Bushings and Rubber Bits

[Karl Lazlo]

Tearing into my 2003 coupe lately. Slowly making upgrades and looking for options.

Right now, the car rides on stock (sport) springs, Bilstein HDs and ZHP control arms:

- Stock front sway bar bushings (refreshed last fall)
- Stock rear sway bar bushings (original)
- Stock upper strut mounts (<1000miles on them)
- Tie rod end and sway bar links less than a year old (stock)
- Powerflex FCABs (about a year old ~30k)
- RE RSMs and RTABs (done last week)

Having the clutch replaced and while in there, doing the RE motor and trans mounts. Now, my question...

What options are out there (I already priced out Powerflex) for diff and subframe bushings. Street car with some track days planned. Rather a "spirited" driver... Not a DD.

In addition to the diff and subframe bushings, will likely do the rear control arm bushings (~30k on them) along with the R sway bar bushings (18mm, right?)

[slater]

powerflex or AKG are options for rear subframe mounts - i chose AKG because they appeared to have the largest, flattest surface area where the mount meets the rear floor. also, i'm not a huge fan of powerflex products (i don't think the quality is there). the quality of the AKG units are superb.

i chose ECS poly for the diff mounts because they are pretty soft (i think AKGs are 75D - that is stiff!). i wanted some compliance, but also longevity.

i would recommend using the OE M3 'ball joint' upper outer rear control arm 'bushings' (they're really bearings) in both upper outer and lower outer locations (they are located in the hub assembly). it's more costly, but you get better articulation (and less slop) - plus, it's an OE solution as this is how the M3 is spec'd. also, i would highly recommend replacing the rear lower outer eccentric bolts (for camber adjustment).

my upper inner and lower inner rear control arm bushings were in surprisingly good shape; lower inners produced about 10% more deflection that a stock bushing; upper inners were indecipherable in difference, so i elected to only replace the lower inners - and really, the old ones would've been fine. i would check those. but if you're pulling the subframe anyway, and your car has 250K miles, perhaps just replace them. they're cheap.

[Karl Lazlo]

also, i'm not a huge fan of powerflex products (i don't think the quality is there). the quality of the AKG units are superb.

Thanks for sharing. Exactly the info I was looking for.

i chose ECS poly for the diff mounts because they are pretty soft (i think AKGs are 75D - that is stiff!). i wanted some compliance, but also longevity.

ECS is 88A and AKG has a street 95A poly option.

i would recommend using the OE M3 'ball joint' upper outer rear control arm 'bushings' (they're really bearings) in both upper outer and lower outer locations

Ooooo. I never thought of that.

but if you're pulling the subframe anyway, and your car has 250K miles, perhaps just replace them. they're cheap.

Pretty much my thought, as well.

Thanks again!

[slater]

ECS is 88A and AKG has a street 95A poly option.

cool, either the 95A option is new or i just forgot.

definitely contact shawn about renting his koch tools bushing tool - that thing will save you hours of work on this project (BTDT last fall - i own the tool as well, it ROCKS).

[BADCLOWN]

Poly motor and trans mounts are tough, I had them on my old ZHP and it was VERY FIRM. at idle, it shook the entire car. I'd advise against it, go with OEM M3 mounts.

[Karl Lazlo]

definitely contact shawn about renting his koch tools bushing tool - that thing will save you hours of work on this project (BTDT last fall - i own the tool as well, it ROCKS).

I was looking at owning the tool. Though, since the car is going in for a clutch soon, I figure have my indy do all the bits. Keeps me from sitting under the car for a whole weekend.

Poly motor and trans mounts are tough, I had them on my old ZHP and it was VERY FIRM. at idle, it shook the entire car. I'd advise against it, go with OEM M3 mounts.

Yeah, that was my concern. OE M3 mounts were the next logical choice. Thanks.

[GotZHP]

Sub'd.

Would like to see others opinions. My suspension is in desperate need of refreshments.

[Aeternalis]

I went with AKG black poly bushings for my rear subframe and differential. No complaints. I don't intended to track my car though.

[Karl Lazlo]

Would like to see others opinions. My suspension is in desperate need of refreshments.

Pretty much the reason I started this thread. One could go OEM or choose from the myriad of aftermarket solutions.

I just did a refresh on my ZHP. Still on on OE springs, but went with:

- Koni dampers
- OE Upper strut mounts
- OE control arms and bushings
- OE Sway bar end links
- RE RTABs and RSMs

As I tear into the ZSP to finish replacing the old rubber bits, looking at options and opinions. Plenty here have already done what I am about to embark upon. Slater's and BADCLOWN's suggestions have already saved me a few bucks... Hopefully what I learn on my 251k mile ZSP will influence my decisions with the 109k mile ZHP and 100k mile M3.

[Vas]

I pretty much overhauled the complete suspension on my wife's zhp. Since it is her daily, I did not want her to deal with NVH or vibrations and etc.

So I went with:

Koni Yellow Shocks with OE BMW dust boots and bump stops
H&R Springs with OE BMW Spring pads
Rouge Engineering Rear Shock Mounts with reinforcement plates
OE BMW Front Upper Mounts with reinforcement plates
Z4m FCAB
Z4m RTAB with Turner Motor Sports Limiters
OE BMW Rear diff bushings
OE BMW front Sway Bar bushings
OE BMW Front Control Arms
OE BMW Tie Rod Assembly
OE BMW M3 Engine and Trans Mounts

I have not touched the front/rear sway bar links, rear sway bar bushings, rear subframe mounts or the 4 bushings on lower/upper control arms in the rear. Those items will be addressed next and I will go with the OE M3 ball joints in the lower/upper control arm location like the E46 M3.

No complaints from the wife and only positive things to say about how her zhp feels on the road and handles on the numerous country back roads she drives daily.