Subframe and differential bushings

[NBN91U]

Hi all

For my first mod i have decided to solid mount the rear subframe with MRF Engineering bushings.

I intend to drop the rear subframe to do this and was advised that i should probably replace/upgrade the differential bushings and sway-bar at the same time given the ease of access.

My question is, with this car predominately being a weekender about to see frequent track time i am looking for a bushing combination that does not overly increase NVH. (any substantial increase NVH will result in considerable NVH from the mrs)

Thanks in advance

[HawkeyeGeoff]

If NVH is an issue, I'd suggest going with the M3 bushings instead of solid inserts.

[NBN91U]

Thanks HawkeyeGeoff

The general consensus from the research I have done is that solid rear subframe mounts do not contribute significantly to NVH.

This is backed up by later BMW having already switched to solid mounts.

Therefore my question is around differential bushing and sway-bar options. I am looking for a combination that tightens/plants the rear with minimal increase in NVH

I accept that NVH will increase, I am after the best compromise

[HP Autosport]

1M has the same subframe bushings as the M3 so the clear upgrade from this point would be the solid mounts. You will get some increase in NVH, but the benefits will likely outweigh it. It's very subjective, some people are fine with it and some aren't.

Diff bushings on the other hand will transfer much more driveline noise to the cabin.

[NBN91U]

there appears to be numerous types of diff bushing offering different performance characteristics.

what would you recommend and is a sway-bar upgrade really necessary?

As I mentioned, I have accepted that there will be an increase in NVH and just looking for the best compromise.

thanks

[HP Autosport]

Originally Posted by NBN91U

there appears to be numerous types of diff bushing offering different performance characteristics.

what would you recommend and is a sway-bar upgrade really necessary?

As I mentioned, I have accepted that there will be an increase in NVH and just looking for the best compromise.

thanks

No rear sway on the 1M. This short wheel base car could be a handful with larger rear bar. Try to do your suspension tuning with dampers and springs first. A larger front bar would be okay.

We already know solid subframe bushings are okay. I would go with the softest diff bushing that are an upgrade over OEM if you must have them. Urethane may be the way to go as delrin and alum. are obviously too stiff and way too much NVH, especially drivetrain noise.

[d k]

I would say go with the hardest diff mounts that you can live with..

The diff moves around a lot, specially when the traction control kicks in. Its really scary.

I would like to see a solid aluminum mount with a rubber 'sleeve' around it to isolate the vibrations but limit movements under load