WJ rear disc brakes?

pentastar01 · 10-22-2009, 11:19 PM

Anyone know anything about it.

Obviously, I've read about the ZJ conversion which is still on my list. But it just so happens that I have the axle from a WJ sitting on a bench at my school.

So, I figure if anyone knows IF it is even possible to convert it to fit my 8.25 they could let me know before I start to con my teacher into letting me rip it apart.

gorman · 10-23-2009, 08:05 AM

The four bolts holding the WJ's backing plate are spaced differently than the ones on a 8.25/Dana 35/Dana 44. You'll have to measure your axle's bolt spacing and see if it would be possible to redrill that pattern on the WJ backing plate. If you could, then I would assume the rest of the WJ disk brake swop would be similar to that of the ZJ which is well documented all over.

sprintagogo · 10-23-2009, 08:20 AM

I don't know what the benefits of the WJ set-up might be (bigger discs maybe? Possible resulting in too much rear braking?) but as well as the backing plate difference you will also have to get around the wheel lug differences. XJ/ZJ/KJ all use 5x4.5" PCD while the WJ uses 5x5" PCD.

Why not just go with the tried and tested ZJ or KJ swap. It is simple and works, there is no point in trying to reinvent the wheel on something so straightforward.

I have a spare ZJ set-up here ready to be cleaned up and sold or you should be able to easily find the full set-up from either a ZJ or KJ in a breakers.

See here for a KJ swap write-up - www.jeepforum.com/forum/f11/fitting-kj-liberty-rear-disc-brakes-xj-cherokee-8-25-axle-750112

99Greenmachine · 10-23-2009, 08:59 AM

Go ZJ man...no offense to Sprint, but KJs are hard to come by in the JYs over here in the states. ZJs are EVERYWHERE

gorman · 10-23-2009, 09:10 AM

Quote:

Originally Posted by pentastar01

But it just so happens that I have the axle from a WJ sitting on a bench at my school.

Seeing that you have the parts already - it should be easy enough to check the possibility of redrilling the backing plate and the WJ disks can also be redrilled to the XJ's 4.5" PCD.

I've used WJ disks when I did my rear disk brake conversion - they are 305mm in dia compared to the 280mm of the ZJ, but the calipers are the same size, so apart from the increase in disk size, you should get overbraking in the rear.

justanotherjpr · 10-23-2009, 10:07 AM

Keep mind the WJ's have a different bolt pattern, so you'll have to re-drill the rotors.

pentastar01 · 10-23-2009, 01:35 PM

Yeah, I thought the backing plate pattern would be different. Alright, cool, thanks for the help guys. If I do happen to swap it all, I'll be sure to post it up here.

skyway0018746 · 10-23-2009, 04:24 PM

if this was to be attempted like stated above the wheel pattern is diffrent 5x5 not 5x4.5 so rotors wont work and they are designed for 16" rims so there might be a rubbing problem on stock rims.

gorman · 10-24-2009, 02:05 AM

Quote:

Originally Posted by skyway0018746

...the wheel pattern is diffrent 5x5 not 5x4.5 so rotors wont work and they are designed for 16" rims...

The PCD is a non-issue as one can just re-drill the holes on the WJ disks - no need for other disks if the original ones are in good condition. 15" do fit over the WJ disks.

Here's how a WJ disk sits inside a stock Jeep 15" alloy rim - the caliper I've used is different to the Jeep one so I can't vouch for that clearance, but I'm 98% sure it should clear a stock rim without an issue.