Jeep rear discs on an 8 3/4 axle solution

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blue missile

blue missile

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Here is what I know so far. A new disk brake set up for an 8 3/4" axle will run me around $700, I still need to buy a set of new axles for around $200 when I cut the B body rear down to the A body length. Since Im going to cut the axle down anyway, why cant I just get the whole rear axle from the jeep ($150)and cut the ends off and graft them to the 8 3/4"? This solves the fitment issue of the brakes on the 8 3/4 axle. Then I can have the jeep axles cut and resplined for the 8 3/4 center chunk. Or have a custom set of axles w/ 5x4.5 made to fit the set up.
Thoughts?
Andrew
 
I know this is old, but I am interested to see if you did this? I think a dana 44 does have the same size axles (spline and thickness).
 
Yea I am interested as well. There has to be a cheaper alternative. If anyone can make this work it is someone here on FABO.
 
Here is what I have done so far:
I cut my axle down to A body length,
Got a complete disc brake setup from a Jeep grand Cherokee.
I bolted up the Jeep backing plates and installed the B body axles.
Because of the backing plate the axle and bearing is pushed out of the tube 5/16".
other than that everything lines up perfectly.
I did have to grind out the hole in the backing plate to allow the MoPar bearing to fit through, and drill the fifth hole.
That 5/16" is what the whole fuss is about.
Since I needed new axles any way(going from B to A), I ordered them 5/16" longer than stock.
Seating the bearings back that amount requires cutting down a spare race to 5/16" and a spare inner bearing core to the same thickness and installing them on the axle after you drop the retainer on and before you press the bearing on.
Then everything will be in the right place and everything should line up.
Andrew
 
Why couldn't you just have the backing plate put on before the bearing, and then press the bearing on? Would that work or am I picturing it wrong?
 
JR.,
Heres what I love about this site, People actually ask
intelligent questions, at least some do:-D
Your question was good enough to make me stop what I was doing, clear the bench and re-assemble the brake assembly.
Because this brake set up was intended to be bolted to the outside of the tube flange under the bearing retainer, it does not have the clearance to be moved out towards the axle flange the required 3/8".
Boy that would have been easy!!!!

You were not thinking wrong.
The drum portion of the disc would hit the bracket and the parts for the emergency brake would not have had room.
Great thinking though.
Andrew
 

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Andrew,
Would have been nice if it worked. I did not mean to cause more work for you, but I am glad you investigated it a bit.
JR
 
JR,
No problem, if it had worked it would have saved me alot of time building a jig and grinding the races and cores down.

Andrew
 
All of your custom made parts have been inspirational to my 72 Dart. I haven't done hardly **** to mine, but when I look at one of your threads, I go and get at least something done on it... Even the axle shortening that chapped that others a$$.
Keep up the great work
 
Those look identical to my Ford Explorer rear disc brake setup. Although I do have a Ford rear in the Dart.

67dart029.jpg
 
Moles,
close but these are really on a 8 3/4" rear.
Here is what's new.
The machine shop wanted $150 to make some spacers for the set up.
I went and got a set of bearings at O Reilly and cut the races and inner cores down to 5/16" with a 4" grinder and thin metal cutting discs using the actual Jeep backing plate as the jig. I laid the disc on the plate and cut through the race as I turned it. After I was done I miced the pieces and again using the backing plates I final dressed them until they were the right thickness.
Now I have the final pieces of the puzzle to assemble the system.
Andrew
 

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I also had to create a spacer for my setup as the caliper mounting bracket is much thicker than a drum brake backing plate. Excellent work using the bearing races for your spacers. Shows alot of effort in doing it right and I give you 2 thumbs up!
 
blue missile said:
Moles,
close but these are really on a 8 3/4" rear.
Here is what's new.
The machine shop wanted $150 to make some spacers for the set up.
I went and got a set of bearings at O Reilly and cut the races and inner cores down to 5/16" with a 4" grinder and thin metal cutting discs using the actual Jeep backing plate as the jig. I laid the disc on the plate and cut through the race as I turned it. After I was done I miced the pieces and again using the backing plates I final dressed them until they were the right thickness.
Now I have the final pieces of the puzzle to assemble the system.
Andrew
Click to expand...

Now put it all together and show us lots of pictures!!!!!!! Im really excited to see this.
 
While the paint on the axle carrier gets hard, I set up the axles for the swap pics enclosed. I am using two adjustable retainers because I just happened to have two.
Andrew
 

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I have created two gaskets for each side out of 1/64" fabric reinforced neoprene gasket material, and installed them between the axle tube and the dust plate and the disc backing plate. I used the metal crush gasket as the template, and secured them with black RTV.
I then installed all the E brake parts.Everything fits fine, and should function as designed. I ran new brake lines on the axle and will cut and reflare them when I have the rubber ones in hand. I will rebuild and paint the calipers when the kits arrive.
Andrew
 

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This is some great stuff. Thanks for your efforts
 
Outstanding!!!
Well Done!!
This deserves to be archived for future reference.
You might fined a magazine would be interested in your
mods for an article if you would submit it..:cheers:
 
Thanks,
here are the final pics of the transplant. I will say this is going as slow as molasses. I still need one caliper rebuilding kit and one hose, will be in tomorrow.
I will say that putting the axle in, requires removing the parking brake parts for access. And getting the race spacer in is a little tricky. you have to get a punch and LIGHTLY tap the bearing into the hole far enough to give the free floating spacer a place to fit into then its easy to get the whole affair into the tube and bolted in place.
Its late now but Tomorrow I will post the list of parts with costs for others.
Andrew
 

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I'm surprised to see those are not vented discs...thought just about all newer cars use vented discs.

Nice work figuring out the mounting of those Andrew, looking forward to see the price list
 
Here are the parts I used, I understand I spent money for stuff you guys probably dont need. The complete total was just under $500 and the satisfaction of solving a problem.
Andrew





BRAKE PARTS
All of these parts are from or will fit Jeep Grand Cherokees 98-01, other years may work Rear Discs were introduced for the 96 models
I PAID WAY TOO MUCH FOR THE STUFF FROM THE JUNKYARD $150 for the brackets and calipers, and rotors that were shot. A bunch of stuff was missing as well such as the attachment bolts, hoses, a banjo bolt. I suggest you get the system yourselves, and get everything.
The Raybestos number for the caliper is #10591
New parts:
Slotted and drilled rotors from Powerstop.com $209
The rest are from O Reilly Auto parts
Brake bolt kit #BHH H5066- $3.29 these are the attachment bolts for the caliper to the bracket.
Rubber bushings ( Boots) #BHH H5593- $2.99
Caliper rebuild kit- #BHH 41147- $3.99-you need 2 of these
Brake Hose #BHH BH178139-$22.99ea- (Ray-380226) Unless your hoses are in really perfect condition get these. You need two.
Disc pad set #BB MKD666-$19.99
E brake shoe set #BB 701-$20.99
Axle bearings #MPB A7-$10.99 ea you need 2 for the making of the spacers.
With the rotors $333
 
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