pikemike428

So my car has been out of commission on Jack stands for 3 weeks after I pulled off my old brakes which were squealing like a stuck pig. My rear calipers were peeling, so I figured I would enlist the services of Mike the powdercoater, and the Calipers came out looking brand new, and he turned them around to me very quickly.

So I had Brand new AC Delco rotors, brand new AC Delco pads, brand new AC Delco Caliper pins, newly powdercoated Z06 Calipers, miscellaneous new items like banjo bolts which are needed of course, and an entire brake flush with new fluid. While my wheels were off I had deep cleaned them, and they were looking great! I had my fathers friend which is a Mercedes Master Mechanic do most of the work.

Prior to starting, I mentioned we should probably grind the pins down a tad just to be safe as I have seen this come up a few times on here where the front pins make contact with the rotor. Well, we didnt end up doing it, and sure as $hit they ended up hitting the rotors (I think)on both the front 2 wheels.

Also looks like the front left caliper is almost/just touching the wheel weight.

See attached photos and let me know if you think its a caliper pin or something else?

pikemike428

for clarification-the last couple shots are left front and left rear when new before I went out for a drive.

pikemike428

Anyone had this on both sides and it wasnt the Caliper pins??

Dirty Howie

I have had the exact same problem. That score mark is definitely from the pin.


DH

pikemike428

Howie-was it a specific pin that was the problem? Were yours on front or back?

Thanks

AimHigh

Sorry to hear about the damage....thanks very much posting,

Any pics of inside the caliper showing the pin?

Howie, what was your fix for the problem?

80atez

New rotors, not tracking car, I'd turn them. I did that once with my tracked car and they did fine even. Or actually, now that I think of it, fix the pin and just drive - I'm no expert on brakes, but I bet it would work just fine. Wouldn't look great, but really, who will notice?

I've not heard of this, is this also possible with one piece pads?

bluemagoo

First off, check the mounting surface of your hubs and clean off any rust or debris that might keep the new rotor from seating all the way. Most likely though your new rotor(s) was machined ever-so-slightly different that the old one.

With the wheel off, look at how the rotor is positioned between the inboard and outboard caliper pins. It's probably offset slightly outboard causing the outer pins to hit the outer rotor face. You can place some very thin washers/shims on the 2 large caliper mounting bolts between the caliper and the upright to position the caliper a bit farther outboard (and evenly centered between the inboard and outboard pins).

Carnac

Agree with bluemagoo above.

Another cause can be from worn hubs allowing the pins to touch (usually on the track). If it wasn't doing this before, then probably slightly off center rotor.

Shim or grind (slightly) the offending pin.

Other than looks, you can leave the rotor as is.

Jim

pikemike428

Thanks guys-yeah was planning to leave rotor as is.

Funny thing is the mechanic and I went out afterwards to bed the brakes, and make sure they were operating perfect, and I stopped from 100-0 a few times very quickly and ran it very quickly from what is basically a road course back street by my house. Came back home and all was fine. I had a weird feeling shortly after that from the front left when I backed up out of the driveway to the left, and the same when taking my wife to the movies and it was progressively worse scarring each time.

pikemike428

Really weird-pistons on one side on both sides of the car look like they are pushing rotor into the pins

pikemike428

Are the inboard side of the rotors supposed to sit a little bit further away than the outboard side?

Seems like that's how they sit on my car...

pikemike428

Other side

bluemagoo

The only thing you've changed (besides new pads) is the rotor. As I mentioned earlier, the dimensions of your new rotor (mounting surface in relation to the inner & outer rotor faces) is slightly different than the old rotor you removed. You new rotor is now offset slightly within the caliper to the outboard side.

The new rotor is subsequently closer to the pins on the outboard side and farther away from the pins on the inboard side. Because of that offset, your inboard pistons/pads have to extend a bit further to reach the rotor surface. This is what you are seeing in your photos.

Take a feeler gauge and measure the space between the rotor and inboard pins (for example .060") and between the rotor and the outboard pins (again, for example .000" -it's up again the rotor face). This tells us that the rotor is offset .030" to the outboard side rather than being centered in the caliper with clearance of .030" on both sides. The numbers above/below are just an example - you would need to take your own measurements.

So to re-center your rotor within the caliper, you could: a.) machine .030" off the mounting surface of the rotor which would realign the rotor into the center of the caliper as it is now OR b.) place .030" shims/washers between the caliper and the upright to move the caliper (with it's pins) back over the midline of the rotor faces OR c.) grind enough off the end of the offending pins to provide enough clearance OR d.) try swapping the front rotors left/right and see if it makes any difference OR e.) I guess you could try to find another brand of rotor that is closer in dimension to the old one.

Hope that helps you get things straightened out.

pikemike428

Bluemagoo thank you for your post. We ended up taking a mm or 2 off the end of the pins and spraying the ends with caliper paint to avoid rust in the future. Seems to have fixed the issue for now. I guess I should have bought GM rotors instead of AC Delco stuff when I was sourcing parts

Dirty Howie

Sorry for the late reply. Mine was a specific pin on the outside of front caliper. Filing it down fixed the problem.


DH

Dirty Howie

I filed the pin, problem gone.


DH