Differential rebuild - gear contact pattern (1 Viewer)

[demos]

I'm rebuilding my 1974 FJ40 rear differential. This is my first differential rebuild of any kind & I can use some advice from the experts.

I've replaced all the bearings but keeping the original ring & pinion gears.

The attached photos show two attempts to get a good gear contact pattern.
The 1st attempt suggests to me the pinion gear was too deep so I reduced the shim (under the pinion inner bearing outer race) from 0.016" (the original 0.4mm shim) to 0.005".
The 2nd attempt result is unclear to me.
I have read experts say on old, worn gearsets to pay most attention to the "coast" side pattern (the right in my photos).
Others say it's the "drive" side you should pay attention to.

Any advice on which way to go on the pinion depth shims?

 

[peesalot]

I'd run that first pattern, what was the backlash on that set up ? Are you using a crush sleeve or solid spacer ?

 

[demos]

I'd run that first pattern, what was the backlash on that set up ? Are you using a crush sleeve or solid spacer ?

Thanks for the response.

Backlash was 0.007". I'm using solid spacer with preload at about 10 in-lbs.

The first pattern contact seemed to be too close to the root on the "drive" side, but the second seems like contact is too close to the face on the "coast" side.
That "drive" side pattern looks OK in the first attempt?

 

[peesalot]

Yeah, I dont like how the pattern goes to a point but it looks good for position IMO. FWIW did you measure backlash prior to disassembly ? At 7 on a used set might be a tad loose, How tight did you run side adjusters ? Maybe adjust like 2 holes moving ring towards pinion and remeber to move both adjusters, back off the far side and use ring side adjuster to push it over. If you have the backlash # prior I would try and get as close tor same if I had the #.

 

[B y r o n]

You might want to check out Zuk.

 

[Living in the Past]

You might want to check out Zuk.

He is only doing local drop off, no more mail in diffs. Have a few diffs I want rebuilt. Luckily location drop off is not an issue for me.

 

[demos]

Yeah, I dont like how the pattern goes to a point but it looks good for position IMO. FWIW did you measure backlash prior to disassembly ? At 7 on a used set might be a tad loose, How tight did you run side adjusters ? Maybe adjust like 2 holes moving ring towards pinion and remeber to move both adjusters, back off the far side and use ring side adjuster to push it over. If you have the backlash # prior I would try and get as close tor same if I had the #.

The backlash prior to disassembly was 0.019". I adjusted the side adjusters to get the 0.007" reading as per spec - I think it was 2 holes worth of turn.
I guess I'll go back to the original 0.016" shim or close to it and then try different backlash to see the effect.

 

[demos]

You might want to check out Zuk.

Looks like a lot of good info there. I wish I had seen it before I started. Thanks!