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| | | | Joined: Apr 2006 Posts: 172 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2006 Posts: 172 | hey guys,
i have found someone here on the bolt that is willing to rebuild my rear end for me. however, he needs to know the gear lash and instructions on installing the bearings for a gm 12 bolt truck rear end. can anyone who has rebuilt this rear before tell me what the gear lash is and the instructions on installing the bearings? or if not tell me where i can get this info? it would be a huge help. and any other info you may have on rebuilding this rear im sure would come in handy. thanks.
patrick
Last edited by 63custom; 07/13/2008 4:14 PM.
| | | | | Joined: Feb 2004 Posts: 29,885 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,885 | Are you replacing just the bearings, or is a new ring & pinion on the agenda? A simple bearing swap just involves pressing the old bearing cones off the pinion gear and the ring gear carrier, driving the cups out of the front and rear pinion positions in the housing, and reassembling with the same shims everywhere. He will need a new "crush sleeve" to put between the front and rear pinion bearings, and do the pinion preload setting procedure.
If new gears are installed, it will be necessary to adjust the pinion depth for the proper tooth contact pattern, and possibly change the thickness of the carrier bearing spacer washers to set the backlash. An "installation kit" that is sold by the same people who sell the gears should have all the shims, gaskets, seals, and bearings necessary to do the job properly. The necessary clearances and bearing preload specifications will be available in the chassis service manual for your truck.
It sounds like your guy doesn't have the experience necessary to do rear axle work, as there's only one chance to get it right.
Jerry
Last edited by Hotrod Lincoln; 07/13/2008 8:54 PM.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Apr 2006 Posts: 172 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2006 Posts: 172 | im possibly doing a new ring and pinion also as i want to have 3.08 gears in it. he said he needed that info in order to rebuild my rear end. he has rebuilt 2 gm 10 bolts and seems to know what he's doing. as far as the chassis service manual goes, would that info be in the shop manual? i have one laying around somewhere for my truck. thanks for the info though hotrod. any other advice you have please feel free to share. | | | | | Joined: Feb 2004 Posts: 29,885 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,885 | If the shop manual covers more than just the engine, etc., it will probably have a section on drivetrain components. (Transmissions, rear axles, etc.) That's the one you'll need to find for backlash and preload specifications. I'm not suggesting your guy doesn't know what he's doing, but rear axle repair is a very specialized skill that only a few professional mechanics bother to learn. The tooth contact pattern is lapped into place when a gearset is manufactured, and even a slight mismatch on assembly will result in a gear howl or a whine that's almost impossible to correct. As a good rule of thumb, new gears need a backlash of around .002" to .008", and pinion bearing preload for new bearings should have a turning torque of about 12 to 20 inch-pounds. That's set by tightening the pinion nut with a new crush sleeve between the bearings until a slight drag is created when turning the pinion gear. It usually takes 200-300 ft-lbs. of torque on the pinion nut before the crush sleeve starts to compress.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Apr 2006 Posts: 172 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2006 Posts: 172 | okay, thanks a lot hotrod i'll pass this info on to him and start diggin around for my shop manual. | | |
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