Ring and Pinion Backlash, What's everyone doing? Options

[Matt Romanowski]

For the folks who are rebuilding their own transmissions, what are you using for a backlash measurement? The manual says around .007, but that seems a little tight. We're trying to get some temperature out of the transmission and were thinking about running a little looser. Anyone tried that?

[Dr Evil]

I use the factory tool, or at least a clone of it. The factory states that .012-.018 (edit:McMark 0.12-0.18mm or 0.005-0.007") is tolerance. The way that the back lash is set at the factory is that the pinion is mated to the ring at a set design measurement "N" and then the unit is run on a machine and slowly adjusted out from the center line of the ring gear until the quietest operation is attained. This number is then scribed onto the pinion head, i.e. n=18 would mean that you need to set the pinion back from N +.018.

To do this correctly, you need the special tool. Varying in or out will not give you much in the form of performance and I do not think it will effect cooling all that much either. One can surmise that the quieter running factory setting is the least amount of friction one can get from the R/P.

[Jon B]

The factory states that .012-.018 is tolerance... scribed onto the pinion head, i.e. n=18 would mean that you need to set the pinion back from N +.018.

These dimensions are incorrect.

New to forum, reviewing old topics and came across this. Numbers above are noted as 1/1000 of something, but incorrect whether mm or inch. Factory dimensions should be noted as 1/100mm:

Backlash range: 0.12mm to 0.18mm
Pinion dimension: N18 = +0.18mm

In inches, equivalent backlash range would be 0.005" to 0.007".
Hope the good doctor wasn't using those dimensions himself, nor anyone else.

Jon B.
Vista, CA