Is a 8.2 "B" cone type posi rebuildable ?

Discussion in 'Got gears?' started by mrBOP, Oct 23, 2004.

  1. mrBOP

    mrBOP newbie

    I have a rear out of 69 GS. This should be a 8.2 cone type posi. Is it rebuildable? and how? where to get parts. It is starting to get tired and needs a little freshining up.
    Any help would be great, Thanks, Dave
  2. Bald Menace

    Bald Menace unauthorized user

    step by step instructions

    1. Remove rear cover, drain fluid.

    2. Remove 4 posi-carrier main bearing cap bolts and 2 bearing caps.
    (Note the number and position of the shims on each side of the carrier so you can be sure to get them back in the right places.)

    3. Slide the posi-carrier straight back to remove. You might have to tilt to one side. Again note position of parts.

    4. Take the posi unit to your bench and remove the carrier case bolts. Use caution - it is spring-loaded - the springs and stuff might jump out at you. Take careful note of how the parts mate for reassembly. The spider gears and cones should be replaced in the same side as original. Check all parts for gouging, cracks, etc.

    5. You should now have the cones separated from the unit. Check their tooth height; they will probably be .020-.030 or about the thickness of a dime.

    6. In the housing youll see the tapered sides where the cones reside; where the axles slide into the carrier. This is the area that needs to be machined. Have a machine shop take .150 (thats 150 THOUSANDS) off this area with a lathe, on both halves of the housing. CLEAN, CLEAN, CLEAN everything.

    7. Now you need a couple hardened (Grade 8) washers equal in diameter to the posi springs. .060-.080 thickness. One goes on the end of each spring to increase spring pressure and force the cones deeper into the tapered housing for grip. I ended up with a combination of springs to get me .120 - .150. I have one big washer for the outside springs and a smaller one for the little inside spring. The important thing is to end up with the correct total thickness.

    8. This is also a good time to check your ring gear bolts. Previously, I had found one missing from my rear end, and I mean missing. It was not in the ring gear and nowhere to be found in the rear end housing. Several others were loose. I replaced the ring gear bolts with ARP #230-3001, torqued to 60 ft lbs. They should be installed with Loc-Tite red. I just replaced one at a time, torqued to 60lb/ft., then removed the bolts one at a time, coated the threads with locking compound and re-installed the fastener, torqued to 60lb/ft. Install and torque the fasteners in a crossing pattern to evenly distribute the load. If you remove the ring gear be careful not to cock the ring gear when pulling it back onto the carrier or it will crack. I also replaced the posi case bolts with ARP #651-3250 (5/16-18 x 3.250) and torqued to 20lb/ft.

    9. Get a couple bottles of GM Posi-Additive for reassembly. Use it liberally. Reverse procedure to reassemble the carrier back into the rear end housing, being sure to get the shims in the same position. This will ensure that your backlash remains as it was. Torque the bearing cap bolts to spec (which I cant remember).

    10. Install the cover and fill with your favorite gear lube. I like Redline synthetic.

    I have PAIRS of black streaks all over my shop floor to prove it works.
    Now Im looking forward to hooking. Thanks to Mike Garrison for the very effective and cheap repair procedure.
  3. mrBOP

    mrBOP newbie

    Hey thanks for the help. Hope you didnt get carpeltunnel typing. It is greatly appericated. I knew there had to be a way to freshin up these rears. And with those details I shouldnt have any problem with getting this done in the winter months. Dave

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