Anyone personally installed a Z3M rear end?

[cpatstone]

Has anyone here ever actually done a rear end upgrade, IE put on the M coupe/roadster trailing arms?

Seems that the brake pipe routing is different. wondering how you solved that issue.

Could modify the arms to accept ti piping, possibly use M3 rear calipers; or modify the body-side hard pipe to mimic the Z3M setup...

References to previous write-ups welcome. Something must be out there. Thanks!

[J!m]

I swapped the whole thing in after I swapped my engine.

easiest thing to do is to swap the ti brake pipes (and pipe holders) over to the roadster arms. You need to trim the pipes and re-flare them (ISO "bubble" flare- get a proper kit for it!!)

Then it is a matter of seven bolts to swap it in...

Yes, you can go with the Roadster routing, but there are no provisions for pipe mounts under the ti body, so you have to cut and/or weld to make it work. Swapping pipes and clips over from the ti is slick, because the holes for the clips are on the roadster arms already, and pretty much bent to drop right in. Plus you can then drop the arms low enough to swap springs by disconnecting the lower shock mounts, which is nice...

It should be noted that you need the M3/M roadster front brakes as well if using these rear brakes, or the bias will be way off and you will wreck driving (stopping specifically) in the rain...

No need to, but some change to the M3 master cylinder too...

[cpatstone]

Thanks Jim. Probably should have thought to email you first.

Did you use the m roadster/coupe rear calipers, with the pipe going into round back face of the piston area, or the M3 ones, with the pipe going in on the edge? guessing the latter?

Also, I think my Mcoupe arms didn't have the clips or provisions, which would mean I'd have to drill and tap holes, and install studs to accept the clips. Will have to look at that again. Suppose that's way easier than welding on brackets and fabricating the hard lines.

Thanks for the advice!

[J!m]

Originally Posted by cpatstone

Thanks Jim. Probably should have thought to email you first.

Did you use the m roadster/coupe rear calipers, with the pipe going into round back face of the piston area, or the M3 ones, with the pipe going in on the edge? guessing the latter?

See above: I swapped the M Roadster assembly in COMPLETE.

Originally Posted by cpatstone

Also, I think my Mcoupe arms didn't have the clips or provisions, which would mean I'd have to drill and tap holes, and install studs to accept the clips. Will have to look at that again. Suppose that's way easier than welding on brackets and fabricating the hard lines.

Strange, because I thought the trailing arms were/are the same part number for the coupe and roadster... Mine had the holes for the clips which I just removed from the ti arms poped in place on the roadster arms. SLIGHT tweaking of the pipes is needed due to larger arms of the roadster, but basically it is simple.

Originally Posted by cpatstone

Thanks for the advice!

No problem...

[cpatstone]

Follow-up:
* I used M3 rear calipers. The difference between those and the Mcoupe/roadster ones is that the latter has the hole in the rear face of the caliper. Regular M3 ones have the flex pipe hole in the same orientation as the ti (otherwise no visible difference).
* Mcoupe/roadster arms have a main mounting point at the body end like the Ti arms. that's where the hardline transitions to the flex pipe. But, in between there and the caliper, there's no stud for the plastic clip, and no hook-thing on the back side of the brake shield, and no bracket to transition from the hard line to the caliper flex pipe. I used some stainless zip ties, then riveted on a bracket improvised from a leftover M3 bracket. It ain't pretty but should be OK.
* the mcoupe/roadster arms have a different offset, so the ti hard lines don't quite fit. need a little mutilation at the wheel end.
* overall - i went that route because it was much easier than adopting the mcoupe/roadster mounting/piping scheme.

[Platanos]

I'll be doing this tonight or tomorrow. I have the complete rear end. I am guessing the lines is the biggest obstacle? I've read and like Jim said, its a matter of bolting it right up, I really hope so!

[J!m]

Pretty straight forward.

It sounds as if you use the M3 calipers you won't have to re-flare the hard lines from the ti. I use the M Roadster calipers (why change them??) and the end of the hard line had to be cut and bent a bit differently and of course re-flared.

[Platanos]

Thanks for the quick reply Jim! I'll be using the roadster calipers. I hope to have this done in just a few hours. I have access to a lift, so that's half the battle I'll try to remember to take some pics and post them up.

[Platanos]

I'm also changing all the bushings. I'm going from a 2.93 to a 3.46 torsion diff. It should feel pretty different

[J!m]

A lift would be nice!

Leave the stock rubber flex lines on the car before the sub frame and clamp them closed. Then pull the original sub down, transfer everything to the new one, send it back up (replace the rubber hose with teflon of course) and the bleeding will go fast. If you allow it to totally drain while messing around with the new sub, it will take longer to bleed than anything else...

Don't forget to bleed the fronts after you do the backs too. You are probably due for a brake fluid change anyway...

[Platanos]

Thanks for the tips!! I have a few cans of that blue something brake fluid. I plan on bleeding the whole system.