open to posi problem?

[bobshotrodblazer]

Removed a 67 open 373 rear chunk and swapped a 72 308 posi into it . Swapped the ring gear from the open to the posi unit . I put the whole thing together and it has alot of free play between the pinion and the ring gear.plus it whines. I reassembled it the same way it came apart. Is there a difference in the 67 and the 72 rears? I know the 72 axles are longer but stiill 30 spline .

[Fitz]

A minor difference in thickness between the faces of the center section where the ring gear is bolted can cause a major change in the backlash between pinion and ring gear. By minor, I mean something on the order of a few thousandths of an inch. You will likely need to re-shim the center using a dial indicator to get the correct pattern and backlash. That will take care of the freeplay. Once it's correctly shimmed the whine should be reduced but probably won't go away for 100 mi or so.

[chevy_mike]

Whenever you swap the carrier (either open, posi, locker, spool, etc.) you have to completely reset the gears. Pinion depth, backlash, gear pattern, etc. If you don't you not only will get all types of weird noises, your gears won't last long.

Even though I was taught how to setup gears, it is still one thing I farm out to have done. Too much money involved to screw it up.

[cdowns]

a service manual is very handy for doing jobs correctly

[bobshotrodblazer]

Thanks guys , I'm making some calls to find the right place to take it. I'd rather pay some one to get it done right.