Setting up new Yukon 4.88 gears with an ARB, high pinion D30.

I think this is about as dialed in as it's going to get, pulled it out 10 times to adjust shims, I think it's about as centered as possible. It doesn't want to move much toe to heel.

Looking good?
.009 backlash

 

Not an expert by any means but it looks pretty good to me. You are decently centered top to bottom which is good. I may have tried to put it just a hair deeper. Your drive side is nicely centered toe to heel.

My set up is just a factory D30 and my patterns look similar though on the coast side I am closer to the toe than the heel. But if I tried to move it closer to center, the drive side moved off center which I didn't want.

 

Any deeper pinion (just a couple thou) and the pattern starts to degrade.

I kept trying to get the drive side to move a bit to the heel and coast side to move a bit to the toe to really get it perfect, but toe to heel movement just doesn’t want to happen. Opening up the backlash doesn’t seem to change much.

I think this may be it!

 

Do you have any pictures of the pattern with a smaller shim on the pinion?

 

#7 - .068 Pinion Shim (2 thou less than previous) .008 backlash - Looks slightly shallow to me...I think I'm going crazy staring at patterns though








#10 - .070 Pinion Shim (Same as first post) .090 backlash - Looks best to me:









#8 - .072 Pinion Shim (2 thou more than first post) - Pattern starting to get too deep I think

 

Any more or less shims than these the pattern was obviously too deep/shallow.

Thoughts?

 

I actually think the .068 shim looks the best.

 

What makes you think so?

To me, the .068 Drive side pattern is just starting to hump from the face side, indicating slightly too shallow. I feel the .070 Drive pattern is darn near perfect (despite being slightly toe) and coast pattern is a more diffuse and straight pattern than with .068.

Here is .065 showing a more pronounced hump from the top side: (too shallow)

 

I tend to look more at the drive side than the coast side. I like how the pattern is fatter and doesnt get as close to the gears edge. The bigger the contact patch, the better the load gets spread out. Maybe .070 with .007 backlash would be better looking but thats on the tight side. Everything here is going to have some sort of compromise.

 

I hear you, it really feels like splitting hairs at this point. You think it’s close enough to call it good, or keep working it?

 

You will be more than fine keeping it how it is or switching the BL up -.002. Good job on getting it all setup on your own! Rear ends suck.

 

Thanks man!! It's definitely a job. I'll try dropping BL just a notch and button it all up- I'll post the final pattern when it's done.

 

Triple check pinion races are all seated. None of this matters if the pinion moves 500 miles down the road and the rear locks up in a molten mess of metal.
aske me how I know. Though its not the end of the world as more practice makes better but never perfect.

 

Appreciate that! I’ll definitely give ‘em a good tap to make sure they’re seated on final assembly. I’m using an impact gun to drive the nut on and off so I’ve been assuming all that vibration has probably been enough to seat the races.

What do you think about the patterns?

 

Are you using the impact on the pinion nut? If you are using a standard pinion nut, you stand a fair chance of messing up the threads on the pinion running it on and off. This could occur whether you use the impact or do it by hand.

I purchased a non locking nut to do my set up and just used the actual pinion nut for the final torqueing.