Changing out my old howling 3:23 for a used set of 3:42's.
This is the best pattern I have been able to get.
I have a old set of pinion bearings that I have enlarged so i can change the shims on the pinion easy. I used permatex anti seize...that's the silver below the yellow compound. The drive side looks OK but what about the coast side. Once I get pinion depth I will set the backlash.

Let me know what you gear experts think.

Thanks.

The contact is too far out.

I haven't adjusted for backlash yet. Do you mean too far out the tooth? If I add some shims to bring the pinion closer the pattern changes to off center pattern on the tooth.

Number 1.
NEVER EVER use anti-seize on ANY oil/bearing filled internal items like that !!!!!!!! CLEAN IT ALL OUT ASAP.

Now, before you check your pattern, you need to have the pinion depth AND backlash within spec.

I guess in a slip rear end that makes sense! Duh.... I feel like an idiot now. Ok I will adjust backlash and check again. Thx.

The contact should be biased toward the inner diameter of the ring gear.

exactly, it will migrate outward if you put the hurt on it...also, try to pull a pattern over more than just a few teeth

OK Round two..... After playing around for a few nights here's where I'm at.
Backlash.010"
Ring gear run out .003"
Pinion shim ( stock one that was on the old 3:23 pinion .035")
both pinion and carrier bearings preloaded to within spec.
What do these patterns say?
Is there any way to get the contact more to the middle of the tooth?
I think the pattern has moved inward on the tooth.

Better Pics!

Of these 2 pics, the top one is the coast side, it only matters when you're in reverse. The second pic looks far better than what you started with. http://www.pirate4x4.com/tech/billavista/Gear_Setup/

Coast matters. Mostly in deceleration. It's still an important noise concern; less of a strength concern.

Try this chart: http://www2.dana.com/pdf/5717.pdf

Do you think or know if this pattern will produce significant whine? Also no matter where I shim the pinion I get the same basic pattern just moved a little. As I understand it with a used gear set this may be the best I get.

Forgot about decel, I'm used to an automatic, haven't owned anything stick-shift in over a year now. Anyway, if it's a choice, it seems to me it doesn't matter how quiet it is if it's not strong.

I'd road test what you have now, so long as you're not doing any drag races in reverse, or backing any heavy trailers up any steep hills. Three times I've run used gears, but that was many years before internet forums. I got lucky all 3 times, minor whine but no real problems, and none of them got the contact pattern checked. Young and stupid.

Thanks for the advice. I will give it a try.

Looks like your pinion is just a bit to deep now.
move pinion out to where your drive pattern is in the middle of the tooth on the drive side and you should get the coast pattern to fallin closer also. (set backlash before checking pattern)

Just so I'm clear. Move the pinion out by adding shims .005 at a time?

OK I think I have it. I will remove the .035 pinion shim and retry with less shim. As I understand it it will decrease the depth of the pinion away from the centerline which should result in a pattern closer to the middle of the tooth. I will have to re shim for backlash an carrier pre-load.

It's all starting to make sense now!
Thanks for the help.

Thinner pinion shim increases pinion depth. Anytime you change it, you will then have to reset backlash via the carrier shims. Carrier preload just requires keeping the same total shims you have now. For example, if you remove 0.005" on the left, add 0.005" on the right. I say you're giving up strength for quietness, and these axles already lack strength in the ring & pinion, but it's your choice. Where it is in your last pic is as strong as you can reasonably expect.

Update..... Ran it as above pics show. As some had forcast good on excelleration, and a loud whine on decel. I will be pulling it apart again till its right.

Thanks to all for their assistance. I pulled the .035" pinion shim and used the combined stack that came with the used 3:42 pinion, which equaled .029". I placed that in the carrier and ran a pattern. Perfect IMHO. Put it all together and there is very little noise from the rear end on decel and excel. What are the chances the pinion shims that came with the used were the same from the previous carrier to mine?
You have to listen to hear the faint whine, but it is not annoying.
That was a difficult job for a DIY project.
All in all I'd say 25 hours start to finish. Next job is to clean the garage.

Here are some pics of the final pattern.

Wow, it did improve! Well, congrats!

Good work ;-) I have done around 300 gear swaps and or complete rebuilds. Not a single one of them are the same !!!