View Full Version : Fixing the YJ (diffs) NEED HELP

02-10-2008, 02:20 PM
Alright guys, been awhile since I've worked on jeeps so bare with me.

The bro has a 1987 YJ, 6cyl 5sp with lidt and 35's.

What he did was got the mechanic to rebuild the rear diff, he gave the mechanic the wrong gear ratio and used the 4x4 on pavement. The jeep dosnt move... diff is siezed solid (or t-case?) Havnt looked into it yet as its burried in a foot of snow.

Now... He's got no mechanical knowledge so I'll be attempting this swap.

Cherokees have the same diffs as YJ's? I found a 4cyl automatic jeep at pyp (might have been the 2.8v6, didnt look very closly) But these will be different gears than what he has. Taller, correct? I wanted to pull both front and rear carriers and swap them into the YJ. Regarding shimming, I was going to use the shims that are in the YJ at the moment to keep things lined up.

Is there anything that I'm missing or in-correct on? I am presuming that cherokees and YJ's use the same diffs. Even if the gear sets arent shimmed absolutly perfect, it just needs to make it mobile for a few weeks so I can get the engine swap on the civic completed.

02-10-2008, 03:05 PM
He could have cracked the t case maybe? If he did get a new case take the front drive shaft out and drive in rear wheel drive only.

02-10-2008, 06:13 PM
Yeah, we've gotta get it working proper again tho. Cant sell it till than... plus the 4x4 is really quite nice to have; afterall its a lifted Toy. So in the process of fixing it we need to find matching gears... hence the cherokee idea.

02-10-2008, 07:23 PM
the yj has leafs in the front and is sprung under in the rear. The XJis coils in the front and sprung over in the rear. you need some extesive fab to do a diff swap. You can do a gear swap easy enough as long as you pay attention to your shims.

02-10-2008, 09:41 PM
As i understand it most yjs came with dana 35s in the rear and 30s in the front. I'm not sure what the cherokee came with, but i think they may have been the same. You may want to do some research there. You might also run into spline count issues, depending on how close in age the donor is to the yj. And if he ran two different ratios on pavement in 4wd then the t-case is more likely. I'd start there before i got too excited about the diffs