Anyone fitted e46 330ci rear brakes on 3.0si?

[Novel]

Hi,

I've been ordering a new rear rotors recently and the application list for the part numbers made me curious: the disc is 294x19 with part number 34 21 6 794 303 and appears to be unique to E85 and E86. I somehow assumed that the rear brakes are same as 330i e46, just like the fronts, but apparently that's not the case. E46 is running 320X22 rear discs.

However, I can see that part numbers for the caliper (34 21 6 758 135) is same for 330i and 3.0si. Part numbers for the brackets are different: 34 21 6 758 134 for 3.0si and 34 21 6 765 885 for 330i.

Has anybody tried installing the 330i bracket, is that enough to fit 320x22 (probably also trimming the dust shield).

Also it seems that the rear knuckle and the rear trailing arm is a single unit, and part numbers are different for E46 and E85/E86. Though changing a trailing arm feels like an overkill for this project.

 

[axelleveau]

My limited understanding of BMW's brake variations make me think a change of bracket would match the change in disc diameter BUT from having done some research and messing around, I would say there is a risk the E46 has 185mm drum diameter for handbrake vs 160mm for our Z4's . Brembo might have detailed drawings of discs on their catalogue website

 

[SqerrNipz]

There’s a fantastic post on the brakes section of the ‘how to’ page on the forum - https://z4-forum.com/forum/viewtopic.php?t=8399

An excerpt below -

320mm vented rear brakes

If you find a E46 330i, you might also want to consider a full brake setup off this car: it would give you 325mm in the front and 320mm in the rear and it would be a bolt on swap...
Alternatively, 320mm rear vented rotors can be sourced off of an X3 (any model, old or new). As noted below, the X3 might not be able to provide you a full front and rear swap: the front calipers are the same as the E46 330i, but the caliper carrier has a different p/n.
In summary, 320mm vented rear rotors can be sourced from the following cars:

E46 330i All
E83 X3 All

320mm can be used only with 325mm front as you don't want to have your rear rotors bigger than the front. Although many variables go into calculating brake bias, the disk size ratio of a 325mm front - 320mm rear conversion is similar to what the 3.0i has so it should be fine. However such a brake setup was never chosen by BMW as a setup for the any Roadster.

Another note regarding 320mm rear brakes. In this case too they have a different protection plate (as for the 325mm front rotors setup), and in this case it gets in the way of the bigger rotor. Once again, removing the plate is not as practical as you have to remove the parking brake assembly and likely the wheel hub. To fix the issue I would personally just bent the plate of the way... Sometimes I agree with the saying that "is something doesn't fit, your hammer ain't big enough"...

 

[Novel]

[ref]axelleveau[/ref], oh, yes, I'm afraid you're right...

And a quick research shows that conversion from 160 to 180 handbrake is not as trivial as it might seem.

 

[Mr Tidy]

Looking at those diagrams it seems the smaller Z4 disc is lighter, but has more fins so maybe performance wouldn't be much different.

Out of curiosity I just looked on realoem for rear discs for my E90 330i, but they seem to be 336 x 22mm!