rear brake upgrade query

[terryo]

i'm planning to change/upgrade my poverty pack 2 litre brakes. i have decided to go up to the 300mm front and 294mm rear which are common on many E85 Z4's

other articles on this site claim E46 is the donor for these brakes

by searching thru real OEM and various brake catalogues, i have confirmed that various E46 models have these sizes, BUT, the rear rotors listed for e46 are not the same part number as rear for E85 Z4

can anyone explain why this might be so??

 

[kis]

Some parts will be the same because the e85 and e46 have a lot in common. Bearing that in mind they are different cars... so will have their differences. So nothing unusual IMO. (So for example the brake calliper and carrier may be the same, but the brake disc may be different).

Pull part numbers off a e85 3.0i and then cross check with that of the e46 and source from wherever is cheapest or most convenient to you

 

[Mr Tidy]

Just a thought, but if you are upgrading anyway it might be worth thinking about going for 325mm fronts as fitted to the Facelift 3.0Si Z4s, and to the E46 330i & 330d.

The only downside is you will need different brackets for the calipers, and will need to use at least 17" wheels.

 

[kis]

I was thinking this too as more breaking power isn’t a bad thing!

 

[terryo]

the really big brakes are much much heavier which does nothing for handling....this is not a track car and i cant really justify going that far. also, my research says you have to replace the brake backing plates for the very big brakes. just another task!

i'm still looking for an exact answer to my query about the rear brakes. it will need to come from someone in the UK as the USA did not use the small solid rear brakes it seems, so no experience with this conversion

 

[LittleZ4]

Source the rear calipers and carriers from a 3.0i or the 3.0si and you'll be able to have 294mm rears. I'm not sure if any 294mm rears on an E46 (if any model has them?) will fit as the drum for the hand brake maybe too large for your handbrake to work.
I know this was the case when I tried to use the rears from a 330i on my 3.0 Z4. Think the difference is around 26mm extra internal space.

Does that help??

 

[kis]

the really big brakes are much much heavier which does nothing for handling....this is not a track car and i cant really justify going that far. also, my research says you have to replace the brake backing plates for the very big brakes. just another task!

Wouldn't class it as really big?
If we talk calipers then the Z4 3.0 is 2.85kg (34116758114) and the e46 330 is 3.84kg (34116765882). Its basically a kilogram... granted other hardware; bigger pads, bigger disc, maybe bigger carriers would add a bit more weight too. But it's hardly over the top (in terms of weight). Whether you feel it's too much braking power is your call

For me, I came from a 300mm and went to a 325mm and didn't need to change my backing plate. If your 2.0 has a different plate then you'll surely need to change it (or modify it) for the 300mm brakes anyway?

i'm still looking for an exact answer to my query about the rear brakes. it will need to come from someone in the UK as the USA did not use the small solid rear brakes it seems, so no experience with this conversion

I think you posted elsewhere but there is surely a difference if the part number differs? Best thing to do if you really want to know exactly is to compare the two. Not that I think it matters? It's a different part number, so probably won't fit? So best using the one specifically assigned to the Zed?

 

[terryo]

FWIW i have confirmed the E46 294mm rear discs definitely will not fit. the height is different. The 294mm Z4 rear disc is unique to that car

 

[paulc_bkk]

You’ll need Z4 3.0 discs/rotors if you want to go 294 vented - the E46 disc of similar spec has a short hat and will not fit

The e46 330 rear setup also will not fit for the same reason, but the e46 (non-m) front is fully interchangeable with the e85/86, and the 330i setup is a decent front upgrade to the standard Z4 spec

There are threads on other forums where X3 rears have been modified to fit, but it’s a lot of work for little reward.

I have Porsche Boxster S fronts with Z4M rotors and the Z4 3.0 tears on mine.... perfectly fine setup

 

[terryo]

agree, various E46 front brakes seem to be able to be fitted. i'm doing mine next week.