2019 m140i pulling left in hard acceleration

[hoddy]

Hi all, new here so apologies if this is in the wrong place.
So the problem has occured, coincidentally or not, after having two new rear tyres fitted (ps5). On hard acceleration the car pulls or pushes me left and feels light on the front end. When I take my foot off the throttle the car then pulls right when the weight transfers back to the front. No prblems previously.
I’ve just had the tracking realigned but that hasn’t fixed the problem.
No knocking or banging happening so this is really confusing me.
Any help would be much appreciated.
For info - stage 2+, down pipe, lsd.

[No one]

Hi,

New tyres need a run in. You know that, don't you? If you mean throwing the rear end it should be less traction than you expect. My car does it passenger side (right ) on a straight slippery line in the "Sport+" (DSC partially off) driving mode. Releasing the pedal helps.

[freakystyly]

Please don't buy a Ford Mustang.

[G30M]

Originally Posted by hoddy

Hi all, new here so apologies if this is in the wrong place.
So the problem has occured, coincidentally or not, after having two new rear tyres fitted (ps5). On hard acceleration the car pulls or pushes me left and feels light on the front end. When I take my foot off the throttle the car then pulls right when the weight transfers back to the front. No prblems previously.
I’ve just had the tracking realigned but that hasn’t fixed the problem.
No knocking or banging happening so this is really confusing me.
Any help would be much appreciated.
For info - stage 2+, down pipe, lsd.

sounds like better traction from new tires and LSD not fully locked

[hoddy]

Update - thought it maybe down to a warped disc so just changed the front discs and pads (brembo grooved and dimpled with ebc red stuff) and checked it over. No signs of issues with suspension or bushes. Haven’t “booted” it fully yet due to bedding in the brakes but still when given it a little blip it appears to pull left.

starting to think it could be the lsd playing up. Genuine BMW lsd fitted by Williams.

Has anyone else experienced or heard about similar issues?

[Sneaky Pete]

I had this exact problem with an E92 M3.
Generally cars that pull left/right on acceleration/deceleration will be due to out of alignment of the rear suspension toe-in.
One rear wheel will be toeing in differently to the other causing the rear wheels to steer the back of the car.
Either the alignment is out or a part of rear suspension has too much play in it.

The rear toe is set to toe-in by around 15 minutes (of a degree) for stability...under acceleration the rear wheels have a tendency to toe-out a small amount (typically no more than 15 mins) and to toe back in under deceleration. It is essential that the rear toe-in is identical left to right for best stability.

Could be a problem with defective tyres or I guess the LSD but being absolutely certain the rear alignment is correct would always be my first step.

[Bc2005]

Swap rear tires from left to right and see if it changes the problem. If it does, it’s probably an issue with the new tires. They can be faulty “out of the box”.