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88 Xj 4wd help!

S

Spnknu

NAXJA Forum User
Location
Alaska
Kinda new to this whole jeep thing so try to be nice.

I have an 88 XJ 4.0 Auto with 3.55 gears. I picked it up with a Rubicon 3.5 lift, 31x10.5 BFG AT and some American Racing wheels. Now, I have this problem with my 4wd not engaging. I have a 4x4 Posi-lock lever install on my front axle (came with the jeep). From what I read its a mechanical version of the vaccum switch for the CAD (center axle disconnect). I've ruled out that my transfer case is not engaging by putting the jeep in the air and pulling the transfer case lever to 4wd H with the posi-lock lever engaged. But my front tires do not roatate or engage when I accelerate. The output on the transfer case does rotate.

So can anybody help me out? I'd like to get this fixed so I can go wheeling this week.

Here are some picture of my jeep.

3n83md3p6ZZZZZZZZZ962647b3f85faf31bda.jpg


3n03me3l9ZZZZZZZZZ96241a637241c2a1042.jpg


Later
 
It sounds like the Posi-Lock is not working. The shifter fork may be broken or bent. Pull the cover/posi-lock off of the CAD and inspect it. If it were me i would just space the shifter fork over to keep the axle engaged all of the time (won't hurt the T-case) so it will at least be reliable and engaged.
 
I see. I will pull the cover tomorrow after work and take some pictures. Will a stock fork be a reasonable replacement or will I have to order one for posi-lock?

Thanks
 
The Posi-lock uses the stock fork which is not strong enough, they offer a stronger replacement fork but its a bit pricey.
 
i have a stock fork on my yj with the posi lock been in for about ayear and a half just make sure you pull the tcase in first the pull the posi lock and if it breaks again you could just move the fork over and weld just a little bead on the shaft its on to make it so it wont slide back then the front is always engaged just lke the newer ones or switch the the new axle shafts they are stronger but you have to put a new seal in the diff
 
I just flipped the fork so it would stay engaged. I heard people use washers but i couldn't figure out how to take it apart. This was on my old jeep.
 
I haven't pulled the posi-lock yet to inspect it but I'm wondering...can I swap a newer XJ axle in that will delete the CAD with the fork design? I have a free 96 D30 sitting at my friends house.

Later
 
Spnknu said:
I haven't pulled the posi-lock yet to inspect it but I'm wondering...can I swap a newer XJ axle in that will delete the CAD with the fork design? I have a free 96 D30 sitting at my friends house.

Later
Click to expand...

Yes, and you will get the MUCH stronger 297X axle U-joints that can be upgraded to even stronger 760X U-joints.

The 96 D-30 is a great upgrade to your rig.
 
sweet, is there any difference between the 96 d30 and the 98 d30? I have a line on a pair of 98 d30 & d35 for $200. I won't be able to pick up the 96 d30 for about 2 weeks since my friend is on vacation and its locked in his garage.

Later
 
Spnknu said:
sweet, is there any difference between the 96 d30 and the 98 d30? I have a line on a pair of 98 d30 & d35 for $200. I won't be able to pick up the 96 d30 for about 2 weeks since my friend is on vacation and its locked in his garage.

Later
Click to expand...

No, they are the same, Just stay away from the high pinion models (2000,2001). I wouldn't bother swapping in a D-35 for your rig, its not worth the trouble. Try to find a 8.25 thats geared same as the front from a 97-01, it will be a 29 spline unit.
 
alright, well I have a 8.8 explorer axle sitting in my garage that I pulled from a 98 explorer. Its geared to 3.55 and I planned on selling it to some jeep friends of mine but now I maybe have a use for it since I just picked up my XJ this last week.

I put my XJ back in the air and I will be checking out the fork on the CAD here tomorrow when I get up. I should have it fixed tomorrow and the new axles in by monday.

later
 
Wait!!! If I read correctly, you said your front drive shaft is not turning when in 4-wheel drive. This means the problem is with the transfer case, not the axle disco.

If the problem was with the axle disco, then the front driveshaft would turn, but would not necessarily send power to both front wheels.

I'd check the transfer case linkage to be sure it's engaging. Did you do a transfer case drop with the lift? If so, then the linkage is probably in need of adjustment. Simple procedure, but if not properly adjusted it will not fully engage. With the wheels in the air and transfer case in 4-wheel (high or low), if you can freely spin the front driveshaft, then transfer case is not properly engaging.

Just think about t he mechanics of the transfer case...when in 4-wheel (high or low), the front and rear driveshafts are tied together (unless you have a 242 and select full time), the front and rear driveshafts must turn at the same speed.
 
xjtrailrider said:
No, they are the same, Just stay away from the high pinion models (2000,2001). I wouldn't bother swapping in a D-35 for your rig, its not worth the trouble. Try to find a 8.25 thats geared same as the front from a 97-01, it will be a 29 spline unit.
Click to expand...
You got it mixed up, the 00-01 have the LP(Low pinion)D30 which is the less disirable of the 2 The rest are HP D30

Flyfisher said:
Wait!!! If I read correctly, you said your front drive shaft is not turning when in 4-wheel drive. This means the problem is with the transfer case, not the axle disco.

If the problem was with the axle disco, then the front driveshaft would turn, but would not necessarily send power to both front wheels.

I'd check the transfer case linkage to be sure it's engaging. Did you do a transfer case drop with the lift? If so, then the linkage is probably in need of adjustment. Simple procedure, but if not properly adjusted it will not fully engage. With the wheels in the air and transfer case in 4-wheel (high or low), if you can freely spin the front driveshaft, then transfer case is not properly engaging.

Just think about t he mechanics of the transfer case...when in 4-wheel (high or low), the front and rear driveshafts are tied together (unless you have a 242 and select full time), the front and rear driveshafts must turn at the same speed.
Click to expand...
He said that the front tires do not spin, but the output from t-case does (which most likely means that the D/S is turning)
 
I figure it out...it wasn't the fork being busted. It was the cable. The cable was frayed in a 3 foot section. The fork was upgraded to a cast iron one. I took the cable to a shop and they're building me a new one and should be ready in a few days.

Thanks for everyones help figuring this out. I should have my jeep on the trails soon. (hopefully this weekend)

Later
 
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