The Z3 based M Coupes and M Roadsters all came with 188mm LSDs. The axles on the Z3 based M cars is thicker than the stock ti and E30 325 axle.
At the bearing, the Z3 M trailing arm is reinforced. You are also correct that the M Z3 axles are offset further in so you will need to add at least 20mm to the spacer you're already using to maintain current wheel position.
That said, I don't think ti arms, E30 axles and a 188mm diff would have any trouble handling 400whp. You can take the arms off and have them reinforced to mimic the reinforcements on the M Z3 arms if you wanted to.
I'm not a fan of the finned diff covers on track cars. They hang too low for my comfort. A real diff cooler is a much better option.
Quote:
Originally Posted by Steve K-B  Hi people, Im looking for an upgrade to my axles and possibly rear arms etc. I'm currently running an S54 in my 318ti making 280 rwhp (what torque I have.... I'm not sure). there is more power to come out of out of it and I'm also looking at a supercharger system for the future so want a set up that can handle up to 400 rwhp. I have two question areas, if you have any of the answers I would love to hear from you. 1: I currently have a medium case 6 bolt 3.91 diff and E30 325i axles (same as E30 M3). What power/torque can these handle before they give problems? Is the 8 bolt 210mm diff an over kill? Has any one put one of these in a ti? What diff did the E36 Z3M use? 2: Since my engine upgrade from 180 to 280 rwhp I have not surprisingly broken the stub shaft off the outer CV. I see there are lots of options of using custom axles like here: https://www.pureperformancemotorspor...ft-axle-s.html The only problem i see is the area where it broke wont have changed. I know little of the Z3M upgrade, Does this give you you a larger axle? I believe the off set in the arm is larger. I use a 20mm spacer on the rear so this shouldn't be a problem other than it being very expensive option. The car is only raced on tarmac roads and I can be pretty rough on my drive line. I'm looking for something strong and reliable. Thank you in advance Steve |