AMC type 20 rear pinion seal

AMC type 20 rear pinion seal
C

cityjack

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Location
Willis, VA
Vehicle(s)
82 CJ5 258 4 spd. No mods
Hey Guys,

I've done the customary search and nothing exactly what I'm looking for and my Haynes is kinda vague. Support the rear end and remove wheels and brake drums. Take an inch/lb torque wrench and rotate the pinion via the pinion nut a few times and record the amount of torque it takes to move the nut the book says. First off, should I really be using an inch/lb wrench? Maybe a ft/lb'er? please explain why? Also am I going in the loosen direction with the nut to see what it takes to move the nut or the tighten direction? Once I get the number I want as far as torque, I hold the yoke and maybe with air spin the old nut off. Then I guess I remove the old seal and replace with new. Then what from here? Kinda lost with the Haynes here.

Thanks guys.

82 CJ5 by the with a AMC 258 i6 / 4.2l .

Thanks again.

Sid
 
You don't need an inch pound torque wrench if you are just changing the pinion seal. Your years Model 20 does not use a crush sleeve - it uses a shim pack to set bearing preload. The inch pound wrench would be used if you were changing a bearing or setting up a new R&P. It is a good idea to replace the pinion nut if you can.

See this thread for a recent discussion on changing a pinion seal. -->> http://www.jeep-cj.com/forums/f2/differential-question-4279/
 
Old Dog... The FSM you linked to is not for a CJ FSM. A CJ model 20 does not have a crush sleeve. Check out H-14

attachment.php



The 76 and up CJ AMC20 -->>

amc-20-rear-cj.jpg
 
CJ said:
Old Dog... The FSM you linked to is not for a CJ FSM. A CJ model 20 does not have a crush sleeve. Check out H-14
Click to expand...

CJ the link is for the 84-86 cj. If it was for a FSJ they wouldn't be showing 2 piece axles.
 
I replaced mine about 2 years ago. I just took the pinion nut off replaced the seal and torque the new nut to the torque specs in the Hayes manual, and I haven't had any problems.
 
79Jeep5 said:
I replaced mine about 2 years ago. I just took the pinion nut off replaced the seal and torque the new nut to the torque specs in the Hayes manual, and I haven't had any problems.
Click to expand...
Yep, that's how you do it.

The inch pound torque wrench is if you have the differential removed. The inch pound torque wrench is to check preload. In other word it's used to see how easy it is to turn the pinion gear when the differential in removed. That shouldn't be necessary if all you are doing is replacing the seal.

Remove your drive shaft. Remove the big pinion nut. Take off the yoke. Remove and replace the pinion seal. Reinstall the yoke. Put the pinion nut back on and torque it down. It is high torque but I don't know the specs.
 
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Done this a few times. When you torque the pinion nut back in, make sure you torque it to the point where you remove all play from the pinion and no further. torque range is about 250ft/lbs from what I read, but didn't use a torque wrench. Just torqued it a bit at a time till I got all play out.
 
Guys....thanks tons for the help. But I must admit, I'm a tad confused. Looking at my Haynes which is for 1949-1986 CJ's, I am following the instructions for the Model 20 AMC/Jeep differential with semi-floating tapered axle-shafts. From the book for semi-floating axle-shafts, its says to put an inch/lb wrench on and record what it takes to move the pinion nut. I did not do this. I just figured because the first gentleman in this post said I do not have a collapsible spacer. I have a shim pack. Just remove and re-torque. Well the book says for the front axle pinion nut EXCEPT tapered shafts(which I have) 210ft/lbs. I am working on the rear. The book calls it a pinion BOLT not a nut but still the same torque. So seeing this before I put the nut back on I figured there must have been something to those instructions for my year and type of pinion set-up with that inch/lb wrench. I am thinking it is to see how much pre-load is put on the bearing once all free play is removed from the yoke to the bearing.
This is how I assembled and I'd appreciate any comments if I did it wrong and should check something before I do any damage and drive it any further. I replaced the old seal with a new and coated the new seal with some gear oil. I put the cleaned yoke through the new seal and onto the splined pinion shaft. I put the new nut on which was tight the whole way down until the flange of the nut seated up against the flat of the yoke. When I got to this point I went very slowly checking to make sure all free play from the yoke was removed and nothing more. I am assuming the tightness of this nut is for lock-nut purposes and 215ft/lbs. of torque was not the case here. Once the free play was removed and since I did NOT use an inch/lb wrench in the beginning to determine pre-load I just rotated the nut about an 1/8th of turn more and that was it. I put the drive shat back on and drove it about a 10 minute drive home. The exploded view of my Model 20 in the Haynes shows a collapsible spacer. I do not know and it does not say which year this model 20 is though in the book. The instructions for removing and replacing this pinion seal were to raise the rear of the vehicle, support, remove both wheels and brake drums. Thats it. I am assuming the differential is still in the vehicle. There must be something to this inch/lb wrench. Lastly the book says on all OTHER axle models other than mine, replace with a new pinion nut and torque to the specified value. I guess this is where the 215 ft/lb amount comes in.
tell me what you think guys.

Sid
 
cityjack said:
From the book for semi-floating axle-shafts, its says to put an inch/lb wrench on and record what it takes to move the pinion nut. I did not do this. I just figured because the first gentleman in this post said I do not have a collapsible spacer. I have a shim pack. Just remove and re-torque.
Click to expand...
That first gentleman in this post is a smart gentleman. He is right and it sounds like you did it right. 215 ft/lb of torque to tighten up the pinion nut.
Forget the inch/pound wrench. It's to measure the preload. That's not necessary to replace the seal. Here's a picture of someone measuring the pinion preload. He is just seeing how easy the pinion rotates. He is not tightening anything.
1011_4wd_15+dana_60_front_axle_rebuild+pinion_preload.jpg
 
I think checking the pre load before breaking it loose would have been a good idea, Having the pre load torque would have given something to compare to. the reading is the torque needed to rotate the differential and keep it moving rather than just break it loose. I am not sure if the axles should be in or out.
I think you should be OK, I think I would be worried about overtightening . As long as there is no slop, check it every 50 miles or so for a couple hundred miles.:cool:
 
Thanks for the quick input guys. I really do appreciate everyones help. I will take your advice and re-check to make sure the nut is not backing off and creating freeplay.

Have a nice night all.

Sid
 
BusaDave9 said:
That first gentleman in this post is a smart gentleman. He is right and it sounds like you did it right. 215 ft/lb of torque to tighten up the pinion nut.
Forget the inch/pound wrench. It's to measure the preload. That's not necessary to replace the seal. Here's a picture of someone measuring the pinion preload. He is just seeing how easy the pinion rotates. He is not tightening anything.
1011_4wd_15+dana_60_front_axle_rebuild+pinion_preload.jpg
Click to expand...
The Gentleman says... :notworthy:

IOPort51 said:
I think checking the pre load before breaking it loose would have been a good idea, Having the pre load torque would have given something to compare to. the reading is the torque needed to rotate the differential and keep it moving rather than just break it loose. I am not sure if the axles should be in or out.
I think you should be OK, I think I would be worried about overtightening . As long as there is no slop, check it every 50 miles or so for a couple hundred miles.:cool:
Click to expand...
You can torque the nut to 100 or 1000 lbs feet (1000 would likely compress the soft shim, but you get what I mean), it will make no diff on the pre load, unlike a crush sleeve pinion, a shimmed bearing does not depend on the pressure of the sleeve for preloaded.
NOTE: This is only if you are just replacing a pinion seal. If you are setting up a new R&P you have to set bearing pre-load.
 
Old Dog said:
CJ the link is for the 84-86 cj. If it was for a FSJ they wouldn't be showing 2 piece axles.
Click to expand...
Weird - no fsm I have has ever shown a CJ model 20 (note: I said CJ - the later 20s do use a crush sleeve) with a crush sleeve (and I can find no parts diagrams, including Dana) Just goes to show you have to be on your toes when working on these old vehicles. :)
 
IOPort51 said:
I think checking the pre load before breaking it loose would have been a good idea, Having the pre load torque would have given something to compare to. the reading is the torque needed to rotate the differential and keep it moving rather than just break it loose. I am not sure if the axles should be in or out.
I think you should be OK, I think I would be worried about overtightening . As long as there is no slop, check it every 50 miles or so for a couple hundred miles.:cool:
Click to expand...

I agree, you need to check when you have a crush sleeve. which I believe you have. Now I would just check it and make sure it's not getting hot, or getting any slop. It's all you can do.
 
And I will say -

There was never a CJ (post 86) model 20 that had a crush sleeve. This post will bite me if I am wrong.
 
CJ said:
And I will say -

There was never a CJ (post 86) model 20 that had a crush sleeve. This post will bite me if I am wrong.
Click to expand...

And I say I have never taken one apart, so I'm only going by what the books says.
They also sell a crush sleeve for a cj and an up-grade to do away with it. So :confused::dunno:
 
I have no issue with the way you approached this. I have done it that way on a handful of 20's in the past and there have been no issues. If I could actually find a dial-type in/lb wrench (clicker style won't work for this application), I may have done it that way, but no one I know has one and I didn't really feel like I needed it.
 
I have one, I am hoping to get to use it once more before I die.:cool:
 
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