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      07-30-2021, 09:03 AM   #1
JayZap16
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M5 Pulling Under Acceleration - BMW gives poor reasoning

So I picked up my 18 CPO'ed F90 earlier this month from a dealer in another state. When I got to my state i realized the car has couple strange behaviors with the handling.

First weird behavior, when the car is started and I begin to drive, it begins to pull to the right on the road, maybe a few degrees on the steering wheel to the left to counter the force. Then after a couple miles it goes away.The second weird behavior, under acceleration (mild or hard, especially on the highway) the car pulls decently to the left. It only does this in 4wd, less is 4wd sport and not at all in 2 wheel rear.

Alignment was checked twice, everything is in the green, techs searched for suspension issues such as blown bushing, no issues found. Now I am thinking, okay, is it the torque vectoring front diff distributing power not equally!?

Service advisor told me they think its my tires, I am running the OEM 19in wheels on Pirelli P Zeros, SA thinks the tires are too thick and warping under power. I dont buy it one bit.

What do you guys and gals think?
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      08-02-2021, 08:39 AM   #2
brava09
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I noticed some torque steering under hard acceleration
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      08-02-2021, 09:46 AM   #3
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On a rwd car pulling to one side under acceleration could well be uneven toe between the rear wheels (one toeing-in more than the other for instance).
With xdrive...I don't know. But note that the front wheels are only driven when there is slip at the rear wheels. At other times the car is in RWD mode.
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      08-07-2021, 01:48 PM   #4
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Quote:
Originally Posted by brava09 View Post
I noticed some torque steering under hard acceleration
Is it always constantly in the same direction?
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      08-07-2021, 01:49 PM   #5
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Quote:
Originally Posted by SenorFunkyPants View Post
On a rwd car pulling to one side under acceleration could well be uneven toe between the rear wheels (one toeing-in more than the other for instance).
With xdrive...I don't know. But note that the front wheels are only driven when there is slip at the rear wheels. At other times the car is in RWD mode.
So even when it’s in 4wd mode the fronts only get power when the rears are slipping?
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      08-07-2021, 01:51 PM   #6
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Quote:
Originally Posted by JayZap16 View Post
Quote:
Originally Posted by brava09 View Post
I noticed some torque steering under hard acceleration
Is it always constantly in the same direction?
No, random, left or right
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      08-07-2021, 02:03 PM   #7
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Quote:
Originally Posted by JayZap16 View Post
So even when it’s in 4wd mode the fronts only get power when the rears are slipping?
Correct.
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      10-12-2021, 09:11 AM   #8
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Update - I finally got fed up with this issues and got my SA to bring it in. I threw 4 new tires at it and turns out now it drives straight as a missile. Looks like one of the fronts had a broken core in it and thats why it was all over the place under load or just coasting shortly after start up.

Cheers!
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