Power flex bushings

[ahtim]

Hi, I have changed to power flex purple series for my 1m, including the 4at rear subframe, 3 at diff, 2 on the lower rear camber adjust arm and 2 on the anti roll bar; the front only 2 at anti roll bar and 2 at the front caster rod(the bent one)

Honestly after the change I don't feel the car got stiffer, i can only say it got tighter a tiny bit, however I have a problem on track during heavy braking that the whole car especially the rear is not very stable, and I asked the Bmw pro guys over here and they say it's because of the caster rod bushing, during heavy braking a lot of the force are going into that bushing and power flex bushing are weak/ soft compare to stock, that's why it can't hold the force and it's moving lead to the car being unstable
I also have a very big vibration on steering while I drive on some uneven fast public road(no matter acceleration of deceleration)

Anyone else experience this?

Thanks in advance

[ahtim]

Originally Posted by ahtim

Hi, I have changed to power flex purple series for my 1m, including the 4at rear subframe, 3 at diff, 2 on the lower rear camber adjust arm and 2 on the anti roll bar; the front only 2 at anti roll bar and 2 at the front caster rod(the bent one)

Honestly after the change I don't feel the car got stiffer, i can only say it got tighter a tiny bit, however I have a problem on track during heavy braking that the whole car especially the rear is not very stable, and I asked the Bmw pro guys over here and they say it's because of the caster rod bushing, during heavy braking a lot of the force are going into that bushing and power flex bushing are weak/ soft compare to stock, that's why it can't hold the force and it's moving lead to the car being unstable
I also have a very big vibration on steering while I drive on some uneven fast public road(no matter acceleration of deceleration)

Anyone else experience this?

Thanks in advance

Anyone please?

[PRTSB1M]

Originally Posted by ahtim

Anyone please?

Are theses the wheels you are running? Are you running spacers?

[markslc1]

Don't 1m's already have the improved rsf bushings from the m3? I know upgrading bushings on a 128 is popular. Most common upgrade is to install m3 bushings. But I figured the M crew took care of that with the 1M.

[balloonsalesman]

If you're running spacers that's a good place to start looking for front end vibration.

If you've done a couple track days with the same tires I'd re-check wheel balance as they wear.

As for bushings, I don't have experience with those but my subframe is solid mounted and I upgraded the diff bushings along with an upgraded diff and I can tell you that the rear end is very stable. I'm not sure the poly bushings alone are going to change that much if you're looking for rear end stability under breaking over stock.

Alignment is always a suspect also…

[ahtim]

Originally Posted by PRTSB1M

Are theses the wheels you are running? Are you running spacers?

Yes, I am running 12mm spacer at the back, changed to longer bolts

[ahtim]

Originally Posted by balloonsalesman

If you're running spacers that's a good place to start looking for front end vibration.

If you've done a couple track days with the same tires I'd re-check wheel balance as they wear.

As for bushings, I don't have experience with those but my subframe is solid mounted and I upgraded the diff bushings along with an upgraded diff and I can tell you that the rear end is very stable. I'm not sure the poly bushings alone are going to change that much if you're looking for rear end stability under breaking over stock.

Alignment is always a suspect also…

Compare to my last track day, I changed all the bushings and top mount and did the aggressive alignment, the alignment and corner weight was done 2 days before my track day. And I was using stock wheels for my last track day and not the fir with spacer