I have been working with Eric Shea to try and guess where thes calipers came from. I got them in a parts car. The guy said he took them off of a 911 with "M" struts. I bolted the calipers up with no problems and they clear my 8" Fuchs. I have included some pictures with compairsion. The caliper pistons are hollow. Eric says BMW or MB.

I measured the openings on the caliper for compairison:

Mystery Caliper "M" Caliper
58 mm 54mm Width
77mm 62mm Length
25mm 24mm Rotor opening

Additional pictures:

the one with the banjo fitting looks IDENTICAL to my M calipers...

the other one is what i have seen when you order a "new caliper" from flaps...

ATE is the brand on my old BMW (75 5 series) but these are not BMW calipers from that vintage.

With the input "peak" and the mount to one side... I'm going to fall back on my Mercedes/BMW caliper. These are virtually identical to A-Calipers with the following exceptions:

A-Calipers are (obviously) on a 3.5" spacing
A-Calipers have the input at the bottom of the peak.

The larger Mercedes sedans went vented and I believe they remained on 3" spacing. I have done a set of Mercedes calipers that were "very" similar to these. I need to check the mounting spacing.

BMW's could have been the same way but I don't know enough about the mark to give an opinion.

It would be great to know what they are.

i tjink slits can run the ATE PN

Look familiar?

That is a BMW caliper. Same exact caliper w/o the spacer. I would imagine a later model BMW would retain the caliper but add spacers and a vented rotor.

Here's an A-Caliper... note the input peak is flattened and the input is on the bottom.

M-Caliper for comparison.

All these calipers have the same piston in them. Later model calipers have a hollowed out piston (better for cooling). The BMW and A-calipers have a larger pad size.

You can buy new/rebuilt "M" calipers from flaps?