Ive noticed recently that my 75k mile X358 is wandering on the road a little and under sudden braking it feels like something at the front moves or shunts a little. Ive also noticed an occasional clunk through the steering at parking speeds, especially with some steering lock on and at low speed on hard lock it feels like the front tyres are scrubbing like something moves on the geometry on full lock.

I can't find anything obvious with a pry bar. The large curved arm bushes are pretty pliable side to side but I'm not sure how much movement there should be in those? I've read that lower shock bushes can wear in the lower arm too.

I don't want to start changing random parts so what are the most likely culprits?

I also read that depressurising the shocks to change bushes can be a problem without the SDD software to reinflate them. Is that true or can this really be a DIY job.

Any experience or advice appreciated!

 

AFAIK you don't need to deperessurise the air springs to change the bottom bushes, as the unit extends to its limit as the suspension drops when you jack-up the car. The curved arm trunnion bushes (the large ones) are the ones that normally fail first. Symptom of this is wear on the inner shoulder of the front tyres, even though the bush may look OK. Geometry checks may not show up this as the tow-out from the wear only occurs when the car is in motion, but eventually it becomes obvious. I had mine replaced on my previous X350 when tyre wear was spotted. Up to that point the car drove OK.

Worn-out lower shock bushes don't affect steering geometry, but can make noises. These things don't last very long, and one can see why, as there are four in total, (one per shock), and these together take the full weight of the car. Not a piece of good design, in my opinion.

 

The wandering could be something loose at the rear (the noise is obviously the front). Check for play in the two rear wheels, the rear tie rod links will cause wandering.

 

I'll have a look at the rear tomorrow. Definitely worth checking

 

x2 on the rear tie bars...also check the front sway bar drop links. Both are very inexpensive and easy to replace but you will need a four wheel alignment if you change them. If you kick down in a low gear and the back end feels squirrely, its almost certainly the rear tie bars. I replaced mine with a pair from Moog. If you ever do need to remove your front struts, they do not need to be de-pressurized to remove and the topic is covered extensively on this forum
Steve

 

 

Just a thought - take a good look at your steering rack to make sure it isn't moving around or leaking. I have not personally experience a steering rack failure but believe it is not uncommon on these cars. I would have thought that if the tires are squealing on full lock at low speed you would have excessive wear on the front tires. A good alignment shop should be able to pinpoint any configuration issues and/or wear in suspension joints. They know what they are looking for and should see any serious issues through the four wheel alignment readings.
In my view, this is one of the least expensive diagnostic visits you can make. If you go this route, I would find somebody with laser alignment kit who works on high value and/or exotic cars
Steve

 

 

 

Hi Eeyoreish, did you manage to identify the suspension problem at parking speed by any chance? I believe I have the same issue on my car. Thanks!

 

I had the Banana arms changed and tracking re-adjusted afterwards, which seemed to improve things.

 

thanks