my front diff is in a bad way, what to do...

[mtl3314]

hello all,

i have a '90 6cyl laredo np231 automatic, i have had front driveline noise for about 3000 miles. i was narrowing down causes, replaced worn motor mounts and trans mount, u joints, all control arm bushings, anyway all this took a while and it turned out to be a failed diff seal, it mustve leaked slowly because im usually good about fixing leaks. when i popped off the diff cover, all i got was about a cup of burnt brown dirt/goo. the spider gears can be moved up/down about .25 inch, the ring gear teeth look ok, i hear theyre pretty tough as well as the pinion. i must assume the side gears and spider gears are shot as well as all the seals and bearings, i havnt removed the carrier yet and am wondering the best route.

should i replace the whole axle with a junkyard unit, taking the risk of having to rebuild that unit anyway?

if i rebuild the installed axle, will i need new axle shafts since theyre mated to the spider gears, what would a rebuild after this type of damage entail?

before any of this happens, ive heard i can gut the axle quickly and safely run the vehicle,
if this is true, how do i do it?

thanks for any info i can get......

 

[Jess]

The easiest route is to replace the whole axle with a salvage one. Make sure you get the correct gear ratio and abs parts (if you have abs).

 

[GrimmJeeper]

if i rebuild the installed axle, will i need new axle shafts since theyre mated to the spider gears, what would a rebuild after this type of damage entail?

they are only matched to the spiders by the splines, i wouldnt worry about the shafts unless you can actually see heavu wear on them

before any of this happens, ive heard i can gut the axle quickly and safely run the vehicle,
if this is true, how do i do it?

thanks for any info i can get......

if you want to gut the axle you need to

A) Remove the front drive shaft
B) Remove the inner axle shafts

you will need to split the shafts from the ujoint, and leave the outer part of the axle shafts attached to the unit bearings (hub bearings). the outer or "stub" shaft helps keep the bearing together, without it the unit bearing will come apart while you are driving (it has happened to more than one person here that i have seen). as long as the front drive shaft is removed, and the inner parts of the axle shafts are removed, you can leave the ring and pinion in there, they will not turn. you could also remove the carrier but it wont matter. make sure you take the drive shaft out so the pinion is not spinning freely in the diff with no oil to keep it lubricated if you decide to remove the carrier.


best of luck to you, hope this helps a bit.

 

[kastein]

You've got probably the most common drivetrain in XJs (4.0, aw4, 231) so unless you have tow package or ABS like everyone said you should just have standard 3.55 gears... go to a junkyard and grab a whole new axle for a hundred bucks. Pick up some new bolts for installing it (another 50 bucks or so) so you don't have to worry about it if you break any, maybe some new bushings for the axle ends of the UCAs. You should be good to go after installing it and getting an alignment.

While you're in there, I would probably do a quick checkup on the brakes and maybe replace the shocks and rubber brake lines just for peace of mind.

EDIT: make sure you get one with a vacuum disconnect if you have a vac disconnect axle... I forget the specs on which years had those.

 

[mtl3314]

thanks for the info to those who posted, while saving for a new axle ill prob remove the inner shafts of the old one, i think i might even drive it like that till i can get something like a super 30 kit or an lsd or something.

the help is most appreciated.

 

[wheelinscott]

sounds like the breather hose came off and water/mud got in there. when you get a new axle or whatever you decide to do make sure you get a new hose on there. i had a k5 blazer that happened to.