Wandering steering in a straight line

[SoupAnxiety]

Hi all,

My car likes to wander when driving straight, it's only subtle but it is annoying. It's persisted from buying the car on 126k miles and the work done along the way (20k more miles) of balancing / bushes / four wheel alignment / front bottom arms / roll bar drop links / shocks / springs / top mounts / tyres RFT to standard / wheels (17" -> 18"). The car is a BMW E92 330i, it has electric power steering but does not have the active / variable speed system.

I don't notice the same issue in other cars that I drive and it could just be a quirk of this one. I'm posting in the general section as this might just be a quirk of electric power steering. Thanks!

[kev b]

Have you replaced the bushes in the rear suspension, are you sure your alignment place has done the job properly?

[HustleRussell]

Tyre brands? Mixed?

[SoupAnxiety]

Not sure on rear bushes, I'm pretty sure they were done when new shocks and springs went on but I'll add that to the list. They might not have been replaced but there was no play at last service.

Tyres are Goodyear Eagle F1s all round. Problem was worse with RFTs but they were mixed brand. I've had the tyres balanced again as they have worn. Alignment place was recommended, £100 job with laser alignment but appreciate they may not be as good as hype suggested.

[HustleRussell]

Did you get a print out for your hundred quid?

[SoupAnxiety]

No, the garage who fitted the suspension took it to the magical garage for alignment. 100% trust that they took the car for the alignment but perhaps the alignment was off.

[Prinny]

If it helps you in analysis, i've got a set of the 19" 225M wheels sat about (came off my 335) - I'm not too far away from Cheshire, (Rochdale) would happily let you try for fault checking, etc... PM me if you're interested. (p.s. response might not be immediate as I'm in Germany right now....)

eta... It might well be the electric pas, I don't rate the epas system in the z4 to be anywhere near as good as the hydraulic pas in the 335. I know it's different cars, different engines, but I do find that swapping the steering to "sport" increases the weight, if not the feel in the z4. Obviously in the 335, that wasn't an option, and the diesel lump is heavy over the front wheels... That said, if you've done 20k, it's probably something "off", especially as car is higher mileage?

Edited by Prinny on Tuesday 22 March 23:29

[SlimJim16v]

It may just be st steering. Tell us what you have and see what other owners say.

[kev b]

This probably won't apply but after I had cured the dreadful wandering vagueness on my E46 by changing the rear trailing arm bushes, the symptoms returned a year later.

I found the steering column u/j's had become stiff because they are close to the hot exhaust manifold, sorting this transformed straight line stability. I am not familiar with the E90 but it might be worth a look.

[SoupAnxiety]

Prinny said:

If it helps you in analysis, i've got a set of the 19" 225M wheels sat about (came off my 335) - I'm not too far away from Cheshire, (Rochdale) would happily let you try for fault checking, etc... PM me if you're interested. (p.s. response might not be immediate as I'm in Germany right now....)

eta... It might well be the electric pas, I don't rate the epas system in the z4 to be anywhere near as good as the hydraulic pas in the 335. I know it's different cars, different engines, but I do find that swapping the steering to "sport" increases the weight, if not the feel in the z4. Obviously in the 335, that wasn't an option, and the diesel lump is heavy over the front wheels... That said, if you've done 20k, it's probably something "off", especially as car is higher mileage?

Edited by Prinny on Tuesday 22 March 23:29

Thanks for the offer of a loaner set of wheels. The problems persisted when I swapped from 17" square to 18" staggered (with new tyres) and after the initial run in rebalance as the new tyres bedded in. I have no steering weight options on my E92, I think it's a fixed rate but electrical instead of hydraulic. May yet send you a PM... what tyres are on the 19" wheels? I'm wondering if mixed Conti / Bridgestone runflats and Goodyear standard tyres all have some sort of characteristic wandering that is causing the upset.

kev b said:

This probably won't apply but after I had cured the dreadful wandering vagueness on my E46 by changing the rear trailing arm bushes, the symptoms returned a year later.

I found the steering column u/j's had become stiff because they are close to the hot exhaust manifold, sorting this transformed straight line stability. I am not familiar with the E90 but it might be worth a look.

The universal joint point is a good one, my E30 had a similar problem and developed an annoying / embarrassing squeak at full lock which took forever to track down. Didn't think to check on the E92 but will put that, rear suspension and rear trailing arm bushes on the list. On the twisties everything is spot on since the suspension refresh, this vagueness is the only niggle left!

[james_gt3rs]

It may just be a trait of the car, the wider the tyres the more a car will follow the cambers...

[SoupAnxiety]

I thought that too, either a quirk of EPAS or the car setup. I've never driven another E9X so cannot comment and mine was bought on intergalactic mileage (but has had a lot of common culprits refreshed etc). It's not a pull characteristic of tracking but more that the steering wheel does match with the ECU central position (it looks to be centred). No fault codes when scanned relating to steering angle position sensor. It's better than when I first bought the car on worn out gear and RFTs but maybe something has been missed. Thanks for all your help.

[james_gt3rs]

Did you check the alignment of all 4 wheels? If the rear toe is out, that will affect the steering for example.

And, you can rule out the power steering by switching engine off while driving or maybe pulling a fuse? Be careful though

[The Moose]

It's obviously a simple thing to check but have you checked the pressures??

[SoupAnxiety]

Alignment was checked and adjusted ~14k ago when I had new shocks and springs fitted. Check my pressures monthly with cold tyres.

[vsonix]

kev b said:

This probably won't apply but after I had cured the dreadful wandering vagueness on my E46 by changing the rear trailing arm bushes,

I was gonna suggest RTABs, they're usually the culprit for wandering, tramlining and rear end 'shimmy' when going over bumps. They're also often put off and put off unless the MOT man insists they be changed as they are a bit of a faff to change compared to most of the other bushes.

[Otispunkmeyer]

Tram-lining? Crown of road? Usually causes a little bit of wander.

[andy118run]

SoupAnxiety said:

I thought that too, either a quirk of EPAS or the car setup. I've never driven another E9X so cannot comment and mine was bought on intergalactic mileage (but has had a lot of common culprits refreshed etc). It's not a pull characteristic of tracking but more that the steering wheel does match with the ECU central position (it looks to be centred). No fault codes when scanned relating to steering angle position sensor. It's better than when I first bought the car on worn out gear and RFTs but maybe something has been missed. Thanks for all your help.

I have an 2006 E90 325i. Matching quality run flat tyres all round.

Only done just over 30,000 miles. I've noticed a similar trait in mine in the year or so I've had it. The only car I've ever have to do this.

Recently serviced, had a general health check and all parts of the suspension appear in good order.

Haven't looked into the alignment as it hasn't really bothered me though it's interesting to hear of someone with a similar issue.

[Buff Mchugelarge]

Sounds like track rod ends to me.. ?

[vsonix]

My Z3 did it really badly until I ditched the 16x7 wheels clad in 'mud and snow' tyres and went to a 17x7.5/8.5 staggered setup with proper summer performance tyres.