Gearing For Tuned Sidewinder

[KnappAttack]

Mike,
Thank you for clarifying things. While the driver issues are A bit out of my league.....
Your approach & explanation on gearing helps clear some of the fog.

Although, the 22t top gear could also help with Traction as well. Kinda dummy down a bit of low/mid torque. Is that a fair statement?

Yes, higher gear will lessen the Tq at the front drive. However, higher gear will also promote belt slippage down low if you have good traction.

The point I’m trying to make ultimately is there is more to it than the gear ratio that’s in the gearcase, front drive size along with overdrive ratio changes the speed of which snowmachine will run out at.

Overdrive percentages will change with belt width and length, along with belt center changes. For instance, 20 thou width change on and equal length belt will change OD by 2%.

There’s a lot more to it then the gear ratio in the gearbox and it’s hard to compare from machine to machine if you don’t know all the specifics.


I myself prefer to lessen the belt slippage down low being a drag racer and like them geared down as I add traction. I spend very little time up at 120-130 mile an hour so gearing up is not at all important to me. For some of the crazy Canucks up north who spend a lot of time living life on piston alley above hundred to 120, then they should by all means gear up.

Stock sidewinders will run 125 miles an hour. Tuned one will obviously get there much quicker. Want to run 130? Just put 22 tooth in it. Want to go faster than that? Then you’ll either need bigger front drives or more gear, but you will sacrifice acceleration.

 

[Motorhead]

Take a circle, put 9 points on it, now make the points 2.52” away from each other.

Do the same with with 2.86” between 9 points and circle gets bigger diameter thus larger sprocket.

Many changes on this animal huh? Overdrive secondary, gearing, drivers.

 

[Motorhead]

Yes, higher gear will lessen the Tq at the front drive. However, higher gear will also promote belt slippage down low if you have good traction.

The point I’m trying to make ultimately is there is more to it than the gear ratio that’s in the gearcase, front drive size along with overdrive ratio changes the speed of which snowmachine will run out at.

Overdrive percentages will change with belt width and length, along with belt center changes. For instance, 20 thou width change on and equal length belt will change OD by 2%.

There’s a lot more to it then the gear ratio in the gearbox and it’s hard to compare from machine to machine if you don’t know all the


I myself prefer to lessen the belt slippage down low being a drag racer and like them geared down as I add traction. I spent very little time up at 120+ mile an hour so gearing up is not at all important to me. For some of the crazy Canucks up north who spend a lot of time living life on piston alley above hundred to 120, then they should by all means gear up.

 

[Motorhead]

Man you really add physics into your sled racing. Knowledge and experience really shows. Nice pointers!

 

[XP123]

Everybody feels the need to change stuff on their stock sleds but in many cases the factory engineers know what they are doing. I know I have made changes over the years because I read how great the changes work. The reality is that sometimes these awesome changes only work on the internet not on the snow. I try to be careful when changing stuff on my stock sled especially when it comes to clutching and gearing. I have in the past geared up on sleds because I was told what a huge improvement it makes only to end up with a less responsive belt burner. I have boxes and boxes of gears, chains, weights, helix's and springs in my shop from previous can't miss mistakes. I like Mike's explanation on this subject and I share his opinion.

 

[Doc Harley]

Very true, Joe

Sometimes we ask for it.

This is why I'm trying to stay away from the big tune. Cause I know deep down inside other issues will follow.

Like a snowball. No Wait, more like an avalanche.....

 

[**sj**]

higher gear makes the clutching work harder when you ask for traction...I.e. belt issues? one of the helps on a belt blower is the gear down...not up...

only thing gearing up can do is make your top end number rise....maybe if you spend a lot of time in midrange to peak give you better fuel mileage....

if you do radar runs I can see gearing up....otherwise traction and low gear wins the race...and ...and easier on the belt

also...anyone when making gear or chain changes not to no mix hyvo with rexnord

 

[KnappAttack]

higher gear makes the clutching work harder when you ask for traction...I.e. belt issues? one of the helps on a belt blower is the gear down...not up...

only thing gearing up can do is make your top end number rise....maybe if you spend a lot of time in midrange to peak give you better fuel mileage....

if you do radar runs I can see gearing up....otherwise traction and low gear wins the race...and ...and easier on the belt

also...anyone when making gear or chain changes not to no mix hyvo with rexnord

Correct.
Drag Racing we gear them in the basement running way out of gear prior to 660 foot and let the RPM's climb 1000 RPM over peak or more as we go thru the stripe at 660.
Speed running we gear them for a 1:1 ratio at the 1000 foot mark at a much higher speed. In a speed run you actually do not want to get there quick. Two totally different setups even more so than just gearing. You can not have both a quick sled and a fast sled without a compromise.

If you smell belt/rubber with good traction its slipping horribly. If you have blue coming out of the hood you're just killing the belt. Even if you smell no belt its still slipping! Lots of times if the ice was too good we'd throw snow under the track rather than scrape the ice. It's better to spin the track than slip the belt! In a trial riding situation the track is generally always spinning, but they are geared so high that belt slippage is always present. Higher gearing and traction products always compounds the slippage issue. There is a reason I always made my own super aggressive clutch arms even gearing down! Gotta grab the belt to the point of stalling the engine!

So one must gear for whats important. Top speed or acceleration.

 

[Doc Harley]

Spinning isn't winning.....I didn't get enough seat time to determine where my sled gets good traction.
As stated by others. The lack of transfer seems to be an area of concern, when trying to get these puppies out of the hole. So I guess for me....I'm hoping something comes to light here in the forum. That would make the added power welcome. Hope that was stated correctly.

 

[**sj**]

Correct.
Drag Racing we gear them in the basement running way out of gear prior to 660 foot and let the RPM's climb 1000 RPM over peak or more as we go thru the stripe at 660.
Speed running we gear them for a 1:1 ratio at the 1000 foot mark at a much higher speed. In a speed run you actually do not want to get there quick. Two totally different setups even more so than just gearing. You can not have both a quick sled and a fast sled without a compromise.

If you smell belt/rubber with good traction its slipping horribly. If you have blue coming out of the hood you're just killing the belt. Even if you smell no belt its still slipping! Lots of times if the ice was too good we'd throw snow under the track rather than scrape the ice. It's better to spin the track than slip the belt! In a trial riding situation the track is generally always spinning, but they are geared so high that belt slippage is always present. Higher gearing and traction products always compounds the slippage issue. There is a reason I always made my own super aggressive clutch arms even gearing down! Gotta grab the belt to the point of stalling the engine!

So one must gear for whats important. Top speed or acceleration.

perfectly said...

 

[Fleecer]

Here are my findings:

RTX SE with TD Ecotrail, groomed rr bed sled would deadhead at 126mph speedo ......could never get 127mph.

Put 22 top gear and groomed rr bed sled would run consistent high 120' low 130s with a best of 133 mph speedo.

Testing with a Buddy on a tuned cat never noticed any loss in acceleration. To me, 22 top gear was good investment!!

 

[XP123]

Here are my findings:

RTX SE with TD Ecotrail, groomed rr bed sled would deadhead at 126mph speedo ......could never get 127mph.

Put 22 top gear and groomed rr bed sled would run consistent high 120' low 130s with a best of 133 mph speedo.

Testing with a Buddy on a tuned cat never noticed any loss in acceleration. To me, 22 top gear was good investment!!

I'm sure that is due to the added power.

 

[**sj**]

Here are my findings:

RTX SE with TD Ecotrail, groomed rr bed sled would deadhead at 126mph speedo ......could never get 127mph.

Put 22 top gear and groomed rr bed sled would run consistent high 120' low 130s with a best of 133 mph speedo.

Testing with a Buddy on a tuned cat never noticed any loss in acceleration. To me, 22 top gear was good investment!!

your testing was for max mph....not acceleration...you would need timers or something like TD performance meter to do that...not a butt dyno lol

 

[Motorhead]

Here are my findings:

RTX SE with TD Ecotrail, groomed rr bed sled would deadhead at 126mph speedo ......could never get 127mph.

Put 22 top gear and groomed rr bed sled would run consistent high 120' low 130s with a best of 133 mph speedo.

Testing with a Buddy on a tuned cat never noticed any loss in acceleration. To me, 22 top gear was good investment!!

That is great to hear Fleecer. You had more power then speed until geared up.

Proves the point that the winders top out at about 126 mph with stock gearing.

I hope to do the same but with machined primary for extra mph with stock gearing.

What muffler with Eco tune?

 

[Fleecer]

I'm sure that is due to the added power.

Yes, absolutely.