Setting up backlash/pinion depth

[THMPN73]

I am putting 4.10s in my 8.25" rearend and I was wondering what is the recommended pinion depth for this rearend...they say the depth for almost every other one. the 8.75 and 9.25 are both 0.20" so maybe the 8.25 is as well? Also I got my gears from summit racing and they came with a free magnet dial indicator, now most of you will laugh but how the hell do i use this thing for determining backlash? thanks for the help

Shawn

[John_Kunkel]

Pinion depth is the distance from the center of the axles to the back side of the pinion gear. .20" is a little less than a quarter-inch; not likely. Aftermarket gears will usually have the pinion depth dimension etched on the back of the pinion, you need a special pinion depth setting tool to use that dimension.

Not to be critical but I think you're in over your head. Don't attempt to install the gears without a good book like the factory shop manual. It will have illustrations of how to use the depth setter and dial indicator. Check the link below:

http://drivetrain.com/ringpinioninstal.html

[THMPN73]

Sorry I did not mean 0.2" i meant 0.02" and I was refering to the required thickness of shims behind the bearings on the pinion gear not the pinion depth. I did see the numbers etched on the gears but I cannot find the shim thickness anywhere. It only says for more common rearends.

[John_Kunkel]

The reason you can't find the shim thickness is because there is no set thickness, the thickness of the shim is varied to achieve the correct pinion depth. Another reason you won't find a reference to a shim between the bearing and the gear is because the factory didn't use any, pinion depth is set with shim(s) between the bearing cup and the case.

If you're looking for the average thickness of the factory style shim to start with, .020" is the thinnest you'll find and they go up to around .080"; I would try one in the middle.

[2harleyriders]

I have the 1969 master tech that explains how to set up the 8 1/4 and 8 3/4 rear ends.  I was going to do it my self but by the time I bought the Miller special tools even at cost it was cheaper to pay the local dodge dealer $ 200 to set it up for me. 

[Yeahmate]

Heed the wise words of above, unless you've had experience, have a press don't go there, out work it 

[oldkimmer]

It doesnt take much to be out of spec and end up with a set of paperweights that will file off the pinion. Ofcourse if u are in need of a shave then they will work great, more expensive than a bic, but will outlast anything on the market. Seriously though get someone that knows their stuff, it will be well worth it in the end......kim.....