wheelspin always on one side, car slides to passenger side

[Dunc]

About 6 months ago I swapped out crusty drivers side trailing arm for a galvanised replacement. At the time, I counted the washers on either side and re-assembled the same way it came off (I know....but I didn't have a tracking system.).

The end result was a car that kicked left as you lifted off the power, so geo was obviously not the same on the replacement galvanised trailing arm and miles out. From the kicking , I deduced I should swap a spacer to the other side, which improved things markedly.

The car now drives okay, but I have noticed that when I boot it hard, it is always the passenger wheel that spins, and the car always steps out to the left.

What's the issue here - I had straight line wheelspin before swapping that arm out. Drivers side too much toe-in? If the passenger wheel is spinning under power, is the drift to the left a result of too much toe in on the wheel that's not spinning?

I have bought a laser alignment kit, and will set it all up correctly after I change the other trailing arm and passenger wheel bearing, but at the moment I am driving around with it as is. If its a simple adjustment, of toe, I could make it in 20 mins, but I am struggling with the logic. Passenger side has not been touched, but could be affected by deteriorating bushes, sagging springs?

 

Shocks are brand new and adjusted to the same rate. Springs probably need changing due to sag.

[andydclements]

The shims you moved will not really (not much) impact the toe in/out, they impact castor (how much the wheel tilts as it turns in/out).

In a straight line, regards the rear wheels, the shims you moved should be almost irrelevant, and toe in/out should also be almost irrelevant. On a curved course, they play a big part, but straight line, any excess toe-in/ any toe-out would be spread evenly by your subconscious turning the steering wheel to keep straight ahead. So, those things all relate to front wheels, nothing you've altered change the rear toe-in.

 

My first thought has to be tyre pressure, even a slight difference can make a big difference to grip. If pressures are equal, then I think you're already got your answer- bushes. They probably allow a rear wheel to move under heavy acceleration, but as soon as you ease off the accelerator the rear alignment then changes and hence the rear end kicks out to one side.

 

 

 

I should add: the worst rear end kick-out I ever experienced was on 6-month old shocks of a certain billet aluminium brand, hence my hatred of those. So, don't assume newish shocks = not those.

[black eclat]

Recently I replaced the trailing arm rubber mounts on my car and it threw the tracking out. I had as much as 2° toe out. 

It was the spacers on the trailing arm mounts that allowed me to correct the tracking.

In relation to your wheel spinning, did you tighten the suspension bolts to the correct torque setting with the car on the ground and the car fully laden?

[Dunc]

Thanks for replying,

Independantly, and unprompted, Simon mentioned he noticeds I had more negative camber on the passenger side when he was following me back from Brands. I suspect bushes and springs if not toe/tracking.