am i going to get better acceleration from running a 21/39 or a 21/41

am i going to get better acceleration from running a 21/39 or a 21/41
[/b]

21/41 gears you down for more power.

the 21/39 is the stock and i have a 41 so i thought id try it is it going to fit with the chain or am i going to have to get al longer one you think

not sure about the poo's , but a doo would need a 2 link longer chain(s or zx chassis)

im hoping not or im not going to do it cause i have the gear and it would be free but i think it will fit the chain has lots of slack that is pushed in so ill see

im hoping not or im not going to do it cause i have the gear and it would be free but i think it will fit the chain has lots of slack that is pushed in so ill see
[/b]
A friend of mine has the same sled except its an 98XC 700 . Last winter we were on a trip in northern MN and his chain had quite a bit of slack in it and it began to slip. So he would just put more tension on it, which in turn would put more slack in the chain. Well by the end of the trip and 500 miles later the chain snapped. the chain also put a hole in the chaincase. He wasn't low on chaincase oil it just got stretched to its limit and snapped. Moral of the story is its easier to get a new chain with two extra links (or whatever the length needed) regear it then you can change it back to stock if you don't like it. Cheaper then a new or used chaincase,chain and gears if necessary. Sorry for rambling. I learned this lesson the hard way. wouldn't want it to happen to anyone else just because they weren't aware of this potential problem. as i was.

Easy way to think of this one is think of your mountain bike gears. Pedal gear is the jackshaft sprocket ( top one ) Rear wheel gear is your driveshaft sprocket. So better acceleration with the 41 driveshaft gear. The 41 will also take some of the slack out of what you have now it should work. You can phone up your local dealer and they have a formula that they use for this. You will loose some top end . As for snowman 21 can't see it. Tightening the tensioner will not put more slack in the chain. Hey by the way remember me asking about the 2 inch track for the sks. It was me. Just a note, didn't change the drivers and it works fine. Thanks anyhow though.

When gearing down you really have to consider traction. Do you really have enough traction to deal with the extra track spin down low? If not than your buddy is launched while you're spinning your wheels and now you don't have tall enough gearing to catch him because you're geared down. I can't recommend gearing for this particular sled and we need more info like track lug height, studs, etc. Lot's of variables.

I can tell you that on my 800 I geared up and it's hooks way better and pulls harder gearing up. Faster from 0-all the way thru. It allows the track to hook up better off of the line and out of the corners.

There's alot of fudging to get things right when you start changing clutching and gears.
To take out some of the confusion I'd stick with a helix with the same last number as stock and adjust operating rpm's with primary weights.

am i going to get better acceleration from running a 21/39 or a 21/41[/b]


easy way to find out gear ratio, on anything, is to divide the large number by the small one. ex: 41/21=1.95, 39/21=1.86!! it's that easy. punch it into your calculator that way and you'll find out your gear ratio. same goes for your truck's rear end. there are many terms that are thrown around that get mixed up. you'll hear tall gearing, low gearing, highway gears, pulling gears, etc. basically, the higher the gearing (lower number numerically) the faster you'll go. the lower the gearing (higher number numerically (ratio)) the better the hole shot!
there is truth in the prior posts as well. just cuz you gear lower, you might not accelerate faster due to spinning. if you were to get 100% traction, yes you would be out of the hole first. keep in mind that if you change your gearing, you must change the clutching. idooski's reply "21/41 gears you down for more power" is not true. gear changes alone will not give you more power, only the 'felt' power. it will accelerate quicker to give you the perception that you have more power. what he was trying to say is it gears you down for more acceleration. no offense idooski, but try to word your replies more accurately.
as far as the gearing goes for the same chain: i'm assuming it's for your 98 rmk. if so, it has a 7.050" center distance chaincase. 21/41 requires a 70 pitch chain and is allowed in your sled. a 21/39 combo is not recommended and should not be used. this is right out of the polaris tech manuals. hope this info helps. if you have any other questions, just ask. -Polaris Doc

This is a really interesting discussion. The only point I think I can disagree with is I don't see how changing your gearing significantly affects your clutching. Since the gears come after the clutches, gearing down just essentially makes the sled easier to move or "lighter" to the clutch, but not by a tremendous amount. I mean I weigh 120 pounds more than my wife but we don't need different clutching. The torque feedback to the helix will be slightly different but in my experience it doesn't change anything noticable. I only noticed a lot more acceleration under all conditions. I changed from a 19/39 to 17/39 over the summer and it didn't make any differences in clutching that I can see or feel, at least no negative differences, and the engagement and shift RPM are the same. But that is a great point about traction. Now my track generally spins more than before, but it also has noticably better acceleration when the track does hook up. I'm not racing or lake running, so I'd just as soon put some finesse into the throttle rather than rely on perfect gearing for my holeshot. Plus I want to spin out on command if it's called for. My top speed is only like 75 right now but frankly I don't want to go any faster than that. It gets to 75 in the blink of an eye and I'm constantly getting scared on the trail not realizing that I'm going so fast. I've only ridden 4 days on the new gearing but so far I give it thumbs-up for hillclimbing, powder turns, and trails.

I am intrigued by the idea that a "higher" gearing gives your track a chance to hook up better. I think there's something to that...but I probably won't tinker enough to test different gearings. Isn't this just another way of saying you're burning the belt while the clutch struggles to engage? I honestly don't know but that's what it sounds like. Anyone care to comment on that? Isn't it somewhat of a guessing game and something that depends on conditions? Because if the conditions are very favorable to good traction, like packed but not icy snow, I don't spin out and I am at 75 before I know what happened. But obviously on icier snow I have to stay easy on the throttle at all times. I went to the lowest gearing possible for my sled and so far it seems to have been a good idea (for my needs) but I'd love to hear opinions as to why I wouldn't want it geared so low.

Check out the snowmobileworld gearing calculator. Top of the page, Tech Center > Tech Tools - it will tell you your maximum theoretical top speed based on your gearing and track driver choices. I've read that the best way to determine gearing for top speed is do test runs with various gears and determine what your true top speed is (where your engine just can't make you go any faster no matter the gearing), then use the gearing that gives you the most acceleration ("lowest gearing") but still reaches your top speed. Anyway, good discussion.

This is a really interesting discussion. The only point I think I can disagree with is I don't see how changing your gearing significantly affects your clutching. Since the gears come after the clutches, gearing down just essentially makes the sled easier to move or "lighter" to the clutch, but not by a tremendous amount. I mean I weigh 120 pounds more than my wife but we don't need different clutching. The torque feedback to the helix will be slightly different but in my experience it doesn't change anything noticable. I only noticed a lot more acceleration under all conditions. I changed from a 19/39 to 17/39 over the summer and it didn't make any differences in clutching that I can see or feel, at least no negative differences, and the engagement and shift RPM are the same. But that is a great point about traction. Now my track generally spins more than before, but it also has noticably better acceleration when the track does hook up. I'm not racing or lake running, so I'd just as soon put some finesse into the throttle rather than rely on perfect gearing for my holeshot. Plus I want to spin out on command if it's called for. My top speed is only like 75 right now but frankly I don't want to go any faster than that. It gets to 75 in the blink of an eye and I'm constantly getting scared on the trail not realizing that I'm going so fast. I've only ridden 4 days on the new gearing but so far I give it thumbs-up for hillclimbing, powder turns, and trails.

I am intrigued by the idea that a "higher" gearing gives your track a chance to hook up better. I think there's something to that...but I probably won't tinker enough to test different gearings. Isn't this just another way of saying you're burning the belt while the clutch struggles to engage? I honestly don't know but that's what it sounds like. Anyone care to comment on that? Isn't it somewhat of a guessing game and something that depends on conditions? Because if the conditions are very favorable to good traction, like packed but not icy snow, I don't spin out and I am at 75 before I know what happened. But obviously on icier snow I have to stay easy on the throttle at all times. I went to the lowest gearing possible for my sled and so far it seems to have been a good idea (for my needs) but I'd love to hear opinions as to why I wouldn't want it geared so low.

Check out the snowmobileworld gearing calculator. Top of the page, Tech Center > Tech Tools - it will tell you your maximum theoretical top speed based on your gearing and track driver choices. I've read that the best way to determine gearing for top speed is do test runs with various gears and determine what your true top speed is (where your engine just can't make you go any faster no matter the gearing), then use the gearing that gives you the most acceleration ("lowest gearing") but still reaches your top speed. Anyway, good discussion.[/b]


ok, this is where people get confused. just for easy thinking, lets use easy numbers and go to extrems to get the point accross. when you gear up, or down, you will affect your clutching. anything that you do from horsepower mods, traction, gearing, WILL affect your clutching. it may not seem like it in the seat of the pants feel, but trust me, it's affected. just as going up and down in elevation changes gearing, the daily conditions can affect it as well. so can snow conditions. if properly set up, the clutches can be very forgiving over a wide range of conditions and minor horsepower changes. most people will just leave the clutching alone due to the complexity of it all. i do agree that for this minor of a gearing change that the clutching will not be affected that much. but in reality, if you wanted to get the absolute best performance, clutching would need to be changed. racers change clutching on a daily basis, and sometimes multiple times during the day as conditions change.
lets say you changed from a 1.5 ratio, to a 2.5 ratio. again, just using easy numbers and extreme situations. the 1.5 would be geared extremely hi and would be good for top speed. the 2.5 low for great acceleration. when the sled is allowed to reach a top speed of say 60 mph that quickly due to the gearing, it upshifts so fast, with the same clutching, that it will probably over rev and not be as efficient. when it's geared to go say 140, the engine would need some serious HP to get to that speed. add to that the fact that it would take a lot longer to achieve a full shift out that again, the clutches would not be set up properly to handle that kind of gearing. again, these are two extreme cases to get the point across. minor changes in gearing will usually not require clutching changes for the average joe.
as far as the higher gearing burning the belt more...well not necessarily. if the clutches are properly set up and have sufficient side loading, they shouldn't burn the belt. some slippage always occurs. if it is geared higher, it will load the engine harder, and will take longer to achieve full shift out. if it has improper primary clutch setup, it will not shift out fully. again, this relates to the last paragraph. without going into too much of the science of clutching, you can change components to reach your desired rpm and engagement. the more weight you can throw at the clutching as far as shift weights go, the harder it will pull. again, it has to have the power to pull it off as well. so with the combinations of primary and secondary clutching, you can get a good setup for the conditions, power, gearing, rider weight, etc. So in the end will you burn the belt, maybe a little more. but if you had the clutches set up properly, no more than before the gearing or stud addition. this can be discussed and argued about all day long. if the gearing suits your needs and there's no adverse effects, then run it. you have to know a lot about the whole system to make the most of it.
the gearing calculator is just that, a calculator. you could put any amount of numbers in there you want and it will #### out a figure of mph for you. but the charts i go off of are from the tech manuals i use. they have a different chart for each different center distance design of chaincase. they have the gear ratios that you can use, and what chain is required. they also state whether or not if that combo is safe, not recommended, or n/r but safe to use. with different combinations of top/bottom gears, you can achieve a wide range of ratios safely. but different combinations of gears will sometimes require a longer or shorter pitch chain. going with too small of gears will cause the chain to make too much of a loop back around the tensioner and will bind and flex the chain to the point of failure. do that at your own risk. will different combos work? yes, but if it's not recommended, it will probably eventually fail. i will never send a customer's sled out with an unsafe combo due to that reason. hope this helps guys. if you want to discuss this more, please do. take care. -Polaris Doc

This is a really interesting discussion. The only point I think I can disagree with is I don't see how changing your gearing significantly affects your clutching. Since the gears come after the clutches, gearing down just essentially makes the sled easier to move or "lighter" to the clutch, but not by a tremendous amount. I mean I weigh 120 pounds more than my wife but we don't need different clutching. The torque feedback to the helix will be slightly different but in my experience it doesn't change anything noticable. I only noticed a lot more acceleration under all conditions. I changed from a 19/39 to 17/39 over the summer and it didn't make any differences in clutching that I can see or feel, at least no negative differences, and the engagement and shift RPM are the same. But that is a great point about traction. Now my track generally spins more than before, but it also has noticably better acceleration when the track does hook up. I'm not racing or lake running, so I'd just as soon put some finesse into the throttle rather than rely on perfect gearing for my holeshot. Plus I want to spin out on command if it's called for. My top speed is only like 75 right now but frankly I don't want to go any faster than that. It gets to 75 in the blink of an eye and I'm constantly getting scared on the trail not realizing that I'm going so fast. I've only ridden 4 days on the new gearing but so far I give it thumbs-up for hillclimbing, powder turns, and trails.

I am intrigued by the idea that a "higher" gearing gives your track a chance to hook up better. I think there's something to that...but I probably won't tinker enough to test different gearings. Isn't this just another way of saying you're burning the belt while the clutch struggles to engage? I honestly don't know but that's what it sounds like. Anyone care to comment on that? Isn't it somewhat of a guessing game and something that depends on conditions? Because if the conditions are very favorable to good traction, like packed but not icy snow, I don't spin out and I am at 75 before I know what happened. But obviously on icier snow I have to stay easy on the throttle at all times. I went to the lowest gearing possible for my sled and so far it seems to have been a good idea (for my needs) but I'd love to hear opinions as to why I wouldn't want it geared so low.

Check out the snowmobileworld gearing calculator. Top of the page, Tech Center > Tech Tools - it will tell you your maximum theoretical top speed based on your gearing and track driver choices. I've read that the best way to determine gearing for top speed is do test runs with various gears and determine what your true top speed is (where your engine just can't make you go any faster no matter the gearing), then use the gearing that gives you the most acceleration ("lowest gearing") but still reaches your top speed. Anyway, good discussion.[/b]
let me guess , you do not see very deep snow often? stay on trails and lakes mostly? I say this because most guys going into the deep need track speed.

I must say I agree with doc, it does change things. I can remember dad running comet clutches on the merc and having differant weights ground for so many conditions.