OK, so Im on JC Whitney ordering...TRYING...to order new rotors and drums. The rotors are asking for the stud length and the drums want to know if its 9 or 10". So, whenever Ive done this in the past Ive gotten them from the local parts store and theyve never asked me this. Do I need to actually pull a couple wheels off and measure or does someone know what size go on a '99? Thanks a bunch!

 

Hmmm... do your drums have fins on the outside? If so then you have 10" drums. If not then you have 9" drums.

As far as stud length... strange but maybe if your Jeep came with alloys the studs where longer? Are there actually 2 different rotor options?

 

Well, here is the thing. I measured the front of the drum and its about 10" and it has fins. No problem, right? Well, on their site the Raybestos are available in 9 & 10" sizes. All other manufacturers offer only the 9", and thats when I put in the make/model/year of my XJ.

Same with the rotors. The Raybestos has 2 sizes: 1 1/8" and 1 1/2" sizes, but they seem to be slightly different products now that I look closer. These are their professional grade and they say:

Original Equipment Composite Rotor Design;1-1/8" Wheel Stud Length;Full Cast Replacement

Original Equipment Full Cast Iron Rotor Design;1-1/2" Wheel Stud Length

Other brands either dont say, or say 1 1/8" only or give you an option of 78mm or 82mm. Buying these were much easier when I went into NAPA and gave them the year/make/model and they gave me the parts.

 

You have 9" drums. The rotors could be either cast of composite.They are different dimensions and do not exchange. The bearing flange is longer than the cast bearing flange. The switch was at some point during 99. They make cast replacements for the composite rotors.