M3 rear subframe bushings vs solid bushings

[Grainwashed]

I'm doing an lsd install so I'm going to be dropping the rear subframe anyway, I'm curious if its worth it to use the m3 subframe bushings or if i should just go all in on solid bushings. Thoughts?

[HP Autosport]

Originally Posted by Grainwashed

I'm doing an lsd install so I'm going to be dropping the rear subframe anyway, I'm curious if its worth it to use the m3 subframe bushings or if i should just go all in on solid bushings. Thoughts?

The subframe can actually stay for the LSD swap, dropping the pumpkin is not required to do the subframe bushings. The only overlapping would be the removal of the exhaust and perhaps the driveshaft(depending on how you are doing the bushing install).

If you are NVH sensitive, go with the M3. If not, go solid.

[amg6975]

Go solid, otherwise you'll be doing it again next year. There is very little downside to it.

[TheLittleOne]

I went solid and convinced my buddy with an e92 m3 to go solid
Really allows the rear end to feel controllable and extremely planted
https://www.bimmerworld.com/Aluminum...-1-Series.html

[racer_951]

amg6975 and TheLittleOne, did you do the solid bushings installation yourselves? Did you have to drop the entire subframe or just lower each end?

[fast1eddy]

I did Whiteline bushing by just lowering the subframe. I thought I was careful to not put too much stress on the short brake lines that connect over the subframe but a couple years later I noticed they were leaking and had to drop the subframe to replace them. I'd say drop the subframe.

[amg6975]

Originally Posted by racer_951

amg6975 and TheLittleOne, did you do the solid bushings installation yourselves? Did you have to drop the entire subframe or just lower each end?

I took it all the way out both times I've done it and used a shop press to push the bushings out/in. If you have the special tool you may be able to leave it in but I'm not sure.

[gjm120]

I just did the Whiteline's week before last. Dropped the subframe a good bit but kept at least 2 bolts partially in to avoid having to align it. (thing is heavy and bulky). I did disconnect the 2 brake lines. Taking the clever advice using a piece of wood to depress the brake pedal, very little fluid dropped out. I bled the rears just in case and it took so little fluid to get the air out I didn't have to add fluid to the reservoir.

Also had bought an assortment of rubber plugs to plug the lines (another good tip from this forum).

[Almuliman]

Originally Posted by gjm120

I just did the Whiteline's week before last. Dropped the subframe a good bit but kept at least 2 bolts partially in to avoid having to align it. (thing is heavy and bulky). I did disconnect the 2 brake lines. Taking the clever advice using a piece of wood to depress the brake pedal, very little fluid dropped out. I bled the rears just in case and it took so little fluid to get the air out I didn't have to add fluid to the reservoir.

Also had bought an assortment of rubber plugs to plug the lines (another good tip from this forum).

Nice! Good to know those tricks work. The other day, I ordered Whiteline bushings and lined up buying the custom tool from another forum member who bought it from another forum member (I love this forum). Can't wait now that it (ostensibly) is trending towards drier, warmer days.

[fe1rx]

Originally Posted by Almuliman

Nice! Good to know those tricks work. The other day, I ordered Whiteline bushings and lined up buying the custom tool from another forum member who bought it from another forum member (I love this forum). Can't wait now that it (ostensibly) is trending towards drier, warmer days.

Good call. The proper tool really helps.

https://www.1addicts.com/forums/show...77&postcount=7

I have installed M3 RSFB using a home made tool, then removed them with the above tool and installed aluminum ones with the above tool. Definitely disconnect your brake lines - anything else is courting disaster.

I used threaded rod to partially lower the subframe. Works well, but you need metric threaded rod. Available at McMaster Carr if not locally.

[135i_Life]

Installed the same bushings as fe1rx - used tool from ebay https://www.ebay.com/itm/333158778716. The install was pretty simple, lowered on a jack, exhaust held up residual weight without trouble. May not be recommended, but had no problems and didn't seem to cause much strain.

[Hybrid G]

Originally Posted by fe1rx

Good call. The proper tool really helps.

https://www.1addicts.com/forums/show...77&postcount=7

I have installed M3 RSFB using a home made tool, then removed them with the above tool and installed aluminum ones with the above tool. Definitely disconnect your brake lines - anything else is courting disaster.

I used threaded rod to partially lower the subframe. Works well, but you need metric threaded rod. Available at McMaster Carr if not locally.

Did the car retain the BMW feel and is there a difference in cabin noise and vibration btw solid mounts and m3 ones?

[amg6975]

Originally Posted by Hybrid G

Did the car retain the BMW feel and is there a difference in cabin noise and vibration btw solid mounts and m3 ones?

Very slight increase in noise but so worth it. The newer cars all come rigidly mounted from the factory if that tells you anything.

[fe1rx]

Originally Posted by amg6975

Very slight increase in noise but so worth it. The newer cars all come rigidly mounted from the factory if that tells you anything.

May be detectable in a back to back test, but I don't notice any NVH downside myself.

I am convinced that the primary function of the original RSFBs is to provide passive rear steer with the goal of severe terminal understeer (in the name of safety for the lowest common denominator). They basically ruin the car for track use. As has been written on this forum many times, getting rid of them should be mod 1 for a car that sees the track. I went to M3 first, which were fine, but when I went full spherical solid made sense.

With the benefit of hindsight, I should have gone straight to solid.

[Olgeezer1]

I used the Whiteline 2pc. bushing for easier install although you still have to press the old one out. Subframe dropped. Probably between the M3 and solid in stiffness. Only significant NVH difference is increase in tire noise, quite noticeable immediately after install but not enough to really bother me. Definitely want this done before you do a LSD.

[bignickmetro]

yeah the 2 piece bushings are soooo much easier to install. the whiteline kit is working out perfect for me, and it was a simple install. I bought a great tool to push the old ones out, it was like $80 on ebay and is really well made

[powerbait]

The e9X M3 community highly recommends solid RSF bushings and I've never heard anyone mention anything about NVH, the only downside is the install. The F8X Ms come with a solid mounted RSF, so BMW also approves of the benefit.

[AshwinLB]

I put Condor Speed Shop uhmw solid bushings in my 135i and there was zero NVH increase. You can install them with the subframe still on the car, and I recommend the eBay tool for ease of removing the old ones

[WrathOTM]

Just throwing it out there, as I have revshift brand solids. There was a mild increase in road noise over crappier, more worn roads like the street I live on. Decently paved roads it's fine. I would argue some ruts in the road do come in a little louder.