big66440 Posted October 30, 2014 Share Posted October 30, 2014 I've been looking into replacing my differential for a while and have been really tempted to throw a mopar 8 3/4 on my MJ, I know there are other options out there (I've already searched) but I love the idea of the drop out center section,just out of curiosity I know if I get an 8.25 or any other diff off of an XJ I have to flip and relocate the spring perches but would I have to mess with the shock mounts as well? is there any one here that has done the 8 3/4 swap to there MJ? thanks. Link to comment Share on other sites More sharing options...
dunnc1991 Posted October 31, 2014 Share Posted October 31, 2014 I just did an 8.25 swap. The perches need to be moved. Also, the shock mounts are different from XJ to MJ. The MJs shocks are both located on the same side, where the XJs have one on one side and one in the other. It's a pretty sttraight forward swap. Link to comment Share on other sites More sharing options...
johnnyc Posted October 31, 2014 Share Posted October 31, 2014 But the lower shock mounts are on the spring plates. So if you're staying SUA, the shocks would mount up just the same as before. You could just cut the shock mounts off the 8.25. Link to comment Share on other sites More sharing options...
big66440 Posted October 31, 2014 Author Share Posted October 31, 2014 Cool, I was thinking if I had to go through the trouble with the shock mounts swapping the diff from an XJ diff to the MJ I would stick to my plan of installing the 8 3/4 I know it might be a little too much for what I have now but I have some serious plans for that truck down the road Link to comment Share on other sites More sharing options...
dunnc1991 Posted October 31, 2014 Share Posted October 31, 2014 But the lower shock mounts are on the spring plates. So if you're staying SUA, the shocks would mount up just the same as before. You could just cut the shock mounts off the 8.25. Good catch I went SOA so I ditched the stock spring plates Link to comment Share on other sites More sharing options...
Jeep Driver Posted October 31, 2014 Share Posted October 31, 2014 OP- 8.75s and 9.75s in my locale are hard to come by and the couple that I found were $350. I never did find the correct width either and the one that I measured was 63" hub to hub, which might have been OK. But when I figured re-gear and other costs...........screw it. Link to comment Share on other sites More sharing options...
Eagle Posted November 1, 2014 Share Posted November 1, 2014 But the lower shock mounts are on the spring plates. So if you're staying SUA, the shocks would mount up just the same as before. You could just cut the shock mounts off the 8.25. Good catch I went SOA so I ditched the stock spring plates But you didn't have to. You could have just flipped them from one side to the other and reused them. That would also have allowed you to keep the same shock absorbers. Link to comment Share on other sites More sharing options...
big66440 Posted November 3, 2014 Author Share Posted November 3, 2014 OP- 8.75s and 9.75s in my locale are hard to come by and the couple that I found were $350. I never did find the correct width either and the one that I measured was 63" hub to hub, which might have been OK. But when I figured re-gear and other costs...........screw it. I see 8 3/4's often in my area, not too expensive and I really don"t mind if I don"t find the more sought after 489 carrier as long as It's not the type with the pressed on drums I figure it would be cool to be able to swap rear gears very quickly and the added strength to boot. Link to comment Share on other sites More sharing options...
Jeep Driver Posted November 3, 2014 Share Posted November 3, 2014 Consider rear discs too. Link to comment Share on other sites More sharing options...
big66440 Posted November 4, 2014 Author Share Posted November 4, 2014 Consider rear discs too. :thumbsup: might as well, I'm pretty sure its a direct swap from the 8 1/4 Link to comment Share on other sites More sharing options...
xjrev10 Posted November 5, 2014 Share Posted November 5, 2014 My next MJ rear swap will be a 8.8. Dealing with putting disks on a axle is a expensive ordeal if you are forced to use new parts. (Referring to the 8.25 I swapped into my MJ and used ZJ discs with all new parts except for backing plates and caliper brackets) Link to comment Share on other sites More sharing options...
Blue XJ Posted November 6, 2014 Share Posted November 6, 2014 Consider rear discs too. :thumbsup: might as well, I'm pretty sure its a direct swap from the 8 1/4 Is that true? I have a set of disks I took off my 8 1/4, that originally came from a D35. I was going to sell them, but if its a direct swap, I'll put them on the 8 3/4 under my Duster. Link to comment Share on other sites More sharing options...
A-man930 Posted November 6, 2014 Share Posted November 6, 2014 I've got a later 8.25 with the 29 spline shafts and an Aussie Locker and I'm happy as a clam; but then again I'm not punishing it really hard with 32" tires. People will tell you that it's nearly as strong as a D44... Link to comment Share on other sites More sharing options...
Blue88Comanche Posted November 6, 2014 Share Posted November 6, 2014 Consider rear discs too. :thumbsup: might as well, I'm pretty sure its a direct swap from the 8 1/4 Is that true? I have a set of disks I took off my 8 1/4, that originally came from a D35. I was going to sell them, but if its a direct swap, I'll put them on the 8 3/4 under my Duster. The KJ Libby's had rear disc breaks. There was a write up on here. It was straight forward XJ 8.25 drums to KJ 8.25 discs Link to comment Share on other sites More sharing options...
Incommando Posted November 6, 2014 Share Posted November 6, 2014 But that doesn't address the 8.25 ->8.75 issue that his Duster would have Link to comment Share on other sites More sharing options...
big66440 Posted November 6, 2014 Author Share Posted November 6, 2014 Consider rear discs too. :thumbsup: might as well, I'm pretty sure its a direct swap from the 8 1/4 Is that true? I have a set of disks I took off my 8 1/4, that originally came from a D35. I was going to sell them, but if its a direct swap, I'll put them on the 8 3/4 under my Duster. Yes it is true you can use the rear brake set up from many jeeps with the 8.25 rear and since the 8.25 and D35 swap over easily it will install on the 8.75,the only issue I've heard of is when you want to install the drum brake combination for the parking brake on the 8.75 I've read it requires a lot of custom work but then again that can vary according to the persons ability. Link to comment Share on other sites More sharing options...
mkbruin Posted November 7, 2014 Share Posted November 7, 2014 If you are looking for a drop out 3rd, stronger than stock, and disc brakes, why not go to the ubiquitous 9"? Parts everywhere, significantly more info online, cheap and proven workhorse... Link to comment Share on other sites More sharing options...
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