Roll out (different spurs)
 

Whats the difference when you change the spur and pinion to get the same roll out??? Or close too it??


Say 86 spur with 36 pinion
then change to
say 83 spur with 32 pinion

I think that gives approx 46.** roll out.

The higher the pinion the smoother the drive.

Robert

Go to www.gearchart.com.

Select "gearchart creator"

Select "Schumacher 1.8:1 option"
enter spur "86" pinion "36"

enter tyre size 63mm

select rollout

The chart you get can then be printed and kept

you will get rollouts for every spur from 81 to 91 and every pinion from 29 to 44.

check across to find out your rollout

86/36 = 46.03
83/32 = 42.39

If you maintain the same rollout with a larger pinion it should react smoother.

With any given ratio or rollout, the smaller pinion and spur you can get away the better - because it means you are lowering the rotating mass of the drivetrain, which will be more efficient and possibly provide a small acceleration advantage.

Ok thanks for that.

Will tinker with it over the weekend.

hey rast i run an ec with a 540 and feel my car has the speed (no drive skill but cars as quick as every ones)
and i run a 76 spur and a 32 pinion i like benders theory=less rotating mass, but supposidly smaller pinions create more friction as the teeth are so tightly bunched, oonce again very small gain if any and it probly isnt true, the main thing is to run a roll out that the motor is nice temp after and ive found that 32 to 76 works really well with the 1.8 internal and sorex(63mm diametre) tires.
just my $0.04

you will not noitice the difference.

in offroad 2wd, a bigger spur can move the motor rearward and in turn give more forward traction.

This is correct but it wont be a factor with the pinions usually used for 540 or Stock ;)

Yeah it is for 540 racing only at present.

Thanks for the reponses and help guys and girls.


Robert.