Brake Rotor Question

I replaced my pads and rotors a couple months ago, and wondered if anyone else has ran into this when getting new rotors. When i went to buy them they said that there are two sizes of rotors, one w/ an overall depth of 3 1/16" and one w/ a depth of 3 3/16". I took the ones off my jeep and they were the 3 3/16" ones. the thing is is that when i had the jeep up on the jack to check something else, i rotated the wheel and i can hear the brake pads touching the rotors. I have never really paid attention to it i guess, but do brake pads always rub the rotor just a small amount? Also, i noticed that toward the outer edge of the rotor, it has a small amount that has that purple/blue color from heat. its just a small area. is that normal?

one of the guys at autozone where i got the rotors has an xj also, and said that he bought the wrong rotors once and they rubbed. would the rubbing be very noticeable if they were the wrong rotor?

I made the same mistake and after torquing the wheels you COULD defintely tell that you had the wrong ones!!!!!!!!!!!!!!!!

so what is it that requires different rotors? is it a different axle or brake setup or what? they said that even for the same year and model XJ, it still asks for the depth.

The rotor issue is for 1999 only. Read this thread for more info --> http://www.naxja.org/forum/showthread.php?t=907146 . If you had the wrong rotors for your XJ the tires would not turn. Disk brake pads rub the disk a tiny bit. If your caliper is sticky or worn out it may be dragging on the rotor more than normal.

It is for 99 only, but they are clueless there. Have them look up the part for a 97 it will be one of the two it shows for yours, then get the other one.

It is a cast or composite material issue. Not sure which one is taller, but i know the cast has a squared edge and the composite has a rounded edge. My 99 has cast rotors.

The difference is NOT only cast or composite. You need to measure the depth. The problem is also there on the 01's as well. AZ had one of each in boxes with identical part numbers. If you get the wrong one, when you torque down the lug nuts the wheel will NOT turn at all. And yes,the pads do 'drag' a little with everything set up properly

I had the same problem with my 95'. The rotors in the computer at AZ and Checker were the wrong ones. I dont remember wich ones I have but there were only 1 pair on the other side of town. If I remember correctly there is a 1 piece and 2 piece design and mine are the 1 piece.

So stop going to Auto-Zone and Checker. Those people only know what they read off the computer screen. If you ask for transmission fluid for your Cherokee AW-4 you will often get the fluid for a Chrysler transmission and then burn up your tranny.

Find an independent auto parts store or a NAPA, someplace where they know how to look up parts in a part catalog. I have been helped by the same counter person at the NAPA for the last 5 years. When was the last time you saw the same counter person twice at AZ or Checker ?

I work for napa there is two different rotors listed in catlog 3 1\16 or 3 3\16 they will not interchange

I've here some D30 89-90 and some 91-93; up to 90 the rotor are cast, after are composite, them aren't interchangeable. The difference on the two D30 types are wheel hubs (older are shorter), knuckle (the older are in two pieces knuckle and caliper support), caliper and rotor. The wheel hub of pre '91 are rebuildable.
I've found that Brembo has cast rotor for '91 and up that are stronger and less prone to bind under heavy abuse then original composite.