Hi,
Im in the midst of setting up my rear end on my 72 cutlass after a ring and pinion change. Its the first time doing it so I need som guidance interpeting the pattern.
Thanks!!

 

You probably should hear the opinion of a real differential expert, but here's mine for whatever it may be worth. Bearing preload should be assured before doing the pattern test. You didn't say if the backlash had been checked, so I'll assume the worst, and think that it hasn't. Your pattern is not "way off" but on the coast side appears to be too close to the heel and perhaps a bit too close to the ring. On the drive side, though the pattern is less distinct, it appears to be again a bit too close to the heel and a bit too close to the ring. On the rear end you have, I'd probably aim for about 0.007" backlash. When I've done it there was always a lot of shim adjustments made before the pattern got "real good". Many of the Olds (& others) service manuals provide some pattern analysis if you'd like to read about it.

 

Thanks Ozzie!
This was the first attempt late last night and my head was not 100% focused so I did one mistake.. I used the old chrush sleeve
Im using (new) set up bearings, both inner and outer and for the first test it was with the original shims.
I did check the backlash and it was 0,0023.. a bit on the tight side since im aiming for somthing between .003" to .006", but my guess is that the reading will be different with the chrush sleeve out..
Every day for somthing new, so today im doing it the right way! hopfully

Found a good guide
https://www.ringpinion.com/Content/B...h-Patterns.pdf

Since this is the first time im doing it I will post updates of pattern just to get the extra reassurance from you guys.
Thanks again!

 

That link should tell you what you need to "get it right". Your backlash seems a bit "tight" to me and may account for the pattern appearing a bit too close to the ring. While rear ends don't get as hot as engines and transmissions, keep in mind that some "wiggle room" is needed when the metal expands, especially in the hotter parts of the globe. I'd probably take it up to the 0.005-0.006" range anyway. Just go slowly and carefully, and you should do well.

P.S. You do good photography also.

 

After 20 somthing attempts later..
Backlash is 0.008

Can i run these? or any suggestion for improvments

Thanks

 

You seem to be getting better. The patterns are improved and the larger backlash is probably also a good thing (but I wouldn't go any more on the backlash). It depends how much of a "perfectionist" you are. "Probably" it would do satisfactorily right where you have it. Here's what the 1983 Olds Chassis Service manual shows as being the desired tooth pattern and how to get there.


As you can see, it shows the desired as being a bit closer to the "toe" end. Of course, trying to get there could cost a bit of frustration & stress.



Hence, it will have to be your decision on how to progress. While I have done this kind of a job before, I don't consider myself an "expert". I wish that an "expert" would have responded.

 

Thanks Ozzie! I do apriciate you taking the time to help me out here.
If im doing anything more with it, Im going to try to get the BL to 0.007 ish. I have been looking at alot of pattern charts now and my conclution is that they are within spec and acceptable patterns.
This has been my first try at this and i must say I have learnd alot..
The most valuble lesson is to take your time and dont rush it��
If I were to do it all over again I would take the whole rear end out of the car and place it at a proper height to ease the multiple "in and out" with the diff operations.
I will leave it like this over the weekend and post on other forums to try to get more opinions, if not.. im trying this setup.

Thanks again!

 

Thanks!
I will press on the new bearings and get a final Reading when everything is at the right spec.
Posting final result when im done.

 

Thanks again to you who took the time responding to this thread.
I have now pressed on the new bearings and tightend it up to spec.
The pattern stayed the same so no point in a pic update.

Now its just to complete the installation of the LS1 breaks and im good to go!

The ring and pinion is from USA Standard Gear which I believe is under the Yukon umbrella.
Anyone have experience with these?