The only thing lower than a centipede with fallen arches is the common wheel chock. It’s forgotten, or it’s in the way 99% of the time. Oh, but what a life saver it can be. You have a good parking brake on your antique, you say; what more do you need? Murphy says that by the time you need that parking brake, it may be well-greased, thanks to a hard day of driving and an axle seal that suddenly leaks. Besides that, old cars with planetary transmissions have no backup to the parking brake. If your car has a sliding gear transmission, putting it into reverse gear will aid a parking brake, but not enough in antique cars with low compression engines on anything but a modest grade. Carrying a spare tire - and no chocks - is folly. Jacking up one rear wheel makes transmission braking useless, and cuts parking brake strength in half.



Last year there was a Model T tour up a mountain in SoCalif. A ’26 pickup’s engine quit while going up a really steep part, so the passenger got out and found a rock to put behind a front wheel. The driver then got out, and right before their eyes, the wheel rolled up over the rock and the pickup charged back down the mountain, headed out over the cliff toward disaster hundreds of feet below. It was stopped by the only tree in the area. The tailgate was badly dented, and the owners were badly frightened.

Are wheel chocks required for the tours you’ve been on? Why not? Curiously, Greatrace requires flares, tow rope and turn signals, but not wheel chocks. We carried chocks through three coast-coast and four regional Greatraces anyhow, and used them on the road once or twice, for a flat tire.

Have you ever seen instructions for use of wheel chocks? Self-evident, right? When should you use a chock? What style is best? Which are unsafe? How many are needed? Which wheel(s) do you chock? There’s more to safely chocking a car than meets the eye.

Placing Chocks:

Most antique cars are nose heavy when empty, and tail heavy when laden with people or cargo. When on an incline, however, the car’s high center of gravity shifts the weight toward the lower end and/or lower side of the car; the steeper the incline, the more the weight shift. It’s more effective to put the chocks on the downhill side of the lowest wheels in most cases. Here’s from “Model T Ford” by Fahnestock:
Even this grossly tail-heavy car becomes nose-heavy.

When you’re on the level and need to jack up one wheel, chocking both sides of the far wheel is best. If you’re on a steep hill, you can use both chocks on the downhill side. This means two chocks should be carried at all times.

Size Does Matter:

A chock that will hold your car on the steepest hill you’ll ever see is needed. When you chock just one wheel, there are still three wheels trying to roll downhill, so bigger is indeed better. Four typical chocks, 4 1/4 inches tall, will hold a car with 30” wheels on a 40 degree slope. Two chocks will hold the same car on a 20 degree slope, and one chock can be expected to hold on just a ten degree slope. Being on a sloping shoulder makes the chock’s job even tougher.

Some modern cars come with chocks, but they may be marginal in design. This one was squished by the car being driven out of its chocks. These chocks are ok for use on level pavement, but would surely sink into dirt or a soft gravel shoulder – where you need it most. In that case, they could be turned upside down. These chocks are just 3½” tall, and not enough for a car with large wheels on anything but a modest slope.

What about using a 4x4 cut diagonally? You then have a 3½” tall ramp, and not a real chock. The wheel will just roll up the ramp, and maybe over the top. If the wheel rolls even a little bit up the chock after you begin jacking up another wheel, it can create mischief.

This is an airliner chock I bought on ebay and cut in half to make two. That makes it "almost good enough for a Model T." It's 5" wide and 4 1/2" tall, and solid rubber, so it won't skid easily. Although not easy to see in this picture, its contact point is at the top, for good chocking.

Although ugly plastic, these 4 1/4” tall chocks are readily available at truck stops and RV stores, and seem to be strong enough. Black paint disguises them a bit. These have the advantage of a full bottom face to hold on almost any surface. They are also light and smooth, which is important for stowage.

Chock on a Leash:

At the least, a tether should help you remember to remove the chock before driving away, and it will be useful to a solo driver. Here’s the ultimate:

1911 Motor Supply Co. catalog.

Ralph Ricks 22 May '04

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