So this is from a diff I pulled at the local junkyard. I realized today when opening the diff that it is either locked or has a LSD because both axles turn in the same direction. I need help figuring out what it is because I planned on swapping my current 8.25 for this (before I knew it wasn't a standard 3.55 open diff) and now I'm thinking it maybe doesn't have the same gearing. It is from a 1998 XJ, it wasn't lifted or modified which leads me to believe maybe it's from factory?

Can you enlighten me? LSD or locker? How do I figure out the ratio? If it is indeed not 3.55, is it possible to change the gearing on that type of diff? I know probably dumb questions but I wasn't expecting this and need to figure out what to do.

Searching the numbers on the bearing caps (3723574 WN24) returned nothing on google

Here are pics :

 

Looks like another Chrysler 8.25 based on the flat bottom of the differential housing. Was there an ID tag on one of the bolts of the cover? Was the 98 that it came out of a 6cyl auto or 5speed? If it were an auto, it should be 3.55. Still looks like an open diff, so surprised that both shafts turned in the same direction. You could always spin it and count the teeth on the ring gear. Look deep underneath and count the teeth on the pinion gear and then simply divide (for example 40 teeth divided by 10 teeth equals 4 to 1) Just an example.

 

Looks like a Chrysler 8.25 to me as well, but I can say with almost 100% certainty that is a limited slip , you can tell because the carrier has a more cylindrical shape as opposed to the semi conical open differential carrier. Make sure you don't loose or break those spider gears cause they are very hard to find replacements for and lockers are nonexistent unless you want a full carrier replacement.

 

Also there are different aftermarket gear ratios you can install including 3.55, only difference with the c 8.25 is that it uses carrier bearings with adjuster screws built in so you don't have to mess with carrier shims.

 

Nice catch. Didn't even look at the shape of the carrier. One other thing, you could always spin the axle shaft one revolution and count how many times the yoke spins. If it is about 3 and a half, then it should be 3.55 to 1. This is an approximate measurement though.

 

That diff is whats called a Trac-Loc. It's a LSD.

 

thanks for all the responses. i knew from the start the axle in an 8.25, but i was wondering about the diff itself because when I opened it I knew right away it wasn't the common open diff.

I'll do my research now that I know how it's called, but can you tell me if it's any good (reliability and ride comfort)? so it's most likely from factory?

also it's so rusty I can't see any print on the axle housing, no tags either.

I'll go try right now to spin the axle and see how many times the pinion spins. the gearing is what will determine what I end up doing with it..

edit: the pinion spinned 3 and a half times exactly. so is it safe to assume it is 3.55:1 ?

 

The Trac-Loc is better than an open diff but some still prefer a locker. As for street driving, it performs way better.

 

from my quick search people say they should be maintained and only used with a special type of gear oil, and if it wasn't the case it's probably toast and should be rebuilt (replace clutches from what I understand). can i do something while it's out of the jeep to test if I need to rebuild it? I'm honestly not interested in rebuilding it, the only reason I got another diff was to avoid paying to get the pinion bearing replaced.

in the event I really have nothing better to do and I do replaced the clutches, are special tools necessary for preload and all that other stuff, or a torque wrench is enough?

 

I just use Lucas gear oil in mine, never had a problem. As for maintaining, fluid should be changed/serviced just as any other part. As for clutches, they're not that hard to change. Yukon Gear makes different level of clutch packs for your driving style. They have Stock, Mild and Aggressive. I chose Aggressive for my axle. It rarely unlocks now as they were meant for high HP or V8s. For you, I'd suggest Stock or Mild.

 

alright i'll look into that, thanks a bunch again!

 

When you pulled the cover was there a tag bolted to one of the bolts, if so that would show the stock gear it came with. Best bet is to count teeth on both ring gear and pinion that will tell you what gear it is in it.

 

 

Thats has 4.10 gear ratio I'm almost positive looking at the numbers on the ring. Am I wrong?

 

Post a photo for everyone to see. What size tires are you running or plan on running the 4.10 gear is the proper gear for a 31" tire if in fact it is.