M3 Upper and lower control arms

[35i-Nut]

What benefits will i get installing these to my Z4 35I ?

Already have H&R sways with poly bushes in the rear drop links and Eibach springs on EDC dampers

Do the control arms throw the standard geometry out ? Can I use standard z4 geometry settings afterwards?

Any feedback from difference in ride ?

[fmorelli]

Well what BMW calls the "wishbone" in the front of our cars (lower control arm, if you wish), 31126786203/4 (left/right) have rubber inner joints on the E89. The E92 M3 has a ball joint. Simply you are going to get less deflection with the ball joint. Note, the arm is not the same wishbone design. Anyway, any time changing structural suspension parts should follow with an alignment. One other note (search threads here) is that you will have to fashion a mount for the passenger-side wishbone mount for the self-leveling lights - totally different on E89 than E92 (thanks BMW). It's not rocket science - forum search will help.

In my case (so this is the, "in my opinion" part), I decided to leave the stock tension strut (if you are an old BMW guy, older models had a "thrust arm" - same basic function except thrust arms come from behind the car and the tension strut on modern BMWs comes from the front). In my case rather than use the E92, I chose to press out the rubber bushing and go with a spherical bearing from AKG. A good alternative is the E92 tension strut for the M3.

Since you are asking about suspension, remember the rear of the car is very E46-like. The rear hub carrier has two suspension mount points (for upper and lower control arm). E46 regular cars were outer rubber bushing. E46 M3 were both ball joints. E89 arms have an upper ball joint and lower arm rubber bushing at the hub carrier. I changed out the lower rubber bushing to a ball joint. As for the inner bushings, they are rubber sleeve and can be replaced, but my suspension guy says the rubber sleeve is so thin that for even serious street use he says it is a waste of time to do the inner bushings.

In the rear, one other thing is the RTABS. With the E46 many run RTAB Limiters. On the Z4, the RTAB is 4mm wider than the E46, so the only real way to run limiters is to push out the RTABs for the E46 M3 RTABs and then install limiters.

You can do all of this yourself if you are handy and can get tools to press bushings in and out. Conversely any good independent BMW shop does this stuff frequently and can do so without much headache.

BMW Factory E46 M3 RTABs or Meyle HD work fine. Limiters can be had (shop around) - I buy mine from FCPEuro. Ball joints I would recommend BMW Factory or Lemforder. Except for the AKG spherical bearing, all my parts come from FCPEuro - those guys rock, fast, good prices—I have ordered probably between 2-3,000 parts from them, never once got the wrong thing. That's for folks in the USA.

Generally speaking the Z4 has been criticized for being too soft as a sports car. The suspension work really helps clean that up, and its responsiveness. The rest is subjective. I'll let those with lots of E89 before/after experience speak to the difference.

Hope this helps,

Filippo

[35i-Nut]

many thanks for your detailed reply! I'm checking out your suspension upgrades in your other thread!

In addition to lower arms etc i'm also thinking of trying the H&R springs to replace my Eibachs , they are slightly lower drop and wondering if this will further help with a slight amount of body roll I'm not happy with at the rear end.

Its worth a shot for the money, if this doesn't resolve the issue then the next upgrade will have to be KW3's.

[jts1981]

Filippo did a great write up, but here is an additional point. The e9x M3 front arms also have increased negative camber. Turner sells the complete package.

I would recommend doing it, plus upgraded bushings. They car will handle better and overall much more enjoyable to drive. Check out my sig fore part list.

[fmorelli]

Originally Posted by jts1981

The e9x M3 front arms also have increased negative camber.

Thanks for clarifying more specifically what the difference in the arm was. Specifically he is referring to the "wishbone" for the P/N I supplied. Camber is not controlled by the tension strut arm.

Originally Posted by jts1981

plus upgraded bushings

Can you specifically mentioned which bushings you are thinking of ... these cars have plenty of them ;-).

Thanks! I wish these threads were way more active ...

Filippo

[jts1981]

Filippo,

I used upgraded RE bushings for the inner lower. I also had group N bushings installed too. Check the email I sent you earlier. It should have all the info.

-Jake

[fmorelli]

Man ... I tried to press lower inner bushings ... oh wait ... you are not running stock lower control arms in the rear, are you? The stamped steel ones, I had a helluva time pressing anything in and out of those (on my E46 project ... same arm as E89)

Filippo

[Tangent]

Originally Posted by fmorelli

Man ... I tried to press lower inner bushings ... oh wait ... you are not running stock lower control arms in the rear, are you? The stamped steel ones, I had a helluva time pressing anything in and out of those (on my E46 project ... same arm as E89)

Filippo

I had a pretty easy time with those bushings on my E46 by using a bushing press kit I borrowed from Autozone. The hardest part was setting the proper preload when reinstalling the brackets. I'm considering going with PowerFlex bushings on my E89 in that application since you don't need to worry about the preload on those.

[fmorelli]

Interesting. Since the arm is split, the bushing would bind and try to compress the arm, twisting it and further binding. I gave up on the E46 (using a press kit). At the end of the day, though, the inner bushing material is fairly thin, so deflection shouldn't be so bad. My vote is for lower outer ball joint (upper is already ball joint) and E46 M3 RTABs with limiters to keep the arm from flopping around.

Filippo

[spiicytuna]

Originally Posted by jts1981

Filippo did a great write up, but here is an additional point. The e9x M3 front arms also have increased negative camber. Turner sells the complete package.

I would recommend doing it, plus upgraded bushings. They car will handle better and overall much more enjoyable to drive. Check out my sig fore part list.

Like to the write-up? e89 specific?

[Xpuzzle]

Great write up and discussion. Looks like a very worthwhile mod to improve E89 handling.

Originally Posted by jts1981

The e9x M3 front arms also have increased negative camber.

To those that have gone this route, what front camber settings did you end up with?

[fmorelli]

My car is for street use and min neg camber we could dial in was -1.5deg with the E9x M3 control arms. Remember the tension strut has nothing to do with camber, so swap in the M3 or just press fit a different bushing into the E89 tension strut.

Filippo

[Xpuzzle]

Originally Posted by fmorelli

My car is for street use and min neg camber we could dial in was -1.5deg with the E9x M3 control arms. Remember the tension strut has nothing to do with camber, so swap in the M3 or just press fit a different bushing into the E89 arm.

Thanks Filippo.

[Vetracr]

This may sound like a stupid question to some but what is an "RTAB"??

[jts1981]

Originally Posted by Vetracr

This may sound like a stupid question to some but what is an "RTAB"??

Rear Trailing Arm Bushing

[fmorelli]

The E46 rear end (which is the designed carried over to the E89 Z4 rear) is known for moving around at the Rear Trailing Arm Bushing. There is a fair bit of space from the sides of the bushing to the cage in which it is mounted. You can read about this exhaustively on E46 forums. The standard solution in E46-land is to use E46 M3 RTAB bushings with limiters. One could leave the factory Z4 RTABs but E46 limiters (there are no Z4 limiters) are too thick, as the E89 RTABs are 4mm wider than the E46. I don't know that the Z4 RTAB is any less dense, rubber-wise, but the change to E46 M3 RTAB is done mostly to support using the E46 limiters. This helps keep the rear trailing arms from deflecting under side load.

Hope this helps,

Filippo

[jannisa]

If anyone would like to get -1,5deg front negative camber without having to purchase any hardware and get the complete alignment specs I got from a racing team in Germany specializing in setting up the e89 for enthusiastic road use and elimination of understeer, just shoot me a pm. Price will be 50 euros and you 'll get detailed instructions on the modifications needed and the precise alignment values.

My car also had adaptive suspension and I had experimented quite a lot to get it to a level I found satisfying, using h&r sways, quaife lsd and going from stock springs to schnitzer (totally crap), then to eibach (not worth it) to revert back to stock springs. Yes, the most enjoyable I got was using the stock springs and the h&r sways gave me a much appreciated precision, I could have spared the $$$ for another 2 sets of springs and the quaife. But in all cases the alignment I 'm talking about made the best difference by far.

[NoQuarter]

So.... You are trying to sell this info.

[Bob20124]

Originally Posted by jannisa

If anyone would like to get -1,5deg front negative camber without having to purchase any hardware and get the complete alignment specs I got from a racing team in Germany specializing in setting up the e89 for enthusiastic road use and elimination of understeer, just shoot me a pm. Price will be 50 euros and you 'll get detailed instructions on the modifications needed and the precise alignment values.

My car also had adaptive suspension and I had experimented quite a lot to get it to a level I found satisfying, using h&r sways, quaife lsd and going from stock springs to schnitzer (totally crap), then to eibach (not worth it) to revert back to stock springs. Yes, the most enjoyable I got was using the stock springs and the h&r sways gave me a much appreciated precision, I could have spared the $$$ for another 2 sets of springs and the quaife. But in all cases the alignment I 'm talking about made the best difference by far.

I guess he believes that's the "Proper" way to help his fellow enthusiasts!
Move it to the classifieds....

[jannisa]

You can thank me later, price is still 50 euros, I paid 200.

[rif75]

Hello Guys

Just want to be sure, some of you have the M3 arms on their Z4? I had it one my 335 but want to be sure that is possible on the z4 since the z4 arms and 335i are not the same ont the etk.

[Vetracr]

Originally Posted by rif75

Hello Guys

Just want to be sure, some of you have the M3 arms on their Z4? I had it one my 335 but want to be sure that is possible on the z4 since the z4 arms and 335i are not the same ont the etk.

E90 M3 control arms fit fine on E89. Only caveat is they add negative camber and toe in which need to be adjusted with alignment. Also you need to fab headlight height adjustment bracket to attach link to control arm.