Gear pattern check

[85 Jimmy]

I just installed 3.55 gears and a powertrax grip pro in an 8" ford diff. Anyone want to look at my pattern and tell me what they think? Pinion depth is 1.188 (that's what was engraved on the pinion, so that's what I went with), backlash is 8* and spec is between 8-10, pinion bearing preload is 25" lbs. and spec is 20-25.

First pass through the compound

Compound that was left on the gear after the first pass.

And the third pass through the compund.

 

[blazinzuk]

Pinion is too deep.

Thin the gear marking compound a bit with some oil.

 

[85 Jimmy]

So I need to add a little bit in the shim thickness?

 

[blazinzuk]

No it's too deep pinion needs to move back so less shims.

The pattern needs to move up on the tooth. Notice at the root you have a straight line. I call em knife edges, you don't want that it's needs to at very minimum curl up at the corners.

That doesn't look far off but if that's your first try I might try a larger change. Say 25 thou

 

[black dawg]

Yes more shim....moves pinion back,less depth, blazinzuk is thinking shim between pinion and pinion bearing.

I like to use a bungee wrapped around pinion yoke to add resistance.....like enough to have to use a wrench on ring gear bolts to rotate and check pattern.

 

[85 Jimmy]

How about this one? Had a .012 shim in it, put the thinnest one I have in at .009 and reset the backlash to 8*

Sorry for the shitty lighting, had to move it into my shed since I go to work in an hour.

 

[85 Jimmy]

And just to make sure there is no confusion. The ford 8" rear is like the 9" with a removable center section, which has a drop out pinion like a 14bff.

 

[blazinzuk]

Yes more shim....moves pinion back,less depth, blazinzuk is thinking shim between pinion and pinion bearing.

I like to use a bungee wrapped around pinion yoke to add resistance.....like enough to have to use a wrench on ring gear bolts to rotate and check pattern.

I misread I was thinking 8.8 yah more shim sorry .

It's been probably 10 years since I've even seen a Ford 8"