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06-20-2003, 09:42 PM
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home mechanic + rearend=???
i know its an area that most people dont like to touch, but is it reall all that risky to do a gear swap myself, i mean i would be extremley carefull. i guess my question is simply, is a rearend really as hard as it is made out to be? thanks guys
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06-20-2003, 10:04 PM
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Depenps on what rear end you are working on. The dana 44-60, or 9in aint that bad. But 10-12 bolt or 8.8 take more time and are harder. Check with your loacl shop, the first rear i had done the mech let me help and obsevre(charged extra haha) but it was a valuble experence.
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06-21-2003, 02:23 AM
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ya its a standard 8.5GM going from 3.08 to 3.73. do you know of any highly specialized tools need for the job?
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06-21-2003, 06:00 AM
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The gear change from a 3.08 to 3.73 will allow you to use the same carrier, so you should not have to replace the carrier bearings if your carefull. Of course if it has a zillion miles on it I would replace them as a matter of course. The books tell you that you need a spreader to spread the housing so you can remove the carrier. If you are very careful and pry slightly and evenly on both sides of the carrier you can remove it without the spreader. You will need a specialized puller to remove the carrier bearings. The rear pinion bearing will have to be removed by someone with a press so you can retreive the pinion shim between the rear pinion bearing and pinion gear. If you are lucky you can get away with using the same shim on your new pinion gear. The new pinion bearing and shim will have to be pressed back onto the new pinion bearing. Going back in with the new gear on the carrier is a bit tricky. Just make sure you install the side shims in the same side you took them from. Slowly tap the carrier in with the carrier bearing races and shims as one unit. Use a rubber mallet to avoid damage. As the carrier assembly nears being seated in the housing it will get harder to insert and may require a brass drift and hammer to finish seating it. Do not tap on the bearing races or shims, only on each side of the carrier. Again, if your lucky you will have a gear contact pattern that is acceptable, if not you will have to do the process all over again with different sized shims..
Vince
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06-21-2003, 12:33 PM
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my plan was to install a posi unit as well, and install all new bearings and shims. i figured i should do the rearend only once, and right. is this a good idea, using all new stuff all at once?
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06-21-2003, 03:42 PM
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Really no need to install new shims, as they are not a part that wears. You must press the rear pinion bearing off to at least see what size shim to go back with. If you do not know the shim size, it's a crap shoot and chances are you will not get it righ by guessing. To start from scratch requires dial indicators and accurate measurements to determine shim size, it is a time consuming process.
Vince
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06-21-2003, 03:57 PM
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so the wise plan would be to use all the identical shims in the same places and make any nessesary adjustments from there.
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06-22-2003, 06:31 AM
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Yes, keep all the original shims in their original locations. You will need a new "crush sleeve" on the new pinion bearings. The crush sleeve preloads the new bearings. You preload the new bearings by tightening the yoke on the pinion until the sleeve crushes and you have the proper amount of drag on the yoke when you rotate it. DO NOT be tempted to crush the sleeve with an air impact wrench. I have seen numerous supposed "good mechanics" do this. The impact will hammer the new bearings and this will dramatically shorten their life. The proper way to determine pinion bearing preload is with a torque wrench. Secure the pinion yoke so it cannot rotate. Then with the proper socket and a breaker bar on the pinion yoke nut, tighten the nut until it is snug. You wil then have to use a cheater pipe on the breaker bar "unless your extremely strong" to tighter the pinion nut further to crush the sleeve. It is hard to describe the proper amount of drag to achieve. The torque wrench is used on the pinion yoke nut to set the preload. There are numbers specified, and with a little research you can determine the required amount of prelod. After you do a few rear axle overhauls, you develop a feel for it and can get real close without checking it. Just keep tightening and checking, tightning and rechechecking. This is an important step.
Vince
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06-22-2003, 11:47 AM
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All you guys have been a huge help to me, thank you very much. Good luck with you'r projects.
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06-22-2003, 09:11 PM
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Your welcome, hope your project goes well also.
Vince
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