Gear up Alpha

Sage Crusher

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Not necessary.
Thousands of sleds with thousands of miles over the last 6+ yrs and zero failures of the aluminum sprocket.....

The aluminum sprocket has a lot of wear initially however, once the sprocket conforms to the shape of the chain..... they maintain that shape for a very long time.

The small aluminum shavings in the oil will not harm the chain, bearings, or sprockets, all those materials are much harder...

Sent it
Naw I have seen the opposite- and it causes some grief and it doesn't belong there it serves zero purpose...
 
Nov 26, 2007
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Stillwater,Mn
I agree with those that suggest a heavier steel gear should have been used instead of aluminum. Even though its rotating mass, its so close to the same rotational surface speed as the track, that 1 pound here over a ~600 pound sled with rider gives you about a 0.2% difference in acceleration. I believe the 1 pound saving here should be used to increase durability and decrease wear. If you want to save 1 pound, skip lunch that day or take a piss before riding.
 
Jan 2, 2009
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Coquitlam, BC
I agree with those that suggest a heavier steel gear should have been used instead of aluminum. Even though its rotating mass, its so close to the same rotational surface speed as the track, that 1 pound here over a ~600 pound sled with rider gives you about a 0.2% difference in acceleration. I believe the 1 pound saving here should be used to increase durability and decrease wear. If you want to save 1 pound, skip lunch that day or take a piss before riding.
1 pound of rotational weight is not even close to comparable to 1 pound of static weight.
 
Nov 26, 2007
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Stillwater,Mn
1 pound of rotational weight is not even close to comparable to 1 pound of static weight.
At the track it is because the track drives the inertia of the sled. All the static mass in the sled and on the sled (rider) is imposed on the track. The rotational inertia of the motor and rotating components connected to the track is added to this static mass. The motor must accelerate it all.
 

summ8rmk

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At the track it is because the track drives the inertia of the sled. All the static mass in the sled and on the sled (rider) is imposed on the track. The rotational inertia of the motor and rotating components connected to the track is added to this static mass. The motor must accelerate it all.
So, no gain with a belt drive over steel gears and chain?

Sent it
 

Sage Crusher

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Ya - I am just going to dump the stock cheapo gear for my son and get a steel gear- I do agree with the comments on rotational weight savings - but the lower drive gear is not the place to be focusing for the rotational weight..
I rather have the durability there- the way these kids ( or younger adults) launch their sleds these day's.
If Santa is good to him he will be sporting a TKI belt drive conversion...and gain in both rotational and static weight.
I may try to gear up a tooth or two and see if it make a difference.. with the way the sled launched last year, it could stand a tad higher gearing and gain more track speed.
 
Jan 2, 2009
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Coquitlam, BC
At the track it is because the track drives the inertia of the sled. All the static mass in the sled and on the sled (rider) is imposed on the track. The rotational inertia of the motor and rotating components connected to the track is added to this static mass. The motor must accelerate it all.
So a 20lb sprocket would have the same effect on power as a 20lb backpack?

Don't think so.
 

kanedog

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Ya - I am just going to dump the stock cheapo gear for my son and get a steel gear- I do agree with the comments on rotational weight savings - but the lower drive gear is not the place to be focusing for the rotational weight..
I rather have the durability there- the way these kids ( or younger adults) launch their sleds these day's.
If Santa is good to him he will be sporting a TKI belt drive conversion...and gain in both rotational and static weight.
I may try to gear up a tooth or two and see if it make a difference.. with the way the sled launched last year, it could stand a tad higher gearing and gain more track speed.
The higher you can get the belt to go up on the primary clutch, the faster the sled will go.

If gearing up causes the belt to go lower on the primary, will the sled go faster or slower?
 

summ8rmk

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Less load on the clutches equals higher track speed. That is why sleds go faster on a groomed trail than climbing a mountain.
If ur sled shifts into overdrive while in a climb, u don't have enough load and would benefit from higher gearing.

If ur sled can go 70mph on the trail and only 45mph up a hill, u don't have enough power or too much load to let the clutches shift up.. gearing up will help on the trail but increase load and heat on climbs.

Correct me if that is wrong.

Sent it
 
Nov 26, 2007
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Stillwater,Mn
So, no gain with a belt drive over steel gears and chain?

Sent it
Same weight and gear ratio, little to none. No gear oil saves a little but so little to not even mention it. There might be a little change in friction loads between the belt and chain but again it is little. Increasing the ratio just a little is huge however as the inertia of the sled is reduced as seen by the motor by the ratio squared. So if you went from say a 2.8 to 1 to a 3 to one for example, 3/2.5 = 1.07, however (1.07) ^2 is 1.15. So a 7% increase in ratio decreases the inertia of the sled as seen by the motor by 15 percent. This squared function occurs because the lower gear rotates 1.07 times slower and there is 1.07 times the torque available to accelerate it. 1.07 X 1.07 = 1.15 A clutching change is required to take advantage of the reduced inertia reflected to the secondary clutch.

There is a lot of placebo effect with a belt drive upgrade but given a one to one change the effect will be negligible. Getting rid of the maintenance concern is good.
 

runner

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I do not think its a simple what is best but what conditions you are riding in. Wide open areas which will allow a faster ground speed can benefit from higher gearing but in slow tight conditions with alot of on/off throttle then that is where low gearing works.
 
Nov 26, 2007
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Stillwater,Mn
So a 20lb sprocket would have the same effect on power as a 20lb backpack?

Don't think so.
Not exactly but pretty close. If the diameter of the lower sprocket is about the same of the track driver and the shape of the sprocket didn't change much, then yes, if not then no. Most people don't have a clue of how things work because they don't understand the physics of the problem. They repeat what they have heard and then that is repeated many times over and a little is lost with each repeat. You may have heard the adage "1 pound of rotational mass is equal to 7 pounds of static mass". Partially true but the ratio is way off.
 

Suzzy-Q

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The higher you can get the belt to go up on the primary clutch, the faster the sled will go.

If gearing up causes the belt to go lower on the primary, will the sled go faster or slower?
this a trick question? Lol jk. But if you ask me, if you gear up a sled the sled will achieve higher track speeds at the same clutch shift ratio. For example if you are getting 60 mph at 1:1 clutch ratio if you gear up you will be at a higher speed when you reach 1:1. It’s the efficiency and load to the driveline that your really changing. There’s a possibility of gaining performance with changing gear ratios because maybe at a climb pulling 45 mph your already into overdrive for example .85:1 ratio. This could be loading up the driveline, where if you gear up maybe you will be at 47-50 mph at 1:1 but can hold it because the clutches are closer to an efficient ratio. Doesn’t hurt to try, take a sharpie with you to help document your shift out, take clutch temperatures etc
 

DITCHBANGER

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Instead of all this theory about what if's, how about just actually play with gearing and see what you get. Its simple to do and is a good learning experience
 
Nov 26, 2007
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Stillwater,Mn
Instead of all this theory about what if's, how about just actually play with gearing and see what you get. Its simple to do and is a good learning experience
I don't have the time as I get maybe 8 total days every year. Also to effectively take advantage of a gearing change you need to change the clutching, which opens up a big can of worms. My opinion is you should gear for the speed range you care about most. In the mountains off trail that for me is about 60 mph max, as the 3" lugs start wearing excessively over that. Once you open that can you have a lot of variables to consider.
 

madmax

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I agree with the leave the aluminum gear. No need to change it unless you're changing ratios.
 

kanedog

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Instead of all this theory about what if's, how about just actually play with gearing and see what you get. Its simple to do and is a good learning experience
I have taken your advice. I went from 2.3, 2.5, 2.6, 2.7, 2.8, 3.05, 3.22, 3.46 and finally 3.65. I’m at 3.65 gear ratio with a 174” na 800. It eats turbos in the deep. On hardpack it’s hard to overcome the sheer power of the turbo.

Not a lot of difference from 2.7-3.2. It really came alive at 3.30+. A total of 70 gear and clutching changes to get there. Was a long 3 years.

Loving the doubters. It’s great.
 
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summ8rmk

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I have taken your advice. I went from 2.3, 2.5, 2.6, 2.7, 2.8, 3.05, 3.22, 3.46 and finally 3.65. I’m at 3.65 gear ratio with a 174” na 800. It eats turbos in the deep. Hard pack, not so much.

Not a lot of difference from 2.7-3.2. It really came alive at 3.30+. A total of 70 gear and clutching changes to get there. Was a long 3 years.

Loving the doubters. It’s great.
Top speed 55?
Probably 50+ mph track speed in a climb too.
Clutches 50° cooler than everyone else.

Sent it
 
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