KICK ASS! How do you like the 3.15 diff?

3.15 dif
 

The 3.15 dif is perfect for this setup. Plenty of kick on both upper and lower ends of the power-band without revving too high at speed. This car is very fast! Very happy! Thanks again

Thank you for sharing your awesome build and congrats on a job well done!

Really like the Euro 3 spoke wheel, I have one of those and a M tech II E36 wheel with no airbag. I have been kicking about swapping out my wheel and installing one of the others. Did you get an airbag light or have any issues to resolve?

Hello Roy!

Sorry for not getting in here sooner- your e-mail to me went right into my junk folder for some reason...

Anyway, I'm glad you got the rear width sorted out.

Also interesting that other than the M Roadster, the rear sub frame is wider on ALL Z3 cars (and I have to then assume all M Coupes as well).

I will make this clarification in the manual to prevent future problems for swappers. I always suggested the M Roadster/Coupe rear sub frame for the obvious reasons; now I can reinforce that argument with this less obvious reason.

The E30 half shaft (and wheel speed sensor shimming) info are already in there.

Glad it worked out in the end and you are happy with the result. These are really fun cars when built up with the right amount of power.

Not exactly... The sub frames on all the ti's, Z3, and MZ3's are exactly the same width. The MZ3 sub frame has a different part number because it has the brackets for the dual exhaust hangars.

The sub frames (and trailing arms) on all MZ3 models are identical, coupe and roadster makes no difference.

The difference in the rear track width comes from the trailing arms... not the sub frame. The best way to demonstrate this visually is to look at the width of the 'hat' portion of the rear rotor. On the M Coupe/Roadster is is not wide at all... think 1-1.5 inches... on the rest of the Z3 line the width is more like the rear rotors on a ti... 4 inches or so. This is why the M Coupe/Roadster rear wheels stick out too far on anything else but an M Coupe/Roadster.

Because of the M Coupe/Roadsters thin rotor 'hats' (and resulting narrower width between left and right) the MZ3 trailing arms are perfect for fit on a ti without having to use a wheel with a giant offset like the M Coupe M Roadster does.

Hope this helps.

OK That makes is more clear.

The sub frame IS different in that besides the exhaust hangars, it also is significantly heavier (duty and physical weight); however they don't often fail, so you could stick with the ti part (although weight savings over the rear wheels is NOT an issue with the ti)...

As I recall, the M Trailing arms were also significantly heavier (duty/weight) than the ti ones as well. These only fail when they meet inanimate objects at elevated velocity.:redface:

I stand by my original suggestion: Use the M roadster or M coupe rear sub frame/diff/trailing arms/brake assembly complete when doing a swap.

This brings up another thought:

If the sub frames are in fact the same, then the M Roadster adjustment bushings could be used in the ti right?

I THINK the size of the bushings is also larger on the M part versus the ti part.

Please correct me if I'm wrong; if I am, then all ti owners can use these M correction bushings (I sort-of think these only fit the M part):confused: which would be a very cool discovery!

I think some of the confusion here is coming from the fact that the sub frame and the trailing arms are different parts. At some points on this thread the sub frame is discussed as the trailing arms are part of it. They are not.

If you want to run a MZ3 spec rear end on your ti you just need the MZ3 trailing arms. Your ti sub frame works fine.

The M trailing arms are heavier. I do not believe there is any difference in the sub frame between the ti and the MZ3 other than the exhaust hangars.

Any bushings that will fit the MZ3 rear sub frame, trailing arms, or differential will also fit the ti.

My memory suggests that the M Roadster sub frame is physically larger (in girth) and also in weight. Bolt hole locations are of course in the same locations and it has the hangars on it, but it is more heavy than just those exhaust tabs would suggest (by a long shot). I scrapped my ti sub frame (no one wanted it) so I cannot do a side-by side (well, over-under) now. Since I had both complete assemblies out of the car, I seem to recall being impressed by the size of the M part.

This is great news! I wonder why no one has ever used them in a ti before (well, not that I'm aware of anyway). I always thought there was a reason for this.

Now I have to find one to be sure... :smile:

Yeah, I wish I had more pictures!

When I installed the new sub frame, I did take pictures but the film was damaged (it was quite a while ago- remember film?)

Anyway, another piece of evidence is that the parking brake cables are just a bit too short to use on the roadster sub frame when installed in the ti. All the cable clips transfer right over (all holes are drilled in the same place) but if you clip the cable in, it pops out of the clips. I had to use ty-wraps to secure it in my car. This could be driven by the brake arrangement being slightly different, but it is not very different at all really, so I think it is the slight increase in girth of the sub frame and trailing arms.

I thought this was common knowledge? I put a M diff bushing in a few years ago. The trailing arm and subframe bushings are the exact same part numbers for the 318ti and the Z3M.

Great! Then the offset bushings CAN be used in a stock ti set up.

Glad we have this confirmed!

Nope, no airbag light. Bolted right up with no problems. Airbags are good