Are Current OE Rear Subframe Bushings Improved?

[01SG]

Turner Motorsports, the actual shop, uses solid in every RACP job they do. Their guy said factory bushings have very little rubber anyway.

[SteelGreyM]

that statement just doesn’t seem correct. the differential carrier cage (or subframe) connects to the chassis. it connects the differential (and its driveshaft, drive axles). yes the diff is isolated by three bushings. but those absolutely transmit some NVH. heck if their was no torque supplied through the diff to the axle carrier there would be no RACP cracking. as we know that on/off cycling flexes the panel of the car.
another would be the impact stress at the mounting points. big reason for the engineered rubber mount design, absorb impact stress and isolate.
so I don’t see how that could not have any change.

if I’m understanding something wrong I’m open to see my mistake.

now the consensus i’ve seen shared is it’s minimal for most with solid mounts and stock diff bushings. not arguing that.
but saying to look at design, it’s just not possible solid mounts increase NVH does not seem correct.

Ok. Maybe there’s some but nothing you’ll notice. Seriously. Or if you do it will be so minimal

[old///MFanatic]

The subframe bushings don’t change anything in NVH. It’s just not possible. Just think about how it’s all bolted up...

that statement just doesn’t seem correct. the differential carrier cage (or subframe) connects to the chassis. it connects the differential (and its driveshaft, drive axles). yes the diff is isolated by three bushings. but those absolutely transmit some NVH. heck if their was no torque supplied through the diff to the axle carrier there would be no RACP cracking. as we know that on/off cycling flexes the panel of the car.
another would be the impact stress at the mounting points. big reason for the engineered rubber mount design, absorb impact stress and isolate.
so I don’t see how that could not have any change.

if I’m understanding something wrong I’m open to see my mistake.

now the consensus i’ve seen shared is it’s minimal for most with solid mounts and stock diff bushings. not arguing that.
but saying to look at design, it’s just not possible solid mounts increase NVH does not seem correct.

[r4dr]

I have CMP solid subframe bushings.

I also installed the CMP rtabs.

So much happier with the end result. Ride is firmer (Rtab only to blame here) but so much smoother? Not sure how to describe it. More controlled and less harsh. Just feels F’ing good!

The subframe bushings don’t change anything in NVH. It’s just not possible. Just think about how it’s all bolted up...

I believe rubber bushings effectively increase the spring rate of the corner. So replacing rubber with articulating ball joints softens the ride (or brings it back down, closer to the actual rate of the spring + tire), which is counter-intuitive.

[BMWahba]

Another vote for just getting CMP.

[SteelGreyM]

I have CMP solid subframe bushings.

I also installed the CMP rtabs.

So much happier with the end result. Ride is firmer (Rtab only to blame here) but so much smoother? Not sure how to describe it. More controlled and less harsh. Just feels F’ing good!

The subframe bushings don’t change anything in NVH. It’s just not possible. Just think about how it’s all bolted up...

[old///MFanatic]

Well doesn’t appear anyone has info either way on if the Genuine BMW M mounts are now firmer or improved.

Also have not heard anyone state new M mounts aren’t good at this location.

[0-60motorsports]

Ya get some PSS10s Ejaz and call it a day. Esp if you have sway bars (they help with soft first portion of progressive springs' travel.

Yes Sir, Just waiting for end of May beginning of june to order from germany. Thanks

[Tbonem3]

Ya get some PSS10s Ejaz and call it a day. Esp if you have sway bars (they help with soft first portion of progressive springs' travel)

[0-60motorsports]

There is no way your subframe bushings caused this. I'm on GC with stiffer springs than you and CMP solid RTABs and subframe bushings that were installed post suspension upgrades and there was no significant change in the general "comfort" level of the car. The car is tighter and more "responsive" for lack of a better word but comfort level hasn't changed.

I saw your previous thread where you were discussing the GC coilovers: https://nam3forum.com/forums/forum/m...oilover-choice

You really seemed to love whatever you had on before the GC so why don't you buy what you had before?

Well I can guarantee you then IT IS the suspension. To answer your question about getting DA's again I am not willing to spend 2k on shocks and shipping all the way from Cali to Bahrain. Less than 2k i get PSS10s which have all parts easily available on the market without this rebuild drama with GC and TCK. The rear shocks I paid for brand new ones, then shipped old ones back and they refunded me after 6 months. So not worth it and I think 7-10 years of GC, it worked great until it needed replacements (oh by the way they didnt have any in stock LOL, hence me switching to SAs otherwise my car would have been stuck on a lift for 2-3 months).

[oceansize]

I installed CMP soilds and its a beautiful product. Everything else i have is stock minus GC coilovers. The ride has become horrendously Hard, turned the shocks to full soft and still harsh AF. Spring rates are 440/550.

Now i dont know if this is related to the CMP bushes or spring rates being too stiff....sugestions?

There is no way your subframe bushings caused this. I'm on GC with stiffer springs than you and CMP solid RTABs and subframe bushings that were installed post suspension upgrades and there was no significant change in the general "comfort" level of the car. The car is tighter and more "responsive" for lack of a better word but comfort level hasn't changed.

I saw your previous thread where you were discussing the GC coilovers: https://nam3forum.com/forums/forum/m...oilover-choice

You really seemed to love whatever you had on before the GC so why don't you buy what you had before?

[Obioban]

I installed CMP soilds and its a beautiful product. Everything else i have is stock minus GC coilovers. The ride has become horrendously Hard, turned the shocks to full soft and still harsh AF. Spring rates are 440/550.

Now i dont know if this is related to the CMP bushes or spring rates being too stiff....sugestions?

Subframe bushings should not be able to effect ride quality in any meaningful way. The spring rates aren't what I'd choose, but they shouldn't be back breaking, either. I'd suspect you have a frozen shock or insufficient travel or something binding.

[0-60motorsports]

I installed CMP soilds and its a beautiful product. Everything else i have is stock minus GC coilovers. The ride has become horrendously Hard, turned the shocks to full soft and still harsh AF. Spring rates are 440/550.

Now i dont know if this is related to the CMP bushes or spring rates being too stiff....sugestions?

[heinzboehmer]

If you weren't lowered then this is the expected outcome. From CMP:

If the car is still at factory ride height, the resulting change in camber geometry limits negative camber adjustment to less than ideal for sporty driving. We'd like to imagine that if you've purchased these subframe bushes this likely isn't your first suspension modification however, if your car is still are factory ride height, adjustable camber arms are required to dial in more negative camber.

Yup, I was expecting it to be somewhat off. Car is now (moderately) lowered and rear camber maxed out at -1.3 deg.

I do see some camber arms in my future though.

[Slideways]

Just ask Cayn AussieE46M3 , he is really good dude within the community and always responds with detailed answers. Obioban just installed the CMP subframe bushings on his car and we all know he isn't one to put something wonky on his vehicles.

Yup, I emailed him and he already replied:

"Yes it does effect the angle of both the prop shaft and the axles however, in a positive way. The prop shaft originally dips down to the diff however, bringing it up straightens things reducing misalignment and taking some of the ‘wub’ out of the UJ in the prop for a theoretically longer life.

Same goes for the axles. When you lower a car they can be angled fairly aggressively up and this helps straighten them there too."