1999 XJ Limited 4.0L AW4...

I attempted to order new hubs this morning and was asked if I had cast or composite rotors. I couldn't remember (nor can I find the receipts) from the last go-round with brake rotor replacement.

Q's: Why does that matter? What's the difference with regard to hub replacement? How can I tell if the brake rotors on my XJ are cast or composite?
__________________

 

go with cast, its more solid and cheaper!

 

I don't need rotors. I need hubs. There are two types of hubs. The hub I need is contingent on the type of rotors I already have. How do I tell which type of rotor I currently have?

 

I had the same problem i cant really remember which on it is but i went with timkin

 

My A/P store carries the National/Federal-Mogul. My cost is about $145 for one and about $125 for the other. I don't want to drop all that dough (buying a pair, so could be as much as $290) wait a few days then find it's the wrong part in the middle of the job. I'd get stuck waiting and would have to leave the Jeep in a state of disassembly for another couple days. It's my DD so I need to go in/out one time on this task.

Did you save your receipts for the Timkins? If so, then will you tell me the P/N and I can get a cross-reference?

 

Go with the hubs for cast rotors. Chances are you have cast rotors on there because you won't find the composit rotors in the aftermarket. They were just cheap factory rotors. The cast rotors will have a thicker hub mounting surface, where as the composit will have a thin sheet metal like hub mounting surface.

I was wrong, Rockauto sells both the cast and composit rotors.

 

I'd rather not take chances. Being wrong costs extra. Maybe a pic will help in determining which type of rotor it is...

 

Those look like cast rotors to me. Also looks like you got those brakes pretty hot a time or two, hows the rear brake adjustment?

 

i answered in the ask a question thread. look there.

they are cast

 

www.rockauto.com has Timkin hubs for $70.00 plus shipping for the cast rotor part number.

 

Thanks for your input BB. The measvals indicated that they are cast (using criteria provided by Dukie564 from "Ask The Question"). I wouldn't doubt that they got heated since I'm looking at compound issues here. The upper slide for the inboard pad in the photo has a deep notch worn into it AND the passenger side hub's wobbling more than a bit. This could be a chicken/egg scenario - I don't know which came first - the notch or the wobbly hub. Pull the photo and zoom on that upper pad hook - you'll see the notch that the pad's sitting in. Since I prefer to do things in pairs then both sides will get equal treatment (broken or not). I'm going to pull the knuckles, weld then machine the slides/notches. Upper and Lower BJ's, calipers and brake lines might also be in the offing. While I have things yoinked apart I might as well machine the rotors a little to be sure they're okay too. You know how one thing leads to another...

 

Sorry, didn't answer the rest of your Q...

Rear brakes are fresh and dialed-in, thankfully.

 

Yes, those are cast rotors.

When you change the pads, make sure to grease the caliper pins.
Clean the knuckles where the pads sit really well. You'll notice a spot where they wear in to the knuckle surface itself. Take a file and just smooth it out so your new pads don't get stuck in that spot. Then add a little antiseize to the area so the pads glide nicely. Just don't over due it. You don't want antiseize on the rotos and pads themselves. Good luck.

 

It's not that simple. Jeep used two different rotor and hub bearing combinations in 1999. If you use the composite rotors in place of the cast rotors, the rotors will drag against the knuckle. If you use cast rotors in place of composites, a new outer brake pad will be too thick to mount the caliper.

 

The easist way to tell is to measure the exposed length (after you remove the wheel and rotor) of the wheel stud.
1 1/8" for composite rotors.
1 1/2" for cast rotors.
There are other differences but this is the quickest way to tell.