away debris created by wire brushing. The last step is to soak a shop cloth with denatured alcohol and wipe everything clean. The cleaned parts are ready for masking tape.

More after the break

Stripped and cleaned

Step 3: Apply masking tape to all parts that you don’t want primed and painted.

Step 4: A good choice to coat both the bare metal surfaces and those with residual paint is an automotive product, self-etching primer; we used Rust-Oleum’s paint (part 249322). Put the vice parts down on a sheet of cardboard or a drop cloth and make long sweeping passes. Apply two coats. Be sure that undercut areas are also evenly coated. Rust-Oleum’s paint allows you to spray even with the can held upside down, which aids in painting undercut areas.

Step 5: When the primer is dry (which depends on temperature and humidity) make two to three applications of the top-coat enamel.

Note: It’s extremely important when selecting the primer and top-coat paints that they work together as a system. In almost all cases you want both to be from the same manufacturer and of the same or compatible chemistry. In this case both the self-etching primer and the enamel top coat are modified alkyds. These are paints in which the resins (the glue that holds the pigment particles together and also holds it to the surface) are a form of polyester plastic made from alcohol and acids. Alkyd paints (both spray and brush-applied) are tough and chemically resistant. They are easy for professionals and non-painters to apply.

Lubricate the vice screw and all threaded parts with a mid-weight machine oil or light grease. Reassemble the parts. When you’re done, the vice should look good as new.

Bolt it to a workbench, and you're good to go.

The key to long life of your VGT turbo basically boils down to proper maintenance

Turbochargers – A common variable

By RMI Admin on July 18, 2019 

When and why did turbochargers become so complicated? First, pressure controlled wastegates, then solenoids that control vacuum to a diaphragm. Now, electronic actuators and hydraulic solenoids control complex internal mechanisms within the turbine housing to vary the air ratio.

The variable turbo concept has actually been around a long time and has been used in small automotive gas and diesel engines for years. The actual purpose and function of them really is quite ingenious and contrary to popular belief, they are not as troublesome as they are made out to be.

There are several different designs of variable turbine technology, but all are using the same concept. A standard turbo without so much as a waste-gate can only provide boost to the engine in a direct correlation to the amount of exhaust the engine produces. The more exhaust pressure and heat, the faster the turbine wheel is driven and the more boost produced. This limits how much performance can be achieved from the turbo.

The smaller the turbo the faster it will spool up and provide boost. The downfall is that a small turbo reaches its choke point at a lower flow. This means that there is a point at which the pressure coming into the turbine housing exceeds the capability of the housing and wheel to exhaust. If the engine is still accelerating at the choke point, the turbo will become an exhaust restriction and rob the engine of power.

By moving to a larger turbo, more air can be moved. The downfall to a large turbine size is the increase in the amount of energy needed to get the turbo up to speed to begin providing boost. This delay in boost is known as lag. Manufacturers have struggled for years walking that tight-rope between lag and restricting the engine's volumetric efficiency.

The waste-gate was one of the first forms of variable geometry. Its essential function was to allow a turbine housing to have a decreased size allowing for higher exhaust speed at lower RPM’s. Once the exhaust pressure neared the choke point, the waste-gate would open and allow exhaust an additional path to atmosphere thus lowering the exhaust pressure.

Essentially you have two different air ratios within one turbocharger. The waste-gate is typically controlled by a solenoid, or by using the boost pressure created to operate a spring loaded diaphragm.

This was the first step at making mid-sized engines both economical and able to perform both low engine RPM’s for city driving and at highway speeds.

A variable geometry turbocharger, or variable nozzle depending on manufacturer, is exceptional in that it basically acts as if it were several different sizes of turbocharger throughout the RPM range of the engine. By simply changing the velocity of the air across the turbine wheel, the turbo is capable of producing boost while the engine is running at low RPM.

Opening the VGT mechanism reduces the back pressure and allows the turbine housing to flow sufficient air for the volumetric efficiency of the engine. The ability to control boost, independent of engine speed and exhaust energy, has revolutionised the light duty diesel pickup industry. Horsepower ratings are climbing faster and torque curves are widening.

Variable turbochargers do however have a challenge that will make them more susceptible to failures than previous styles. What’s that problem? Moving parts.

Imagine having anywhere from five to 25 moving parts in the worst possible environment imaginable. The temperatures ranging from ambient to 1300°F, condensation from heat cycles causing rust, leaky EGR coolers depositing sticky coolant and additives, and the never-ending enemy soot. The VGT mechanism is constantly battling contaminants that seem to want nothing but its demise.

On a properly running engine, the chances are you can expect a long trouble free life from your turbo. Problems begin to arise, however, when you factor in things as simple as driving habits. The addition of EGR to the diesel engine is the equivalent of “diesel cholesterol” as it deposits unburnt fuel and soot into the turbo and back into the intake manifold.

Exhaust gases are recirculated back into the engine through the intake at light load conditions. As the gas passes through the EGR valve, EGR cooler, and intake, particulate matter from combustion is carried with the gas and deposited along the way.

These particulate deposits begin to cause performance problems. These deposits can create intake restrictions by clogging the intake, EGR valve malfunction by restricting movement, and deposit soot into your VGT components causing them to seize or react slowly.

These issues then actually cause more particulate creation and deposits and the problem worsens exponentially.

The key to long life of your VGT turbo basically boils down to ensuring proper maintenance of your engine and addressing any issues with engine performance as they arise. The majority of all VGT failures can be prevented and allow you to enjoy that boost performance from idle to wide open throttle, just the way it’s intended.

Source: Engine Professional magazine


We rebuild classic and vintage automotive components ensuring that not only do they work as new, but usually better than new. We also give you finishes from “as overhauled” through to the highest concours winning standards. The vast bulk of our work is done in-house, thus ensuring proper quality control and no loss of components. This includes welding, painting, most machining, electroplating, micro bead blasting, metal polishing.

Any outsourcing only goes to totally trustworthy sub-contractors where relationships have been established over many years. The business is owned and run by a highly qualified and experienced Mechanical Engineer, with most work carried out by him. He has decades of experience working on older vehicles having started in his early teens.


1) CARBURETTORS: Complete overhaul, including rebushing, micro welding of shafts etc. 

2) CARBURETTOR SPARES: Large stocks of new and used, especially SU and Weber.

3) DISTRIBUTORS: Complete overhaul.

4) ENGINES (Including specialised head development.)












16) COMPUTERISED GAS FLOW RIG (Design of manifolds, ports, branches etc, incl for best bottom and mid-range.)


18) SILVERWARE & EPNS ITEMS: Skilled repairs undertaken.

CONTACT: ROBIN PHIPSON on 076-5339219 or phipson@wandata.com.

6 Moss Place, Montrose, Pietermaritzburg, KZN.