Need help identifying clunk in rear end

[nchandler]

Hey folks, I have a 1972 K20 that makes a loud clunk when putting it in reverse.
The U-Joints are good, there is no Left - Right slop in the yoke.

The yoke rotates a bout 1/2 or so inches clockwise before it catches.


There seems to be appropriate amount of play for the backlash but the ring gear seems to turn with the yoke about 1/2 or so of an inch before it engages.


What would cause this amount of play on the ring gear?

Thanks

[Fitz]

Originally Posted by nchandler

Hey folks, I have a 1972 K20 that makes a loud clunk when putting it in reverse.
The U-Joints are good, there is no Left - Right slop in the yoke.

The yoke rotates a bout 1/2 or so inches clockwise before it catches.
Attachment 1329509

There seems to be appropriate amount of play for the backlash but the ring gear seems to turn with the yoke about 1/2 or so of an inch before it engages.
Attachment 1329511

What would cause this amount of play on the ring gear?

Thanks

Backlash can not be correct and have that much rotation unless the pinion gear bearing preload is non-existent. It should take 6-8 in-lbs of torque to turn the pinion gear. if it is free spinning what is happening is the hypoid pinion gear is 'climbing' the straight ring gear before it engages. Get a new crush sleeve and pinion nut, remove the old sleeve and re-torque the pinion nut. It takes a boatload of torque to crush the sleeve (~200 ft lbs) so go in stages checking the preload as you go. I guess you have figured out by now that you have to remove the axles and the ring/carrier assembly to check pinion bearing preload. Before you do that it is a good idea to check pinion depth before you disassemble. Then you know if the pinion is shimmed correctly or not.