Adding Posi

[Bonnewagon]

Swapping a non-posi carrier for a posi is the least dramatic rear end operation, but still needs attention to details. Very rarely are the shims the same when you swap carriers. An inexpensive shim kit takes all the guesswork out and assures a successful operation. But before attempting a carrier swap, find a factory manual and read what's involved. You WILL get a headache but once you grasp the concept, you can do the job with a few basic tools. A carrier is held in place with zero clearance, PLUS a pre-load, of .004" on each bearing, which works out to .008" more shim than zero. And this must be achieved while maintaining the correct pinion/ring gear backlash. Understand this and you will have a quiet long lasting set up.

 

[pontiacgp]

No carrier are ever cast the exact same so a check of the gear meash is a must. Anytime I change the carrier I always check the mesh pattern, its kinda late when its all back together and the gears are noisy. Better safe than sorry.

Changing a carrier only affects the backlash and not the position of the pinion relative to the crown gear. You never adjust the pinion to adjust the backlash. Another thing with the pinion if it was already set up in a rear end the pinion will be properly set for about 99% of the rear ends.

 

[Bonnewagon]

"Another thing with the pinion if it was already set up in a rear end the pinion will be properly set for about 99% of the rear ends." This is true. In all the rears I've built (many) the pinion depth was never changed by more than .001" or .002" from what was in there already. This was checked with a GM dealership Kent-Moore pinion depth tool. So for all intents and purposes, leave the pinion shimmed as is. I believe this had to do with the machining process and that the pinion bearing area was more precisely controlled as opposed to the carrier bearing area. Or the thick bearing shims could be to accommodate the position of the ring gear due to different size of pinion gears depending on ratio. Or I could be completely wrong.

 

[HurstandGN]

All great information. Thanks. I am making great progress and should have the frame ready to go out and get blasted and painted by the weekend. I hope to start putting things back together in a couple of weeks.