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Contributed by Larry Coleman from Forwardlook.net

Click on images to enlarge

33 Photos - Page : [1] [2] [3]


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.
     

 

2004
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