rear disc from grand cherokee on a 8 3/4

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I went and got jeep Cherokee rear disks over the weekend. I have not yet cut down the axle so there is room to make mods.
I did a quick bolt-up and it appears in my situation that the rotor is offset to the outside, and the bracket needs to move away from the centerline of the car.
Currently it is a B body axle tube with the factory adjuster and tapered bearings.
I will re-assemble the rear end with the pumpkin and get precise measurements, and pics for all to see. This will be with the mounting plate mounted between the axle tube flange and the exterior axle seal retainer.
By the way both of my axles are the same length is there a left or right orientation for the one with the adjuster?
Andrew
 
adjuster goes on the passenger side, but if you upgrade to the "green" bearings you don't need the adjuster.
 
Thanks Belmateo,
I have come to the conclusion that the green bearings do not meet the side load requirements for the car. That has really shortened the list of brake set-ups that I can use.
I will keep you guys informed
Andrew
 
OK,
here is what I have learned:
Jeep changed their rear disc breaks in the year 1999,They went from an 11.25" rotor set up to a 12" rotor set up on all of the models. Maybe these are the ones everybobies having trouble with.However before that the 11.25" rotor setup will bolt directly on to the 8 3/4" axle and everything centers up. I even got new pads to check the fit and all is good.
As it happens without knowing this I ended up getting the smaller setup.These were off of a Cherokee not a grand Cherokee.It couldnt fit more perfectly if it were engineered for this axle!Isn't God good!
Yes you still have to drill the fifth hole and you still have to enlarge the axle hole in both the backing plate/bracket and the dust shield.
The only real issue I have left to solve is the off setting of the bearing because of the backing plate. I will tackle that tomorrow.
In the mean time here are the part numbers of the smaller setup:
Backing plate-3212245
Dust plate-1E3257A
11.25" Rotor-53601 mine was made in Canada

I just noticed the post comparing the distance flange to flange on each side. Yes this is a B body set right now, so when I cut it down I will have to order a B body axle in an A body length.
the current measurements are:
outside face of adjuster to back of axle flange is 1.75" plus the flange which is .375" equals 2.25" to the face of the axle flange.

I promise pictures as soon as my cell phone cable gets here.
Andrew
 
I am happy for you, seems you are a lucky guy. The only thing I question is the parking brake.....is that something you can merge together to make it work?
 
More updates,
It turns out that the 98 Grand Cherokee uses the same rear brake system and the parts I listed are also the same for both of that year.
I ordered a new set of rotors slotted and drilled, and went to a specialty bearing place and learned that there is no taller bearing to solve the bearing offset problem.
So I will have 5/16" spacers machined out of the old races to take up the space of the bracket and put the bearing back in the carrier tube all the way.
So those are the solutions to the two problems with the swap.
Andrew
 
Quick update, here are pics of the new rotors.The new axles are still a few days out but it looks like it will all come together.
Andrew

Photo024.jpg
 
blue missle, the spacer is going between the bearing and axle to put the bearing all the way into the rear end or this is for the seal plate to bearing?
 
Rick,
The spacer goes between the outside bearing race and the outer seal/bearing retainer. It actually sits inside the Cherokee bracket and dust shield. And because its made out of a stock bearing race the contact area is exactly the same as the stock set up.
Now as far as the axles go, unless you order new axles and have them made 5/16" longer you do lose that much contact within the differential.
Since Im cutting cutting down a B body rear I needed new axles anyway. There was no extra cost ordering the axles with the extra length.
So far with the salvage and new parts I have $400 in the brake setup.
Andrew
 
ramenth said:
To answer your questions I don't believe there to be a true "bolt on" rear disk assembly for the 8 3/4. Not in the perspective of just bolting on and go with just a few, no hassle mods. Not in the sense I believe you're looking for from the tone of the first post quoted above.
Click to expand...

There is one that I did that nobody mentioned here. 1975-1976 Chrysler Imperial rear disc brakes, yes you do have to drill the fifth hole at the bottom. Other than that it is a DIRECT BOLT IN including parking brake.
 
ok, so if im understaniding this corretly, 98 grand cherokee rear discs will fit the 8 3/4 with bbp axles, right? i was thinking that the whole way through this thread, as i am currently running drums and backing plates off a bbp 8 1/4 on mine.

i have green bearings. will this setup work?

also, can you post the pictures of how all this went together for me? im trying to picture it in my head, and having a hard time.

michael
 
Michael,
there are two problems with the swap that need to be overcome.
First is that the stock length axles are 5/16" too short, this is the space taken up by the cherokee backing plate. by using the plate, there is that much less contact at the diff of the splined end of the axle.
Second moving everything out brings the bearing out of the end of the axle tube that much. Using the spacer (cut down race) and having your machine shop set the bearing 5/16" back from its normal position solves these problems.
I have not yet assembled everything, still waiting for 4 link parts before assembly.
Andrew
 
Question (& maybe one of ya'll addressed it already): "What is stopping someone from pulling the entire Rear End ***'y from the Jeep & swapping it into the A-Body?"
I'd imagine that some mods will be necessary, but just from my (half-axxed) estimations, the Jeep RE should be a compatible width, etc, etc
 
arch,
Im sorry for not seeing your post, I called and talked to the people at the yard first and asked on this forum, The amount of work necessary to make the swap is not worth the effort because what they have is essentially an 8 1/4" rear. which is why the swap is a bolt on for the 8 1/4. However the entire suspension built around the jeep rear end is completely different from our A bodies.
Andrew
 
archlab said:
Question (& maybe one of ya'll addressed it already): "What is stopping someone from pulling the entire Rear End ***'y from the Jeep & swapping it into the A-Body?"
I'd imagine that some mods will be necessary, but just from my (half-axxed) estimations, the Jeep RE should be a compatible width, etc, etc
Click to expand...

I'm thinking nothing but a little fab work. I've toy'd with the idea for my Dart (same direction, just new stuff) and think I will actually put one in my '70 Satellite.

The WJ Model 44 axle has a 59.5" track width and a '62-'70 B Body is 59.2". So... close enough.

The Model 44 is a Spicer/Dana 44 with tons of aftermarket support which makes it a good choice. Cut all the coil over and other mounts off, weld on (or use circle track bolt on) spring perches and call it good.

You will now have a B Body rear in your A Body. Good rear disks, a nice limited slip and either 3.55 or 3.73 gears.

If you want to go a bit narrower, then use a XJ (Cherokee). I believe they have a 58" track, the Dana 44 only came in towing/heavy duty optioned vehicles and they are the early models ('89 and earlier). These would be leaf spring as well with less stuff to cut off. But, you will have to get all the rear disk stuff because I believe these were drum only. Gear ratio would be 3.07 or 3.55. Car-Part.com lists a 3.54 as well, but not sure what the differences are with that assembly.

Thanks,

Kevin Wesley
 
Sorry to reply so late - Some interesting pros & cons. But definitely some potential. Thanks Guys
 
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