Powerflex Rear Subframe Bushing Inserts / Interesting Article

[PSUEng]

Somehow I came across the linked article below, with BW.com info sourcing regarding the Powerflex rear subframe bushing inserts. Anyone here run these? What say the brain trust on these? The article suggests these are a suitable upgrade to an otherwise crack-free RACP and coupled with good stock bushings, may help mitigate RACP cracks/failure. In theory I can understand this point and believe it valid to some degree.

https://grassrootsmotorsports.com/pr...bframe-mounts/

[01SG]

Reads like a shameless sales pitch. So much bad information.

"The root of the issue is the bushings"

No, it's a design flaw. No car should have the floor tearing out because of worn bushings. Who knows what having solid or always new bushings would do from new. But none of them are new. And seeing how it is designed, I 100% think it would fail no matter what.

"like a Powerflex, which is a premium material"

Garbage.

"So it's not a part of the E46 experience, just a possible pitfall.”

It is the e46 m3 experience, sooner or later.

"He even included the BimmerWorld trailing arm bushing installation tool."

More garbage.

[bmwfnatic]

The right front subframe mount has a 'ridge' in it internally that looks like a tunnel, the lip of the stock bushing just happens to sit exactly where that internal ridge is.
When the stock bushing gets worn past a certain point, every time you press the throttle, that right front mount hammers into the outside skin of the mount.
Due to the ridge being there, the outer skin is rather weak, it cracks the metal, which is the most common damage in that area for these cars.

Installing a stiffer bushing that does not allow the stock bushing to hammer, but instead sits flat against the outer skin will 100% solve this issue.
However I am not even convinced that this would solve the entire cracking problem for the front mounts, they are simply not strong enough and will let go at the top first, which will cause the bottom to crack again as well due to the movement, that is my guess.

The rear 2 mounts failing has nothing to do with the bushings at all, it is caused by the floor just being very thin and not having a good structural load path (read: not connected to anything at all).

So yeah, these bushing inserts will probably help against one of many ways that the RACP can crack, but certainly will not keep it crack free.

[Altaran]

Reads like a shameless sales pitch. So much bad information.

"The root of the issue is the bushings"

No, it's a design flaw. No car should have the floor tearing out because of worn bushings. Who knows what having solid or always new bushings would do from new. But none of them are new. And seeing how it is designed, I 100% think it would fail no matter what.

"like a Powerflex, which is a premium material"

Garbage.

"So it's not a part of the E46 experience, just a possible pitfall.”

It is the e46 m3 experience, sooner or later.

"He even included the BimmerWorld trailing arm bushing installation tool."

More garbage.

Agreed with this.

Bushings are not the issue. Most motorsports guys will actually urge you for topside reinforcement If you install stiffer bushings or even solid.

No way is some regular PU bushing going to solve the issue.

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[bigjae46]

Poly anything is ALWAYS a waste of time.