930 Caliper/ Rotor Alignment...

Mitch Leland · Mitch Leland's Garage

Howdy,

I have rebuilt my 930 calipers, installed the rears all is well until I mounted the front left caliper. It was difficult to get the two 12MM bolts started, but after getting it mounted I find that the upper caliper bridge is hard against the outside face of the rotor. There is no paint on any of the mating surfaces, all the spacers are the same thickness, plus the bottom bridge is centered nicely on the rotor, it's just the top bridge is too far one way.

I could turn .020"- .030" off the top spacer, but before I jump into the frying pan I wanted to see if there is something going on.

The struts are existing, I have new races, bearings and rotors... I have not tried to mount the front left until I resolve this issue.

Thanks,

Bill Verburg · Bill Verburg's Garage

Are you using a non stock rotor?

oem size is 304x32mm

Bill Verburg · Bill Verburg's Garage

or do you have a rear on the front?
oem rear was 309x28mm

Mitch Leland · Mitch Leland's Garage

Bill,

Thanks for your quick reply.

No the rotors are OEM, from PP... The rears went up nicely. I might try and hang the right front and see if I have the same problem. I measured the inside distance from the face of the rotor to the face of the caliper and it appears that the caliper is about .080" out of parallel with the rotor...

Bill Verburg · Bill Verburg's Garage

So you have oem front 930 rotors, are the calipers the correct fronts?

It's common to shim the caliper to center on a rotor

Mitch Leland · Mitch Leland's Garage

Bill,

The pads will still fit, it's the area that the pads rest on that is against the rotor, not the cavity that receives the pads.

I did mix up all the caliper parts, but I didn't think that would be a problem. Like I say I'm only talking about .020"-.030" on the upper bridge. The bottom bridge is centered perfectly...

Thanks,

Mitch Leland · Mitch Leland's Garage

Bill,

OK, then I guess if you can add shims to center the rotor I can reduce the spacer to achieve clearance. As you know the fronts are 38MM, the rears are 30MM. So I haven't screwed that up. I also have the pistons facing the right way which I still don't understand what's that about.

Aaah, recreation and education... Thanks,

Bill Verburg · Bill Verburg's Garage

Is it possibl;e that you mixed the bridges up? there are 4 different bridges
front leading
front trailing
rear leading
rear trailing

Mitch Leland · Mitch Leland's Garage

Bill,

Reference: 930 Calipers...

I thought the bridges were all the same... Each one was a mirror imagine of the other, at least I thought so, but this is my first time with these calipers.

I turned a new spacer for the front left top (leading) 12mm mounting bolt. The factory spacers were .151" thick, the new one that I turned to center the caliper on the rotor was .091". The trailing 12mm factory spacer was fine.

I'll install the front right and see what I've got. It all seems right, however I don't know why I had the alignment problem when they all fit before. I did not measure the width of the bridges.

Thanks,