E46 M3 Strange Veering Around Issue, Diff??
Discussion
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
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
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.
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!Take it to a specialist for alignment and suspension and have them have a look.
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?
I had some problems with the rear of my 2013 M3 steering the car under acceleration especially if it hit a bump and on checking the rear toe was out.
I had mine done by a main dealer and they were OK but I wish I'd spent the money at a specialist like centre gravity in Atherstone as its still not 100%. Way better but not perfect.
I had mine done by a main dealer and they were OK but I wish I'd spent the money at a specialist like centre gravity in Atherstone as its still not 100%. Way better but not perfect.
This happened to my E36 and my E46. On rhd cars the u/j is right next to the exhaust manifold and the heat eventually dries out the grease, resulting in weird steering.
The plastic bush at the bulkhead can dry out and become stiff as well.
I put some motorcycle chain lube on mine after freeing it off with thin oil as a temporary fix but it has lasted nearly a year now.
The plastic bush at the bulkhead can dry out and become stiff as well.
I put some motorcycle chain lube on mine after freeing it off with thin oil as a temporary fix but it has lasted nearly a year now.
If its not RTABS or wheel alignment...
Then sadly could be rear sub frame crack issues....get an inspection for chassis cracks.
You can look in the boot (under the floor) where the spare wheel area is, and if its really bad you can see the stress cracks (and if this car is driving this badly) i'm sure you'd see something. Otherwise its drop the rear sub frame and ask an Indy to inspect underneath.
If you google image the sub frame cracks you'll see the examples of what to look for in the boot.
Only other thing is the M Diff is it part locking, or faulty? neither issue is going to be cheap though.
Good Luck.
Andy
Then sadly could be rear sub frame crack issues....get an inspection for chassis cracks.
You can look in the boot (under the floor) where the spare wheel area is, and if its really bad you can see the stress cracks (and if this car is driving this badly) i'm sure you'd see something. Otherwise its drop the rear sub frame and ask an Indy to inspect underneath.
If you google image the sub frame cracks you'll see the examples of what to look for in the boot.
Only other thing is the M Diff is it part locking, or faulty? neither issue is going to be cheap though.
Good Luck.
Andy
Worth checking lateral acceleration sensor too - if it thinks the car is going slightly sideways then it will brake the inside wheel to try and pull it straight, if it's already seeing a faulty value then it could be doing it even when straight. If unchecked the bushes and wheel alignment then I'd check this next
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