AWD Grand Cherokee

[Bear Chow]

Buddy of mind picked up a 95 Grand Cherokee, he said the rear end is definitly shot. You can here it grinding away when you put it in drive (later they pulled the cover to see the ring gear had lost it's bite). Now this is where I'm confused:

He said the front drive shaft was spinning albeit much slower than the rear. But the vehicle still did not move. If the front drive shaft spins even just bit shouldn't it propell the vehicle forward? Is there something special about the front axle in a AWD?

[Trigger]

The AWD system in those vehicles are screwy at best. I had one a few years ago and they are really bad with driveline bind due to the viscous coupling on them. You'll find it's real bad at low-speed turns. However, if it's a 50/50 split transfer case, the front drive shaft should be able to pull the vehicle around. If it's spinning much slower than the rear, it could be that it's spinning because of drag and not because it's actually engaged with the front differential. I'd suggest taking the front diff cover off and seeing if there's any visible issues.

[sarge]

They have a Viscous coupling in the transfer case . they are known to go out . however, it is not uncommon for the front to not pull at all if the rear is not engaged or the DS is missing. This is because of the VC , the split for power is something like 60/40 with no spin the VC gets confused ???? if it detects no movement to the 60 side is me guess. Alot of folks pull the AWD X-case and put in a 231 in its place. If he needs a ZJ rear there are a few down at Mitchell's that can be had complete for a good price.

[sarge]

The AWD system in those vehicles are screwy at best. I had one a few years ago and they are really bad with driveline bind due to the viscous coupling on them. You'll find it's real bad at low-speed turns. However, if it's a 50/50 split transfer case, the front drive shaft should be able to pull the vehicle around. If it's spinning much slower than the rear, it could be that it's spinning because of drag and not because it's actually engaged with the front differential. I'd suggest taking the front diff cover off and seeing if there's any visible issues.

The binding you are refering to is the first sign of the VC going out . My 94 was beat to death and worked flawlessly. It was a little strange the first time I wheeled it , you get a spungy feel with the AWD. But it did great.

[Bear Chow]

The front drive is turning though. It is turning slower but still turning. I told him, he must have an issue with the front diff too.

I think I'll go look at it tonight and make sure it really is turning. Thanks for the VC lesson. He supposedly already has another rear axle lined up. Can I assume any 23 spline 231 can be swapped in place?

[blazerbrad]

Assuming everything is still stock you are correct in assuming that if the front driveshaft is spinning at all it should be making the vehicle move. There is no axle disconnects or anything of the sort found stock in the AWD Grand.

What modes does this model have? Just AWD and lo-lock? Is the case a NV249?

Pretty sure it has a fixed rear output, meaning there is a direct connection between the engine and rear axle, and the viscous coupling only supplies variable torque to the front axle. At least I know the NV247's used in the '99-later WJ were set up like this (only had AWD, Neutral, and 4 low lock). You could pull the front shaft and still get 100% power to the rear axle, but couldn't pull the rear shaft and drive on the front unless you locked it in.

They also used the NV242 on some models, and it had 2hi, 4hi, 4 hi lock, N, and 4 low lock. However it was just an open diff in the t-case.

[Bear Chow]

Turns out the bolts are sheared on the ring gears both front and back. How the hell does that happen?

One ring has some slight damage and he wants to run it in the front unless he can find a replacement. How the heck do you interprete ring gear numbers heres what is written ( 11 1 94 DANA D 37768 P8L119 41 11 )?

Does anyone have one sitting around?

[blazerbrad]

Turns out the bolts are sheared on the ring gears both front and back. How the hell does that happen?

One ring has some slight damage and he wants to run it in the front unless he can find a replacement. How the heck do you interprete ring gear numbers heres what is written ( 11 1 94 DANA D 37768 P8L119 41 11 )?

Does anyone have one sitting around?

In my experience that's pretty unusual to have the ring gear bolts sheared off, especially both front and rear.......anyway, on to the ring gear numbers:

11 1 94 = manufacture date, not sure if it's Nov. 1 or Jan. 11, but 1994
Dana = self explanatory
37768 P8L119 = probably a part number/serial number or combination
41 11 = 41 is number teeth on the ring gear, 11 is teeth on pinion. Gear ratio is 41/11 = 3.73