E46 M3 Strange Veering Around Issue, Diff??

E46 M3 Strange Veering Around Issue, Diff??

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ThePurpleBeemer

Original Poster:

47 posts

196 months

Monday 22nd August 2016
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Hello, could anyone help me diagnose a strange issue with my E46 M3. Essentially the straight ahead position keeps slowly creeping round to about 15 degrees to the left, then what ever I'm compensating for randomly disappears at absolutely no warning so I'm effectively turning 15 degrees to the left and have to sharply go back a neutral steering position to avoid ending up in the grass which I'm now travelling in the approximate direction of.

I've done over 100k in E46's of various size shapes and forms so I'm quite experienced in identifying lollypop and trialling arm bush issues. There's no knocks and rattles and no rear bushes which obviously need replacing, the trailing arm bushes, front wishbones, lolli pops, rear dampers and springs have all been changed in the quest to resolve this issue.

There's no clunking, banging, rattling or grinding occurring at any point of driving the car and the boot floor is perfect.

The issue is more or less gone in the dry, but in the wet unless you either drive really slowly or let it slide ever so slightly on more or less every corner or get it light on its feet on crests the issue isn't present either. But if you say pull onto the motorway for example, and accelerate hard it'll require a 15 degree steering input to go straight until you hit a large bump or something then what ever I'm compensating for completely disappears immediately.

On a bumpy but even twisty A road in the wet it's pretty hard going it's essentially like you're in a constant 'tank slapper' without actually losing grip.

I'm going to give as many examples of the situation as I can think of so that maybe someone can help.

If you pull out to overtake in the wet and nail it in third, it'll pull violently to the right to such an extent that it feels like the rear has broken loose and you instinctively lift off, where as it hasn't actually lost traction.

Sometimes if running with the ASC on when coming off of curved slip road for example the TC light will flash frantically even though it's not actually lost any traction.

What's everyone’s thoughts on this? I'm actually thinking of getting rid of it but I'm not going to trade it in for something when someone less switched on may go out and kill them self in it the first time they drive it in the wet.

I'm thinking Diff personally. Has anyone had any experience of the symptoms I've described who could perhaps assist in diagnosing the problem?

Thanks

ThePurpleBeemer

Original Poster:

47 posts

196 months

Monday 22nd August 2016
quotequote all
Doofus said:
Sounds a lot like tyre pressures to me
They're all good, 2.8 Bar on the rear and 2.3 on the front, gives even tire wear throughout the tyre. Continental contact 6's all round

ThePurpleBeemer

Original Poster:

47 posts

196 months

Monday 22nd August 2016
quotequote all
clarkson22 said:
first i was going to say rear trailing arm bushes, unless you have checked them dude i wouldlnt rule them out as that sounds like the symptons and have you had 4 wheel alignment done?
Thanks for the reply!

They're solid, they're the first thing I had changed for ones of the OEM manufacturer (cant remember their name right now). When the issue continued I had the rear alignment done, not knowing that the garage didn't have the equipment to do 4 wheel allignment. So once the issue continued I took it to the main dealer explained the issue, they checked the bushes and did a 4 wheel alignment which still didn't remedy the issue in the slightest.

ThePurpleBeemer

Original Poster:

47 posts

196 months

Monday 22nd August 2016
quotequote all
Max Maxasson said:
I'd be checking the alignment as well...if the rear toe is out it will try to steer the car.
Take it to a specialist for alignment and suspension and have them have a look.
Thanks for the reply!

It was done by the main dealer, I have heard people saying that it sounds like a rear toe issue before too, I've just been assuming that after the dealer has alligned it to spec it should be alright. Would you trust the dealer or should I take it to a reputable specialist too?