Rear end scoot

I am driving a '74 TR6 that I recently finished a complete frame off restoration on.I am having a curious problem that occurs intermittently.As I accelerate and change gears from first to second,and occasionally from second to third,the rear end of the car feels like it "scoots" or slides to the right.The car has new springs,shocks,bushings,etc.Everything back there is new or reconditioned and all the original equipment was used in the restoration.It is the weirdest feeling.I have checked all the fittings to be sure everything is tight and all appears fine.The differential mount studs were checked and were fine when I blasted the frame.I am at a loss.Anyone have any ideas?

Hi, you said that you replaced or reconditioned all the parts in the rear. You didn't mention whether you had a four wheel alighnment done. I'm just guessing but this could be the problem. Hope you figure it out. Good luck

reavestr6, you also didn't say if you have wire wheels, if so they require a good tight fit and the proper short studs. Helped a friend last year who had one long stud mixed in the batch and he had the same problem with his solid axle. Wayne

This is not an uncommon condition with the TR IRS set up. It's caused by either worn trailing arm bushings, which you said have been replaced during a restoration. The softer rubber bushings may still deflect enough to cause the twitch you describe.
The second is the sliding action of the spline axle shaft. Under hard acceloration they can bind , on the shift they unload letting the trailing arm shift causing the twitch. This is difficult to eliminate , but stiffer poly bushiings & a moly grease on the axle splines might help.

Hello Reavestr6,
I agree with Mitch, spline lock is almost certainly what you are experiencing. I would split the drive shafts and give them a good greasing using Moly grease. If it still occurs the splines are too worn and you can either:- live with it (it's not dangerous, just a bit disconcerting), buy some new shafts or for a lot more money buy modified driveshafts with modern CV joints.

Alec

I would agree that bushing deflection is likely involved, unless you have poly bushings in the trailing arms.
When the back end squats under acceleration both the camber and the toe of the back wheels may change, which gives a "squirmy" feeling. The poly bushes reduce the toe change, stiffer springs will reduce the camber change that causes it.
My guess is that splines locking and unlocking would be heard as a clicking or clunking sound more than the sensation you describe; at least accelerating in a straight line.
Simon.

The Old "Triumph Twitch." It's the splines on your half shafts binding. Think about it...When you accelerate, the rear end squats, effectively shortening the shafts. When you let off the gas (as in between shifts), the springs return to their normal ride height, forcing the axles back to their normal length. If one side is a little sticky, it causes the car to "twitch". Mine does it too. I did almost eliminate the problem by fitting higher rate springs (lowered), uprated lever shocks and a sway bar. It still does it a little though. I just live with it.