Are Current OE Rear Subframe Bushings Improved?

[BMWahba]

Another vote for just getting CMP.

[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.

[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.

[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

[01SG]

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

[old///MFanatic]

With seeing all the favorable replies to suggested use of solid mounts. (Thanks all for previous contributions/information)
I’ll just keep next question in this thread. I’m sure there’s things I’m missing. Thanks for any and all input.

*What are the largest advantages of:
Solid aluminum mounts vs. Condor’s (UHMW) mounts?*
Aluminum mounts: One piece design(less failure options), Solid no flexing, Some brands make shorter to compensate for plates.
Condor Speed UHMW material: Absorbs vibrations, Lighter weight, Top hat stability(?), Easier to install (tolerances in subframe), Cost advantage.

> Condor Speed Shop subframe mounts
https://www.condorspeedshop.com/coll...ngs-e46-e46-m3

[SteelGreyM]

With seeing all the favorable replies to suggested use of solid mounts. (Thanks all for previous contributions/information)
I’ll just keep next question in this thread. I’m sure there’s things I’m missing. Thanks for any and all input.

*What are the largest advantages of:
Solid aluminum mounts vs. Condor’s (UHMW) mounts?*
Aluminum mounts: One piece design(less failure options), Solid no flexing, Some brands make shorter to compensate for plates.
Condor Speed UHMW material: Absorbs vibrations, Lighter weight, Top hat stability(?), Easier to install (tolerances in subframe), Cost advantage.

> Condor Speed Shop subframe mounts
https://www.condorspeedshop.com/coll...ngs-e46-e46-m3

You are overthinking this. Use this energy and time on comparing RTAB choices instead

FWIW I have CMP mounts on CMP plates. CMP Rtab as well (my favorite RTAB on the market). Very happy with the setup and will be repurchasing the CMP Rtab in the future.

[heinzboehmer]

Very happy with the setup and will be repurchasing the CMP Rtab in the future.

Best thing about the CMP RTABs is that they use a lemforder (I think) bearing. So if it wears out you can just press a new one in. No need to get everything again unless it's for another car.

[old///MFanatic]

You are overthinking this. Use this energy and time on comparing RTAB choices instead

Already researched that, fun stuff. Yeah I don’t really want that new topic in this thread. Figured since this was a subframe mount topic with others already in thread it could get new answers. Seeing nobody can provide info between aluminum and UHMW material I may have to make a new thread.
Why am I researching? I don’t have free access to a lift any longer so don’t want to do job twice. I want to make the best choice for my car and needs. If Condor Speed is everything aluminum is but absorbs vibrations, lighter, easier to install and less expensive. Seems like the logical choice over aluminum.

[r4dr]

If Condor Speed is everything aluminum is but absorbs vibrations, lighter, easier to install and less expensive. Seems like the logical choice over aluminum.

Condor's UHMW stuff has popped up in the E30 world a fair amount. I don't buy that it's this magical material that's as solid as aluminum but somehow absorbs vibrations.

[old///MFanatic]

Condor's UHMW stuff has popped up in the E30 world a fair amount. I don't buy that it's this magical material that's as solid as aluminum but somehow absorbs vibrations.

Hit a chef knife on a professional culinary cutting board (similar material). Then hit that chef knife on an aluminum board.
Seems very possible it absorbs some vibrations that aluminum would not. No?

[SteelGreyM]

Dude everyone here is telling you there’s no noticeable difference in solid mounts vs OE rubber mounts. The condor ones are so similar to solid that it makes sense to just get the solid ones. It seriously doesn’t matter. You aren’t sacrificing anything here...

I get it. We all like splitting hairs and planning every detail about our cars. That’s why we are on M forum. But seriously there’s no difference. Just buy one

[r4dr]

Hit a chef knife on a professional culinary cutting board (similar material). Then hit that chef knife on an aluminum board.
Seems very possible it absorbs some vibrations that aluminum would not. No?

It's been a while since I remember the debates on R3vlimited, but one major downside of UHMW is that it's not as solid as metal but also doesn't rebound like poly.

[old///MFanatic]

Dude everyone here is telling you there’s no noticeable difference in solid mounts vs OE rubber mounts. The condor ones are so similar to solid that it makes sense to just get the solid ones. It seriously doesn’t matter. You aren’t sacrificing anything here...

I get that majority in thread is contributing there’s not much difference in NVH at this point. Accepted.
Manufacturer of aluminum mounts states CON of solid is harder on impacts at the studs. *Best to use with bottom and topside reinforcements. So there’s that straight from the horse’s mouth.
I’ve currently asked between Solid aluminum and Condor Speed now because I’m between the two. Similar lack of material flex but some design differences. Now I’m simply asking for anyone in the know what are Pro/Cons between those two. Not hearing any. Since no one yet has provided info that aluminum solid are superior then Condor Speed appears in the pros vs cons best choice at this point. If “top hat” or lack of is better or worse that would be a factor. Vince mentioned this.

Your point they’re similar is not lost on me, I already considered that. Just looking for knowledge from a few here who actually know this stuff compared to other forums where true details aren’t known because they must pay people to work on their cars and know very little. This forum actually has legit knowledge from a few. That’s why I am here.

[Tbonem3]

Agreed, and it was only a guess on m3f that solid would be ok since it comes that way on new bmw Ms.

As it pertains to you, it was also guessed that rubber bushings cause cracks as they give and subframe can rock and pull on racp.

I hedged my bets with poly, big foot print, more solid than rubber, but gives vs solid. Plus no rotation, which is why only poly on my car is camber plate, subframe, diff & rsm. Fcab rtab and control arm inners must be rubber or bearing.

I for one appreciate you mentioning the condor ones, I think they're worth a shout, though r4dr's comment causes pause.

Having said all this, it could just be a abundantly cautionary sales disclaimer. It does not prove that manufacturers of solid e46 m3 sub bushings truly believe installing them will cause worse fatigue.