I have a 2002 f250 rear end I am changing from 3.73 to 4.30 using Ford gears.
My question is. Do I have to get the pinion depth the same for the 4.30 that it was for the 3.73.? The 3.73 has a much bigger head on it than the 4.30 and its shorter across the head too. I didn't know if the thicker ring gear compensated for any of that smaller pinion
I put the same shim in that was in the 3.73 with 5 thou extra shim and used the same shims on ring gear, but I have about 8 thousandths too much back lash
Any help much appreciated
Andrew.

 

Regardless of where it was with old gears, you need to get a good pattern well centered in the gears with the new gear set. Use gear marking paint and rotate gears both directions while holding resistance on the ring gear.
You can use the old pinion depth as a good starting point tho; and go from there.

 

Guessing you're talking about a V10 or 5.4 Super Duty????

 

Use the same shim that was in the 3.73 and add nothing. Most of the time that shim will be just right. Then add or subtract shims to the carrier to get the backlash.