Horrible vibration at 100km+

[Big T]

Hey all.

I have an odd one for you. Car is fine up to around 90km or so. Over this speed, putting the car into neutral/clutch in creates a horrible vibration. Something like going over those rumble strips on the side if the road but far worse. With the clutch engaged, even if there is no throttle, there is very little vibration. So the diff needs load to stop the vibration.

Car is an ae86 4agte with w57 and f series with tru trak torsen, single piece tailshaft. The vibrations became more noticeable after putting in the twin plate clutch but it was only on accel and decel whereas now it is in neutral.

I did originally have rose jointed 4 link but they were destroying shock bushes and mount points so just switched back over to oem links. The adjustable arms were set to factory length.

My guess is that it is pinion angle related and going back to rubber arms has allowed greater misalignment of the angle. Would like to see what other people think.

Fire away your thoughts.

Eddie.

[Sam-Q]

Classic signs of an out of balance tailshaft

[Big T]

The tailshaft is new with 8000kms on it. Was built by Sydney driveline services. I did not have this issue prior to switching out the rose joint links hence my thoughts about pinion angle.

The only other thing I can think of is it might be an issue with the torsen. Normally when both wheels are off the ground, it should act as an open centre but both wheels will track in the same rotation even with no load.

[LittleRedSpirit]

One of the little weights that balances it was probably knocked off when you were under there. Maybe they didnt attach it so well.

[drift kid]

Exactly my thoughts

[Futo_gt86]

Uni joints?