1911 Ford Model T Restoration: Diffusing a bomb

Restoring a Model T is not an inherently dangerous activity. Sure, you should take the usual precautions like wearing safety glasses if grinding, wearing respirator if painting, using jack stands etc. However, you reallllly need to do be careful when disassembling the leaf springs.

Modern cars often use a combination of a coil spring and a shock absorber attached to each wheel to soak up the jolt you would otherwise get when driving over a pothole. The Model T, and other early cars, instead used a "leaf spring" consisting of several steel rectangular pieces stacked together. Basically it was a carryover from the horse wagons and buggies used before the car was invented. It is no surprise that the bodies for the early Fords and other auto makers came from buggy manufacturers.

If you ever had to take a physics class, you probably learned about springs. How much a spring deflects under a certain amount of load depends on the physical dimensions of the spring, and the spring material's physical characteristics. Leaf springs are sometimes preloaded and formed into an arch in order to provide the desired characteristics such as how high the car sits off the ground and how it handles while turning a corner.

The Model T springs uses a lot of preload and curvature; a lot. Not so much in the front axle spring as the rear. Restoring the springs requires taking them apart to strip and repaint the individual pieces. Taking them apart is like diffusing a bomb; something done with great care so that pieces don't go flying everywhere and hitting or hurting whatever is in its way.

This is the second time that I've taken T springs apart, so I was less nervous this time. I start with the front spring because they have less preload. The procedure for either spring is the same. I start by using at least two parallel clamps to hold the spring together. I then remove the pin holding the U shaped brackets toward each end that help the keep the leaf spring pieces stacked up correctly. Then I loosen the nut on the bolt at the center of the spring assembly and carefully loosen the parallel clamps until the loosened center bolt is under load again. I repeat the process until all the preload is removed. The picture below show the process, including how much preloading the spring was under. That was a lot of stored energy!

After painting but prior to reassembly, the individual pieces have a coat of "slip paint" applied to improve the sliding characteristics between the individual spring pieces. The process is reversed for assembling the springs. Reassembly is also less nerve wracking!