VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Rear end problem

My 26 has been making a thumping noise since I first got it 18 months ago. At first we couldn't locate it. Recently it has become much louder and appears to be coming from the rear. Using a stethoscope I hear noise from the hub and also at the end of the torque tube about 6-8" back of the universal.

I replaced the speedometer gears in the transmission a few months back and the universal is in excellent condition. Besides, I would recognize a bad universal sound. Even using the stethoscope I hear no noise coming from the universal.

With the car on axle stands and in neutral I can spin one wheel and the opposite wheel does nothing. If I put it in gear I can spin one wheel and the other will go in the opposite direction.

Again, on axle stands, with the engine running and the car in gear the left rear wheel moves as it should while the right rear wheel moves in a jerky motion, as if it's missing a gear.

Any ideas? Suggestions? Critisicm for running it while on axle stands withstanding. :rolleyes:

Thanks in advance.

Does it make any noises synchronous to the jerky motion of the right wheel when on jackstands? Could the brake be grabbing on that wheel? The rest of what you said sounded normal for a differential.

One wheel jerking is nothing more than unevenly adjusted brakes, it being a bit tight on the jerking side. If that side spins by hand easily, maybe the other side is too slack. Testing the car on stands produces these effects because the drive goes to the wheel of least resistance such is the nature of a differential operation, and also is the reason one wheel will spin when in mud. Limit slip diffs many years later got over the problem.
The noise you hear just rear of the universal might be the source of your problem.
There is a bush here which is prone to wear because it gets precious little lubrication.
Remove the universal and see if the propeller shaft can be moved up and down. If so it is in need of attention, even if it proves to not be the source of the noise.
A thumping is hard to diagnose, but have you checked the obvious like collapsed wheel bearings.
Take the back cover off the diff banjo and look inside for anything adrift, often indicated by metal in the oil at draining. Lever the gears up and down with a screwdriver to check for any play.If there is any then you had better seek help from a differential expert. You will also see how the diff works if you turn one wheel slowly by hand while locking the other one with a chock. Louis Renault who invented it was indeed very clever.
Good luck.
Geoff.