e46 subframe bushing Solid or Powerflex or OEM

[tonylauno1 7]

I am looking to replace the 3 diff & 4 subframe bushing.

I have been searching for what bushing to use, the 3 diff bushing i will stick with OEM like Lemforder however unsure about the 4 subframe bushing.

Turner Motorsport is saying subframe tearing the chassis is due to movements in worn subframe bushing, i was thinking of replacing them with solid bushing.
There is also the option of Powerflex Black bushing 25% stiffer than the yellow ones for street use.

Has anyone used powerflex or solid bushing for their e46 subframe, and any comments?

[gjm 3258]

For street use I'd advise against solid bushes. Great for the track, but that's about it.

Uprated bushes will transmit more road vibration into the car... Perhaps not enough to matter but that's a personal taste thing.

Poly bushes - yes, but perhaps stay with stock or marginally increased hardness. Poly bushes won't wear as quickly as stock rubber.

[M3AN 4016]

Oh gosh no, do not use solid bushings for a street car!

And you'll need your subframe reinforced anyway so don't look to bushings to get out of that task. Although I thought the tearing was only an M3 problem?

[Michael. 2313]

Make it solid so you start cracking the subframe, that is always fun.

[M3_Power 636]

The F80 M3/4 run solid rear subframe bushings ala the old E92 M3 GTS ... It is simply brilliant for a road car. So I am not sure what all this negativity is about?

The rear subframe floor will tear the same way with rubber or solid bushings, It makes no difference as the torque loading from the differential loading and unloading is verticle and upwards on the front right and downwards on the rear left not side to side. In fact I would wager that the solid bushings will probably place less stress on the verticle torque load as there's no actual verticle movement as you get in the rubber bushings. Force = mass x acceleration.

Edited February 14, 2016 by M3_Power

[M3AN 4016]

The F80 M3/4 run solid rear subframe bushings ala the old E92 M3 GTS ... It is simply brilliant for a road car. So I am not sure what all this negativity is about?

Those cars were designed for it Tom and distribute the NVH elsewhere.

[M3_Power 636]

I have friends in the uk that run solid rear subframe bushing in CSLs and they have told me emphatically that you'd hardly notice any significant NVH as a result over the stock bushing. It's not like an engine mount or a shock absorber spherical bearing mount.

The E92 M3 wasn't designed on solid rear bushings ... Only the F80 M3/4 was.

[M3AN 4016]

With CSL seats they'd have no concept of NVH from bushings lol! They could use bricks as struts and not feel any difference.

I disagree in principle that solid bushings should be used on a road car. Anecdotal evidence ain't gonna sway me.

[Michael. 2313]

I think if you're going to stiffen one part up, any movement / stress is simply going to shift to the next weak link, IE the sheet metal holding the subrame to the chassis

Having dealt with an E36 falling apart at the rear it was plain to see how the sheet metal in various places split from the welds.

My thought on rubber mounts is they would dampen the shock / stress transferred, of course the older they get the harder they become.

I don't know what the new F80s are designed like, but if its anything like the E36-E46 setup that is concerning.

[tonylauno1 7]

For street use I'd advise against solid bushes. Great for the track, but that's about it.

Uprated bushes will transmit more road vibration into the car... Perhaps not enough to matter but that's a personal taste thing.

Poly bushes - yes, but perhaps stay with stock or marginally increased hardness. Poly bushes won't wear as quickly as stock rubber.

have you changed out your subframe bushing? Have you used any Powerflex bushing in any parts of your car?

Have also heard of Powerflex bushing cracking, that's why i'm asking.

[tonylauno1 7]

Oh gosh no, do not use solid bushings for a street car!

And you'll need your subframe reinforced anyway so don't look to bushings to get out of that task. Although I thought the tearing was only an M3 problem?

Subframe tearing has happened across the e46 range, maybe more on M3 as it's more powerful and driven harder?

It's only subframe that i'm thinking of using solid bushing, differential, rear trailing arm, front control arm are still oem bushing, those i would never use solid.

That is the other question, reinforced or not. Do i really need to, it's a lot of work, i doubt my mechanic can weld, need to transport the car to panelbeater to weld those extra plates, cut open a section from the trunk and weld in there as well and the time to prepare it then also painting it.

Currently the mechanic said there is not movement in the subframe bushing, so no need to change it. I was thinking it's a 15year old car now.

Edited February 15, 2016 by tonylauno1

[tonylauno1 7]

Make it solid so you start cracking the subframe, that is always fun.

Turner Motorsport says with solid subframe bushing, you will avoid subframe cracking the chassis, that issue comes from worn rubber bushing.

[tonylauno1 7]

The F80 M3/4 run solid rear subframe bushings ala the old E92 M3 GTS ... It is simply brilliant for a road car. So I am not sure what all this negativity is about?

The rear subframe floor will tear the same way with rubber or solid bushings, It makes no difference as the torque loading from the differential loading and unloading is verticle and upwards on the front right and downwards on the rear left not side to side. In fact I would wager that the solid bushings will probably place less stress on the verticle torque load as there's no actual verticle movement as you get in the rubber bushings. Force = mass x acceleration.

I think the negativity with solid bushing is from using it on engine mount, transmission mount, differential, front control arm, don't know what affect it has on rear trailing arm.

ok, i see, differential loading and unloading creates more forces on those two corners. Thank you.

[tonylauno1 7]

I think if you're going to stiffen one part up, any movement / stress is simply going to shift to the next weak link, IE the sheet metal holding the subrame to the chassis

Having dealt with an E36 falling apart at the rear it was plain to see how the sheet metal in various places split from the welds.

My thought on rubber mounts is they would dampen the shock / stress transferred, of course the older they get the harder they become.

I don't know what the new F80s are designed like, but if its anything like the E36-E46 setup that is concerning.

That's very true, when one part is stiffen up, another part is taking more stress, maybe it's the diff bushing?

[gjm 3258]

have you changed out your subframe bushing? Have you used any Powerflex bushing in any parts of your car?

Have also heard of Powerflex bushing cracking, that's why i'm asking.

I've only used OEM on our car, and they've only been changed once in (very nearly) 500000km.

The only bush I'd seriously considered replacing with a poly(urethane)bush is the rear mount for the front lower control arms. These are known to wear quickly.

I've used polybushes on many other cars, road and track. Only ever had problems when they were the wrong size or not greased correctly.

I've never used Polyflex - I assume you're referring to the brand/manufacturer? I'd not heard of them failing, but anything is possible.

[zero 1162]

So what type bushings were decided on, and how did the car feel?