Suspension Refresh - Poly or OEM?

[JJJames]

Hi all,

Debating a suspension refresh of sorts over the winter - of all the various control arm/sway bar/trailing arm/diff/subframe bushings out there, which are worth upgrading to polyurethane, and which aren't?

Its a street driven car only. Interested in the upgrade only for longevity/durability reasons more than anything. Worth it?

[pbonsalb]

I doubt most people could tell much difference over fresh stock. For example, I recently went from poly RTAB to stock Z4 RTAB plus Vorshlag limiters and cannot tell any difference. I have run poly and delrin FCAB and find the delrin too noncompliant to make for a great street car, but have not tried the upgrade solid rubber FCAB that Bimmerworld sells (I did not like Bimmerworld's poly RTAB limiters -- they squeaked). I would probably be just as happy with them.

I do like the poly subframe mounts. There are no stiffer stock versions. I also like the poly differential mounts. Again, there are no upgrade rubber ones.

For engine mounts, Bimmerworld sells an upgrade solid rubber mount. I have run those and run Vorshlag poly engine mounts. The poly have a tiny bit of NVH but are not at all objectionable. However, I was also perfectly happy with the Bimmerworld solid rubber.

I tried some hard poly race spec tranny mounts and removed them almost immediately. I now run UUC regular black mounts, which are larger than stock and an upgrade and totally fine for a street car.

I would be selective. I would also buy poly only for a performance upgrade and not for durability or longevity. They are probably more durable in the RTAB location -- mine were in such good shape when I removed them after 6 years that I put them in another car. I am not sure anything is super durable in the FCAB -- my first set of poly cracked after about 4 years. Poly tranny mounts are probably more durable than the small stock ones. Other than those 3 locations, I think all the stock stuff is pretty durable.

[ThreeD]

^great post

[Eric98Sedan]

Hi all,

Debating a suspension refresh of sorts over the winter - of all the various control arm/sway bar/trailing arm/diff/subframe bushings out there, which are worth upgrading to polyurethane, and which aren't?

Its a street driven car only. Interested in the upgrade only for longevity/durability reasons more than anything. Worth it?

I'm planning a full refresh as well. The only poly I will use is an AKG front diff bushing and AKG 85A (the super softies) Rtabs. Otherwise 100% OEM.

As an OEM *upgrade* I use E46 M3 rear shock mounts and tranny mounts. Both stiffer than 36 parts and bolt right in.

[JJJames]

I doubt most people could tell much difference over fresh stock. For example, I recently went from poly RTAB to stock Z4 RTAB plus Vorshlag limiters and cannot tell any difference. I have run poly and delrin FCAB and find the delrin too noncompliant to make for a great street car, but have not tried the upgrade solid rubber FCAB that Bimmerworld sells (I did not like Bimmerworld's poly RTAB limiters -- they squeaked). I would probably be just as happy with them.

I do like the poly subframe mounts. There are no stiffer stock versions. I also like the poly differential mounts. Again, there are no upgrade rubber ones.

For engine mounts, Bimmerworld sells an upgrade solid rubber mount. I have run those and run Vorshlag poly engine mounts. The poly have a tiny bit of NVH but are not at all objectionable. However, I was also perfectly happy with the Bimmerworld solid rubber.

I tried some hard poly race spec tranny mounts and removed them almost immediately. I now run UUC regular black mounts, which are larger than stock and an upgrade and totally fine for a street car.

I would be selective. I would also buy poly only for a performance upgrade and not for durability or longevity. They are probably more durable in the RTAB location -- mine were in such good shape when I removed them after 6 years that I put them in another car. I am not sure anything is super durable in the FCAB -- my first set of poly cracked after about 4 years. Poly tranny mounts are probably more durable than the small stock ones. Other than those 3 locations, I think all the stock stuff is pretty durable.

This is exactly the kind of response I was hoping for. Thanks a ton - looks like I'll be going poly dif/subframe, maybe solid rubber FCAB/engine mounts, and OEM for the rest.

[jayjaya29]

Spot on for street.

[KnudsonsM3]

I have akg 80A on my 323i and they're great. I would use a 95A or 60D on my m3. We're hard on our cars and I think the poly will last longer.

Another thing about poly is the ease of install. OE is a pita.

[pbonsalb]

Poly is easier to install, since most of the poly bushings are two piece and not metal sleeved. Getting the old stock ones out, since they are often stuck or corroded in place, is probably harder than getting new stock ones back in but still far from easy. Having DIY or professional tools helps.

[RatedM3]

+1 for rubber everywhere. Get delrin RTAB limiters. And for the front diff, upgrade to the 10.9 grade bolt.

[Hova]

+1 for rubber everywhere. Get delrin RTAB limiters. And for the front diff, upgrade to the 10.9 grade bolt.

This right here!!!!

I can not stress enough how great this advise is. Rubber is the only bushing street cars should have.

[MMMGP]

If in doubt... go OE rubber all 'round! Can't go wrong!