I have a 1980 el camino, with a 7.5" 10 bolt

pinion bearing went out and caused the drive shaft to let go.

I replaced all the bearings, reused my ring and pinion and all shims.

Its my belief that the current ring and pinion were installed new, with used bearings in place. hence it was shimmed up with used bearings.

The new bearings have now made the carrier vary tight. I can still move it with one hand, but i dont know how tight is too tight.

any thoughts?

I'm not an expert but a friend told me to take a dollar bill and run it between the gears. If its set correctly it will make slight cuts in the bill appx. 3/4 inch. If to tight it will cut the bill and if to loose it will not cut it.
I did one on a Dakota and it worked fine. The manual shows how to use a gage to set it. I've shimmed up an old Ford 3/4 ton by just shimming enough to take out slop so it felt correct and it worked fine. It depends on the tools you have.
I had one for a 1969 Chrysler Newport I took to the Chrysler garage they brought it out in 20min. charged me 1.5hrs. shop time I done my own after that or bought a used rear end.

The issue is'nt pinion depth yet, just the pre-load on the carrier. The pinion is not installed yet because i was test fitting the carrier and i had to pound it in, in order to get it out i have to use a long dowl rod and beat it out from the other side of the case.

I just dont know what to do, i can't afford to screw it up.

"Preload" is necessary. It should take approximately 15 in. lbs. to turn both the carrier and the pinion (independent of each other). Make sure they're lubed well before buttoning it up. Use a new crush-sleeve, too, no matter what your buds tell you!

The shim under the rear pinion bearing is to set correct pinion depth. They come that way, so I doubt it was added for "used" bearings. If all things are correct, bearings don't "change" from use (harder than Chinese arithmetic, and THAT'S HARD!). I've found pinion depth will stay correct if shims stay with housings, not gears. I would imagine gears are much closer tolerance than housings.

Jim

Ok so, i sure just go a head install the pinion, get the carrier in and check the pattern and see where it is. then check the total preload on the pinion nut and drive off into the sunset?

PS, the old bearings on the pinion just slid right off no stuggle or tools used. whats that say about the previous job?

I did use a crush sleeve I thought you had done that.

Feel is not the way to set up a diff, a dial indicator is used for back lash, about 005-007", as MrP says a inch lb torque wrench for the pinion and diff preloads, gear marking compound is used to check the tooth contact pattern. A case spreader is the proper tool to remove and install the diff, not pry bars and hammers, too easy to remove metal from the case doing this. The pinion bearing should be pressed on to the pinion, ( rear bearing), if it is loose there is a problem. Total pinion preload assembled is usually 25 in/lb with a new seal and bearings. As you can see this requires the proper tools and some sort of manual for specs.

where on the carrier should i put an inch pound wrench to measure it? a ring gear bolt perhaps?

I noticed you said the drive shaft came out. Look carefully at the yoke as their are little stops so the universal doesn't fly out one of my mechanics put one in with it broken and the vehicle was towed in. I had to buy a used tail shaft for the transmission another drive shaft and a used yoke. Look very carefully at this item as your spending big money for bearings. Much easier to change with it out. As Max said the bearings are pressed on look very carefully for worn spots on the spot where the bearing sets.Very easy to feel with your fingers. A skilled machinist can feel around .001 with his fingers.

stops on what end of the drive shaft? which universal?

He's talking about the 'towers' on the yoke, the image below:

http://www.silicon212.org/yokeimage.jpg

Recommended tools by Max Wedge http://www.ntxtools.com/
OTC-1130 OTC-1824 OTC-7071 CEN-6410 Just type in the numbers in their search. You indicated you had a torque wrench

Thanks guys, yeah my yoke is fine, i got a new driveshaft too, aluminum its 18 pounds. The floor is still all cut up though. Scary to lose a shaft at 120+

I would weld a cross brace at the speeds you drive you don't want it coming through the floor.

NHRA driveshaft loop, should be considered for this type of driving! Inch/lb torque wrench is used on the pinion nut when checking pinion bearing preload. Again, I strongly suggest a shop manual or guide while you are attempting to do this complex set up.

NHRA driveshaft loop, should be considered for this type of driving! Inch/lb torque wrench is used on the pinion nut when checking pinion bearing preload. Again, I strongly suggest a shop manual or guide while you are attempting to do this complex set up.


how do i check the carrier preload?

thanks guys i got it back together 2 crush sleeves and 3 pinion seals later, it makes sense once you do it yourself. carrier preload is difficult to do when the rear is in the car. i had to do it with feeler gauges and just guess if it was zero'd in. i ended up just using the old shims everywhere and checking the measurements.

i ended up with 7-8 thou. backlash with 22 inch pounds preload on the pinion and 10 thou. preload on the carrier bearings.

I had a book that called for 5-9 thou. backlash, 8 thou. preload on the carrier and 20-32 inch pounds for the pinion


i have a few miles on it and its quiet, but the pinion seal is leaking so i have to replace that again.