Question on 5-lug REAR brake options

[Bimmerman325i]

I'm looking at 5-lugging my car in the near future, and want to pick your brains on some options. I have a full machine shop and welding center at school I can use if I have to, but I'd really rather not.

Car is a 89 325i which is mostly a track car (sig). I have the front 5 lug pretty well figured out, I just have a few questions about rear brakes.

The 318ti and Z3 rear rotors are the same size at 272mm, right? For those of you who drive aggressively and/or track on the E36 M3 front/Z3 rear, how is the brake balance? Any issues?

Is a new/different master cylinder needed or is pedal feel similar?

I looked in realoem and saw that the rear rotors and caliper carriers are the same between a Z3 M and E36 M3-- only the calipers are different. Assuming I can find a set of Z3 M rear calipers, will the rotor/carriers bolt on to my E30 trailing arms without issue or spacing problems?

Since the car is going to be a track car I'd like to keep the bias as close as I can to stock/stock M3/MZ3. How do you all like your setups for feel and bias?

Thanks all.

[Aptyp]

you'll need to get mz3 trailing arms, hubs, axles, and diff flanges to fit m3/mz3 rear brakes.


I DD 272mm in the rear. brakes are absolutely amazing and changed my mind about needing to upgrade.

[Bimmerman325i]

you'll need to get mz3 trailing arms, hubs, axles, and diff flanges to fit m3/mz3 rear brakes.


I DD 272mm in the rear. brakes are absolutely amazing and changed my mind about needing to upgrade.

Great info, thanks! So there's no easy way to make the MZ3 rotor fit without buying all that expensive stuff? Damn. Would simply machining a 1 1/16 spacer to fit between z3 hub and M3 rotor fix the problem? Or would that just screw with the wheel offset and fitment? I ask because I've found a few full M3 package brake deals, less so for Z3 stuff.

With the 272mm brakes, have you noticed any change in forward/rearward bias? Did you change the master cylinder when you swapped?

[Aptyp]

If you get a pair of e30 m3 hubs and modify dust-shield, e36m3 rear rotors fit the hub and have same center bore. You'd have to make caliper bracket adapters, though. Something I've considered, but m3 hubs are tough to find at a good price.

Dimension wise, e36m3 and e30 rotors are very similar. Drums are the same and parking brakes would still work.

[Bimmerman325i]

If you get a pair of e30 m3 hubs and modify dust-shield, e36m3 rear rotors fit the hub and have same center bore. You'd have to make caliper bracket adapters, though. Something I've considered, but m3 hubs are tough to find at a good price.

Dimension wise, e36m3 and e30 rotors are very similar. Drums are the same and parking brakes would still work.

Awesome. I haven't had any luck finding Z3 stuff locally, but E36 brakes on an E30 M3 hub swap....that's doable.

The E30 M3 rear bearing is the same as the non-M, right? So all I'd need to do is swap in the other hub, cut the shield, then fabricate spacers? I might just do this.

EDIT: Just checked Tischer, new rear E30M3 hubs are $165 each. Not that bad if I can't find used ones.

[Aptyp]

yeah, you'll keep same factory bearing (I'd still replace them) and the extra bonus is that you'll keep axles and diff, so it's a lot less stuff to buy.

[Bimmerman325i]

sweet. I think I'm set then unless I find a sweet Z3 setup. Thanks for your help!

[Massive Lee]

Drums are the same and parking brakes would still work.

I would be interested to see how you make them fit. The e30, e30M3 and non-M e36 rear handbrake drums are about 160mm. Rear e46M3 is 180mm. e36 M3 is in between. So, it is a no fit.

[Bimmerman325i]

I would be interested to see how you make them fit. The e30, e30M3 and non-M e36 rear handbrake drums are about 160mm. Rear e46M3 is 180mm. e36 M3 is in between. So, it is a no fit.

Is there a way to retrofit M3 / MZ3 parking brake hardware onto an E30 trailing arm? Or is the issue the spacing?

[Aptyp]

I'll measure it again tonight, I have both laying around. They fit over parking brakes very snugly for my first test.

[hoveringuy]

Anyone have the specs on the stock '90 bias valve for the rear? The Porsche guys swap them for units with a higher knee pressure.

My rear brakes (325is units) feel under utilized.

[Massive Lee]

I'll measure it again tonight, I have both laying around. They fit over parking brakes very snugly for my first test.

If you had a digital caliper, I'd be happy to know how your e36 M3 drums measure. And let us know if they are newer or older (worn) as it will affect the overall diameter).

TIA ;-)

Lee

PS e30 handbrake shoes are about 25mm wide, while e36 shoes are 32mm

[psyber_0ptix]

subscribed!

[Massive Lee]

Anyone have the specs on the stock '90 bias valve for the rear? The Porsche guys swap them for units with a higher knee pressure.

My rear brakes (325is units) feel under utilized.

The knee should be at 25bar (400psi) and only compensates for weight transfer of soft springs.

What are your front and rear pads?

[hoveringuy]

The knee should be at 25bar (400psi) and only compensates for weight transfer of soft springs.

What are your front and rear pads?

Stock pads, as far as I know (front M3 stuff was dealer serviced with new rotors and pads). Rear, same.

Stiffer springs equals less weight transfer?

How does the math work out with M3 front and e36 rear?