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When installing a ring gear be sure the case and gear are both VERY
clean. Any dirt trapped between them will cause the ring gear to
have excessive run-out. Start all of the bolts by hand (remember
they are left hand threads so turn them COUNTER CLOCKWISE to start
them) |
Use a socket and ratchet and tighten the bolts one or two turns each
to pull the ring gear on to the case evenly. Check the gap between
the gear and case and keep a even as possible. Then torque the ring
gear bolts to the proper torque for your rear-end assembly. (check
your service manual for the proper torque specs.) |
Then press the differential carrier side bearings on, using your
other Special Tool that you made. |
Install the pinion gear, spacer, preload shim pack, front bearing,
and yoke with washer and nut into the case. DO NOT install the
pinion seal at this time. Torque the nut to the proper specs and
check turning torque of the pinion with the inch pound torque
wrench. This sets the bearing preload. To much turning torque -
increase the shim pack thickness. Not enough turning torque -
decrease the shim pack thickness. This is the shim pack behind the
front bearing, NOT the shim pack in the case behind the rear bearing
cup. |
Install the carrier, bearing caps,and adjusters. Be careful not to
cross thread the adjusters in their bore. They should turn by hand
if the threads are clean and lightly lubed. Move the adjusters until
the proper backlash is reached. Usually around .005" to .006"
minimum backlash for most rear ends. In this picture you would loosen
the left adjuster and tighten the right adjuster to decrease
backlash. Always make your first adjustment with the right adjuster
to ensure that it will not move under load. The last movement with
the right adjuster should be in to move the bearing not away from
the bearing. Then preload can be set using the left adjuster one or
two holes on the adjuster at a time. I usually tighten the left
adjuster until there is resistance to movement and then force it to
move one more hole. Preload keeps the pinion gear or case with ring
gear from moving under load, even after the bearings wear in. Not
enough preload and the whole thing will be to lose after the
bearings wear in. To much preload and the bearing will wear to fast.
You may need to go from side to side several time to get backlash
and preload set properly. |
Check the gear contact pattern using a marking paste and increase or
decrease the shim pack in the case, behind the rear pinion bearing
cup until proper gear tooth contact pattern is reached. The service
manual has very good pictures of what the pattern should look like.
Backlash and preload will have to be reset after each shim pack
change. It is time consuming but must be done. A few thousands of a
change in the shim pack will change the tooth contact pattern a lot.
Go Slow and get it right. Note: if you put the pinion depth shim
pack behind the bearing cup in the case, when you increase that shim
pack, increase the pinion bearing preload shim pack the same amount
and your pinion preload should stay the same. If you decrease that
shim pack, decrease the preload shim pack the same amount and
preload should stay the same. |
After the gear tooth pattern is set and all of the preloads are set,
disassemble one last time. Install the front pinion bearing seal and
reassemble the rear-end assembly setting all of the preloads. I use a
drop of blue Locktite on the pinion nut upon final assembly just for
security. Be sure to install the adjuster locks. If you look closely
at the picture you can see my tooth contact pattern in the yellow
marking compound on the gears. |
There it is, you are ready to install it. If you are asking why I am
using an engine hoist, this thing is heavy when assembled, and I'm
getting old and lazy. I use an engine hoist and a jack on a drive on
lift to do this work now. Some of you young bucks can do it by hand
if you like. I used to, about 30 years ago. |
There it is installed and ready for oil and a road test. Remember,
if you have a posi unit, it will require the additive along with the
differential oil. All 8 3/4 rear ends are the same except for the
type of posi unit it has and how the pinion bearing preload is set.
If you have a rear-end that has the crush sleeve to set pinion
bearing preload, don't install it until the final assembly. They can
only be used once and should be changed every time the rear-end is
disassembled. They are VERY hard to get to crush down to set the
preload. That is what the yoke holding tool is best for. Also, tight
them very slowly and check pinion turning torque often. They
shouldn't be loosened to get the proper torque, if over tightened.
You are supposed to start over with a new crush sleeve. GOOD LUCK,
and feel free to e-mail me with questions. |
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