XC70: Suspension Undiagnosed Steering Pproblem

[Tatsfield]

Up date but not concluded. The car has been returned from its underside cosmetic repairs. The rear drive electronic control unit was replaced and the car is returned to the condition before it was driven over the concrete block. This means to say that it has AWD and the dodgy handling has returned. I took it to a tyre shop who specialise in steering geometry and have the same Hunter tracking rig that the Volvo dealer has. They confirmed that the steering geometry was as good as it gets and that Volvo had got it correctly set up. Based on the history of the two wheel drive condition eliminating the steering problem, they suggested that the problem probably resides in the Haldex rear transmission.

Volvo are going to take another look at it and concentrate on the rear transmission. They will start by draining the rear transmission oil to see if it evidences any damage such as metal shards or burn oil. I will suggest before they do that, that they disconnect the new control box and see if that improves the handling.

[Tatsfield]

Up date. Now looking a lot more satisfactory. The car was due to go in to have the Haldex drive investigated because the steering problem seemed to be associated with the AWD system. However on the day it was due in the weather was appalling and I cancelled the booking and moved it to the next available which was two weeks later. In the intervening time I used the car regularly and over the two week I noticed that the steering problem grew less and today the car seems to be handling as it always used to do.

I can only surmise that the problem was in some way in the AWD electronic control unit and that the new unit has adjusted itself as the car is used. I've considered the placebo effect but the steering was so out of kilter and with hands off the wheel it steered one way or the other and does not do this now. The cause may remain a mystery but at least the car seems to be back to how it always was before the unfortunate series of slow speed impacts.

[Tatsfield]

Update: Spoke too soon. The pull has returned. I took the car to an independent Volvo specialist who reported that the rear trailing arm bushes were shot and needed replacing regardless of whether they were the cause but they cannot have improved the handling. More seriously he reported that the control rod ends were worn and need replacement and surmised that the impact could have caused damage to the already worn right side control rod ends and that replacing them should improve the handling.

Well yes and no. The handling is better but the bias to steer left is still there. That is, it still requires more effort to turn the wheel to the right than it does to the left. Not a great deal but in the handling of the car it is discernable and my right arm gets more tired than my left one.

The car goes back next week to examine the struts and strut turrets, particularly the right side where the wheel struck the kerb. After that, who knows.