Ive had a question thats been bothering me for a Long time and thats how to check for a posi rear end, ive herd that one way to tell is to look on the diff cover for a tag that indicates it has frictionless fluid in it and thats a way to tell but ive been to many pick and pull junk yards and looked at alot of axles and never been able to find one with a tag on it, is there any other way to tell if a rear end has posi in it?

 

With tranny in neutral, jack it up in the middle of the rear end, and turn one wheel. If the wheel on the other side spins the opposite direction its an open (non-posi) diff.
Just jack up one side and try to turn the wheel. If you can't turn it, its a posi, if the wheel turns the drive shaft its open diff.

 

Gravel road...burnouts.

Or what ^ he said above.

 

thats if the xj will do that !!! hahaha

 

haha yeah I was kind of joking...but it is how I checked lol.

 

hey if you have no rear brakes it works !!!

 

Just for info purposes, the word "posi" or "posi-traction" or "posi-trac rear end" is an old Chevrolet term for their particular type/style/brand name of a clutch type limited slip differential (LSD) dating back to the 1950s and '60s. Jeep called their's "Trac-Lok", American Motors called their's "Twin-Grip" and Chrysler called their's "Sure Grip".

 

Burn outs don't work. Jack up one side and spin. Shouldn't move.

 

........unless the clutches are completely fried. If they are, about the only way to tell a LSD from an open diff is to remove the cover.

 

Thanks for all help guys, it really helps me out because im looking for a Trac-Lok for my 8.25 and you have no idea how hard it is to find one, ive been to so many pick and pull junk yards and checked alot of xj's and theyve all been open diffs then....im suprised how rare they are in xjs

 

On the rear axle there should be a tag on the back of the rear differential cover. On that tag should be the letters LSD for limited slip differential. That is the easy way to find out if it has it or not only if the tag is still there.

 

Ive been trying to find them, there on the right side of the diff connected to the diff cover by one of the bolts and ive never been able to find it, or even find the small amount of one that mightve rotted away or broken off, its either jeeps in my area just didnt come with trac-loks or there just alot rarer then i keep thinking.

 

Must be in the rust belt like me.

 

The rustiest of the rust belt. They literaly COAT the roads with salt and it destroys my paint and body pannels, pisses me off to no end. Id rather drift in 4HI and deal with snow drifts then this damn salt

 

Even if u find a lsd rear end, it's middle name is "SLIP". Get a locker for that puppy and don't look back. Here's a decent video demonstration of the different types of differentials. It's easy to see how a lsd can be no more effective than an open diff in certain situations.


We installed a PowerTrax No-Slip locking diff in our '98 XJ 8.25. No messing with ring/pinion set-up, couple of hours and you're done. One wheel can be on the ground and the opposite wheel in the air and they both turn at the same speed when locked.