I need a Gear Ratio guide for dummies

[Muzzie]

Can someone point in the direction of a dummies guide to gear ratio's?

I'm running a CAT SX with the internals gears:

23t Layshaft
33t Idler

How do I work out the ratio?

Also the motor I'm running is a Fusion Exceed 6.5t and I've been using different pinions from 22t to 24t with the standard spur gear. The motor user manual does give any recommendations to what gearing to uses, so I'm a bit confused .

How does it work, the less (t) on the pinion the more stress to motor is under / the hotter it gets and the faster you go?

Can anyone help me with a good base line setup for a beginner?

[Cruise]

For the correct ratio check the manual as there are the charts for all three internal ratios.

Generally shorter (smaller pinion/larger spur) gives more acceleration/ less top speed and reduces stress and temperature. Too short could raise the temperatures but you will lack of top speed anyway.

Longer does the opposite and too long means that the motor will take too much current and will get hot.

This means there is a "sweet spot" for the gearing of the motor which depends on track, motor wind and driving style.
So start with the recommended gearing - check the temperature (90°C should be the maximum) and work your way forward and back to get the best gearing.

The internal gearing of the Cat gives different feels to the cars reaction on/off power.

Cruise

[Steven Forster]

Smaller Gear Ratio (bigger number means smaller ratio)

More punch and accelleration.
More runtime.
Lower top speed.

Bigger Gear Ratio (smaller number means bigger ratio)

Less punch, but more top speed.
Less runtime.

Smaller Pinion Gear = Smaller gear ratio

Bigger pinion Gear = Bigger gear ratio

Smaller Spur Gear = Bigger gear ratio

Bigger Spur Gear = Smaller gear ratio

Overall Ratio = (Spur/Pinion)*Internal Gearbox Ratio

Rollout = (Pi*Tire Diameter)/Overall Ratio
(mm/rev)Rollout


here you go

[john333]

I run a 6.5 motor indoors on a 21 or 22 tooth pinion which is a good starting point.

Did you get your speedo sorted after last week Muzzie?

[moth898]

you should have a guild in the last pages of the instruction manuel.

[Muzzie]

No, with the supplier 7-14 days not happy