2WD Pitted Brake Rotor Question

[1987Comanche]

I saw something this evening I've never come across before. My friend brought over his 2000 XJ complaining of vibration when braking. I'm thinking typical warped rotors, deep groves worn in them, etc. I looked at them through the wheels (base steelies) and the area where the pads ride is riddled with pockmarks in the rotors. I'd guess they vary to approx 0.030" deep and there were easily 100+ on the outside edge of the Dr side rotor. If I remember correctly the rotors looked ok when I saw the truck last year and it's definitely driven (12K this past year) so I don't think it's rust. What causes this? :dunno:

[mule13]

never seen that,only thing i can think of : rotors were made of cheap metal and they've gotten really hot,cheaper metals are usually made of different alloys or steels melted together.if this were the case some metals when heated up and cooled back down heat and cool at different rates thus expand and shrink at different rates,so the slower cooling metal would shrink slower and maybe break away in places from the rotor.i cantr imagine anyone making rotors from metal like this but with everything coming from overseas now who knows!

[Automan2164]

When was the last time he had his brakes done? Could it be possible he wore through the rotor to the fins?

 

Rob L.

[JeepcoMJ]

at least a 2000 2wd front axle uses 4wd brake rotors and calipers.

[1987Comanche]

I think I figured it out. I think it's porosity in the casting. It's not terribly uncommon in poor quality grey cast but the fact that they were able to turn the casting down without breaking through to it is interesting. It's my best theory anyway. I'll have to post some pics after I help him do a brake job.

 

at least a 2000 2wd front axle uses 4wd brake rotors and calipers.

 

I was pleasantly surprised by this after doing a brake job on the old '87 2WD. I thought it would involve new wheel bearings, etc.