Did you try Z3 M hubs? I've read that the Z3M subframe/trailing arm combo is the same overall width as the 1.9L subframe/trailing arms. The non-M 6cyl Z3 subframe and trailing arms are wider than both of the other versions.

Looks like the subframe part number is the same for the Z3 2.8 and the 318ti. Do you still have your ti trailing arms? bolt those up and it should fit perfectly.

No fit
 

Thanks for the tip. Unfortunately, the ti trailing arms will not fit the Z3 rear axle. Not sure what to do now. I might just be stuck rolling and pulling the fenders out about a whole inch. Hope it doesn't look to weird. Anyone else? Thanks in advance

The ti trailing arms won't bolt up to the 2.8 subframe?

Yes, they will bolt up but will not be the correct length. The 2.8 Z3 subframe is much bigger and stronger than the ti.

That's weird because realoem says the subframe is the same part number between the two cars. The trailing arms are different part numbers though.

That's the problem: The trailing arms

Yeah I know, if you still have the ti trailing arms why don't you install those? That would put it back to "stock" for the ti fenders.

Won't work. The ti trailing arms will bolt on but the Z3 axle (which is now on my ti) is W-I-D-E-R the the ti axle by about 2 inches.

Use your ti halfshafts. The output flanges pop right out of the diff and you could use your ti output flanges, halfshafts and trailing arms. As Dave said, the subframe is the same between the ti and 2.8L Z3, so swapping the subframe and trailing arms serves no benefit.

BTW, the reason the 2.8L Z3 halfshafts are longer than the ti halfshafts is because the trailing arms stick out further than the ti trailing arms. The only benefit of swapping rear subframes and trailing arms would be if they came off of an MZ3. Then you'd be able to use MZ3 rear brakes. The MZ3's trailing arms probably wouldn't stick out as far as the 2.8 Z3 trailing arms because the MZ3 uses wider wheels in the rear. The 2.8L and 1.9L Z3's use the same size rotor as the 318ti, 272x10mm while the MZ3 uses a 312x20mm vented rotor.

Yeah, use the ti axles or get some E30 axles if you want to run a medium case diff.

Good call Dave, I didn't think about that. RCV7, if you're running the 2.8L Z3 medium case diff, the ti halfshafts will still be too long, you'll need to get 6cyl e30 halfshafts and output flanges, which will also require you to shim your ABS sensors(just a washer).

So to clarify, use your current 2.8L Z3 subframe(same as 318ti subframe), 318ti trailing arms, 2.8L Z3 medium case LSD, e30 325i or 325is halfshafts and output flanges, pick up two washers with 5/8" centers at your local hardware store and shim your ABS sensors. Problem solved!

NICE!

ahem jesse ahem ur next... hah

Did not fully read the thread... sorry. Jess gave you the correct info. The Z3 arms are just more weight... no real upgrade. Have you ever seen a bent ti trailing arm?

I really like your part choices, great build. I have an aluminum block 2.8 that I have not decided what to do with.

Shot
 

Great suggestions. I'm going to give it a shot. I happen to have the e30 parts and will let you know how it works out. As per J!m's manual and email advice, I installed the Z3 subframe with larger dif to match the Z3's trans and 2.8 engine. He highly suggested it. Hopefully this will all work out. Thanks again!

SUCCESS!!
 

Very happy as I had success with cooljess76's recommendation on the e30 halfshafts and output flanges. The wheels and tires now fit perfectly. I also installed the Comforti Shark injector and the e46 330i front brake setup. Now for some fun, spirited driving. Thanks to all who contributed. :wink: