Alright, I'm looking for someone to give me some insight on snowmobile clutching. I know the basics of how the clutches work, but I don't understand exactly what changing a certain component does for the snowmobile. I know that changing weights, primary/secondary springs, and helix are typically changed to achieve maximum performance. How does each change affect the snowmobile???

For example: putting heavier/lighter weights in the primary, how would that affect the acceleration or top speed...?

I guess if someone could touch on each clutch component for me and how changing each one affects performance that would be awesome!!!

Thanks!!!

Check out this thread, some good info on clutching basics
http://www.hardcoresledder.com/forums/inde...howtopic=179693

Best way to learn would be to purchase Aaen's clutch book.

Don

Its an excellent book. A buddy of mine bought it over 20 years ago to learn what he now knows....says hes still learning...claims he could publish another couple additions to it.

yeah, forgot to mention the Aaen book. Was unavailable las time I checked though, but there's 1 used one on amazon.com and some on ebay.

Clutching is a very complicated subject with many opinions about what does what and what to do to create a desired effect. At the risk of starting a big debate, it helps to understand that the primary (front) clutch is rpm sensitive and this is where you typically add and subtract weight/spring resistance to obtain the ideal rpm for various modes of operation.

The secondary (rear) clutch is what controls the rate of upshift/backshift to best suit the conditions ridden in. This unit also establishes the efficiency of the entire CVT system. The grip of the belt in both clutches is determined in this clutch. For best efficiency, you reduce belt grip to the absolute minimum. For best acceleration, you may need to make changes in both clutches.
The secondary also determines rate/sensitivity of backshifting.

The modern CVT (Continuously Variable Transmission) is set up at the factory to provide a balance of performance, durability, efficiency, etc that is reasonable for most riders, and most importantly, minimizes warranty issues. But, the CVT can be reworked using springs, weights, helixes, to favor one mode of operation over another. This will usually cause some potentially more troublesome effects. Increased belt wear, detonation sensitivity, reduced fuel economy, increased drivetrain wear, etc, are some potentially negative effects.

Aaen has a good book to use for understanding the system, but research among credible users and personal experience with various changes is the best way to set your own sled up for your riding style/conditions.

Good luck

Anybody use the EPI clutch kit part # 2876035 made for the 07-08 sleds polaris offers? Thoughts?

The problem with CVTs is that there is no one thing to do for any given desired result, there are often ten or more right things to do and they are hidden behind an infinite number of wrong things....

I have never seen anyone's clutch kit work as advertised, some may be an improvement over stock, but all seem to need other components to make work, and that may change as conditions change. I would stick to seperate components and test, test, test.

Don

I normally don't make clutching mods looking for "more/better performance", or buy kits because they're the hot setup according to the manf. or someone else running one. I make a mod to deal with something specific. Higher/softer/lower engagement, quicker backshifting, etc. In other words, to deal with a specific issue I'm not happy with currently.

The problems start when dealing with that issue in particular, and I create others, which create others, and pretty soon you are hopelessly lost. The hard part is to realize you are chasing your tail at that point, when you should be going back to stock (or some other reference point) and starting over again in a different direction. FWIW -Al

I think too many guys automaticly think once somebody offers these clutch kits its a cure all for their sled....guy buys a 500 cc sled...not enough power...now thinks buying a clutch kit its going to run like a strong 600 or better... what a misconception. I agree with the same as the last reply about only tuning out a certain problem related to your sleds clutching you don't like rather than to shot gun the whole cvt system with some of these so called expensive kits....you can end up in a can of worms fast.

Then again there were sleds such as the 1998 XC700 that were clutched horrible. An after-market clutch kit brought them to life. I find the best way is to find someone who has been there done that with your model sled.....They will get you real close and you can empty your wallet from there....

OK let me ask this. WHo has a 07 switchback 600 CFI and has a good clutch set up to get to 90-100mph quickly I dont want to go 120.

Who honestly believes a 600 cfi switchback will do 120.. ..well...dropped out of a plane it will. I think you should be working on the gearing and then clutching or just buy a bigger class sled.

IF you look real close. I said I DONT need to do 120. If I want to buy 120 I would buy a 1000

I agree , bought a MCB clutch kit for my 99 XC700SP, it was a huge improvement in about every area. I maybe lost a couple mph up on top end but sure got there a whole lot quicker. I'm sure there's faster setups , but as an all-round setup it worked very well.
Still got the "kit" in the sled, but as I've learned more about clutching, I've substituted worn springs/helix with what I've had available of similar components to achieve the same result.

Getting the right helix for you is the key.From there you can tune the weights to the top rpm to match the spring you have,the weights change the whole range but mostly the top you can use different primary spring to fine tune it for take off & top rpm .myself I don't like the high engagement springs ,because the track will spin more & its harder on the drive train you work on the secondary spring to get the belt to not slip ,to much pressure cause heat ,not enough & it Will slip burning belts,but like I said the helix makes a big difference here also.One helix might be great back shifting trail set up but then take it off trail & the belt gets hot back shifts too fast(epi pro kit).After you make changes check your clutches to see if hot to know if it helped or not.Took me three years & three helix's to get my 700 the way I like it now its great,& I'm trying to get my 600 the same consistency,Which is 8000rpm when I pin it rather I'm in snow or ice or what ever.When it came right down to it I should have took Pockets advice from the beginning on the helix instead of try to make another one that I thought would be about the same to work.

.........Lighten up....i'm just having a little fun. Seriously...i already thought these sleds were oem setup pretty good already. Don't think polaris left a lot on the table to improve on.