[Coupes33]

Hi Guys,
Ever since I have installed the M3 rear sub frame mounts, I get a harmonics/residence through the vehicle if I put the pedal down while at low revs in top gear. Also, I get it going up a hill at low revs in top gear. At the time I had the mounts installed, I had a HR stabilizer also installed. I was wondering if anyone else has had the same experience. It is quite annoying and it would be good to get rid of.

[JJH]

I am sure that must be annoying. I also have the M3 sub frame bushes installed (I assume you meant bushes rather than mounts?) and have had no such issue. These M3 bushes are basically of similar material to the original 335i version – metal centre/rubber exterior, just stiffer. They should not be causing your issue. I would look first at the way that stabiliser bar is mounted and whether you have any contact on the underside.

[Stuart@BMRAutowerkes]

Is it a manual and are you tuned?

If so you're putting too much load on the drivetrain.. with all that torque trying to transfer it to the ground in a higher gear may cause vibrations as described. Downshifting will solve this.
Whilst this may not have been as noticeable before with the softer subframe bushings, the M3 bushings are still compliant and isolate NVH well (unlike a solid aluminium one).

[Coupes33]

Originally Posted by JJH_335

I am sure that must be annoying. I also have the M3 sub frame bushes installed (I assume you meant bushes rather than mounts?) and have had no such issue. These M3 bushes are basically of similar material to the original 335i version – metal centre/rubber exterior, just stiffer. They should not be causing your issue. I would look first at the way that stabiliser bar is mounted and whether you have any contact on the underside.

I have had an inspection of the stabiliser and cannot see anything wrong. It is not touching anything and appears to be mounted correctly. I may remove the rubber mounts of the stabiliser to the subframe and put some rubber grease on the rubbers and see if that makes any difference.

[Coupes33]

Originally Posted by Stuart@BMRAutowerkes

Is it a manual and are you tuned?

If so you're putting too much load on the drivetrain.. with all that torque trying to transfer it to the ground in a higher gear may cause vibrations as described. Downshifting will solve this.
Whilst this may not have been as noticeable before with the softer subframe bushings, the M3 bushings are still compliant and isolate NVH well (unlike a solid aluminium one).

The vehicle is auto putting out 297 rwkw and 700nm of torque. You are correct is saying that by downshifting a gear stops it. However, this issue wasn't there before installing the M3 bushes. If I am the only one who has this problem, I will check out the installation with the installer and also lubricate the rubber mounts on the stabiliser.

[froop]

I don't think it would be the rear subframe mounts. I have solid aluminum ones and I don't reckon they add any noise or harshness.

I get resonance, but that's from the exhaust and didn't change at all with the installation of suspension mods.

I know a guy who had his installed just by themselves and he said he didn't notice any change in NVH over the stock ones.

[Kiwi Peter]

Check to see if the bushes have been installed the correct way up, as they can be fitted ether way.
If you followed the 335/135 bush set up you have installed the front two M3 bushes upside down.
They are a bugger to fit and are easily damaged during fitting, have a good look around the bush and make sure it is fitted correctly.

[Coupes33]

Originally Posted by Peter@Advan

Check to see if the bushes have been installed the correct way up, us they can be fitted ether way.
If you followed the 335/135 bush set up you have installed the front two M3 bushes upside down.
They are a bugger to fit and are easily damaged during fitting, have a good look around the bush and make sure it is fitted correctly.

Thank you for that advice. I will check that out.

[Coupes33]

Originally Posted by Peter@Advan

Check to see if the bushes have been installed the correct way up, as they can be fitted ether way.
If you followed the 335/135 bush set up you have installed the front two M3 bushes upside down.
They are a bugger to fit and are easily damaged during fitting, have a good look around the bush and make sure it is fitted correctly.

I have jacked up the rear of my car and had a look at the bushings.
Front ODS Bushing

Rear ODS Bushing

Front DS Bushing

Rear DS Bushing


From what you have stated, I believe the front bushings have been installed correctly. Let me know if you believe they have been installed incorrectly.

[Kiwi Peter]

Originally Posted by Coupes33

I have jacked up the rear of my car and had a look at the bushings.
Front ODS Bushing
Attachment 1116713
Rear ODS Bushing
Attachment 1116714
Front DS Bushing
Attachment 1116715
Rear DS Bushing
Attachment 1116716

From what you have stated, I believe the front bushings have been installed correctly. Let me know if you believe they have been installed incorrectly.

Yep looks fine