M3 rear brakes on a 335i

[E92 420]

Ok so I have a forge motor sport front BBK and couldn’t be more happy with it however they do not make a rear kit for the general e9x models they only make a rear kit for the M3!

Anyone fitted m3 rears before? If So what’s needed to get the m3 rear brakes to fit on my 35i?

 

[doublespaces]

@aus335iguy knows about this I think

 

[aus335iguy]

Sorry guys I’ve bought m3 rear hubs but that was for my f30 brakes not M3 ones. I know that the m3 rear hub is a different offset and so spacers and a bigger rotor would likely be needed. I’m sure someone has done it before ...

 

[dyezak]

I've heard it works but I've not tried it.

 

[E92 420]

Shame nobody’s got anything conrete on this. I can’t see it being a major PITA tho so guess I’ll just have to buy the rear forge bbk kit and go from there! Hopefully not too much needs swapping.

 

[JMARS]

Shame nobody’s got anything conrete on this. I can’t see it being a major PITA tho so guess I’ll just have to buy the rear forge bbk kit and go from there! Hopefully not too much needs swapping.

Keep us posted, I'm interested in doing the same thing.

 

[aus335iguy]

Because the m3 hub places the callipers further out radially and also further outboard I would say making it plug and play won’t work the rotor will need to be roughly 15mm smaller and offset by about 8mm.
The easiest thing to do to make it plug and play buy a set of m3 rear carriers.

* I’m not an expert I’m basing this on observations on how f30 brakes fit on both rear carriers. Feel free to critically examine the logic

 

[lilg1993]

Well this is an old one, but did anybody ever figure anything out about this?

I have M3 rear hubs/knuckles that I was considering swapping onto my E92. @aus335iiguy you're saying that the hubs by themselves push the wheels 8mm further out?

 

[aus335iguy]

I don’t recall exactly
From what I recall and what I wrote at the time the hubs are different in that they placed the disc further out and by my reckoning by 8mm.

IMHO
The f30 brake setup I ended up doing on mine is a better easier upgrade
Fronts are bolt on 370mm
Rears are easy enough (almost plug and play as well with eccentric bushings and e65 discs.

e92 M3 stuff is good and all but to get the front to match the back you need uprights and all sorts of stuff and they are still sliding callipers etc

 

[aus335iguy]

Also, regardless of what you do get the M3 master cylinder to avoid a mushy pedal

 

[martymil]

The m3 hub places the rotor further in not out by 10mm each side on a 135i not sure if its the same on the e92 as I never measured it
but should be the same.

 

[lilg1993]

I don’t recall exactly
From what I recall and what I wrote at the time the hubs are different in that they placed the disc further out and by my reckoning by 8mm.

IMHO
The f30 brake setup I ended up doing on mine is a better easier upgrade
Fronts are bolt on 370mm
Rears are easy enough (almost plug and play as well with eccentric bushings and e65 discs.

e92 M3 stuff is good and all but to get the front to match the back you need uprights and all sorts of stuff and they are still sliding callipers etc

I was looking into getting another BBK but ordering fitment for an M3 and swapping on the hubs/knuckles. My biggest fear is that the wheels would then be pushed out too far and be past my fenders or something, as obviously the wheel track on an M3 is wider, but maybe its less of a concern than I thought by what @martymil is saying, that it brings the hub mounting flange in tighter...

Also, regardless of what you do get the M3 master cylinder to avoid a mushy pedal

Yes, already have one of these ready to swap in regardless.

The m3 hub places the rotor further in not out by 10mm each side on a 135i not sure if its the same on the e92 as I never measured it
but should be the same.

Interesting that it brings it closer. I thought it would push it further out with the M3 having a wider wheel track. That was your experience from swapping M3 hubs/knuckles?

 

[martymil]

Its the control arms that bring it out not the hubs.

The m3 has a wider track because of the wheels

 

[martymil]

I fitted a m3 rear end to a 135i and had to get lower offset wheels.

It went from a +50 to a +40 which means the axel is shorter.

 

[lilg1993]

Its the control arms that bring it out not the hubs.

The m3 has a wider track because of the wheels

Oi, I gotcha. The only rear arms on my car at this time that are not M3 are the camber links - been waiting until I get new coilovers to swap that one out.

Never realized it was only the wheels (mainly the offset I guess...?) that brings the track out further. I used to have OE 359M's on mine. The already stretched tires I had scraped the fenders even after rolling (and pulling a tiny bit) on large road dips.

I always get confused when trying to visualize wheel offsets and wheel & tire sizes. But in essence what you're telling me is that if I were to swap on the remaining M3 parts in the rear (at this point it is just the camber links, hubs, and knuckles) I need not worry that it will stick my wheels and tires out to the edges of my non-m fenders, but I will need a lower offset number on the wheels?

 

[martymil]

the factory wheels are too aggressive for a non M car as the wheel arches are a lot wider on a m3.

I would run the whole m3 rear end and adjust the wheels to suit with custom offsets

 

[martymil]

I have BC ER's to suit a 335 with m3 control arms but I gather your in the USA so shipping would be a nightmare if you wanted them.

 

[lilg1993]

I have BC ER's to suit a 335 with m3 control arms but I gather your in the USA so shipping would be a nightmare if you wanted them.

Appreciate the offer, but yes I'm in the US and don't want to deal with that shipping headache