Quote:
Originally Posted by spidertri
So I don't want to take over Mike's thread with brake discussion but I want to clear up a few things that don't transfer from E9x to E82.
1) The E9x N52 cars use the same MC as the N54/N55 335i cars, this is not true with the 128i and 135i, the 128 uses a smaller MC. The 135i uses the same larger MC as the E9x cars. So there is a definite advantage to swapping to the larger 135i/328i/335i MC if you have a 128i.
2) The performance brake option for the 128i is very unbalanced compared to the performance brakes for the 328i. Adding the 135i front caliper/rotor and only increasing the rear caliper piston diameter to 42mm on the 128i moves the brake bias forward by quite a bit.
3) If the coding for the performance brakes on the 128i does anything, it's going to be for the heavily front biased set up of 135i brakes in the front and 42mm piston calipers in the rear. If you end up swapping rear 335i brakes you really should change the coding back to the stock because you'd no longer have such a front biased system.
4) None of the larger rear brake options, besides the 42mm caliper, are a direct fit on the 128i. 135i rear brakes still require an e-brake solution, 335i calipers/rotors require the hub mod and e-brake, and F30 rears need a special rotor, e-brake, and caliper mounting.
5) Do whatever you can to increase cooling air to the front and rear brakes on the 128i. The front m-sport bumper is very good at sending air to the wheel wells, and you can trim a great deal of the backing plate away to allow air to get into the center of the rotor. The rear backing plates are incredibly insulating, trim as much of them away as possible, a little more difficult in the rear due to all of the control arms but it still makes a difference.
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I'll add the 42mm rear calipers from a 328i to the plan. The F30 brakes & rotors are already purchased, and the master cylinder is planned as well. If 42mm turns out to not be enough, I'll move up to the 335i rear brake option.
My stock front calipers were measuring ~900-1000 degrees coming off track. I still daily the car and I'm hoping with the extra thermal capacity of the larger F30 rotors and calipers I'll be able to avoid brake ducting. I'll see what the temps say next season and go from there.
Thanks for all the brake input!