next purchase is clutch STM or CV Tech

Barbara,
This is from the other forum and it may help answer your question. I personally think Adam at Airdam is the only one that has a good working clutch at this point for the Commander and if anything comes along that is better he will set you up with that. He will sell you the best setup of aCV Tech or STM Primary clutch if that is what you really want.

I would say call and talk to him if you have any questions, Adam is good about telling you how everything compares. You may have to call a couple of times he is crazy busy.


Below is straight from Adam at Airdam except for one post where i asked a question.



I will try and give an accurate description of both, their strengths and weaknesses

CVtech with machined secondary:
runs and drives better than stock, awesome belt life and reliability. runs at a constant tension, meaning the belt is ALWAYS tight from idle to top speed. never having a loose belt gives better belt life. along with the better belt life, you also get more performance. since the CVtech has a lower gear ratio over stock, you gain a lower gear ratio giving you more low end, and since the clutch is a larger diameter than stock you also can gain more top speeds. the CVtech is super easy, will come to you already set up and ready to bolt on your machine and is SUPER simple and easy to tune if you ever decide to do more things.

CVtech and STM secondary:
will also run and drive just like stock, acceleration is actually hurt, the CVtech and STM secondary made 5less hp on the dyno than the stock machined secondary. the STM secondary however is far superior in the dunes. yes it actually slowed the commander down, and i have tried two different helix and three springs now and the commander is slower with the STM secondary on it in a straight line drag race, but it backshifts SOOO much faster which helps on the long pulls up super steep dunes. when i say slower, we lost 4 seconds to 74mph. we are at about 20seconds to top speed. regardless of how i tune the STM, its slower in a straight line, but far better up the big hills.

STM primary and STM secondary:
this setup is a full billet setup. looks super pretty, and the price reflects its beauty. the STM 8 weight is by far the most tunable clutch on the market, but if you are not a clutch tuner, you will be lost the minute you look at it. if definitely takes some love to get right on each machine. once the STM is properly tuned, they will run nearly like stock, however the STM does have its own achilies heel. it has no one-way bearing. so steep descents down hills where you use the engine braking, the STM wont quite work like a normal clutch. as long as you are in the gas, and the belt stays engaged you have the engine braking, but if you get completely off the gas and go back to idle your machine will free-wheel. the STM uses belt deflection similar to all kawasakis meaning the belt stays loose at idle. this loose belt can and will slip at very low throttle in technical situations. the STM is mainly geared for racing, in a straight line drag race it is a great clutch. i myself would not own it for a trail riding or pleasure machine due to its querks. also when the clutches are cold, the STM will give a jerky engagement due to the loose belt.

there have been multiple instances where owners have tried both clutches, and even one STM dealer himself have tried the CVtech clutch and machined secondary and preferred it over the STM setup. it really all depends on what you are doing with your machine. the CVtech setup will not outperform the STM rage 8 in a straight line drag race, BUT!!! the STM will also not outperform the CVtech. there have been too many comparisons done, by myself and others, and the STM setup does not give any more performance gains, nor does it give any more horsepower. it just gives superior tuning ability
__________________
///Airdam Clutches



the video i posted christmas day is of the CVtech and machined secondary with 2200 stall (same as stock) and it accelerated WAAAYYYY faster than stock. the STM secondary did slow it down a taste, but will obviously perform so much nicer in the dunes. it may be a trade off that some do not want, but untill i can get out to glamis myself and tune on a bike with my own hands, we can not figure out why the STM secondary is slower than the stock secondary. i have tried different helix, and springs and to no avail. it is still slower than the stock secondary in a straight line drag. the CVtech and machined secondary is kinda the best of both worlds, gives super ease of operation, literally maintanance free. bolt it up, ride out. with the STM you will need to do some tuning, for the big turbo builds that will come in the future, we will definitely need the STMS for them, although i have already done one 1000cc turbo setup with the CVtech, and seen 140+hp with no problems, but the STM will offer more tunability, and therefore more usable power when we get up over 120hp. i have never had a CVtech come apart, never had a catastrophic failure, since all the moving parts are incased inside the clutch, even if one fragged, everytihng is inside the housing. an STM however, when they fragg, they tear the world up. it does not happen often but it does happen. i am not downing STM, i sell them, and they do offer alot of tunability. but for most of the casual recreational riders, the STM is definitely over your head, and for the duners, the CVtech will give you the same performance as the STM, at a fraction of the cost of the STM. i will be gald to help anyone in any way i can, and i will sell you and set you up with whatever makes you happiest.
__________________
///Airdam Clutches



i feel certain john and greg will jump in soon, and go on and on about how the STM has engine braking, well in theory they do, as long as you stay in the throttle and keep the clutch engaged it will give you some engine braking, meaning as the engine lowers its revs the machine will actually slow down, but just about anything under 5mph, the STM primary will disengage and basically freewheel on decelleration leaving you basically in neutral stomping on the brakes to stop. the STM again like i have said, is a great racing clutch, but a good durable trail riding and technical riding clutch it is not. the loose belt at idle gives jerky starts on the lightweight ATVs, and on the 1500+lb side by sides will eat up belts. dont believe me, please watch the fishers ATV world video with the 3 commanders that smoke the belts. those had STM primary and secondary setups on them
__________________
///Airdam Clutches




Adam, thanks for the info. You told me a lot of that on the phone too but this makes it very clear how it all works. Most of us keeping up with everything here will kinda know what we are talking about now when someone asks us about our clutch.

Another question that i was thinking and i have heard around is, when you get your GIZMO up and going will that affect the clutch setup and if it does can we just send it to you to adjust it or would we do it our self?
__________________
Bryan




there wont be anything needed in the clutch to run the "GIZMO" the clutch will act the same, and run the same. the only difference is the throttle plate dont close, and we gain ALOOOTTTT more throttle response. to give you a little insight, put your machine in reverse, and tap the throttle about 5% just a quick stab. nothing happens. then put it in low range and do the same. about a 5% quick stab. nothing. then put it in high sport range, 5% stab and bam it moves. in low and reverse the throttle needs to be pressed nearly 7% before the ECU will even sense you want the machine to go, then it SLOWLY and progressively opens the throttlebody up to give you power, in reverse it will only allow about 35% of the available power. in low its only about 50-60%, in high range sport mode you can get 100% throttle but you have the slow response of the fly-by-wire setup which does NOT keep up with your foot and your wants. with the box hooked up, and the swtich flipped, you can literally flip your commander on the tailgate if you can get the tires to hook up. 100% throttle, the instant you hammer down with no cut-back when the ECU senses too much wheel spin.
__________________
///Airdam Clutches




The CVtech company makes tons of clutches, some that do fit small go-carts and pee-wee scooters. this clutch however is not a scooter clutch. it is a snowmobile clutch and is balanced to withstand more RPMs than any rotax ATV or UTV engine will put out. this clutch, since you have never seen it, is better made than any other cast clutch like it. the comet will not hold a candle to the durability of the CVtech clutch, nor the craftsmanship. a comet is not even on the same planet as the CVtech in terms of how well the casting is. yes i konw you saw comets blow up and you think all cast clutches are alike, i can assure you sir, this is not the case with this clutch. i have multiple owners reving 9500RPM with this clutch, which is 1500RPM more than any comet would have handled. this clutch is cast WAAAYYY better than you think, about 2/3rds of them are so near perfection in the casting that there is no balancing needed, and they will not have any balancing done to them. not all parts are created equal. just because the comet road ended up burning down in flames and did not end up being the savior you once thought it would be, does not mean every cast clutch is junk.

the STM is NOT smooth as silk on take-off on a 1500lb UTV. especially when the clutches are cold. it is a bucking bronco. dont believe me, well get your machine back together and see for yourself. i seen it with my own two eyes and you will too.

there are NO metal to metal parts in this clutch greg. the only friction parts are the fiber busings in the throat of the movable sheave and the sliders. the sliders are a graphite/nylon composite designed by CVtech just for that clutch to give the least friction possible, the stock sliders wont live on the stock plate with the way the rotax fires, so therefore i built the delrin, aluminum, and Ti sliders to fix the issue. now with the new plate i have, i am using the original sliders that CVtech makes specifically for this clutch to give -0- resistance on upshift. the inner slider weight blocks are also made with this friction resistant graphite and nylon composite. which i will repeat, was designed in house at CVtech specifically for this clutch. this is not two pieces of sand paper sliding back and forth. i can assure you it works regardless of your skeptisizm

the overrev was not enough weight in the primary i believe if you would also check that other thread i did say i got overzealous and put a clutch on and did not get the weights correct before i put it on. i just bolted the setup up and trailered the machine out to the test strip and made a video. overrev, and too high of a shiftout and it was still nearly twice as fast as stock. i read you claimed i doctored the video, ha. you believe whatever you want pal. i will put another video labeld "just for greg" and the next time i take that commander out i will be SURE that the shiftout is spot on and there is -0- over-rev. the tires will hook and that machine will fly. when you catch up to me let me know but for now you are way behind.
__________________
///Airdam Clutches



UPDATE FOR EVERYONE from ///AIRDAM
i apologize i have been away, and apologize further for not filling your many orders in a timely fashion. i have been waiting on a shipment of the new covers for the clutches. i built the first 10 and spent $241 of my own dollars on each cover, in order to reduce the cost and make them affordable so i can put one on each clutch without having to go up on the price of your clutches, i had to committ to 150 covers to get my price point down. i just received an email from the builders, they confirmed the covers are going into hardening, and i should see a delivery date for the covers around 01-19/20-2011. i have 40 primary clutches waiting for these covers. if you are waiting on me for your secondary machining, ship it in with your name and complete info. when i get it i will machine it and be able to ship your secondary and CVtech primary. i will fill every order i have, and any other existing orders. i still have my list, and have many of you on it and will go down the list of commander owners one at a time filling your order. i apologize for the delay, but i promise i will get you rolling.

if i receive the covers on wed, i should be able to ship about 20 by friday, and i will have the weekend to finish the other 20. i hope to be able to fix you all up within the next two weeks. after i get over this hurdle of stress, i can move back onto the torque limiter over-ride setup dubbed the "GIZMO" i have all the parts in place, just need time to build it. as mark said the other day i have been working to 2 and 3 in the morning the last two weeks. i am super busy but not trying to hide from any of you. i promise making you happy is my number one goal. i have hired a secretary that begins monday. i have been receiving nearly 100 calls a day since the end of december, and i apoligize if your call went unanswered. trying to answer the phone while i am on the line with someone else is nearly impossible because folks wanna chat about things and i get hung up. hopefully the secretary will be able to dilute my call volume so i can still answer important urgent calls, while she just takes orders and fills requests on shipping details ect. thank you for your patience, i believe xelvic has been waiting the longest sir and i TRULY apologize for the long delay but i can promise you i will make it worth it for you all!
__________________
///Airdam Clutches