anyone ever had anything like this? 79SA, front brake rotors. its about 1/4 inch divit in the brake rotor itself. its like a marble was stuck on the pad and it ground a ring in.

 

Maybe a rock stock in the pad? But a rock that large stuck in the pad is very unusual, but you never know.

 

sounds like the pad may have had a flaw or something in it, the only time i've seen wear like that was when I ran the pads to thin on one of my other cars before I knew better and it was caused by the studs that held the organic pad onto the metal calipers.

 

maybe one of the rivets in the pad?

 

I'm going to say either...
-Rock in the pad
-Magic

A pad would have to be pretty worn down for the rivet to carve a groove in the rotor like that. What did the pads look like?

 

Check your mounting bolts. One may have the end worn off of it.

 

I found the same thing on the my GSL when I bought it. I didn't take the time to investigate the cause, just swapped rotors and pads along with the engine from a donor car to get it running. Rivets seem unlikely, just recently replaced front pads on both sevens which were worn down to almost metal, rotors were still fine.

 

Yah, like trochoid said if the bolts are switched on the caliper mounting bracket I think that can happen. Its never happened to me before but that is a possibility.
Is the groove on the outter or inner surface of the rotor??

 

I've seen it millions of times in all the brake jobs I've done. It's caused by imperfections in the brake pad friction material.

Either a rock gets wedged up in there or something... Brake linings are kinda like particle board. They're soft material compressed with an adhesive. It depends a lot on the consistency of the soft material and how much adhesive gets put in the mix.

In fact, some brake shoes, I've seen ingredients lists on the back of the box. On that particular box, the first ingredient was "crushed walunt shells"...

 

I had something just like that on my FB. Not sure if it applies to SA because the front bakes are different, but on the FB the pads are held in place by some little metal springs. In the case of my FB, the springs rode low and put the groove into the rotor.

 

Rotors are dirt cheap at www.rockauto.com I just got a set of the cheapest they sell, and they look fine. Put a cheap set on the Audi too, and the brakes have never been better.

My guess on your condition is that at one time someone ran the pads down too far, and the rivets dug a groove. I'd say this is most likely, unless you are shure that this hasn't ever happened. However, its always a good idea to pull the caliper off and lube those pins. If you're lucky, you'll get catch them before they become "welded" to the caliper. Good luck...

 

we usually see that on half the brakes that come through my work, either debris got in there or someone has been using the same rotors for multiple brake jobs, not uncommon. (never pad slap your cars!!!!!,don't just buy pads and call it done, measure your rotors and machine them down if enough material is left, otherwise replace them, or else your gonna have a brake job thats barely worth the 20 bucks you just spent on the pads)

 

Thats probably it then, i hardly think a rock got caught on both sides making the same wear pattern...

any idea were to get good rotors at? im planning on slotted. if i have to replace it, why not do it right?

 

Cheap place to get rotors at....

 

you quoted yourself??

 

He asked a question that had already been answered.