ford differential gears question for experts

[kingranch]

swapping gears on a foxbody w 8.8 rear end. I took the oem stock 3.27 out and swapped for the ford racing 3.73.
My question is on setting the pinion depth... My gear mesh pattern is as shown. According to the manual I need to add some thickness to the pinion shim. What is a good starting point as the stock shim I put back in was a .025 thousandths? Should I jump to .030? Just curious what is the typical size to see the mesh move deeper to the center of the gear.
My backlash seems too large now but i think thats bc the pinion is too far from the gear and it will tighten up w new shim.

Thx

[offthemap]

Shim it

[175gr7.62]

Do you have a set of setup bearings? If not, they make adjustments much easier. I tend to try and overshoot that way I can bracket the correct shim load.


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[kingranch]

Do you have a set of setup bearings? If not, they make adjustments much easier. I tend to try and overshoot that way I can bracket the correct shim load.


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No I don't
I was planning to take a new bearing and grind out the center so it slides off and on easily as a test bearing... then when j find right shim just press on a brand new timken bearing

[175gr7.62]

No I don't
I was planning to take a new bearing and grind out the center so it slides off and on easily as a test bearing... then when j find right shim just press on a brand new timken bearing

That's the best way. You should be able to get a good pattern pretty quickly. The cost of the bearings is well worth it to be able to work your way into it.

[BETTERLUCKYTHANGOOD]

Add 10 to what you have in there now. That will also put you closer to the middle of the gear and not out on the heel of the ring gear like it is now. Test and show what you have after that.

[RifleBowPistol]

Just curious, what are you setting the pinion bearing preload to? If you use a dummy bearing on the rear of the pinion gear, make sure it's the same brand pinion bearing. I have found that going from a Chinese bearing to something like a Timken bearing, there will often be .003" to .005" difference in pinion depth with different bearings, but the same shims and same pinion bearing preload.

I use a pinion depth tool, that works very well, very easy to find the correct shim. Then I also have a universal pinion depth tool, that takes more time to take the measurements and do the math, I only use that one, on non Ford axles, that I don't have the pinion depth tools for.

Make sure whatever pinion bearing preload you use, when determining the pinion shim thickness, you use the same pinion bearing preload, when you actually set the gear set up. Also make sure you have plenty of preload on the carrier bearings, when checking the backlash and when doing the final set up. Bearing preload, is one of the things most people don't have a clue on and as a result don't do a good job of setting up the gears, for any application that might actually have some hp.