C8.25 carrier swap question (Need a gear guru)

ThatsMrGimp2U · **Joined:** Wed Feb 22, 2017 9:15 pm **Posts:** 2

Hi guys. Long time lurker, first time poster. In a bit of a hurry as I am headed out the door so here's the skinny

I bought a lock-right locker to install into my 8.25. Come to find out I have a LSD, and the lock-right isnt going to work. I'm purchasing an entire rear axle (open diff) from my buddys junk liberty with 90k (60 less than mine). Im trying to guage whats more of a pain in the booty...

1) Cleaning up the replacement rear end just swapping the whole thing over. This will involve painting it with chassis saver, swapping over all the brake components (mine are new), and fighting with all this mostly by myself. Ill have to buy some saw horses or something for the prep

2) Doing a carrier only swap. I'll need to check backlash and all that once the carrier is in, something I haven't done before. Would need to purchase a dial indicator. I would swap my ring gear onto replacement carrier obviously. What I am most concerned with is having to adjust pinion depth. My hope would be that I do not have to, I really don't want to mess with that. I don't mind shimming from left to right though.

Thoughts? I really appreciate the help. I will get to the intro section and update my sig when I get some time. Thanks!

*Update* The replacement axle has drum brakes and my lib has discs, so thats not going to fly. Waiting on a detroit locker to show up. Completely rebuilding my rear end now (seals, bearings, brake lines) so its going to be down a bit longer. I guess in the end it will be nice to have all new components back there. Just turned 150k so I will count this as my big maintenance item for that interval.

JeepinJarhead03 · **Posted:** Sat Feb 25, 2017 6:07 am

i'd just swap the whole thing over, and its for a fairly simple reason , it would leave you with an intact, working spare (or parts fodder to sell, or give to your buddy or whatever.)

as for the saw horses, once you have yours up and the rear tires off, put your tires on the newer axle, put black trashbags around them and tape them up and stick a block of wood under the yoke, when youve painted one half , flip it and paint the other half

WWDiesel · **Posted:** Sat Feb 25, 2017 11:02 am

If you are using the same ring gear on the new carrier, and as long as you do not disturb the pinion gear or change the bearings on the pinion gear and it remains in the same housing it was originally set up in; pinion depth should not be an issue.

Be sure and use some locktight on the ring gear bolts when bolting the ring gear to the new carrier... Also, some ring gear bolts use left handed threads!

Just be sure and use the ring gear that was mated to the pinion gear, they are matched sets.

You will have to adjust backlash, which is ring gear depth into the pinion gear, when installing the new carrier.
On Mopar units, you adjust the side to side backlash using a long rod type tool with a 36 MM hex shaped head on the end while the axles are out. Search for wrench C-4164, there are plenty of them available on the web for purchase or you can build your own using a piece of heavy rod stock or 1/2" pipe and weld a 36 MM hex nut on one end and a 1/2 adaptor or driver of some type on the other end so you can use a 1/2" torque wrench. See pictures below:
See this article on how to:> http://www.jeepforum.com/forum/f11/size ... a-1013730/
See pictures below:

Backlash- is the freeplay between the ring and pinion, its adjusted by moving the carrier bearings left or right with the adjuster nuts on each side of the carrier, and checked with a dial indicator by rocking the ring gear by hand forward and reverse. It is very important that backlash is within spec to allow smooth operation, correct gear contact, and proper lubrication between the gears...
Most list the backlash on the 8.25 saying that it needs to be between 6 and 10 thousandths, I like to always set on the low side and shoot for 3 to 4 thousandths... :wink:

Carrier bearing preload - means how tight the carrier and its bearings fits in the housing and is set simultaneously with backlash , carrier bearing preload is important for a strong setup and differential longevity. if preload is set too loose it could cause early bearing failure or ring and pinion teeth wear and / or be very noisy.

If backlash is within spec but preload is set too loose on the carrier, you can add equal amounts of tightness to each side of the carrier by tightening each side adjuster nuts equally. This increases the preload while maintaining the backlash setting. I normally start by setting the preload to 10 foot pounds while maintaining the proper backlash setting.
Keep in mind, all the adjustments with the carrier adjustment nuts must be done with the carrier bearing cap bolts only snugly tightened (bearing caps tightened down just a little past finger tight) which allows for the adjuster nuts to rotate but still hold the bearings in place.

Once you get the backlash set correctly ~.003-.006 (ideal is 3-4 thousands) and carrier bearing preload set correctly ~ 10 ft. lbs.
Using Wrench C-4164, or a homemade equivalent, tighten each threaded adjusters back and forth equal amounts on each side until you get to ~75 ft. lbs. Continue to tighten each side adjuster and seat bearing rollers until the torque remains constant at 75 ft. lbs. and backlash is still 3-4 thousands. If backlash is not correct, you can loosen one side slightly and tighten the other side the same amount to reset the backlash. In the end, you want the correct backlash and correct torque on the carrier bearing adjuster nuts...
Torque down the carrier bearing caps to the correct torque.
Now rotate the ring and pinion and recheck the gear backlash in several locations on the gear to make sure nothing moved and backlash remains constant and correct.
Now paint the ring gear with some gear paint and check the heel and toe contact pattern, it should be correct! See Chart below:
Have fun, it is not as hard as it sounds, just take your time and do it right.
If you have any more questions, just ask...
:SOMBRERO:

ThatsMrGimp2U · **Joined:** Wed Feb 22, 2017 9:15 pm **Posts:** 2

WWDiesel wrote:

If you are using the same ring gear on the new carrier, and as long as you do not disturb the pinion gear or change the bearings on the pinion gear and it remains in the same housing it was originally set up in; pinion depth should not be an issue.

Be sure and use some locktight on the ring gear bolts when bolting the ring gear to the new carrier... Also, some ring gear bolts use left handed threads!

Just be sure and use the ring gear that was mated to the pinion gear, they are matched sets.

You will have to adjust backlash, which is ring gear depth into the pinion gear, when installing the new carrier.
On Mopar units, you adjust the side to side backlash using a long rod type tool with a 36 MM hex shaped head on the end while the axles are out. Search for wrench C-4164, there are plenty of them available on the web for purchase or you can build your own using a piece of heavy rod stock or 1/2" pipe and weld a 36 MM hex nut on one end and a 1/2 adaptor or driver of some type on the other end so you can use a 1/2" torque wrench. See pictures below:
See this article on how to:> http://www.jeepforum.com/forum/f11/size ... a-1013730/
See pictures below:

Backlash- is the freeplay between the ring and pinion, its adjusted by moving the carrier bearings left or right with the adjuster nuts on each side of the carrier, and checked with a dial indicator by rocking the ring gear by hand forward and reverse. It is very important that backlash is within spec to allow smooth operation, correct gear contact, and proper lubrication between the gears...
Most list the backlash on the 8.25 saying that it needs to be between 6 and 10 thousandths, I like to always set on the low side and shoot for 3 to 4 thousandths... :wink:

Carrier bearing preload - means how tight the carrier and its bearings fits in the housing and is set simultaneously with backlash , carrier bearing preload is important for a strong setup and differential longevity. if preload is set too loose it could cause early bearing failure or ring and pinion teeth wear and / or be very noisy.

If backlash is within spec but preload is set too loose on the carrier, you can add equal amounts of tightness to each side of the carrier by tightening each side adjuster nuts equally. This increases the preload while maintaining the backlash setting. I normally start by setting the preload to 10 foot pounds while maintaining the proper backlash setting.
Keep in mind, all the adjustments with the carrier adjustment nuts must be done with the carrier bearing cap bolts only snugly tightened (bearing caps tightened down just a little past finger tight) which allows for the adjuster nuts to rotate but still hold the bearings in place.

Once you get the backlash set correctly ~.003-.006 (ideal is 3-4 thousands) and carrier bearing preload set correctly ~ 10 ft. lbs.
Using Wrench C-4164, or a homemade equivalent, tighten each threaded adjusters back and forth equal amounts on each side until you get to ~75 ft. lbs. Continue to tighten each side adjuster and seat bearing rollers until the torque remains constant at 75 ft. lbs. and backlash is still 3-4 thousands. If backlash is not correct, you can loosen one side slightly and tighten the other side the same amount to reset the backlash. In the end, you want the correct backlash and correct torque on the carrier bearing adjuster nuts...
Torque down the carrier bearing caps to the correct torque.
Now rotate the ring and pinion and recheck the gear backlash in several locations on the gear to make sure nothing moved and backlash remains constant and correct.
Now paint the ring gear with some gear paint and check the heel and toe contact pattern, it should be correct! See Chart below:
Have fun, it is not as hard as it sounds, just take your time and do it right.
If you have any more questions, just ask...
:SOMBRERO:

By far the best response I have gotten on this matter. This sums up the information that a weeks time and countless phone calls has gotten me. But its nice to have this for reference. Thank you so much!

C8.25 carrier swap question (Need a gear guru)

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