install posi

[doood]

I believe you're becoming the new "differential guy" and you'll soon be setting them up for drag racing.

Putting together a stockish diff is pretty simple compared to most carb/tuning stuff or engine rebuild. I need a garage.

 

[jcelk]

thanks johnny i don;t know why i never thought of it but i have a gm service manual it says with new bearings pinion preload should be 24-32 inch pounds and 8-12 with used bearings does that sound right guys ?

 

[doood]

thanks johnny i don;t know why i never thought of it but i have a gm service manual it says with new bearings pinion preload should be 24-32 inch pounds and 8-12 with used bearings does that sound right guys ?

Yes.

Also, the preload spec is different in different references; my one book shows 19in-lb maximum for the 8.5" ring gear with new bearings. The highest I've seen for the GM 10 bolts is the 32 in-lb from the shop manual you mention.

For the 7.5" I just finished last night the pinion bearing preload increased from little to almost too much with the last 1/8 of a turn on the pinion nut. I was using a very gutless (underpowered) half inch impact that has less than 350 ftlb and gave it all the ugga duggas for about 30 seconds, watching the engravings on the socket move ever so slightly during the final torquing. Then I banged [hard] the pinion on the threaded end, and on the pinion head, with a thick brass drift and a 4lb hammer (whack!) and rotated by hand a bit, and then my calibrated eyeball saw 30+ on a beam-type torque wrench after final assembly with a crush sleeve and new pinion seal and no carrier installed. Scale read around 30 in-lb, but impossible to read exactly while spinning (like rubbing your belly while tapping your head).

All references I have show the greater pinion bearing preload applied to NEW bearings. 64nailhead says the opposite. I'd be surprised 40in-lb of rotational torque would toast new or old bearings - we may be making mountains out of mole hills as long as the bearings are seated and compressed and the yoke feels good in your hands. The break-away torque to start the spinning was more than 60in-lb. The torque is a difficult to measure. Good luck.

 

[justdandy]

i have a used posi carrier to install in my 7.5 rear i;m not touching the pinion just putting my ring gear on the new carrier i have a formula to measure carrier preload ... total inch pounds of pinion and carrier minus inch pounds of pinion only multiply that number by gear ratio = carrier preload my question is what should my carrier preload be with used bearings ? and should i use locktite on ring gear bolts and bearing caps ? thanks all for your help with my winter project if temperature matters i;m doing this in my basement work shop temps about 65 deg

OK interesting plan. Any gear set should be replaced in pairs. When I did mine, the used bearings added a little to stock values. Use locktiteon the ring gear with NEW bolts. Other bolts and caps locktite is optional. Just remember locktiteit lubs. the threads so you may increase the max torque by 5%

 

[jcelk]

thanks guys i feel good about this now my orignal plan was just put in a new posi carrier and leave the pinion alone that changed when i saw the bearings were bad didn;t make any noise though