Differential Pre-load shim, size up or down?

[settlingabyss12]

Hello all,

I'm in the process of installing my wavetrac diff/new gears and was wondering if it's better to go up a size on the shim or down a size.
These are the differential float mesurmeants:
0.10, 0.09, 0.10, 0.11, 0.11, 0.10, 0.10, 0.11, which averages to 0.1025mm.
Ford recommends using a differential preload of 0.14mm, which means I need a 0.2425mm shim; however, the shims are only sold in .10mm increments.
The shop manual suggests when this happens to "then use the next closest thickness of adjusting shim."

I'm wondering if it's better to move up to the .30mm shim rather than use a .20mm shim. With the .20mm shim, the preload will only be .10mm (instead of the recommended .14mm).

Any help is appreciated!

 

[PhoenixM3]

Good luck, I await installation results. This mod is in my car’s future.

 

[Chaski]

Personally I’d go up. With new bearings I would rather be a little high on preload and just take it easy speed and distance wise for the first couple hundred miles. Once the bearings break in it should be perfect.

 

[settlingabyss12]

I'm going to size up to the .30mm shim. It looks like everything I've read says it's better to have slightly more preload than not enough preload. Most have said the 0.05mm-0.06mm difference wouldn't have a noticeable impact, and I would probably be fine either way.