Trailing arm reinforcements

[grib]

One of the members of our local board just had reinforcements fabricated (among other things) onto his RTA's. I have Z3 RTA's that I plan to install as part of my 5-lug swap. I'm curious if anyone else has done/considered this in conjunction with a higher-output swap.

I ask because it seems like this is one of the key design changes that BMW made when putting the S52 into the ZM chassis (which has a suspension setup very similar to the e30). The reinforcements basically consist of a triangular plate connecting the hub/knuckle carrier to the main arm and then a cross bar which turns the V arm into an A arm.

http://e30m3performance.com/installs/installs-3/jl_sub/index.htm

[1990m3]

funny you mention it. Since my swapped car is turning into my track car I just removed the entire rear suspension last weekend so I can begin to beef it up a little bit. Swaybar reinforcements along with toe/camber adjustments too. I also plan on a similar M couple style a-arm reinforcement for good measure. Whether or not its necessary is not the point for me, I'm trying to make this a relatively trouble free track car (if that's possible).

[Mike B.]

I've done the re-inforcements just for good measure.

I didn't use weld-in camber/toe adjusters though. I just picked up some shortened, aluminum subframe bushings to effectively raise the subframe. They are cut-down by 12mm, and you need 12mm spacers for the diff and subframe brackets.

This helped dial out a good portion of the camber/toe issues you get when you lower a car.

[cheades]

Mike B - can you give us mroe info on this, where you got them from, etc.

[gobuffs]

http://e30m3performance.com/installs/installs-3/jl_sub/jl-2.htm

I put on the M coupe trailing arms on my car to get larger halfshafts and vented brakes on the rear for the Euro swap.

[Mike B.]

I picked mine up from Muzzi Motorsport, but I am working with AKG Motorsport to get some made here in the States.

Here is a picture (very fuzzy) of one installed. Notice the spacer at the bottom. 12mm doesn't seem like much, but it significantly helps the camber/toe. My car is on coil-overs and I gained around 1.75 to 2 degrees of camber back based on rough measurements. This improved handling significantly.

[1990m3]

Mike B. - do you need a modified bushing that will allow the subframe to sit up higher?

[Mike B.]

Yep, the modified bushing is 12mm shorter, hence the need for spacers to properly locate the diff and bolt up to the subframe brackets.

It is similar in principle to roll-center spacers on E30M3 front struts (which I also installed).

[Jason89i]

Yep, the modified bushing is 12mm shorter, hence the need for spacers to properly locate the diff and bolt up to the subframe brackets.

It is similar in principle to roll-center spacers on E30M3 front struts (which I also installed).

NICE! ive also heard (never tried) installing the bushing upside down.

what did you do with the diff mounting? slotted or offset bushing?

cheers, jason

[Mike B.]

Since the bushing is 12mm shorter than the stock bushing, you can use 12mm spacers for the diff bolts and the subframe brackets.

I found some M12 nuts from McMaster-Carr (12mm thick) and drilled out the centers to use as spacers.

I suppose a slotted or off-set diff bushing would work as well. You would still need the spacers for the subframe brackets.

Since I already had 2-pc poly bushings installed, I was just able to lower the whole subframe as a unit on a jack and pop the new aluminum ones in place. Compared to the task of replacing stock subframe and trailing arm bushing, it was really quite easy.

[cheades]

What were the roll center spacers for the front struts, do you have any pictures of those?

[FredK]

http://www.gsperformance.com/products/rc-spacer/spacer.htm

[Mike B.]

Yep, those are the ones. I should mention that I am running E30M3 suspension componants. The roll center spacers won't work with the 4-lug struts.

[Tom944]

I've got the same subframe bushings from Muzzi as Mike B. Very nice quality and they give a good correction of the camber in the rear.



Diff bushing for stressfree mounting :

[Farbin Kaiber]

I have a feeling I want to see more of your car ^^^^^^^^^^^^^^^^^^