C8.25 swap SUA

[Dzimm]

So I came across a cheap C8.25 out of a 97 XJ with 3.55 gears. Exactly what I need. I'm looking to put it in my MJ but want to stay SUA. All I can really find is information on the 8.25 going SOA. What I'm wondering is what it takes to swap it SUA. The info on everything else is easy enough to find like brakes and such but the perches are what I'm wondering about. What is the difference between SOA and SUA perches and is it as simple as welding on the new perches? It just seems too simple to me. The biggest issue will be setting the pinion angle. I need to take the axle elsewhere to be welded so how can I set the angle without having the truck where it will be welded? My thought is take the D35 with and use that for measurements for the perches. Is this a viable option? I have no experience swapping axles in this way so any advice would be appreciated. Obviously measuring and tacking it with it in the truck would be ideal but that's just not an option.

[SBpunk]

Just did this / in the process of.
Brakes are exactly the same with the exception of having the piece that holds your rear load sensing valve. You can use some metal wire/hanger if you want to keep it or can delete it which takes a little more work.

 

You can reuse your ubolt plates with the shock mount in them but you'll need longer ubolts. You should replace them anyway they're pretty weak.

 

Driveshaft will have to be shortened by a few inches.

 

The easiest way to get the right pinion angle with the leaf perches (you're probably going to need to just get new ones) is find someone with a small burner box welder. Get the axle set in with tires and what not and bolt the ubolts to the loose perches snug. Use a floor jack to get your pinion angle and tack weld the perches. Doesn't even have to be pretty just steady enough to where they won't break when you pull everything back out and take the axle to a welder. That's the most difficult and expensive thing to do. I screwed up and didn't put the axle in to get the right pinion angle and had it up a bit too high. Used shims to get the angle back down. Waste of money since I was being lazy.

[Strokermjcomanche]

Cut the old perches off the 8.25 and weld the new perches on , the mopar perches are cheap( under $20 ) and work well . Are you planning any lift ? If not the pinion angle shouldn't have to be changed , you can buy magnetic angle finders for cheap and copy your angle ( and spring perch width ) off of your old axle , weld the perches on and you're good to go . If the pinion length is the same the driveshaft will bolt right in , use the Mj emergency brake cables also . If you keep the height sensing valve , flipping and reversing the bracket mounted on the diff cover will work .

[Dzimm]

I will see about using a small welder, my problem is the wiring throughout the house and sheds is super old and I'm worried about using a welder on it. We had to swap a breaker in the power pole in place of fuses just to run a dryer and we have to cut all power to the sheds to run the grain bin fans... And yes I plan on 4.5" of lift but that will come at a later date so I was planning on setting the pinion angle pretty much where it was and shimming later if need be. It is also a 97+ swap so the drivetrain is different, does the 97+ trans/t case sit at a different angle than a 90 drivetrain? I don't see why it would but thought I'd ask. I will have to get the driveshaft shortened no matter what so that isn't a problem and I need new e-brake cables since the ones in it where cut off at some point. Could I just use the rear sections (after it splits to two) from an XJ or is it a different length? As for the height sensing valve it'll be easier to remove it since the entire brake system needs replaced.

[desbennett004]

find your pinion angle like this on your old axle by making sure your perches are level, then measure as in the above picture. Then level out your new perches on your new axle and replicate the angle, as in the above picture. The process is the same weather it's SUA or SOA.

 

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[Dzimm]

find your pinion angle like this on your old axle by making sure your perches are level, then measure as in the above picture. Then level out your new perches on your new axle and replicate the angle, as in the above picture. The process is the same weather it's SUA or SOA.

 

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Thanks. This is probably what I'll do. I figured this would work but I wanted to make sure.