brake upgrade, BMW Callipers Options

[Petepat]

So I've looked at the links using Boxer callipers and it looks quite complicated where as some where I read one can do a straight swop using BMW callipers. Has anyone done this and was it an improvement? Yours thoughts in this direction welcomed.

[technicalninja]

I'm doing exactly this on the 75 I am resurrecting.

Changing piston size to the larger BMW caliper mimics the 914-6 calipers.
If you're using a 3/4 bore master (more common, cheaper) you will regain the stroke you lost when you changed to the 3/4 master. This also slightly affects brake balance, Changing the front without also changing the rear pushes the balance slightly rearward.
If you're using the standard valve in the rear this won't be an issue.

The larger pads on the 320i caliper should wear slower and you might get more miles out of them.

You will need to modify the lines a bit. Mine came with new copper/nickel lines.

You will add un-sprung weight to each front corner (not good).

I did mine for cost and appearance reasons. I needed everything anyways and the BMW calipers were less expensive in my case. I like the look of bigger calipers and the set I purchased had just been re-plated and are very pretty.

If you think you're going to improve the brakes in a way you can feel you will be disappointed...

If your stock stuff is working properly, I would not suggest it.

Changing the stock pads to a "performance" pad will have a FAR greater "feel" improvement than anything else IMO.

I'm using Porterfield R4-S on all corners.