Which big brakes for an e28?

[genphreak]

Hallo fellows!

I know I might be better asking this on firstfives or one of the e28 forums, but peeps here probably know just as much... :) but here goes-

Some of our state-side cousins are doing me a great favour in sending me some parts (thanks a heeeeap good fellows), so soon I should be about ready to fit new brakes to the e28 and the e34...

What I have planned:
e34: Present
Front; Stock calipers 302/22mm vented rotors;
Rear; 300/10mm solid rotors

to become;
Front; e31 single piston calipers with 324/30mm rotors,
Rear; 300/20mm ventilateds

e28: Present
Front; Stock 282mm/25mm vented rotors
Rear; Stock 284mm/10mm solid rotors

to become;
Front; e34 (540) calipers with 302/28mm rotors
Rear; ? (not sure)

What is a good choice for the rear of the e28 ('86 535i) with the 540 setup on the front?

Do I go with a set of 300/10mm or should I go 20mm ventilated to match the heat that the fronts can take? Stock it looks like the rear is much smaller than the front so I am figuring 300/10 is suitable as the stock ones are only 284/10... the e28 is a much lighter car after all.

Thanks in advance... Nick



ust got my old e28 flying again, except the brakes are shot. She's awaiting some rust repairs and the e34 brakes once I get these pads etc from you. So that makes two cars to be back on the road once I get these from you. The e28 is getting 540 brakes up front and 535 solids at the rear, emulating the same difference in the stock brakes which have a diameter difference as well. Both cars should withstand serious driving after that, espeically as the e34 is getting offset bushes installed.

[genphreak]

Here's an awesome resource on this topic...
http://member.rivernet.com.au/btaylor/BMWText/technical/BrakeRotorUpgradeE28M5.html

but I still can't figure out what to use... :p

[Brandon J]

Any e34 upgrade to the e28 is much better. Ther rear piston size of the e28 is also smaller than a stock e34 and the rear piston of 540/M5 calipers are even bigger. So you can use your old e34 ones. You don't have to go vented out back. Might turn out worse as far as balancing the car out. You don't have the weight of sls in the rear, you don't have a staggered set-up, you don't have the extra weight of the e34. The vented rotors also weigh more. It sounds like this e28 isn't going to be a track car, but more of a performance street. So, go e34 basic set-up, plus a 750i master cylinder, and some good pads. This will make a big difference as you might have to push longer and harder to stop with the e34 brakes if you don't use the 750 master cylinder.

I have done a few of these e34 upgrades and they go very well. Stock pieces are great using the 750 master cylinder. They will fit as long as you have at least 15in wheels instead of the metric ones and with 205/60 15 tires. I can't remember if I trimmed the rear backing plate or not to fit the rotors, but that is something to keep in mind.

Here is a relevant story. I went to the track with an e39 M5 supercharged. The guy had Brembo Monoblock, with the rotors that were something like 15in big. He HATED the brakes on the street. They never got warm. They made noise and stopping was there, but not feeling good. He had to brake real hard at the track to just get them warm enough and to clean them off as they began to create uneven spots on the rotors from daily driving. He said he wants to get rid of them now. So, get what you need for 95% of the time. If you go to the track, buy loud/dusty track pads that can withstand the heat.

Good luck with your decision.

[genphreak]

Thanks Brandon. Sounds like I can get away with fittng my 535 e34 kit on the e28 and get all the performance I want. I was considering 540 fronts, 535 rears but maybe now I'll use 535 fronts. The spare 540 front setup I can offload more easily that way... and not have it cost so much.

Thanks for the advice, that sounds very good to me. Will throw on a new master cylinder when I can find one... this e28 is really just fun and for the gf to use. Its waaay too good to just give away, so I'm going to register it. The engine is already tuned, tranny and suspension tweaked. Only brakes and some TLC to go. I left the dash dirty so my gf can do that and feel like she owns it ;)

Leatherique did wonders on the rock-hard leather...

[Brandon J]

Thats a great car to give the gf. A can or two of rust neutralizer is good to have at hand too, lol. Let us know how the conversion turns out.