Anyone running 87 MJ Rear Leafs

I have found a set of 1987 MJ rear leafs in the bone yard today. I see that they are about 3" longer and look to have agreater arch. I am planning on refabbing the front spring mount on my XJ and using an extended shackle in the rear to correct the penion angle. Using this set up my concerns are the flex and load handeling capability of the Spring under MJ pack in a Spring over XJ application...

Thanks,
Michael

The base MJ was rated for more than a half ton, IIRC, and the optional "Metric Tonne" package had a load capacity of 2200 pounds. I don't think you need to worry about capacity.

My Metric Tonne MJ converted to SOA mode (minus the short 9/16" thick overload leaf) flexed like mad! Probably would have flexed great with that leaf too...they only did just get barely flat when the 33"s started to rub. I agree with Eagle that "load handling" shouldn't be a problem.

I imagine an intact MJ leafpack would do well on a SOA XJ, but instead of refabbing the front mounts, why not just cut the eyes off the MJ Main leaf (Warning: contents under pressure!) trim to length and install these under your XJ main leafs?

My XJ main leaf looks like " ~ " ... Chopping the MJ main leaf and adding it to the XJ would work for now, and would be easy, But I think the leaf is stressed and may adventually break. By going to the MJ pack I can get rid of the funky/weak XJ main leaf and build an inch or two lift into the new frame mounts while still using a Jeep leaf pack that some one paid big $$$$ to design. Shackles will correct the penion angle. I'm looking to go 33 - 35 " Swamper TSL's and a welded rear + I expect to beat on this truck and am trying to bild now to avoid breakage later.

Thanks,
Michael

The MJ leaves are 3" longer in the front and 2" longer in the rear, 5" longer total. You'll need to make new spring hangers in the front and use a good boomerang shackle in the back, and you still may have clearance issues in the rear with the 2 additional inches.

I changed to MJ main leaves last month, so I know what's involved. It's a good modification, the extra five inches is nice, but you need to have a good design for the new spring hangers and make sure you have clearance in the rear, maybe re-mount the spring shackle below the existing shackle box. Mine is cut up in the back with a home made tube rear bumper, so I didn't have much of a problem, but I did need boomerang shackles.

Richard,
Thanks for the info on the MJ leaves. How is the flex? Any extra lift? Did you keep the overload leaf, I'm thinking of keeping the overload to reduce axle wrap. I am also considering placing the centerline of the rear axle 1" rearward, ( thus my OEM XJ drive Shaft legnth Question). As far as running a Boomerang shackle or cutting up the rear mount / bumper, I hope to work all of that around the suspension. I am looking to build a set of (Light weight) thin wall 6" C-channel bumpers.

Hmmm Might look into mounting the MJ's in the original location, Cutting Lots O sheet metal, Running a 2wd Drive shaft (3" longer???), and fabbing in a short buggy leaf in place of the rear shackle that would rest in/on the New custom bumper. Greater Flex, Wheel, base and DS legnth :farmer: + More room to cut sheet metal (4-dr) which = less lift to run 35's , + Cheap and Homegrown...???

Michael

I just used the MJ main leaf on top of my other leaves. I had pretty good flex with my other springs, but it did increase a little. I rub some and I didn't before. It also rides a little better, which I was after since I'm a little lighter in the back now. It won't droop more in my case, because I wasn't running spring clamps before, which didn't work well with the weight of the D60. I put the spring clamps back on when I changed to the MJ main leaf, and the hope is that with the longer leaves and the spring clamps the droop would be about the same. I actually had droop that did no good because the leaves were fanned out too much, now the spring stays together.

I'm not much of a fan of buggy leaves and funny shackles. That extra bit of droop doesn't do anything for trail performance, and can hurt stability on off camper situations and steep downhills. On the rocks that we run, stability is important, and so is grip on the steep climbs, so keeping that rear end firmly planted by a good set of rear springs is a good thing. The torque will open up the rear of the springs on the steep stuff, which can hurt your climbing ability. We can all crawl over most of the stuff if our diff doesn't get hung up, regardless of how much flex we have, so it's the short, very steep climbs that seperates the men from the boys. Build for the climbs........