[dono2454]

When I go to accelerate onto the on ramp the car seems to dart from left to right and feels highly unstable. Have owned many bmws and never felt this before. It seems like it has been like this since Ive owned my m235i. At first i thought it was just normal because the tires are only 255 wide on 18's on square setup but now that I have a stage 2 tune it seems like it has got worse.
Is the suspension on these cars far inferior to the e46 m3s and e36 m3s?? is it the lack of a lsd? Also my father has driven the car and complains that the steering rack is way to quick almost like it takes way too much input to keep strait line driving.

[hwntime]

Originally Posted by dono2454

When I go to accelerate onto the on ramp the car seems to dart from left to right and feels highly unstable. Have owned many bmws and never felt this before. It seems like it has been like this since Ive owned my m235i. At first i thought it was just normal because the tires are only 255 wide on 18's on square setup but now that I have a stage 2 tune it seems like it has got worse.
Is the suspension on these cars far inferior to the e46 m3s and e36 m3s?? is it the lack of a lsd? Also my father has driven the car and complains that the steering rack is way to quick almost like it takes way too much input to keep strait line driving.

You sure you don't have a bulge in one of your tires? The only time I've ever felt that in this car was when my RFT had a bulge. The rear end got really squirrely all of a sudden and when I went to inspect, sure enough, sidewall bulge. Your symptoms sound exactly what I experienced with the darting from left to right and having to give it way too much input to keep straight. You might want to give your tires a quick check to rule that out.

[dono2454]

I just bought two new Michelin as3s to replace the fronts but instead i rotated the rears to up front and put the new as3s in the rear. and yes the right front has a buldge but why would that affect it? Because of balance?

[aerobod]

Mis-matched tyres will also cause this sort of instability. If the two front tyres aren't also the same as the rear (i.e. Michelin AS3s), then that could be the problem.

If you bought the car with Michelin AS3s all around, then they are not factory original and may have been installed due to a tyre failure caused by a pot hole or other impact, which would also place suspicion on the alignment of the car, which could also be the cause of your instability.

I find our F22 M240i is more stable from a tramlining perspective than the E46 323Ci we owned in the past.

[overcoil]

Originally Posted by dono2454

I just bought two new Michelin as3s to replace the fronts but instead i rotated the rears to up front and put the new as3s in the rear. and yes the right front has a buldge but why would that affect it? Because of balance?

Sidewall consistency probably induces pull under acceleration.

[hwntime]

Originally Posted by dono2454

I just bought two new Michelin as3s to replace the fronts but instead i rotated the rears to up front and put the new as3s in the rear. and yes the right front has a buldge but why would that affect it? Because of balance?

There's your answer. It's definitely the bulge in the tire. As mentioned above, the same thing happened to me and the first thing I did was inspect my tires. Lo and behold, there was a bulge in the RFT. Replaced all 4 with non-RFT's and haven't looked back since.

[dono2454]

The fronts are Michelin sport cups and the rears are Michelin as3 I would have got the sport cup but they don't make them anymore. Hopefully they will replace the tire under warranty due to defect. This death wobble is not safe.

[aerobod]

Originally Posted by dono2454

The fronts are Michelin sport cups and the rears are Michelin as3 I would have got the sport cup but they don't make them anymore. Hopefully they will replace the tire under warranty due to defect. This death wobble is not safe.

Sport Cups or Pilot Sports (which are a standard option on the 2-series)? If they are Sport Cups, you have a recipe for disaster if you are mixing them with AS3 all season tyres, as their grip relative to temperature and heat in the tyres is quite different. If they are Pilot Sport tyres, they still shouldn’t be mixed with all season tyres and handling inconsistencies should be expected if they are mixed.

[ChristosD]

Originally Posted by dono2454

I just bought two new Michelin as3s to replace the fronts but instead i rotated the rears to up front and put the new as3s in the rear. and yes the right front has a buldge but why would that affect it? Because of balance?

how did you rotate the rims? the rears are wider then the fronts 7.5j front 8j rear

[dono2454]

oops my tires are 225 all around all square typo! and the fronts are pilot sports zp which they dont make anymore i dont think.

[aerobod]

Originally Posted by dono2454

oops my tires are 225 all around all square typo! and the fronts are pilot sports zp which they dont make anymore i dont think.

You shouldn't mix tyre types from a stability perspective. Run flat max performance summer tyres (Pilot Sport ZP) will not work very well with ultra high performance all-season conventional tyres (Pilot Sport A/S 3+). You need four tyres of the same performance category to get the car to handle well under hard use.

[aerodavew]

Originally Posted by dono2454

When I go to accelerate onto the on ramp the car seems to dart from left to right and feels highly unstable. Have owned many bmws and never felt this before. It seems like it has been like this since Ive owned my m235i. At first i thought it was just normal because the tires are only 255 wide on 18's on square setup but now that I have a stage 2 tune it seems like it has got worse.
Is the suspension on these cars far inferior to the e46 m3s and e36 m3s?? is it the lack of a lsd? Also my father has driven the car and complains that the steering rack is way to quick almost like it takes way too much input to keep strait line driving.

Is this straight line or on a curve as you enter the ramp?

[Hpirx]

Check control arm bushings for wear.

[dono2454]

this is straight line acceleration.

[r0nd3L]

What I suspect is rear subframe bushings. They are extraordinarily soft on these cars. I have a video where I'm able to move entire subframe up and down with minimal force.

I installed poly bushing inserts before storing the car for winter. I think it felt a lot better, but I was not able to put many miles so feedback is limited. Hope I can update in few months.