Your opinion on this gear pattern

What do you think? This is with about .010 lash. I have had a good amount of gear noise going down the road the last year or so and thought I would check the pattern. It was more to the inside to begin with, so I moved the ring gear away just a bit and that moved the pattern more to the center as you see here. I am hoping not to have to move the pinion, but we'll see what you all say.

Deep. I would pull the pinion out maybe 010 and see what it looks like. If it's been run for a year, you may have to rely on the coast side since the drive side has been run in the wrong mesh. Used gears can be a pain.

I tighten up the back lash on my old A/SA NHRA stocker, 1963 Plymouth 415 HP 426 M.W., it had 4.56 in the stock 742 case with the clutch type Dana posi like yours, that help make it quieter on the down hill return road in neutral I didn't try looking at the pattern, it had over .012 back lash with grease on both the ring gear and pinon gear.
I have and do set up my own new gear sets in 8 3/4 and Dana 60 using a pinion depth tool for the pinion depth, not using just the pattern only
I've been told many times over the years by race shops and other who do a lot of gear setting up to always go to the minimum back lash on both 8 3/4 and Dana 60 with new gears, street and strip or drag race only I do that now
On your deal I would set the back lash to the minimum now and relook at the pattern to see if that helps make you feel better or not

As I said in the post, the lash was actually tighter and I backed the ring gear off a little. That improved the pattern. It moved the pattern back, closer to the middle of the gear. Especially on the drive side.

As I try to at least reduce the rear noise going down the road, I am also trying to understand the cause and effect of changes. So, since I pulled the ring gear away from the pinion and that improved the pattern by moving it back away from the toe and more into the middle, will moving the pinion away from the ring gear (as suggested) do the same thing while allowing me to move the ring gear back closer to the pinion giving it a tighter lash, as suggested?

Thanks for the help!

Moving the pinion fore and aft is not the same as adjusting the lash. Backlash just allows for a tight enough engagement so that there's 1) room for oil and 2) room for thermal expansion. Pinion depth is primary and needs to be right. If the crush sleeve is keeping you from wanting to pull the pinion, it's not a bad time to invest in a crush sleeve eliminator.

The sharp cutoff on the pattern shown looks to be too deep, to me. Most pattern books will show a fading clean spot, without a sharp line like that. Also, you want to make sure you get enough preload on the ring gear when running the pattern, or it won't show well. I usually use a pry bar or something similar to load it up pretty hard.

I do understand that moving the pinion is very different than moving the ring gear. The point I was asking about was if moving the pinion forward (away from the ring gear) would influence the pattern change in some similar ways as moving the ring gear away from the pinion. I understand that they are doing different things, just wondering if the movement of the pattern was similar.

I already have the spacer and shims in there. And I use a pry bar to put some load on the mesh.

Thank you and I appreciate the tips. I have done this several times before. It's just been a while and then some of this info I never knew at all.

I'll pull the pinion tomorrow.

The pinion depth shim is 0.003"-0.005" too thick. At this point, I doubt you can cure the gear noise, however.

The differential cross shafts are also installed backward.

Nice catch there Doc.

Pinion depth will influence the depth of the pattern on the tooth (face to flank). Backlash will influence the pattern mostly from heel to toe. Some shops recommend .010-.012 backlash, some say .008-.010. No two gear sets are the same. I usually end up in the .010-.011 area. Changing the depth will require the lash to be changed as well - move shim from one side to the other in just about the same amount you changed the depth to get it close.

This is for new gears. Again, if you have used gears, you may have to base your settings on the coast side pattern. Used gear can be frustrating and you may never get them quiet.

Yeah, I fully expect that there is no way to get them completely quiet. I just thought I would try to reduce the noise some and at the same time experiment with the set-up to learn on a set of gears that I really can't hurt.

I'll blow it apart today and see what I can do.

Now, is it realistic to expect to be able to remove the pinion bearing without ruining it? And tips, tricks, or suggestions are welcome.

yes but the tools are not cheap. TOOLING.

I have bought "set up bearings" for the more popular rear ends. IE: buy a new bearing, dremel sand the center to allow a slip fit on the pinion. You can now use it to get the desired shim thickness without destroying the bearing removing it. Once you have you pattern where you want it, press a new bearing on and assemble.
Another method is used on the 9" ford (I think). They put the shims behind the race

I have pulled them with a good sharp bearing separator, sometimes not. The shims should be under the bearing cup. Test bearings would be smart, spend some time at carl jantz superjeep on you tube and watch how to slam a dana setup out. With test bearings you can change the shim and get a pattern in 5 minutes. Worth your time.

Well, well, well. What would you do, replace the cross shafts (are they even available) or spool it? The gears and clutches look good. Primarily a street car that runs 295 drag radials.

I wonder how much noise those broken pieces where causing?

Wow...good thing you took it apart. Doc sells new SG internals, at least he used to. Don’t know if you can buy just the shafts though.

Plus what has gone through the bearings.

The reason I pulled it apart was due to the gear noise at road speed. I would guess that the forward shim being beat out was the root cause of that. But, believe it or not, the Sure Grip worked good, even with drag radials. It pulled both tires. Now, it would pop on some corners, especially going slow and turning tight, like backing into a parking place. But I have had that before on rears and just figured I needed more clutch lube in it.

Anybody got any shafts?

Might this be the root cause ?

Most likely. Dr Diff has the shafts for $50 a pair, so it must not be that uncommon of a problem.

I am now trying to decide whether to repair the Sure Grip or to swap in a spool. And whether or not to replace the ring and pinion along with the bearings. I have never ran a spool before, so I am not sure if I would like it or not. And I only put 1,000 to 1,500 miles a year on the car. So I doubt I would wear the bearings out even if they have had some trash ran through them. They are smooth now and look good. And I won't know until I re-set the gears and run them, just how quiet they might be. As long as I can hear the radio and talk at road speed, then I would be happy. But, of course, I won't know that unless I run them.

I would welcome opinions and experiences on running a spool on the street.

Decisions, decisions.

I've ran a 35 spline 8 3/4 Strange spool on the street long enough to crack the teeth on 4 different ring gears
Spools on the street area pain to drive around sharp corners, it wants to slide the outside tire to make it keep up with the inside tire regular corners are no problem but I do make sure that both tires are within 1/4 inch of each other on the circumferences
I ended up bending that 8 3/4 housing bad enough that the axles would not slide in properly, I had to pound them in with a block of wood and a hammer It finally tore the ladder bar mounts loose from the passenger side doing a burn out at the track
I swapped it out for a Dana 60 with a spool and never had another rear end problem with that car

I run a spool in my S 60 with no issues. The only time I notice it is turning tight pulling into a parking space.

Was that spacer and beat up shims on the pinion? If so whoever set it up did not do it right, the pinion was moving in and out, so the gears are plain junk. If you say the bearings are good I would sand roll or dremel them out to make them slip bearings so you can get the pattern perfect, and buy new shafts, new R&P, new bearings and be done for about $400. Drag radials did not break that suregrip, it was put together wrong, factory service manual for that, carl jantz u-tube to learn how to slam a dana 60 setup in 5 minutes with slip bearings. If I recall the new shafts will not have the hole in the middle, so if you have tapered axle bearings you will need to drill them, and add the thrust spacer. If you have greens then you do not need them. One other thing would be if you have aftermarket axles make sure they are not to long and that is what broke the shafts.

The damaged shim was in front of the pinion spacer. It may have been beat out by the pinion moving back and forth, but the other shim beside it was okay, so I think that the shim slipped out of place during installation. Just a guess on my part.

I know that the drag radials did not play a role in this mess, I only mentioned them as a point of reference on my question about spool vs Sure Grip.

And it has the green bearings with aftermarket axles. So that is a good tip to check the length of the axles. Thank you.

Had dana 60 on my mind, sorry as I see it is an 8-3/4. You only need one slip bearing, well worth the time, you will never set a rear without one after you use one.

Close inspection of the shafts and axle ends revealed marks that I believe show contact with each other. Good catch, I really appreciate the heads up. I will definitely shorten them.

The thrust block moves about 3/8", so half that is 3/16", that would be the minimum clearance, I would do 1/4". As long as you have full spline engagement you can do more.

I prefer to polish the pinion to reduce the rear bearing press fit enough to install and pull the bearing with just a light effort. Not sloppy, I still want to use a press. The front bearing is made to just tap on and off of the shaft. I want to use the same bearings for set up that will be used in final assembly.