Yet another 8-3/4 setup question. 3.73

[Mark Barnes]

First time I've tried setting up my own gear. Last time I paid a guy to set my 3.91 up...sounded like a freight train coming, drove it from my kids house to mine and sheared 6-7 teeth off the ring gear. When I pulled it, the pinion had about 1/4" of end play.
So here I am, schlepping and shimming. Take a look at the pics and give me your thoughts on whether it's close, or what I can do to improve the pattern. Thanks!

 

[#41]

Need a wider, thicker, centered pattern. Do you have a service manual to guide you?

 

[Tman100]

This may help you.

 

[john-9]

you are too high on the coast side and too low on the drive side ,, start by pulling .003 out of your pinion shim thickness ,, set backlash to spec .006 - .008 and recheck pattern ,, keep pulling out shim ( .003 at a time ) until the pattern is centered on the drive side ,concentrate on getting a proper drive side pattern if you get the drive pattern correct ,, the coast pattern will follow and be ok, make sure when you do your pattern check you have some preload on the pinion bearings and carrier bearings with pressure on the ring gear as you turn the pinion. pattern should look similar to the pic i posted of the 3.55 i set up.

 

[Mark Barnes]

you are too high on the coast side and too low on the drive side ,, start by pulling .003 out of your pinion shim thickness ,, set backlash to spec .006 - .008 and recheck pattern ,, keep pulling out shim ( .003 at a time ) until the pattern is centered on the drive side ,concentrate on getting a proper drive side pattern if you get the drive pattern correct ,, the coast pattern will follow and be ok, make sure when you do your pattern check you have some preload on the pinion bearings and carrier bearings with pressure on the ring gear as you turn the pinion. pattern should look similar to the pic i posted of the 3.55 i set up.

View attachment 1509137

OK, thanks. I have another question though- I have already removed the original beveled shim from under the inner pinion bearing and replaced it with a couple from the gear kit that are slightly thinner. Is that kosher? Starting to make me a little nervous. It seems like I'm getting the pattern to move up the drive side a little, but the coast side is doing the same thing.

 

[AR67GTX]

This is kind of a summation below, of my novice learning experience on setting up a 489 last year with a crush sleeve eliminator kit.

When I set up my 489 last Fall I made some set up bearings and ran probably 20 some trial set ups with different pinion depth and backlash and took pictures of each pattern. I don’t know if this is always true but I experienced that the drive side pattern would hold up over a wider range of pinion depth than the coast side. On the drive side it would vary up and down from the toe to the heel as I changed the pinion depth, but the imprint pattern didn’t vary a lot and it stayed out of the root and crown for a pinion depth range of around .010”. But the coast side imprint pattern would only hold up over a range of about .007” before sliding off on the crown or into the root.

And the ranges for coast and drive did not exactly coincide. The acceptable pattern imprint for the coast side was over a shallower range of pinion depth than it was the drive side. So I kind of had to focus on where the acceptable tooth imprints/patterns overlapped.

I didn’t find that backlash made a huge difference as long as I stayed around the .006 to .010 range.

I don’t know if this is typical or even good guidance. The experienced guys see small details in these patterns that it takes years of experience to recognize. I had problems getting as good a quality of pattern imprint with the yellow grease as many guys were used to dealing with so a lot of the feedback was - try to get a better imprint - something I never fully succeeded at. But I had had two shops try to set up gears in my 489 earlier and both has failed. I took photos of their work before installing the center for a try. In going back over their pictures and comparing to mine, it looked like they both concentrated on the drive pattern and just blew off the coast side. But I still have some of what DVW described recently as float whine so there’s that.

 

[dvw]

Doesn't matter if coast and drive don't match. What matters is if the pattern is in the middle of the tooth from the root to the top edge of the tooth. You are at the bottom now. That tells me you have to much pinion shim, not to little. Use an electric drill (not an impct they vibrate) to spin the pinion while holding soft object on the outside of the ring gear (I like a trim stick). You'll get a much more readable pattern. You should end up with something like this.
Doug

 

[Mark Barnes]

Well, after the helpful responses, this is where I ended up. Zero shims under the inner pinion bearing. Guess I'm gonna have to accept this, I'm all out of adjustment options.
This is with 30 in/lbs. of pinion preload and .008 backlash. Any other suggestions (other than pay someone...already got my pants taken down once).

 

[dan juhasz]

How does one hone a pinion bearing to make it removable for this process of trying different shim combinations. Are brake cylinder hones capable of removing metal from a bearing ?

 

[steve340]

What pattern or how good you can get it depends on the quality of the gearset manufacturing.
If that is good as it gets you either decide to run it or buy another gearset.

 

[Mark Barnes]

How does one hone a pinion bearing to make it removable for this process of trying different shim combinations. Are brake cylinder hones capable of removing metal from a bearing ?

Die grinder with a polishing roll. Goes pretty quick.

 

[Mark Barnes]

What pattern or how good you can get it depends on the quality of the gearset manufacturing.
If that is good as it gets you either decide to run it or buy another gearset.

Running it. Dicked around too long already.

 

[AR67GTX]

From all the patterns I ran on mine, that one looks like when I tried too much pinion shim under the pinion head. Pinion was too deep. I think DVW said that already. If you don’t have any shim in at all then I’m not sure what you do other than have the shoulder under the pinion head turned down. What manufacture is the gear set?

 

[john-9]

no shim ?????? pattern needs to be improved -- lets start from the beginning which case are you using ,,, 489 start with a 0.030 pinion shim ,, 742 and 741 start with a 0.090 pinion shim and set your preload and backlash then check the pattern ..if too much toe ( inner part of tooth ) remove 0.003 (so 0.087 shim ) if too much heel ( outer part of tooth ) add 0.003 ( so 0.093 ) continue removing or adding shim in 0.003 increments until the pattern improves as seen in the pics above. you are measuring your shims not eye balling them i hope. and your bearing races are seated in the case bores . what brand is the gear set.

 

[dvw]

You can say screw it. But not only will it be noisy. It may break teeth as well. You were mad about your previous set-up. This one will be no better. Something isn't right. Your pinion is way to deep. It doesn't have a shim under the race does it? Or are there burrs under the race not allowing it to seat all the way? as fas as honing the pinion bearing. Instead I polish the pinion shaft itself with crocus cloth for a snug but not tight fit.
Doug

 

[dan juhasz]

You can say screw it. But not only will it be noisy. It may break teeth as well. You were mad about your previous set-up. This one will be no better. Something isn't right. Your pinion is way to deep. It doesn't have a shim under the race does it? Or are there burrs under the race not allowing it to seat all the way? as fas as honing the pinion bearing. Instead I polish the pinion shaft itself with crocus cloth for a snug but not tight fit.
Doug

Doug wouldn't I just take a new pinion bearing and hone the inside and use it as a tool for the setup? once the correct shim is determined then press on a new bearing?

 

[Mark Barnes]

From all the patterns I ran on mine, that one looks like when I tried too much pinion shim under the pinion head. Pinion was too deep. I think DVW said that already. If you don’t have any shim in at all then I’m not sure what you do other than have the shoulder under the pinion head turned down. What manufacture is the gear set?

Motive Gear set. The pinion bearing sat all the way flush because it's got a matching radius. BTW, thanks for your earlier post. The excellent info you provided was just what I needed. You and DVW convinced me that I was doing it at least halfway right.
Now if it holds up!

 

[fourgearsavoy]

There is NO "halfway right" when setting up a rear gear. There is either something wrong with your pinion gear or your bearing. Since you have double checked the cup is seated correctly in the housing and there are no burrs or shims anywhere there is only one conclusion you have some wrong parts.

Gus

 

[dvw]

Doug wouldn't I just take a new pinion bearing and hone the inside and use it as a tool for the setup? once the correct shim is determined then press on a new bearing?

Per Strange Engineering I just polish the shaft. Then run it that way. No need to change anything after set-up. They claim to use this method in their set-ups. Been doing this way a few years on probably 5-6 axles. None have had an issue. I do have slide fit bearinngs for a Dana spool. As the side shims fit between the spool and the bearing.
Doug