Article about "
gearing down"
Changing gear ratio does "something", it changes torque converted by the secondary clutch to the drive shaft; so then the results is a certain ability to maintain track speed at a certain load and/or normal distribution. Staying power is; endurance, a continuing of full power without sinking or yielding much to load variations.
If you keep that rule of thumb in the back of your head about "track speed staying power" and "you are going to achieve whatever track speed you are going to achieve."
The track speed you observe/achieve is by virtue of your available power, weight distribution, suspension calibration, sled attitude(angle) augering through the snow, add all these resisting forces up compared-to-the-power you apply, will reveal a certain track speed.
Heck, one can just merely change the “paddle type” on the track and gain 1~2mph track speed by virtue of the flexibility of the paddle itself. A softer paddle actually throws less snow out the back, less weight out the back, therefore higher track speed observed.
(whether that makes any additional sled velocity is another story for another day)
By virtue of snow weight displacement, a 2.5 stiff paddle track can pump 8% more weight than a 2.5 soft paddle track 1 lbs of weight = 7 lbs on chassis.
.....and then remember as elevation increases in a climb, the engine power reduces a certain percent and the lower gearing helps compensate for load variations as power decreases, therefore helps maintain rock-solid track speed for longer period of time or maybe until you reduce throttle.
The secondary shaft speed increase (via a smaller top gear) performs more work done and resists the deceleration of the drive shaft (current track speed) to a lower track speed.
Remember this - there is a point to where one can go outside of the range that a primary spring can work efficiently with a certain gear ratio range. (bell curve) Gearing lower there is a point to where you might start to see rpms drift low.
Many people ask me "do i need to add flyweight when i gear lower" and that is not necessarily so. Dont put the cart before the horse. Change the gear, then go test at full throttle with the kind of exercise which is a representation of your normal driving for 80% of the time. Do the rpms drift low, yes or no?
If yes, then take a look at your primary spring forces. Say you were starting to drift low with a xxx/230. Raise the final force to the next stiffer force spring and that would be a xxx/260.
In a midrange track speed say at 45mph, the clutch could be using 195 lbs spring force. If you have rpms drift low then yes you can clicker up, but say you liked the start of the shift up to the rpms drifting low. Then only change the "portion" of the calibration to where you observed a deficiency.
A xxx/230 might reveal 195 lbs spring force at 45mph track speed.
A rule of thumb is 10 lbs increase of spring force will raise rpms by approximate 100.
So then where do you get a spring that can provide 10 more lbs at 45mph?
Answer - xxx/260. By only raising the final force, you will not be changing hardly any forces in the beginning of the shift, but rather at the shift portion where you observed rpms drifting low.
That xxx/260 will now put out 207 lbs spring force at 45mph track speed. The spring force is resisting the flyweight that is trying to push your engine rpms down.
ok...so go retest. Wow!...the rpms dont diminish at 45, 43, 42...etc anymore and now i might be getting 46, 46 45 46 and the track speed recovers and stays.
.........just trying to stir some thoughts. :becky:
