Been thinking about a rear brake upgrade...

[Robson Rover Repair]

Been thinking about this a lot last few days and wondering about suggestions, more for visual purposes than anything else.

Firstly, does anyone know exactly what BMW our rear brake calipers are off? The front 190's are off a E46 330, and the none 190 are E46 320 (or similar) engine. I think the rear is also from a E46/Z4/E39 320 spec car as the calipers look identical and the disc size.

Now my obvious thought was fitting a set of 190 front calipers to the rear and using 190 discs again, but im unsure about the handbrake shoe clearance. Im thinking how to do this on the cheap!

I wish I had checked when I had them off the car, doh.

Now ive done the 190 vented set-up in the front and it fills the wheels perfectly, but ive always felt the rear discs look a bit lost in the rear wheels, mine where already vented mind you instead of solid.

Now, front discs are 325mm for 190, 285mm for none one 190, and rears are 275 (despite what some sites show as 280 or 282mm etc).

Now ive got the exact OEM specs of the rear vented discs.

Vented - Mountings 5
Disc diameter 275.0mm
Disc thickness 19.0mm
Overall height 61.7mm
Centre diameter 64.1mm
Minimum thickness 17.0mm

I have for example found 316mm rear subaru discs that i think would work are the follow spec.

Vented - Studs 5
Disc diameter 316.0mm
Disc thickness 20.0mm
Overall height 67.0mm
Centre diameter 58.0mm
Minimum thickness 18.0mm

With the centre diameter of 6mm being the only issue, but 6mm might even improve how the handbrake holds as the shoes would have to move less, prehaps. But that leaves the issue of rear calipers again.

However using BMW E46 330 rear calipers which would bolt onto everything already, you could fit a maximum of the following if you could find rear discs to match.....

Vented - Mountings 5
Disc diameter 320.0mm
Disc thickness 22.0mm
Overall height 60.7mm

Now the down side would be this would push the rear wheels out about 7mm further into the rear arches afaik from what im reading here but theres plenty off room for them.

Now obviously I would need slightly longer rear brake hoses, but I have a feeling that the 190 hoses for the front would solve that issue also, keeping things very OEM also.

Only major hurdle is the rear disc guards from what I can see and im sure 190 fronts could be made to fit.

What are peoples opinions on this? Its something i wish to investigate when funds allow after Christmas but ive limited mechanical ability to DIY it.