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8.25 LSD or Posi

B

bugout

NAXJA Forum User
Location
Florida EVERYDAYS forcast: Hot and humid with a 50
How can I tell if I have an LSD in what I pretty sure is an 8.25 without opening up the diff? If I don't have a limited slip, is it a true posi trac??? When I'm on grass or sand, and I floor it or power brake to get the rear to break loose, both wheels spin to dig a hole until the pumpkin in on the ground. However, when turning in full lock in either direction, I still cant hear the rear either of the tires dragging.

96 Country, HO, AW4, NP231, D30 front, 8.25 rear, 3in RC lift, 31x10.5 on Crager 15x8 ATs

Also, my rear differential cover only has a rubber plug in it, where all others have had a threaded fill plug? Is this normal or a sign or something sketchy the PO didn't fill me in on?
http://www.cherokeeforum.com/f59/cherokees-towing-174076/

I'm really only diving into this because we've had some deep water around here lately. The other day I was parked on a pretty steep incline and there was a tiny bit of seepage coming from out side of that little plug. It wasn't quite water but it wasn't quite diff fluid either. So I know it's time to replace the fluid and that little plug and maybe find where the breather tube terminates and check out it's condition.

Also is this what they mean when they refer to a "corporate" rear end?
 
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The best way to tell if you have a LSD (which a posi is a LSD, just what GM call theirs) is to pull the cover and look. If you see spider gears, its a open diff, if you see a round clutch like assembly is a LSD. You can check with the cover on, however a worn out LSD that needs a refreshing will act like a open diff.

The plastic plug is a factory item, no jerry rig. Could be a bad plug, but I bet if you pop that cover youll find a mess in there of water and oil that needs to be cleaned out.

My advice would be to take the 5 minutes to take the rear diff cover off, check things out and use the .50 cents in permatex to seal it back up, then formulate your game plan. Then you know for sure 100% where you are at, and what needs to be done.
 
Get yourself a lubelocker gasket and some diff fluid and pull the cover.
 
Johnnie Walker said:
Get yourself a lubelocker gasket and some diff fluid and pull the cover.
Click to expand...

I plan on pulling the cover but with how often I'm gonna have to do it because of all of the water I go through, I mean daily basis, a 20 dollar gasket is not in my future.

From what I've read, there is no way to actually water proof the rear end no matter how much lube, or gaskets, RTV or fluid you throw at it.
 
bugout said:
I plan on pulling the cover but with how often I'm gonna have to do it because of all of the water I go through, I mean daily basis, a 20 dollar gasket is not in my future.

From what I've read, there is no way to actually water proof the rear end no matter how much lube, or gaskets, RTV or fluid you throw at it.
Click to expand...
There are things you can do that will help seal it.
The $20 gasket is made to be used over and over with no sealant and no waiting for it to cure. It's worth it if you pull the cover often.
An aftermarket cover will have a sealed fill plug.
The vent tube is often too short for water crossing and can let water enter. Check that and maybe lengthen it.
Up front the axles and tubes are open to the elements all the way to the pumpkin where the seal is. The axle tubes can get filled up with water and mud. 'Axle tube seals' remedy this.
Good Luck
 
bugout said:
I plan on pulling the cover but with how often I'm gonna have to do it because of all of the water I go through, I mean daily basis, a 20 dollar gasket is not in my future.
Click to expand...

You've got it backwards. If you plan on pulling the cover all the time, you NEED a lubelocker. Clean the RTV off once when you install it, then re-use the LubeLocker as many times as you want.

As for waterproofing the diff, make sure your vent line is higher than the water your driving through and is in good shape. An aftermarket cover with a threaded plug may be a good idea but isn't necessary. I've driven through lots of water (including at least one occasion where I was pushing water over the hood for a while) and I always check the diffs but I haven't had a real water intrusion issue.

Just something to keep an eye on and change the fluid as needed.
 
Just jack it up and put it in park or gear without the parking brake on, and try to turn a rear tire. If you turn it, its open. If you cant then its posi/LSD (Trac-Loc).
 
donthelegend said:
You've got it backwards. If you plan on pulling the cover all the time, you NEED a lubelocker. Clean the RTV off once when you install it, then re-use the LubeLocker as many times as you want.

As for waterproofing the diff, make sure your vent line is higher than the water your driving through and is in good shape. An aftermarket cover with a threaded plug may be a good idea but isn't necessary. I've driven through lots of water (including at least one occasion where I was pushing water over the hood for a while) and I always check the diffs but I haven't had a real water intrusion issue.

Just something to keep an eye on and change the fluid as needed.
Click to expand...

Thanks for taking the time to explain that, I should have read the whole brochure. Now, whats up with the friction modifier I'm suppose to add if I have and lsd? And if I ask what is a fair gear lube for dding, am I going open up the same can of worms as the "what oil is best for my engine?
 
bugout said:
Thanks for taking the time to explain that, I should have read the whole brochure. Now, whats up with the friction modifier I'm suppose to add if I have and lsd? And if I ask what is a fair gear lube for dding, am I going open up the same can of worms as the "what oil is best for my engine?
Click to expand...


The friction modifier is not optional for LSDs. Follow the manual and you should be good (never had an LSD so I don't remember off the top of my head).

As for gear oil, its not quite as bad as engine oil debates, but only because there are fewer options. If you are going to be changing it frequently because of water issues then don't bother with anything fancy. I changed mine with Amsoil the first time I did it thinking I'd be able to take advantage of the fancy synthetic over the life of the vehicle... then had to drain it less than 10K miles later because of a bad inner axle seal on the front axle and a leaking cover on the rear axle (rock peeled the cover back).

I think the manual recommends 80W-90 for normal use and 75W-140 for heavy use/towing. Use whichever fits your needs (and double check those weights, they're close but probably off a bit).
 
You need the friction modifier for LSD because without it, the rear end will make a VERY annoying groaning sound whenever you make a turn. This stuff simply modifies the gear oil to reduce the surface friction from the clutches in the diff. Most of the stuff is the same and comes in a little bottle that you add after filling with gear oil. You can find the Mopar stuff on ebay for cheap or you can just hit a local dealer. I've used Ford friction modifier in a Chrysler diff without issue but the purist would go with the Mopar stuff. NEVER trust the guys at Mr. Lube. They always say "our gear oil already includes it" but it doesn't.

I must say that personally I hate changing gear oil and would look to find any way possible to not have to do it often. The stuff has a horrible smell and it sticks with me for days....
 
Thanks everybody for the info. Its a used beat up old rig but it runs. Its got a lot of work to get done before it'll be a real daily driver or even a trail rig. Right now, I'm picking my battles with the maintenance trying to decide if Ive got the time to stay ahead of it OR if I need something a little newer BUT I have always wanted an XJ and I couldn't pass up the opportunity to get this one.
 
I use Amsoil Severe Gear 75w-110 front and rear. Also used it in my dakota, which has LSD. No friction modifier added. This oil is created to be able to use it without additional modifier.
 
nice kit-that drill bit will not be cheap 15-20$- and you can't use a common hand drill
I had a GMC S15 that had a seized plug- I did something similar to this kit with a big nut cut in half and short bolt that I welded on. But that was not offroaded-not flush...
I have not had an issue with the rubber plug on the 8.25 in 13 years- but don't hit 2 feet of water every day either... thinking a little (very little) rtv when reinstalling the rubber plug may be enough.
I would like a locker/LD for the 8.25 in time as well.
I used Royal Purple when my wife's LD d44 on her TJ started to groan- it has LD additive- and nearly immediately after changing fluid it operated properly again. That was 2 years ago. BTW- the factory LD works great in snow on that TJ- I have always been jealous with my open 8.25.
 
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