M Rear end.....

[Defy]

Ok so if i could afford a Z4M, better yet if my wife would let me sell my house to buy one , i would. But i kinda of fancy not being poor so i am trying to go for the next best thing.

I am happy with the power from my Z, so i am looking to do all the suspension stuff i can to really make it kick but. Right now it is strait stock with runflats and all and i break it loose at least once a week (sideways, ahh the old days with my 95 240sx in Colorado). I thought i read somewhere that you can put a M rear end in the 2003-2005 2.5/3.0's. Can you? Is it fairly plug and play? When i was watching the megafactories i saw them put in the whole rear end subframe and it look like 8 bolts plus all the hoses and such. Will a z4m rear end fit or any other M rear ends?

Or should i stop over analyzing and just put a good suspension and some non runflats?

 

[epbrown]

The Z4M and E46M3 rear ends will fit physically, and Simpson Motorsports did it, iirc, back when BMW was saying there would be no Z4M models. If you're looking for a limited slip differential, I think it'd be cheaper and easier to get a Turner Motorsports aftermarket slippy diff. Personally, if I were in your situation I'd save up a bit of cash and move from a 2.5i to a 3.0i first, then get a 3.46 ratio LSD down the line.

 

[Curtis]

The Z4M and E46M3 rear ends will fit physically, and Simpson Motorsports did it, iirc, back when BMW was saying there would be no Z4M models. If you're looking for a limited slip differential, I think it'd be cheaper and easier to get a Turner Motorsports aftermarket slippy diff. Personally, if I were in your situation I'd save up a bit of cash and move from a 2.5i to a 3.0i first, then get a 3.46 ratio LSD down the line.

I had an E46 M3 rear axle fitted at Simpsons. It was a fairly straight swap however you do have to shorten the propshaft due to the M diff being longer and change the wheels for a different offset because the M axle is narrower than the standard Z4 unit. This suited me fine as it allowed me to fit original CSL rims. It is a much tougher rear axle which is great if you give your car a lot of punishment plus is has the 3.62 ratio however an aftermarket LSD such as the ones epbrown describes would be a simpler install.

 

[Defy]

Personally, if I were in your situation I'd save up a bit of cash and move from a 2.5i to a 3.0i first, then get a 3.46 ratio LSD down the line.

I almost bought the 3.0 but i drove both and really didn't notice a 5000$ difference ( i got mine for 17 and the 3.0i was 22 and some change) and the 2.5 had the red interior that loved. I figured for 5k i could turbo/supercharge it and make up the difference in the end. So i think i will keep my eye out for an E46 M3 rear end and go from there. Thanks.

 

[vachss]

This thread (and my lingering annoyance at always losing power and watching the bright yellow DSC indicator light up in the hairpins of my favorite mountain road) is rekindling my interest in Limited Slips for the 3.0si. While I know a new custom built unit will work fine the $3-4K price tag just seems prohibitive (that's almost half the difference to the M right there). So I wonder if the whole rear end of a wrecked E46 M3 could be had for less. While this certainly would be no weekend project the idea of swapping out everything from the driveshaft to the rims has some appeal. The question is what the rear clip of an M3 will go for when parted out. Anybody know some typical numbers?

 

[Defy]

The question is what the rear clip of an M3 will go for when parted out. Anybody know some typical numbers?

now were talking