Squared rear caliper mount flanges to axle, now calipers won't line up - FYI

[Cobra4B]

The rear mount flanges were angled outward on each side. I confirmed with John @ Panoz that they should be square. I had a local shop square them and add a reinforcement gusset. Test fitting the calipers this weekend I found that each side was now perfectly square, but the caliper was too far inboard; it would not center on the rotor. Flipping the mount brackets and/or adding shims would only serve to move the caliper further inboard. I dropped the brackets off today at the local machine shop to have 1/16" taken off the mount surface so I can move the calipers outward and get them centered on the rotor.

So it appears:

1. Someone angled the flanges outward to center the caliper on the rotor at the expense of being square.

2. The misalignment of the caliper on the rotor somehow caused the caliper flanges to bend outward over time i.e they "self-centered" over the years. Again, at the expense of being square.

Just something to check next time your looking your car over. For the record I tested multiple hub/rotor assemblies and made sure the assemblies were fully seated on the axle. I could have shimmed the rotor inward off of the hub, but I didn't want to worry about runout issues if the washers I used weren't of uniform thickness. Plus, doing it that way would mean I have to shim the spare assemblies too. Not in any rush so elected to take the caliper brackets to the machine shop and do it the right way.

[NZGTRA17]

Originally Posted by Cobra4B

The rear mount flanges were angled outward on each side. I confirmed with John @ Panoz that they should be square. I had a local shop square them and add a reinforcement gusset. Test fitting the calipers this weekend I found that each side was now perfectly square, but the caliper was too far inboard; it would not center on the rotor. Flipping the mount brackets and/or adding shims would only serve to move the caliper further inboard. I dropped the brackets off today at the local machine shop to have 1/16" taken off the mount surface so I can move the calipers outward and get them centered on the rotor.

So it appears:

1. Someone angled the flanges outward to center the caliper on the rotor at the expense of being square.

2. The misalignment of the caliper on the rotor somehow caused the caliper flanges to bend outward over time i.e they "self-centered" over the years. Again, at the expense of being square.

Just something to check next time your looking your car over. For the record I tested multiple hub/rotor assemblies and made sure the assemblies were fully seated on the axle. I could have shimmed the rotor inward off of the hub, but I didn't want to worry about runout issues if the washers I used weren't of uniform thickness. Plus, doing it that way would mean I have to shim the spare assemblies too. Not in any rush so elected to take the caliper brackets to the machine shop and do it the right way.

Thanks Brian, was going to check this on my car so good to know what has occurred during assembly.

Kel.

[CMPanoz]

They make a lot of noise when they break off!!!

[Cobra4B]

Update - Had 1/16" taken off each caliper mount bracket. This actually moved the caliper out a tiny bit too far. This was my intention as I could then shim it back to perfect. After experimenting with various shims (got a Brembo shim kit from PAD) it took a single .01" shim to get everything perfect. This shim kits come with 3 thicknesses: black = .05", gold = .03", silver = .01".

You can see where the bracket was machined... no more "purple" anodized coating.


Done

[Panoz60]

Just an opinion that probably wont be widely shared....Are you being too exact and critical? Yes, an "angled" bracket would create issues, but (in my opinion) you may be a bit too critical on the centering issue.

(Another of my long winded stories coming up) When I got into SCCA A/S racing, the rules had just changed to allow 4 piston calipers. Since I had yet to address the brakes during my build, I opted for the better package only to learn that only one manufacturer made a kit for SN-95 spindles, and it was $2,400.00 just for the fronts. After speaking at length with Wilwood Techies, my solution was a pair of Wilwood Forged Dynalites ($180.00 each), hats, 48 vane GT rotors, and homemade adapter brackets. I mocked everything up on the bench and used a Stanley tape measure for the in/out spacing. I used PFC -01 pads, placed them in the calipers, and used that to mock up the distance of the caliper from the spindle centerline by nothing more than eye-balling them. I used a bolt-on 4 piston kit for the rear and a Wilwood M/C and the whole thing cost me under $1400.
My point? I gaurantee they were not centered to the degree you are trying to achieve, and that set-up stopped a 3200# car from 150+ for four seasons without an issue, failures, or unusual pad/rotor wear. I'd get 4-5 weekends out of a set of front pads, and a full season out of the rears.

I'm just saying...and trying to be helpful.

[Cobra4B]

The angled brackets were a sign of wear and I didn't want one to shear off as other owners have reported happening.

After squaring the brackets the inner part of the outer-half of the caliper was nearly touching the outer rotor face. Any rotor movement from heat expansion or flex and it would have been touching. The brackets had to be machined to make it work at all.

The wilwoods on my Corvette aren't 100% centered, but there's plenty of clearance for the rotor and room to get new pads at full thickness in w/o much hassle.

In this case I got them perfectly centered simply because I could, but the machining of the bracket had to be done just to put it together at all.

[Panoz60]

Originally Posted by Cobra4B

After squaring the brackets the inner part of the outer-half of the caliper was nearly touching the outer rotor face. Any rotor movement from heat expansion or flex and it would have been touching. The brackets had to be machined to make it work at all.......
In this case I got them perfectly centered simply because I could, but the machining of the bracket had to be done just to put it together at all.

OK, that makes perfect sense. Good question though, why was it like that? You (We) may never know.