Caliper/rotor interference problem (Page 1/1)
billy bee AUG 31, 07:53 PM
We have rebuilt calipers (unknown origin; came with car) that don't seem to fit quite right. When we tighten the caliper bolts the slides bind up, forcing the inner pad against the back side rotor. The slides work just fine when not bolted to the knuckle and the LF is fine. Just the RF has problems. It seems like the caliper bolts should have shoulders that keep them from tightening too much, but they don't.

One additional variable -- we installed new front hubs that appear to be extra heavy duty. They are not made with sealed bearings and the bearings are serviceable. Since this is for endurance racing, it seemed wise. The hubs may have the wrong offset spacing to the rotor mounting surface. Any experience with aftermarket hubs and bearings?

Any other thoughts?

Thanks in advance,
Bill

[This message has been edited by billy bee (edited 08-31-2022).]

Raydar SEP 02, 09:06 PM
What year is the car?

Pics would really help.
billy bee SEP 03, 11:10 PM
Well, we figured it out. There were some very minor irregularities where the caliper slides contact the knuckle. That face of the knuckle was not flat on either the LF or the RF knuckle. So, when we would bolt the calipers to the knuckles, the slide would cant slightly, just enough that the slides were not perfectly parallel. Hence, they would bind up and the caliper would not slide easily. It would get stuck in a position where the caliper body was pushed outboard and the inner pad was pushing against the back side of the rotor.

It was a very minor irregularity. All we had to do to fix it was take a long flat file and make the surfaces uniform. About five minutes of filing both bosses on the knuckle flat did the trick.

I'm curious if anybody else has had to do this. We have some spare knuckles; we will be sure to check them before we mount calipers to them.
fieroguru SEP 04, 01:50 PM

quote
Originally posted by billy bee:
Well, we figured it out. There were some very minor irregularities where the caliper slides contact the knuckle. That face of the knuckle was not flat on either the LF or the RF knuckle. So, when we would bolt the calipers to the knuckles, the slide would cant slightly, just enough that the slides were not perfectly parallel. Hence, they would bind up and the caliper would not slide easily. It would get stuck in a position where the caliper body was pushed outboard and the inner pad was pushing against the back side of the rotor.



If you are working on an 84-87 front and attaching the bracket on the outboard portion of the caliper bolt boss, then yes, this is pretty common. The machined side is on the inboard side and the outboard side is an as cast surface, which won't be flat.
ericjon262 SEP 04, 08:36 PM

quote
Originally posted by fieroguru:


If you are working on an 84-87 front and attaching the bracket on the outboard portion of the caliper bolt boss, then yes, this is pretty common. The machined side is on the inboard side and the outboard side is an as cast surface, which won't be flat.



it's part of the reason I want to design my own knuckles that accommodate a better brake package.

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