Amc 20 Axle rebuild

[OrganizedChoas]

I have and 86 J10 that NEEDS its rear axle serviced. Some background knowledge is that all my vehicle knowledge and skills started when i got my truck, so deciphering truth from insanity in the regular internet is hard. I acquired the truck a 1.5 years ago and have discovered that everything except what ive done to it is from the factory. Id love to take the time and completely rebuild with new parts the entire rear axle including shafts, differential gears, the whole shabang just to treat my Cranky Truck since it hasnt been cared for till now. But that isnt in the budget.

I know i need to do bearings, every seal on the axel (leaking fluid from multiple points; base of differential, between differentialand drive shaft), and new fluid. Is there anything eles i should add in to this service? Also any tips or tricks yall have learned doing this? Lastly, since one of my leaks is between the differential and drive shaft should i replace the pinion yokes? (Ive looked up exploaded veiws and that is what that part seems to be called)

Thank you in advance! Im sorry if these seem like silly questions, im just starting and a girl that really wants to SPOIL her truck but cant currently and doesnt have much guidance on the way of axles.

[Chubbinius]

Good afternoon and welcome to the forums. There are a ton of great folks and great information on here. One of the places that you can look for documentation on these vehicles (TSM/FSM-the service manuals, and parts catalogs and such) is here-https://oljeep.com/

Manual/TSMs button-https://oljeep.com/edge_parts_man.html, and the Parts catalog for 1981-1986 is here-https://oljeep.com/parts_man/81j.pdf.

I didn't see the TSM for your year, but one of the more knowledgeable folks on here can probably help you along with whether you can use the 1984 or one of the later ones for yours. Good luck!

[rocklaurence]

If you have to dig into the axle, you may as well replace the bearings as well as all the seals. Randy's Worldwide and 4wParts are good places to get the parts. However, you'll need some special tools to replace the Diff' bearings. Also, decide now if you are going to run bigger tires and re-gear. Do it all at the same time.

[Stuka]

I am going to assume you just need to do the axle shaft bearings and seals. These require a press to install and uninstall them. I typically bring the shafts and parts to a shop and have them do it.

I would not pull apart of the differential to do the carrier or pinion bearings unless you KNOW they are bad.

[tgreese]

Yes, leaks do not indicate tearing down the gears. Differentials typically last well beyond the vehicle life in normal use, unless they have been abused or run out of oil. There is also a seal at the pinion end ... this is the one between the driveshaft and housing. If this leaks, it needs replacing. Check the TSM and follow the procedures for that axle. It's reasonable to replace the seals and bearings at both wheel ends of the housing, as Stuka describes. Unlikely there are new axle shafts available for this vehicle, and you would not replace them unless they were physically broken in two.

[OrganizedChoas]

However, you'll need some special tools to replace the Diff' bearings. Also, decide now if you are going to run bigger tires and re-gear. Do it all at the same time.

What type of tools? Are they just called "differential bearing tools"?
Also I'm running 235/75/r15 which according to the original tire size paper I found in my truck was the larger of the two stock options, and happened to be what the tire shop we use had in stock without special ordering. Will this require re-gearing? I've had them on for a few months with no issues that I've noticed.

[OrganizedChoas]

Also thank you very much everyone!!

[tgreese]

Have you read the TSM? Read section 2F in the '82 TSM here - https://oljeep.com/edge_parts_man.html

Not everything about the '82 will be the same as an '86, but service of the rear axle is the same.

If you can, buy the proper TSM for your Jeep. https://www.bjsoffroad.com/1984-87-Jeep ... _1056.html BJs will give you a modest discount as a member of this forum.

There are gears in the axle, and they need to be set up with proper clearances to operate properly. Some parts you can simply replace in a rear axle, some you cannot without special tools and methods. Study the TSM and ask specific questions. Setting up gears in an axle is about as advanced as auto mechanic-ing gets.

235/75R15 tires are small by modern standards, and you can run them without any changes. Don't assume you have to change a bunch of stuff. Just get it running and reliable, and drive it.

[Stuka]

Have you read the TSM? Read section 2F in the '82 TSM here - https://oljeep.com/edge_parts_man.html

Not everything about the '82 will be the same as an '86, but service of the rear axle is the same.

If you can, buy the proper TSM for your Jeep. https://www.bjsoffroad.com/1984-87-Jeep ... _1056.html BJs will give you a modest discount as a member of this forum.

There are gears in the axle, and they need to be set up with proper clearances to operate properly. Some parts you can simply replace in a rear axle, some you cannot without special tools and methods. Study the TSM and ask specific questions. Setting up gears in an axle is about as advanced as auto mechanic-ing gets.

235/75R15 tires are small by modern standards, and you can run them without any changes. Don't assume you have to change a bunch of stuff. Just get it running and reliable, and drive it.

86 came with both M20 and D44 rear axles. So depends which he has.

But to the OP, setting up a hypoid gear set not only requires several special tools, but if its not done properly, the gears will destroy themselves in short order. So like I mentioned above, you don't change those just to change them. The axle shaft bearings and seals can be done without much issue.

[rocklaurence]

The guys are correct. With your current tire size you dont need new gears and if your Differential bearing are good--dont replace them. However, if you were going to 33/35" tires a Re-gear would be needed. IMO, the most important tool for gear changes is the bearing puller-specific to axle gear bearings. I have a couple videos that cover some of the import steps.
https://www.youtube.com/watch?v=LBpVBH58JKU&t=360s
https://www.youtube.com/watch?v=6ysJaDBzyQQ&t=296s

[OrganizedChoas]

Ive landed on doing the differential and yoke seals that are leaking as well as the axel shaft bearings and seals. I'll check differential bearing when i take the cover off to replace the seal but wont do them unless they need it as my truck is my current daily driver and cant have it off the road to long. In the mean time i will be reading the TSM's and dping more research and reading into the internals of the differential.

[threepiece]

In the mean time i will be reading the TSM's and dping more research and reading into the internals of the differential.

Before you get too involved in the actual process of setting up axle gears I STRONGLY recommend developing an understanding the objective first. Having an understanding of how the gears are located to each other, what preload is and how it affects the location of the gears and what backlash is will help greatly in understanding the setting up process.

I jumped in blindly on my first axle. I did not have the benefit of the internet at the time and as I recall it took more than a month, perhaps three. this included making all of the tools'. I remember near the end I finally realized what it was the I was trying to accomplish. The task seemed much easier after that.