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What Rotors? ZJ Discs on XJ 8.25"

Blk96XJ

NAXJA Forum User
Location
Columbus, Ohio
Im about to get all the parts for rear disc brakes for my 29-spline 8.25 from a donor ZJ with a D35 with disc brakes. I know what I need from the ZJ; Calipers,brackets,hardware,backing plate, p-valve, soft-lines.

BUT what rotors do you use??? That something I cant find...Its a 8.25" and I don't know what rotor will fit on it. I have a 15" wheel BTW. 5x4.5"

PLZ HELP I NEED TO KNOW WHAT ROTORS TO USE ON A 8.25 REAR AXLE WITH ZJ DISCS FROM A D35!!! AND STILL GOTTA FIND A GOOD SOLUTION TO HOW TO GET MY E-BRAKE TO WORK PROPERLY AND RELIABLY.

Sry for all the capitals but i feel its real important.
 
I used the rotors from the donor ZJ. Got new ones, of course.

From the donor, get the studs that mount the caliper brackets and also the lug studs. They're both too short otherwise.
 
Just to be clear im worried the hub wont fit thru the hole in the rotor seeing as how the 8.25 is 3" an the dana are 2.5-2.75"

You will have to open them up to fit over the hub.

JIM.
 
That's weird. Mine fit right on. 8.25 out of a 99 and discs off a 94 Grand.

I did have to open up the caliper brackets to fit over the 8.25 housing though. Very minor.

Don't forget to get the studs!!

Have you measured the hub size on a ZJ or are you assuming it's the same size as an XJ Dana 35?

If it wasn't 15* outside, icy, and dark, I would go measure the hub diameter on my XJ donor axle assembly in the driveway.
 
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As said there ^. The rotors do not have to be modified. The backing plate does. Get the parts. You'll see. It takes 5 minutes with a dremel.
 
Same. I am actually running the rotors and pads off the donor, they were in perfectly fine condition. Did the whole swap for $70 including new axle seals.
 
IDK guys...Im looking at the rotor for a 96 and 97 ZJ thru NAPA, and it has specs listed. They list the center hole in the rotor as 2.84"...

Correct me if im wrong but isnt the 8.25 3"? Did anyone have to also grind the center of the rotor out at all? Was it a tight fit? Lots of ppl have the rear ZJ discs so it has to work, but what if its on the dana35 axle?

Someone Reassure Me.
 
The 8.25" axle tube is 3" (or there about), but you aren't putting the rotor on the axle tube. It goes on the axle shaft, which is the correct size for the rotor ID. Works the same on the D35 or the 8.25. No grinding on the rotor. It slips on.
 
Oh yeah, if you have alloy wheels or wheel spacers, you will need longer lug studs. If you have steel wheels you probably can get away without.
 
Ok that god to know. I dont have spacers. Just Steel Cragers. But if i look to need the lugs ill get some. Just get the same lugs that are on the donor vehicle?
 
I'm not sure, I considered doing just that but the knurl diameter may be different. I've also heard that the lug studs from a 99.5 and later XJ's front brake setup will work, but haven't verified. I ended up getting some universal chrysler/ford ones like 2" long from Summit Racing, they're made by ARP. Stock lug nuts will NOT work with them.
 
I'm not sure, I considered doing just that but the knurl diameter may be different. I've also heard that the lug studs from a 99.5 and later XJ's front brake setup will work, but haven't verified. I ended up getting some universal chrysler/ford ones like 2" long from Summit Racing, they're made by ARP. Stock lug nuts will NOT work with them.

Guys, it works fine. The lug studs and the caliper mounting studs can be knocked out of the donor axle and installed into your 8.25. I just did this. Put a little never-seize on the splines and pull them in with the nuts. Easy.
 
Guys, it works fine. The lug studs and the caliper mounting studs can be knocked out of the donor axle and installed into your 8.25. I just did this. Put a little never-seize on the splines and pull them in with the nuts. Easy.
Great news. I will have to remember this for next time I do it!
 
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