Which pinion ?
 

Sorry for my English.

I have a X-6 squared with a 9.5 Speed Passion motor and i make a race of 24 hours.

Which pinion is good with a 78 spur ?

Thank you.

26? Depends on the tyoe of track. When we ran out X6 in a 24hour race the only problem we had was breaking 2 servo horns (AE ones are CRAP) and dogbone/diff outdrives wearing out completely. We did 3 diffs and all were completely knackered by the time they were changed.

We ran an 8.5 but would use a 10.5 if we did it again.

The type of track is astroturf.