WHEN M35s ATTACK

When I jacked up the front of my 1963 M35, the wheel suddenly spun and removed some skin off my lower jaw. This was painful but it could have been worse. Do you have any idea why this happened? The engine wasn’t running and the transmission was in neutral.

—Leo Pagnini

M35s with Sprag type transfer cases were prone to what was called “sprag clutch windup.” Basically, tension built up between the front and rear axles. This was often caused by letting the truck roll backward by stepping on the clutch while still in a forward gear on a slope. It can also be caused by not coming to a full stop when shifting from reverse to first gear. In extreme cases this windup can damage the transfer case and/or other drive line components.

Early M35s with sprag type of transfer cases should be checked occasionally for windup by jacking one of the front wheels off the ground...but expect it to suddenly spin, and stay clear. Even if the wheel doesn’t spin, one can check for windup by putting the transmission in reverse (engine off) and trying to turn a front wheel by hand. It should turn backward easily, but should not turn forward. Then shift to first gear: the wheel should forward but not backward. If your M35 fails these tests, you may have serious transfer case problems and the truck should not be driven until the trouble is diagnosed and fixed.