Driveshaft hits the floor?..........

[SShep71]

Im working on my 72 GTO and the ears of the drive shaft hit the floor . It does it under braking and turning, but not accelerating. It does it right at the transmissions, but the mount isnt broke. Its the stock crossmember,and a TCI 350. Any ideas?


P.S. Im still looking for a set of grills from a 71 GTO...

[paul67]

I would put a jack under the trans pan and see if it moves up off the crossmember when jacking it up , put a block of wood under so not to damage the oil pan, sounds like the bolts are loose or gone.

[JEFFTATE]

Check the crossmember bolts , and the u-joints.

Also , since it only does it under turning or braking , maybe something in the rear suspension is messed up and is allowing the rear axle housing to move around.
Thus , changing the driveshaft angle and causing driveline vibration and movement.

Maybe the motor mounts are broken and are allowing the powertarin to move around and twist.

Are you sure it's the driveshaft yoke ears and not the transmission hitting the floorboard because of a sagging floorboard ?

[streetk14]

My buddies 65 Malibu had the same problem. I think the cause was the motor mounts sagging which in turn made the tailshaft of the trans sit higher. We replaced the motor mounts with some poly Energy Suspension mounts and also changed the trans mount with a slightly shorter one. I can't remember if the rubber or poly one was shorter, but there was a difference and it stopped the rubbing problem.

I'd also look at your body bushings. If they are in really bad shape the body and tunnel are going to sit closer frame.

Andy

[SShep71]

I have new (rubber) motor mounts in, and the trans mount is new too. Its rubber too, im gonna check if I can get a shorter trans mount. The body bushing dont look too bad,

[streetk14]

I have new (rubber) motor mounts in, and the trans mount is new too. Its rubber too, im gonna check if I can get a shorter trans mount. The body bushing dont look too bad,


It could be something in the rear suspension. My buddies car was fixed by what I described, but maybe what we did was just enough to stop the rub but not really the root of the problem. Same thing though, it hit under braking. Hope ya get it figured out.

Andy