Differential gear pattern?

[Hedgehog]

I do know a little, but far from all there is to know about installing a new Truetrac carrier and new gears. The pinion is set as it was VERY close to the old pinion gear as per the scribed numbers on the pinion face. Pinion preload seems good. The back lash is set to ~0.0055 (should be 0.010 and 0.004). But when it comes to the pattern I'm completely lost. After using snap line powdered chaulk mixed with white lithium to mix up a paste this is what I got:



Not as focused, but you can see the gears aren't too deep.



Some patterns have a nicely centered oval shaped swipe, at least one says this is a good hand turned pattern. I don't have a clue which is right.

 

[Lumpy Grits]

Is the carrier bearing cap bolts fully torqued?
Bring the ring gear .003-.004 closer to the pinion.
Use far less grease--
Ck pattern in at least 2 places.
How much back lash do you have?
What did the pattern look like on the old carrier?
LG

 

[Hedgehog]

Is the carrier bearing cap bolts fully torqued?
Bring the ring gear .003-.004 closer to the pinion.
Use far less grease--
Ck pattern in at least 2 places.
How much back lash do you have?
What did the pattern look like on the old carrier?
LG

The bearing cap is torqued down

Agreed on using less grease

Both patterns were identical

Backlash as stated in the original post is 0.0055" or 0.005+" factory setting should be 0.004"-0.010" with 0.006 being a good target.

Different gears, well used or well lapped used gear set.

 

[Lumpy Grits]

My CRS was in full bloom as you did in fact post the BL.
.005 BL is fine-
Use less grease and lets see what the pattern looks like before any changes are made.
What axle is this?
Hint: Turn the pinion by hand, as you add resistance/drag by hold'n the carrier with the other hand. That should give you a clearer pattern to 'read'.
LG

 

[Hedgehog]

Lumpy - I cleaned off the excess grease and painted on a thin oat. Not a whole lot better, but a pattern that's easier to read.

 

[Lumpy Grits]

Good pattern to start. Move the carrier .004-.005 towards the pinion.
What's the 'coast' side look like?
Ck your BL after the 'move'.
Are you using a solid spacers or a crush sleeve in the pinion?
LG

 

[Hedgehog]

Solid, this axle is old enough not to have a crush sleeve.

Both sides look about the same.

 

[Hedgehog]

Doing that closed the back lash down to 0.003". To tight. I'm going to try going the other way.

 

[Lumpy Grits]

Back the pinion out .003.
That second pattern shows the pinion gear needs to be 'deeper' into the ring gear.
Take a picture of every pattern ck you do so you can see the change. Always check the drive and coast side for contact.
LG

 

[Hedgehog]

I'm having trouble with the shims. They are the shims made for a Dana 30 , but the id is fairly big so the fit is sloppy. We did find some tighter shims, but the deform.

After fussing around a bunch I've settled on a 0.007 backlash with what appear to be good patterns on the drive and coast sides.

The internet can be a wonderful place for information and there is a ton of information on acceptable patterns with some of the examples being inconsistent. The patterns I have now are acceptable in the majority of the patterns I've seen. It does take some practice to see the changes. I'm beginning to wonder if a pattern past that dries like paint would be better. Not real hard paint, but a substance that dries or sets some. Then the true pressure areas would wear through.

One thing that I'm beginning to believe makes this a little more difficult. The gears aren't new, they are well driven and well lapped together. A new gear set hasn't had time to truly lap in and more than likely would clearly show pressure points. This doesn't come from my little brain, a guy at work sets up race vehicles (cars and trucks). He asked if the gears were used or new, then went on to describe how to read each one. That included a need to put serious back pressure on the gears sometimes as much as 200lbs to be able to see a proper pattern.

 

[Lumpy Grits]

I always put the thin shims in the middle of the pack and have the thickest on the outside.
Are you using new bearings??
.007 BL ain't bad for a used set.
I wanted you to get deeper on the ring gear to take the load of the edge of the gear teeth.
Lets see what pattern looks like, that you have now.
LG

 

[Hedgehog]

New bearings..... I suppose I could go tighter ...... I understand wanting to move the pinion deeper in the ring gear, but every time I moved in that direction backlash was lost. Moving slightly further improved the pattern.

 

[Lumpy Grits]

Bring the pinion in .002.
LG

 

[Hedgehog]

it was at 0.005 and the pattern wasn't good enough.

 

[Lumpy Grits]

it was at 0.005 and the pattern wasn't good enough.

Take .002 OUT of the pinion shim stack.
Torque the p'nut to the high side of specs and use some blue locktite.
Make sure you oil the bearings when you ck the pinion's break away rotational torque.
LG

 

[Lumpy Grits]

How's the pattern look'n now?
LG

 

[Hedgehog]

To be honest, I'm debating just giving up and paying the money to have it done. For some reason I hate the idea of pulling the pinion again, yes it's stupid but I'm still having trouble doing it.

 

[Lumpy Grits]

Understand-many times in the last 40+ years of set'n up R&P's-I have wanted to take a 20lb. sledge hammer to them
Try just one more time-Bring in the 'P' .002.
Good luck,
LG

 

[Hedgehog]

So, I'm a little confused, if I wanted a deeper pinion, with the taper of the gear wouldn't I bring it up? It seems like that would bring the gear closer AND tighten up the back lash. Also, the spec's say 0.004"-0.10" and 0.007" seems to fall in there to me, even given bearing break in. ...... 'm not saying that I won't do what you are saying, just asking.

 

[Lumpy Grits]

I used incorrect wording You want the pinion to go .002 deeper into the ring gear. This means you ADD to the shim pack .002-SORRY for MY error
The patterns you had posted, the pinion need'd more gear tooth contact(deeper towards the bottom of the gear tooth on the ring).
Take a look at this--
http://www.moserengineering.com/moser/wp-content/uploads/2010/05/ringandpinion.pdf

and this-
Ring and Pinion Gear Pattern - Interpretation & Setup

lastly-
https://www.ringpinion.com/Content/Book/Reading-and-Adjusting-Ring-and-Pinion-Tooth-Patterns.pdf

Wish I lived closer, as I would be happy to do this for you.

LG