Another amatuer looking for help reading gear patterns

[Nothing Special]

I'm setting up new gears in a Dana 44 high pinion for my '71 Bronco. I changed a differential once before, but since I didn't move the pinion it was quite a bit simpler. This time I'm starting from scratch.

Here's my first attempt at a pattern. I know the backlash needs adjusting (it's at .004", should be .006" - .010"). And the total torque to turn is only 5 lb-in above the pinion torque to turn (should be 5 - 15 lb-in). So it could use a little more case preload. But I thought I'd take a look at the pattern and see if my first shot at pinion depth was anywhere close.

I'm thinking this looks pretty close, but maybe I could increase the pinion depth a little to get the pattern a little lower on the tooth.

Drive side:

Coast side:

What do people think? Should I get the backlash and case preload dialed in better before making any pinion depth adjustments? And does it look like increasing the pinion depth would be a good direction to go?

Thanks

 

[Timmy390]

No expert....I'd run it......

Tim

 

[rjrobin2002]

No expert....I'd run it......

Tim

I agree. I ain't that picky with a front axle.

 

[Nothing Special]

Thanks for the feedback. I'm probably going to end up about here, but especially since this is my first full gear set-up I decided I'd try to bracket it to get a better feel for what I was getting.

I decided that the pinion depth was probably close enough that I should get the backlash where it belongs before I decide if I wanted to change the pinion. So my first step tonight was to add .011" to the button side of the case and take .005" out of the flange side (which turned out to have .044" from before, so now down to .039"). That should add .006" preload (and I was still a bit low) and give a bit more backlash.

It did just that, with .007" backlash (spec is .006" - .010") and now the total torque-to-turn was 9 lb-in over the pinion torque-to-turn (spec is 5 - 15 lb-in). I could live with those numbers!

Running the pattern I got much the same as I got last night. Here's the drive:

and here's the coast:

I was thinking that seemed probably good enough, but if anything still a bit high, so I decided to shim the pinion a little deeper to see what it did. I added .010" behind the inner pinion race and left the case shims where they were. That gave me .0075" backlash, and 5 lb-in from the case preload. I'm not sure why the torque dropped.

The pattern I got confirms that I moved the pinion deeper, and that's a very good thing, because it means I sort of know what I'm doing! Here's the drive side:

and here's the coast:

As I said, it confirms I went deeper. And now I'm definitely too deep. So I'm thinking that I want to take probably .008" - .010" back out (after just putting .010" more in). Once I have the pinion depth dialed in I need to put an oil baffle in. That goes where the shims are and will add shim thickness. So I'll need to take out shims to compensate. I think now I'm going to figure that I know where I want to be and I'll add the baffle while taking the .008" - .010" out. If things go well that should be the last time I need to put the pinion in.

I'm liking where the backlash is, so I'm not going to try to change it. But i think I will add a little more shim on both sides of the case to increase the case preload a bit more. But that will be a job for a different day.

 

[Yeller]

You are right on target. move the pinion back 5-8 and reassemble for the last time.

 

[Nothing Special]

Thanks for the confirmation!

 

[Nothing Special]

I won't bore people with the entire process, but I ended up getting the pinion depth right on the next attempt (removing .009" while adding the oil baffle). It took three tries to get the pinion nose bearing shims dialed in to get good pinion preload. And I ended up with 2 more installations of the diff.

Now I'm at 13 lb-in pinion torque to turn without the seal, 22 lb-in total torque-to-turn without the seal (26 lb-in with the seal). I've got .0065" backlash. And here's my pattern. Drive side:

Coast side:

I'm happy with that! It took about 10 hours work over 4 nights, installing the diff 6 times and the pinion shaft 3 times. I was expecting a lot worse!

 

[Yeller]

Nice!!

 

[rjrobin2002]

Did you buy some set up bearings I guess while you did all this install and removing?

 

[Nothing Special]

Nope, I made pullers to get the case bearings off and the pinion races in and out.

By the way, nice color on the Bronco in your avatar. It looks just like mine. Ford Sonic Blue?