U Joints
Hey Team!
So I took the old girl in for a check and they said "Play in the U Joints" and "Pinion Seal".... (along with other things)
I got under the truck and gave the joints a shake - Front and rear shook maybe 1-2mm.
Now a couple of questions:
- How long will I get out of the current u joints with a 1-2mm shake?
- How hard are they to replace?
- Do I just do 4 (2 in the rear and 2 in the front)?
- Do I do the pinion at the same time?
Thanks in advance!
So I took the old girl in for a check and they said "Play in the U Joints" and "Pinion Seal".... (along with other things)
I got under the truck and gave the joints a shake - Front and rear shook maybe 1-2mm.
Now a couple of questions:
- How long will I get out of the current u joints with a 1-2mm shake?
- How hard are they to replace?
- Do I just do 4 (2 in the rear and 2 in the front)?
- Do I do the pinion at the same time?
Thanks in advance!
Senior Member




Joined: Sep 2016
Posts: 970
Likes: 473
From: North East USA
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
1) if the universals have that much slop in them they are shot, they need to be replaced. It's unclear from your post if you are just talking about the front and rear driveshafts or also the front axle joints but in any case they shouldn't have slop in the joint.
2) they are not hard to replace if you have done it before, if not it can take a while and it can be done wrong.
3. How bad is the pinion seal leaking? If it's just a little damp I probably wouldn't worry about it. If it's actually dripping/leaving a puddle you ought to get it fixed before you run the diff dry
2) they are not hard to replace if you have done it before, if not it can take a while and it can be done wrong.
3. How bad is the pinion seal leaking? If it's just a little damp I probably wouldn't worry about it. If it's actually dripping/leaving a puddle you ought to get it fixed before you run the diff dry
Senior Member




Joined: Dec 2020
Posts: 923
Likes: 250
From: North Augusta, SC
Year: 1998
Model: Cherokee (XJ)
Engine: 4L
There is no way to tell how long you'll have. 1-2mm is a lot, so do them asap.
Watch a YouTube video:
Now, the pinion seal is a different story. There is a LOT of wrong info out there, and it's often debated.
The only correct way to replace the pinion seal (without removing the entire pinion gear) is to mark the nut in relation to the yoke and count the turns it takes to remove the nut. The other correct way is to completely disassemble the differential. There are 2 torque specs in the FSM that are discussed. The first is the "don't exceed this torque when crushing the crush sleeve" torque, and the other is "pinion preload torque", as measured by a flexible beam inch-lb torque wrench. You DO NOT TORQUE THE PINION TO A SPECIFIC VALUE. That is wrong wrong. You also don't "torque it until you feel enough gear backlash". That's another big no-no.
Anyway, the pinion seal is easy to replace, but can also be screwed up by an improperly trained technician. The steps are simple. Match mark the nut, loosen the nut, count the turns, dig the old seal out, drive new seal in, tighten the pinion nut until the match marks are aligned. That's it.
Commence the arguments.
Watch a YouTube video:
Now, the pinion seal is a different story. There is a LOT of wrong info out there, and it's often debated.
The only correct way to replace the pinion seal (without removing the entire pinion gear) is to mark the nut in relation to the yoke and count the turns it takes to remove the nut. The other correct way is to completely disassemble the differential. There are 2 torque specs in the FSM that are discussed. The first is the "don't exceed this torque when crushing the crush sleeve" torque, and the other is "pinion preload torque", as measured by a flexible beam inch-lb torque wrench. You DO NOT TORQUE THE PINION TO A SPECIFIC VALUE. That is wrong wrong. You also don't "torque it until you feel enough gear backlash". That's another big no-no.
Anyway, the pinion seal is easy to replace, but can also be screwed up by an improperly trained technician. The steps are simple. Match mark the nut, loosen the nut, count the turns, dig the old seal out, drive new seal in, tighten the pinion nut until the match marks are aligned. That's it.
Commence the arguments.
1) if the universals have that much slop in them they are shot, they need to be replaced. It's unclear from your post if you are just talking about the front and rear driveshafts or also the front axle joints but in any case they shouldn't have slop in the joint.
2) they are not hard to replace if you have done it before, if not it can take a while and it can be done wrong.
3. How bad is the pinion seal leaking? If it's just a little damp I probably wouldn't worry about it. If it's actually dripping/leaving a puddle you ought to get it fixed before you run the diff dry
2) they are not hard to replace if you have done it before, if not it can take a while and it can be done wrong.
3. How bad is the pinion seal leaking? If it's just a little damp I probably wouldn't worry about it. If it's actually dripping/leaving a puddle you ought to get it fixed before you run the diff dry
Yeah just the front and rear on the driveshaft seem to have issues, so was going to do those..... 4 total?
2. Never done them and wrong is no good. I will get online and watch a bunch of videos before doing them.
3. I have never seen a puddle or anything under the truck at the point.... I have seen leaks under the motor, but never that far back.
I will get under it tomorrow and take a pic.
Cheers!
Anyway, the pinion seal is easy to replace, but can also be screwed up by an improperly trained technician. The steps are simple. Match mark the nut, loosen the nut, count the turns, dig the old seal out, drive new seal in, tighten the pinion nut until the match marks are aligned. That's it.
Commence the arguments.
Commence the arguments.
Cheers!
Senior Member
Joined: Feb 2022
Posts: 578
Likes: 159
From: Indiana
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0L
Now, the pinion seal is a different story. There is a LOT of wrong info out there, and it's often debated.
The only correct way to replace the pinion seal (without removing the entire pinion gear) is to mark the nut in relation to the yoke and count the turns it takes to remove the nut. The other correct way is to completely disassemble the differential. There are 2 torque specs in the FSM that are discussed. The first is the "don't exceed this torque when crushing the crush sleeve" torque, and the other is "pinion preload torque", as measured by a flexible beam inch-lb torque wrench. You DO NOT TORQUE THE PINION TO A SPECIFIC VALUE. That is wrong wrong. You also don't "torque it until you feel enough gear backlash". That's another big no-no.
Anyway, the pinion seal is easy to replace, but can also be screwed up by an improperly trained technician. The steps are simple. Match mark the nut, loosen the nut, count the turns, dig the old seal out, drive new seal in, tighten the pinion nut until the match marks are aligned. That's it.
Commence the arguments.
Senior Member




Joined: Dec 2020
Posts: 923
Likes: 250
From: North Augusta, SC
Year: 1998
Model: Cherokee (XJ)
Engine: 4L
The right way? Rebuild it. My way? Pull the ring and carrier out, pop the pinion gear out, replace the crush sleeve and torque it down until you get the correct pinion preload (12-15 in-lbs). Then paint the teeth of the ring and check for the correct gear contact pattern.
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Senior Member
Joined: Feb 2022
Posts: 578
Likes: 159
From: Indiana
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0L
The right way? Rebuild it. My way? Pull the ring and carrier out, pop the pinion gear out, replace the crush sleeve and torque it down until you get the correct pinion preload (12-15 in-lbs). Then paint the teeth of the ring and check for the correct gear contact pattern.
Senior Member
Joined: Oct 2020
Posts: 934
Likes: 282
From: PA
Year: 1994
Model: Cherokee (XJ)
Engine: 4.0
Word of caution on replacing u-joints in a double-carden driveshaft, or more specifically, paying someone else to do it; it's not uncommon to be near the cost of a new shaft...
Marking the nut and shaft is my preferred way to replace the seal; pretty much impossible not to get it "retorqued" exactly like it was so long as you don't do anything super stupid...
Marking the nut and shaft is my preferred way to replace the seal; pretty much impossible not to get it "retorqued" exactly like it was so long as you don't do anything super stupid...
Senior Member
Joined: Feb 2022
Posts: 578
Likes: 159
From: Indiana
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0L
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Senior Member




Joined: Sep 2016
Posts: 970
Likes: 473
From: North East USA
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
BTW
if someone thinks the pinion seal needs to be replaced you ought to check the diff juice NOW if you haven't recently just in case they are right
if someone thinks the pinion seal needs to be replaced you ought to check the diff juice NOW if you haven't recently just in case they are right
Just to confirm, I need 4 joints to do the front and rear driveshaft?
Cheers!


