Re: Ken's 1937 120 Touring Sedan

Posted by TxGoat On 2023/4/19 18:37:46

Even slight looseness of the U-bolts that hold the axle to the springs could cause a clunk on takeoff.

Stopping the car with the brakes makes the axle try to roll with the wheels, which would take up any slight looseness and allow the axle to move to the limit of any small amount of travel the u bolt looseness would permit.

It would not have to be much, and the u-bolts would not need to be sloppy loose to allow the slight movement, since the forces involved are significant. Friction would probably keep the axle at the forward rotated position until you put the car in gear and began to release the clutch to move forward. This action makes the axle houing attempt to rotate backward, which could cause the axle to slip back to its normal position, or a little beyond, making a thump or clunk sound. Even a very small movement could cause the noise. The cure would be to clean everything up and torque the u- bolt nuts to spec, taking care to pull them up evenly. Make sure that all related parts are not bent or worn, and that the u-bolt nuts aren't bottoming out before they are actually holding the axle and hardware securely. Some cars had rubber or leather pads between the spring pads on the axle housing and the springs. If those are flattened, rotted or missing, they may have to be replaced for the hardware to tighten properly and hold the axle housing correctly. Be sure the shock bodies are tightly bolted to the frame, too. If one is a little loose, it could cause a clunk.