Obtaining / Setting a Ring and Pinion Gear Pattern

[Wulfie]

Need some guidance bmorgil . Trying to set up this rear end axle . Got some pics of the pattern ,looks like I might have to go in with pinion gear some more . What you think ? Need a link to patterns if you have or a place to find em. First pic is the drive side ,looks to be hitting on the heel , there abouts. Second pic cost side , looks to be hitting toe end . Any comments would be helpful.
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[gmwillys]

Dr. Dana will be by shortly, but here is some helpful diagrams/explanations to setting up a ring and pinion. From your pictures, you are definitely in the ball park of being properly set. I would try one more shim to gain a touch more contact, to center the pattern on the ring gear tooth. Bmorgil is the master at the driveline, and we will see what he thinks on the matter.

https://www.yukongear.com/blogs/how-to-create-read-ring-gear-patterns_1

https://www.sierragear.com/differential-repair-help-topics/ring-and-pinion-gear-pattern/

[bmorgil]

It can be very difficult to get a good pattern read on a used gear. That said you can get a good idea of tooth contact. First you need more load on the output so the pattern will print a little better. Once you have a good load on the gears, pay attention to the drive side. The coast is what it is. If there are complaints of coast noise, then worry about it.

In your photo the pinion is not deep enough. You need to look for a spot that is showing good contact as close to the middle of the gear tooth as possible. You will get the biggest pattern changes from the pinion position. Always start with the pinion position. If it was mine I would add about .020" on the pinion and try to move the contact pattern down into the tooth (providing the backlash is correct). The pattern will move forward on the pinion and deeper into the root as the pinion moves in towards the ring gear. The pattern will also move forward towards the toe of the pinion gear. It is normal to have a new gear set show the contact towards the toe. This is OK. The pattern will move back towards the heel and become more "full" as load increases. The more used the gears are the bigger the pattern will be. On well worn gears you may end up with the pattern covering the whole tooth. That's OK as long as the backlash is correct.

Try to get a pattern near the center of the gear tooth. Make sure to adjust backlash as you go. As the pinion gets closer to the ring gear backlash will decrease and it will change the pattern. The reverse is also true. As the backlash increases it will change the pattern. Stay with the pinion, adjusting the backlash as you go.

Setting up an axle is a bit of an art because if you can hit it in a couple of tries, you will save a lot of time and money. I have looked at a lot of patterns and adjusted till I could not move my arms anymore. It can be tough if you are chasing noise. Not so bad if you just need a good pattern that will last and not too noisy. The most difficult time I ever had was getting the high end "Lingenfelter" Corvettes in the late '90's to run quiet. In a Vette you sit almost on top of the differential. If it is slightly off on the ring and pinion pattern, you will hear it. Especially at high RPM. In a Jeep it just needs to be close. Contact in the middle of the tooth as best you can. Towards the toe of the pinion is OK. Try it again and lets see another pic Wulfie!

Addition: Here is something I use to help myself set these things up in a fairly quick manner, relatively speaking.

The top of the tooth, the "Top Land" will make a straight line in the gear pattern if it strikes the actual face of the tooth. You do not want the top of the tooth striking the face of the tooth and making that straight line. That is too far off. It will make noise and it will be weak and it will run hot. If I do not see that straight line, I am very tempted depending on the application, to let it go.

Look at Wulfies pic. You can see the straight line in the paint. It is the top of the tooth striking. That is why I am saying move it a bunch. It should swing down in and show you how close you were. It is either going to stop making that straight line, or it is going to make a straight line going the other way. A straight line the other way is a big clue you were close. Split the difference and things are going to hone in for you. Look at the actual photos gm provided. You can see the straight line in the "bad" pattern. Notice it is not there in the "good" pattern. Also notice they don't seem to care where the pattern is as long as it is near the middle and there is no straight line appearing at the top or the bottom of the tooth.

So there it is. Don't think I ever gave up that tip. If it doesn't make any sense, I seldom do.

If this is confusing, "fahget" about it! Haha, I would be glad to try to clarify or sketch it out. Now a day's the machining capabilities are such that you can set up a gear set quite a bit easier, and with tooling. The gear marking method is still a gold standard in my book if you know what you are looking for. It would be good to make sure we all can pass it on.

[Wulfie]

Tnx bmorgil , found good pics of correct contact and lil explanation how . Heres a good pictorial of building d 44 and useful tips ," DANA 44 pictorial build NAXJA " . I will trudge along need to get more bearings and inner pinion race to make the on and off for the set up .

[Wulfie]

Tnx gmwillys , I finally found good pic of ideal contact pattern . Plus bmorgil book on how . You guys have been very helpful. Found site that makes kits of the ring gear bearings and pinion race for easy on and off but for the 30 spline shaft

[gmwillys]

See, we can all learn a little bit more than we thought we knew. I live in a world where diffs make noise/sing. Failures are not common except the occasional haunting vibration. Our diffs, (four per vehicle) are hard mounted to the hull, so the noise reverberates through the chassis. In the days of Sportsman class dirt track racing, we would set up Ford third members with different gear ratios for the variety of different track lengths and conditions. Then we invested in quick change transmissions to where we could change out the gearing in minutes, in between heats. Long story short, as long as the ring and pinion where contacting in the center of the ring gear, we thought we were golden. We didn't look at sharp lines in the pattern, because noise didn't matter. I'll have to save this thread in the memory bank for future diff building.

[bmorgil]

In your case gm, those gears were not made to be quiet, just brutally strong. There is a lot to making a gear set quiet so a Cad owner doesn't complain. Strength isn't always the main criteria. The first introduction of a Dana IRS into a Corvette, was a proto-type modified fork lift axle. The initial ring and pinion was not quiet to say the least. That was long ago.

You have too curved surfaces that you are going to try to get to touch on their high spots for lack of a better explanation. The closer you get to that spot the quieter the gears will become and the more efficient. The gear design is such that there is a wiping action between the teeth as they mesh. You want to be right on that spot on the teeth where the contact is the best, to hit the sweet spot for everything. The gear set will still only be as quiet as its tooth profile and machining. Cheap gears can be impossible to get any pattern on.

[Wulfie]

Some more trial patterns , seems like I failed again to get the ideal pattern. Bmorgil suggested I go in ..02 on pinion did that now looks like went in to much. So going to come out .01 and run pattern again. Before I had not enough now too much so split it and maby Goldie Locks . The pics are not that great but appears in to deep. First pic coast side second drive , but its not very clear gonna try rag drag next time maby get better defined pattern. Bmorgil if I take .01 off the gear pinion side do I take .01 off the preload side ?

[51 CJ3]

Some more trial patterns , seems like I failed again to get the ideal pattern. Bmorgil suggested I go in .20 on pinion did that now looks like went in to much. So going to come out .10 and run pattern again. Before I had not enough now too much so split it and maby Goldie Locks . The pics are not that great but appears in to deep. First pic coast side second drive , but its not very clear gonna try rag drag next time maby get better defined pattern. Bmorgil if I take .10 off the gear pinion side do I take .10 off the preload side ?

Did you really do .20 (2 tenths) or .020 (20 thousandth's)? The recommendation I read said .020.

[Wulfie]

No lol. I meant 20 thousandth . .02 ! Sry my bad .

[bmorgil]

You are a lot closer than you think. Don't change anything yet. I cant see the pattern on the drive side very well, you don't have enough load on the ring gear. The shadow I do see looks like it is wide in all directions and positioned to the toe. If that is it you are there. I cant see it however so it is very possible "wishful thinking"! The coast side is too deep. That will howl when you back off the gas. Get the drive side first. Make sure the backlash is correct. On a used gear set use the larger specification for backlash (.010"). We might tweak the coast side with the backlash. More on that later if needed.

You are on track. The number was twenty thousands on the shim. Lets see what a good clear mark looks like. More drag on the ring gear. You should not be able to turn the pinion easily by hand. If you are pushing something against the ring gear, be careful you don't want to crack the axle housing. Use a wedge block of wood (like a doorstop) or nylon against the ring gear and the case. I did see a guy break the case using a crowbar against the ring gear. Roll the ring and pinion several revolutions with load. Look for the marks on the opposite side of the paint spot. See what the marks look like out of the paint. Your getting close. Shoot pics of the painted spot and the unpainted spots where the gear transfers the paint.

If you have the preload set on the carrier bearings (you should have .015" of preload), just move shims from one side to the other to change backlash. Keep the total shim pack the same. So take from one side and add them to the other.

[Wulfie]

Will get a better pic with load but my preload on carrier bearings is not right yet. How do you know when u get the proper pre load on carrier bearings ? Im gonna get a new set of carrier bearings and make some set up bearings . This reminds me of the movies when they played serials when I was a kid ," Commando Cody " comes to mind had to wait a week for the next serial ha.

[bmorgil]

You need to set the carrier preload without the pinion in. With no pinion it should take a firm steady pull to rotate the ring gear. It is hard to measure but if you put a torque wrench on a ring gear bolt, at least 50 or so inch pounds to rotate it. To set it by the book, you find the right amount of shims to obtain a "slip fit" of the carrier in the axle's housing. Then .015" is added to the bearings to obtain the proper preload. Once you "feel" one assembled this way, you will always know what the proper preload feels like when you pull on the ring gear with no pinion in the housing. The second link below address the set up of the carrier preload pretty well.

https://willysjeepforum.kaiserwillys.com/showthread.php?2820-1953-M38A1-differential-setup/page2

https://willysjeepforum.kaiserwillys.com/showthread.php?2308-Pinion-shimming

https://willysjeepforum.kaiserwillys.com/showthread.php?2323-Spicer-23-2-differential-backlash-question

I have seen guys make their own axle dummy bearings for setting up axles. It works quite well. Take a used set of bearings and hone with a "brake cylinder hone", the I.D. of the races until they will slip on the carrier and the pinion respectively. You can also epoxy the bearings together to make the "tool" into a solid dummy bearing. This makes it much easier. Use the slip fit bearings to quickly swap the shims in and out until you get it set.

[Wulfie]

Got some clearer pics bmorgil . First one drive side and other coast . Still looks like I need to move pinion out some . But my ring bearings not set right yet , the preload . Looks like drive side hitting on more of the toes and to deep. If not still to clear ill try again .

[bmorgil]

You are good at this Wulfie. I am in agreement with you. There are some clues. Look at the "ghost" marks where there wasn't paint. The marks left by the teeth almost match the original wear pattern. You are very close. I agree it is to deep. I am concerned about your carrier bearings not being set. You need to have them set before the final pattern. That said, I have to think bring it back out about .010" and tighten up the carrier bearing preload (first) before the pattern check. Notice how now, the drive and coast side are closer to the same deep contact pattern and moving to the toe on the drive and the middle on the coast side. That pattern is almost there, a little too deep. Your .020" adjustment successfully moved it right through the sweet spot. That tells us you were within .020". Since it moved it from too shallow to too deep, you know you were within .010" of hitting it.

I misinterpreted your question about the preload shim change. I was talking about the carrier shim pack. You are correct the preload will change on the pinion as you move it. Hold off on the pinion preload adjustment until you are done with pinion depth. Remove most of the shims from the preload and tighten the pinion nut gently until you achieve some preload (not too tight you will ruin the bearing). Set the pinion depth and then go back and set the preload.

Addition: Shoot pics of the pinion if you can get the camera in there. The long teeth also give some good indications where the paint transfers from the ring gear. I have always found it to be faster to make large changes in the shims until you can successfully go past optimum and then bring it back. I find this method much quicker than "sneaking up" on the pattern.

[Wulfie]

Tnx bmorgil , after lasft pattern i took out .007 but havent tried it until i get carrier pre load set up . I assume the .015 is divided between the 2 sides ?

[bmorgil]

The .015 is added to the pinion gear side, once the total amount of shims required to move the ring gear to Zero lash is obtained. The procedure to get it correct is to find the amount of shims required to slip the carrier into the axle housing to a slip (Line to Line) fit. Then you remove the shims and install the ring gear and the pinion. You then force the pinion into the ring gear while indicating the amount of travel. Then you place that amount of shims from the total amount you measured for a slip fit, on the ring gear side. Now you place the remainder of the shims on the pinion gear side PLUS the .015" required for preload. The .015" pushes the ring gear away from the pinion for backlash and provides the preload. The carrier is now a .015" press in fit into the housing. This should put the backlash within spec. From now on as you adjust backlash you remove shims from one side and move them to the other side. On a used ring and pinion shoot for .010" of backlash. If it needs to be less it will show up in the pattern.

After another look, I was also thinking .007" on the pinion. It looks close.

[Wulfie]

Got another addition to pic of gears , first drive side second coast side . Also some shoes for "RIPPER" , and another bunch of goodies from Walcks , they sure pack em good . Got the .01 backlash right now if nothing changes lol. Suspect maby one more move out on the pinion , a lil more . Wish I had done the .01 .

[bmorgil]

Man that's close. Classic used gear set, wont leave a good mark unless its in the exact spot as before. I am in agreement again, damn I though .007" also. Looks like the .010" would have done it, .002" or .003" more might show a better pattern. Because the gears have run together for so long, it will be difficult to get a good print on the pattern unless you hit it exactly in the position it was in when it came apart. We are looking for a clean spot near the center of the tooth. If you look hard you can see you almost have a nice contact. It is not a picture perfect clean spot like a new gear set but, it is there just not real clear. Make sure to hold the .010" backlash.

And "Ripper's" got a new pair of shoes!

[Wulfie]

Thinking .003 . And the carrier pre load seems correct now , added .014 to teeth side . Tight fit now around 40 inch pounds . If I move pinion out will it change backlash , which I think it will.

[bmorgil]

Yes as you move the pinion out it will change backlash. You aren't going very far. It may stay in spec.

[Wulfie]

Got her done not ideal but im going with it , First pic drive side , second coast , third , pattern in circle is what its close too I think.

[bmorgil]

The pinion is a little too "shallow" or you need to decrease the backlash. What is the backlash? Look at the coast side. The sharp line at the top of the tooth indicates the top land of the tooth is striking on the coast side. On the drive side the contact is good, just to the heal of the ring gear tooth. Moving the pinion in will bring those two things closer together. Moving the pinion in should move the coast side out of the "strike zone" and bring the drive side closer to the middle. Decreasing the backlash will have a similar effect, though less. How far did you move it from the last adjustment? It looks like it must have been very close the last time.

Wullfie I think you are all over it. However I think you were closer on the last set up (prior to this one). It was very close the last time. Better than it is now in my opinion. I would have been tempted to run it. The only thing about the last pattern before this one, is the slight deep contact (light straight line) on the coast side at the root of the tooth. A little more backlash or, a very slight pinion movement out and that was probably as close as you are going to get. I would go back to the last set up and either vary the backlash slightly or, move the pinion slightly, depending on what these current changes were. As you chase it remember, nothing will be more difficult to get a good pattern on than a well used gear set!

[Wulfie]

I moved it .003 out , the backlash was .008 , Im gonna go to other things for now ,let my patience return , then work on it some more. When I do ill move it back in .002. I see the sharp line ur talking about.

[gmwillys]

Sometimes, you just have to back away from project. Expensive things happen when pushing too hard to make something perfect. TJ and I like the sit on a bucket, look at the problem, have a beer or three, then have a Winston or two to regulate the nerves. More often then not, when you get back to it, it often falls right together. Most of the time...

[bmorgil]

I think you are very close. Move the pinion back and see if you can hold the backlash close to .009" - .010".. I think that's as good as it will get. Sometimes it does help to walk away from it for a while! You had a usable pattern the time before the last set up. It should come in nice this time.