Bushing recommendations

[Henry Loh]

Moderators, not sure if this is the right place to ask this… please let me know if not!

I need to replace the rear subframe bushings, rear trailing arm bushings (rtab), and differential mounts (am I missing anything else back there besides sway bar bushings?) on my e30 318is. I of course do autocross it and use it for the occasional driving school. It is otherwise a daily driver. I’ve tried to do some online research and there’s too much scattered, old information. I’m hoping some recent 1st hand information from you fellas will help.

I don’t want insane NVM and I do want it to last another 200k miles

Here is what I’m considering based on my research:
subframe bushing – powerflex street PU; OEM and fill with PU?; other suggestions? I really would like solid rubber OEM, but it doesnt exist anymore.

rtab – PU – not sure what brand or Durometer rating

Diff mount bushing – solid rubber if I can find it; PU (again, don’t know what brand or Durometer rating)

Thoughts?

Henry (car #413)

[Jeff Roberts]

I can’t speak specifically to your application, but do some reading on AKG Motorsports bushings. They aren’t marketed like Powerflex, so they don’t have as big a forum following, but when I dug in doing research myself, they kept bubbling up to the top. I used their mid-grade RTABs in my car.

http://www.akgmotorsport.com/catalog/catalog.php?maincat=e30

Some decision help… I went with the middle-ground RTAB bushings on my car. Reason being, it was suggested to me that race grade may put stress on components that were not designed for that level and may cause unexpected problems if not reinforced.

I also went with the same for my rear diff, yet to be installed.

[Nigel Mott]

Hi Henry
The Z3 uses the same rear suspension as the 318 I believe. There is a lot of information on the E36/7/8 Bimmerforum that I read before replacing all the rear bushings in December. The consensus on that forum was Powerflex purple (street) rear sub-frame bushings and OEM RTABs and Differential mount bushings. The rational is that you want more stiffness (less movement) in the sub-frame, but more compliance in the RTABs and Differential mount, for the reason Jeff states. I’ve been happy with the results of this combination on my car. If you need the DIY sub-frame bushing removal tool, let me know. I found the trick to removing the sub-frame bushings was to apply plenty of heat from a hot air gun. This made the rubber ‘slippery.’ Coupe owners who have fitted PU all around tell me they got more NVH in the cabin and this was not my personal preference.

[Henry Loh]

Cool. Thanks guys for the quick feedback!

I’m going to have to look at the differences between the AKG and Powerflex. I forgot I had read some good reviews (and a few bad) on the AKGs as well. In the end, I wnat the one that is more reliable/lasts longer and won’t need to be continuously greased to avoid the squeaks.

So, no PU for the RTABs then?

And for the Diff, I’m going to see if I can get oe/oem solid rubber (Meyle HD?).

PS: Might be buying a swaybar kit that comes with rear subframe, so I might not need the removal tool We shall see!!

[Henry Loh]

Hmmm… yet another indecision impasse. I’ve decided on AKG subframe bushings (their softer, blue, 85a ones). Here’s the rub… $40 for their differential matching 85A diff bushing, or $135 for solid rubber (link below)?
http://store.vacmotorsports.com/bmw—z3m-z3-e30-m-rubber-differential-mount-bushing-p428.aspx

Have not decided on RTABs yet – oem or AKG 85A.

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