So yesterday i put new pads and rotors on my '99 xj. I thought everything went smoothly, but after i got everything put back together and got the jeep off jack stands, i went to pull it out of the garage and it wouldn't even move! Some how the brakes locked up. I pumped the pedal a bunch of times and that didn't help anything. I jacked it back up and tried to spin the wheels and they wouldn't budge! What did i do wrong??? Please Help.

 

I had the same happen to me. I took them back and got new ones. I was told that some pads have paint on the back and will mess with them as far as fitting. Do they have paint or the metal shims on the backside of the pad?

 

Yes they do have two little metal shims on the back of the pads. I thought this was my problem until i looked at my old pads and they had the same two things on the back.

 

The weird thing is before i put the wheels back on, i spun the hubs with my hands and they seemed to move fine. They weren't super easy to spin, but still moved. Then after i put the wheels back on and got it off jack stands, the suckers wouldn't move at all.

 

You have the wrong rotors. I had this exact thing happen to me - the "top hat" is just slightly shallower so when you tighten the tire down, it freezes the rotor. I also bet if you tighten the lug nuts tight with just the rotor on (not wheel/tire) it will be locked up tight.

If you still have the old rotors throw them on and tighten the tire on and see if they are locked up. If they are locked up with the old rotors, it is the break pads, if it is free with the old rotors, then it is the rotors.

 

x2...

 

The 99 has two or three different discs. There is two that have a different offset and then some kinda 2 piece composite rotor. Take your old ones to the parts house and compare or measure from the wheel face (where the lugs are) to the rotor. One is 3 1/16 and the other is 3 3/16.

 

So i compared my new rotors with my old ones and my old ones are just a tiny bit more shallow on the top-hat part. I would say just under 1/4". This makes sense, because the new ones are longer in the top hat part, and when i tighten down the lug nuts all the way it forces the disk against the hub, which makes it lock up my wheel... Am i thinking of this right??

 

Yep that is what is the issue is. If I remember correctly I ended up having to get grand cherokee rotors (or that part number they had in the computer at least).