Brake rotor issue

[coldstart]

I am having some difficulties getting my brakes reassembled and installed.

On the rears, the brake caliper rubs the rotor at one point when the rotor is spun around. The bottom of the caliper itself rubs the rotor, not the brake pads. I have yet to attach the brake lines to the calipers. This is the same fit both rear brakes. I have taken off the rotors a few times and made sure they are installed properly and there is no interference or dirt that would cause them not to be flat against the hub.

The calipers were rebuilt (I regret not splitting them and replating them for aesthetics). All the hardware was replated or bought new. This is for my 1972 911T which is stock and has the original brake calipers.

I have changed brakes beforehand and never had any problems. Any insight into what I am doing wrong?

[DerkPerk]

Sounds like the wrong diameter rotor. How else could the caliper rub if all is bolted up???


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[Trackrash]

Is the rotor centered in the caliper? IIRC my rear calipers used a washer as a spacer between the caliper and mount. Did your set up have those?

You might try re-installing the old rotors for comparison.

[coldstart]

The rotor doesn’t appear to be centered in the caliper which is the issue. If I use a washer as a spacer, it would pull the caliper more towards the car and create even more rubbing (as the rubbing is on the outside part of the caliper)


I watched kav911’s videos on the rear brakes and he doesn’t appear to use additional washers. I will look further into it.

Thanks for the suggestion about comparing my old rotors. I think I still have them around.

Originally Posted by Trackrash

Is the rotor centered in the caliper? IIRC my rear calipers used a washer as a spacer between the caliper and mount. Did your set up have those?

You might try re-installing the old rotors for comparison.

[coldstart]

Originally Posted by DerkPerk

Sounds like the wrong diameter rotor. How else could the caliper rub if all is bolted up???


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The rubbing is occurring between the outside edge of the caliper, not the top of the caliper. The diameter of the rotor doesn’t appear to be the issue, it’s the rotor thickness (more so the rotor not going round evenly as it clears for 90% of a turn)

[Rawknees'Turbo]

Is the rotor all the way back against the hub (the center of the first pic looks strange, but maybe just a shadow)? I see you've got the two little screws installed, but try hand tightening a couple wheel nuts down and see if that changes anything.

[FrankM_]

Measure your disc thickness, I believe it should be 20 mm for a 1972, it changed to 24 mm on the Carrera of 1984 or later. Make sure you are using the right one

[pete3799]

Did you change the rear wheel bearings? Might be your hub is not seated all the way,

[76FJ55]

may be worth mounting a wheel and torquing the lug nuts to make sire the rotor is fully seated. than pull the wheel back off and check to see what your clearance is.

[911pcars]

If the rotor is centered in the caliper and no other issues or anomalies are apparent, here's one backyard process for that edge-interference.

The 914 I have is equipped with a set of over-the-top 930 brakes and rotors. Due to normal wear, a ridge formed on the outer edge of the rotors where the pads didn't contact (ridge visible in photo). I conjured up an on-the-car rotor edge grinder using an angle grinder and a flap disc to remove said ridge.



Using a sturdy milk crate, heavy machinist vise and C-clamp, I snuck the spinning disk up to the ridge which also spun the rotor. Manually-fed grinder, manually-controlled rotor speed, face mask, heavy gloves - evenly removed the ridge. Repeat on the back side. Count fingers. All good.

Sherwood

[coldstart]

The problem appeared to resolve when I put on the wheel and tightened down the wheel lug nuts.

Thanks guys.