Shake, Rattle, and Shake, Rattle Some More

[Bib_Overalls]

Friend is working on a Ford F1 pickup with a SBC, TH-350, Camero clip and Chevy 10 bolt rear riding on Camero springs.

It starts shaking at 34 mph and really gets serious about it around 58 mph.

Before you say drive shaft:

Two different shops have tried to fix the problem.

The truck has had three custom made and balanced drive shafts.

The pinion angle has been checked and adjusted and it is right on.

The transmission and torque converter have been changed.

The axles have been swapped out (not the housing or third member).

Several sets of balanced wheels and tires have been tried.

None of this did any good.

Today, the truck was towed with the drive shaft out and the front wheels elevated off the road.  It started shaking at 35 mph and was really getting it on at 58 mph.  

This afternoon my friend was swapping out the entire third member.  If this does not work he is going to get 5 gallons of gas and a Bic lighter.

Actually, this was supposed to be a quick fix for a good customer and the job has gone on so long it can not be reasonably billed at the shop's hourly rate.

Does anyone have any idea what the problem could be?

[donsrods]

I think you have found your problem. Smart way to do it, you have eliminated every potential source, the only thing it could be is the rear axle assembly or the wheels and tires mounted to it. It is the only component that could possibly be causing trouble, as everything else was just sitting there.

Stuff like this will drive you nuts.

One thought, maybe in the life of the 10 bolt the car was hit hard, tweaking the rear end. Don't even think about it, just get that whole assembly out of there.

[Uncle Bob]

Axle tubes tight in the center section?