[chrisguyw]

Hi Al, Firstly all of the MrSlotcar gears are cut by a very well respected/trusted  manufacturer of high end  commercial slot car gears, one that has been around for years, and , their quality is second to none . I (as have thousands) have used gears from this manufacturer for years (including the MrSlotcar offerings) with no issues whatsoever.

As with all the fixed dia./different tooth count .5 module pinion and spur gears on the market, it is important to use ones that do not deviate too much from "perfect"

The following is one of those handy dandy conversion thingies you can use to find the "perfect" tooth count for any .5 module pinion/spur. (When I say "perfect" I mean very close), as all these conversion thingies only get you close, but, close enough that only a blind man will know the difference  

To calculate the "perfect" tooth count for  any fixed dia. 5. module pitch. gear (pinions/spurs) ...do this

Take the gear dia. and multiply by 2.......subtract 2 from this total

Eg, (A 6.5mm pinion)...........6.5 x 2 = 13.....subtract 2  = 11........."perfect" tooth count (closest to .5 module)  for a 6.5mm .5 module pinion is 11T.

In my experience you can deviate about 10% either way  from "perfect" on any gear without issue......so.... for a 6.5mm pinion (11T "perfect"),...you can use either a 10T or a 12T.......any more/less and there are mesh issues.

Cheers
Chris Walker