[WVXRS]

This goes against the grain....and I know the quick answer is the stock primary has two much belt slip. However I believe I am going to take my max, and install an STM Secondary with (straight 40* Helix and gold spring), a couple high altitude weights in the stock primary and see how that does.

My only concern is how does the STM engine braking will work with the stock primary?


I was literally going to buy a Full STM setup today, but I believe I will try this route then I can always slap on a QSC.

 

[RTB]

This Video demonstrates the side to side play I have in my two way bearing after blowing a belt and loosing the thrust washers. I talked to Mat at STM about this and he did not sound overly concerned. I have some new thrust washers but I need the primary holding tool before I can attempt to take the spider off to replace them. Not sure why the sent to wrench but not the holding tool?

Turn down the volume and don't laugh at my accent eh!

 

[RTB]

Here is the last one in my collection. It demonstrates my concern with the moveable sheave hanging on the two-way bearing. I am thinking this might be the reason I have reduced top speed as well as it could be at least partially contributing to my belt slipping.

Opinons from the experts appreciated.

 

[RTB]

BTW sorry for the Hijack, we have kinda gone off on a tangent here. My clutches were not tuned by KMS performance.

 

[RBRK]

When I was looking at clutches I didn't go with the STM because they didn't have a one way bearing. He said they would by July approx. I think they are finding out some issues with their bearing and will improve the bearing or whatever is needed.

 

[LBSwank]

Matt from STM called me yesterday and all I can say is I'm happy I went with STM he talked to me for a while offered to overnight the primary back to me n explained everything. Now my buddy went to our local UTV shop not dealer, accessory shop n had "clutches"put on
He couldn't even tell me what kind they were(more $than sense) anyways they had his maverick a month we went n picked it up took it to his house where in the back yard is a hill so we climbed it like we always do n Bang,Splat,Bow, then RIP within 100 ft it tore the belt up. I don't know how. So he took his maverick back. The owner of that said bike shop called me a hour ago because he heard when I had my bearing issue I called Matt at STM an got a hold of him immediately and he can't get my buddies Mav to stop eating belts. He said he can't get a return call from QSC for a week. You know I am in NOWAY bashing QSC they have to be busy as hell n who knows said owner might have pissed someone at QSC off. But even with the little issue I love the fact I can pick up the phone n talk to an expert in two min.

 

[carsner2004]

Here is a video of mine last night. I was trying to demonstrate that the clutches do not seem to be properly aligned. Watch the video and pay attention to the fact that the belt is riding tight to the moveable sheave at idle (enough that it squeaks and causes it to turn a bit in neutral) and there is about a 3/16" gap between the belt and the inside fixed sheave. In order to engage the belt has to be pushed over to contact the inner sheave causing it to bend between the primary and secondary.

Hoping on of the clutching gurus will chime in a let me know if this is acceptable or if it should be addressed.

on snowmachines clutch alignment is a huge importance, and you can add or remove shims behind the secondary to achieve proper alignment, on the maverick you are stuck with what you got, no shims for alignment... and oem clutches the belt is centered in the primary, STM clutches on my machine was like yours, clutch not centered... wasnt happy about that either...

 

[KRIS]

Tuning is key to these clutches. If you're losing mph you may want to verify that you are getting a full shift on your clutches.


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[RTB]

Tuning is key to these clutches. If you're losing mph you may want to verify that you are getting a full shift on your clutches.


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I don't think I am getting a full shift. If I draw a line on my primary with a sharpie and take it out and run it as fast as it will go in low until it hits the rev limiter (about 38MPH on the speedo) there is still a quarter inch of marker at the top of the primary sheave. I don't think it is in the tuning though. I have weight on the tip and it pulls about 7950rpm until it stops shifting than goes to the rev limiter. I think it is my sheave getting hung up on the two way bearing. I don't know what else it could be. I have tried many different weight and spring combinations as well as the 45/35 helix it came with and the 50/40 helix I have in it now.

 

[heavysledz]

I don't think I am getting a full shift. If I draw a line on my primary with a sharpie and take it out and run it as fast as it will go in low until it hits the rev limiter (about 38MPH on the speedo) there is still a quarter inch of marker at the top of the primary sheave. I don't think it is in the tuning though. I have weight on the tip and it pulls about 7950rpm until it stops shifting than goes to the rev limiter. I think it is my sheave getting hung up on the two way bearing. I don't know what else it could be. I have tried many different weight and spring combinations as well as the 45/35 helix it came with and the 50/40 helix I have in it now.

Belt deflection......if the belt deflection is too tight, it will act as if the belt is shorter and will fully open the secondary early and in-turn will not allow the belt to fully climb the primary sheaves all the way to the top. Too loose will have the opposite affect and will act as if the belt is longer and will let the belt climb the primary too fast and not get full shift out of the secondary.

 

[RTB]

Belt deflection......if the belt deflection is too tight, it will act as if the belt is shorter and will fully open the secondary early and in-turn will not allow the belt to fully climb the primary sheaves all the way to the top. Too loose will have the opposite affect and will act as if the belt is longer and will let the belt climb the primary too fast and not get full shift out of the secondary.

Does not make sense. Belt deflection is regulated by shims that limit closing in the secondary, does not have any effect on how much the secondary opens

Your theory would only come into play if the belt was to short or if you could change the distance between the primary and secondary like on a snowmobile

 

[Suprjet]

Something I noticed in your video is that you have a tungsten weight and washers on your launch arms. This is what happened to my clutch with that much weight on the small arms. This is what's left of the axle. No sign of where the arm went after exiting the belt box.

 

[heavysledz]

Does not make sense. Belt deflection is regulated by shims that limit closing in the secondary, does not have any effect on how much the secondary opens

Your theory would only come into play if the belt was to short or if you could change the distance between the primary and secondary like on a snowmobile

Exactly…so if you are not shimmed properly (incorrect belt deflection) you will limit the range of motion of your clutches. If too loose (too many shims) the primary will start out in a higher gear ratio (higher on the primary sheaves) like starting in second gear.

Think about it this way. When placing a belt in the secondary, the distance around the secondary (circumference) with 1 shim in it will result in a greater distance than if you had 2 or more shims in it. So you are compensating for belt width and length with the shims. So if not shimmed correctly, you will have the same affect as if you had your clutches too close together (too many shims =too loose) or too far apart (not enough shims = too tight) as you mentioned on a snowmobile.

Also, consider the fact that as your belt wears and stretches an becomes narrower…..you naturally loose top speed on the stock clutches because you have no adjustment for belt deflection to compensate for this. With an STM secondary, you do….the shims. So hopefully, this better explains what I am trying t point out. Belt deflection is just as important as proper weight placement in the primary. It is a tuned system and if you modify or change any of the adjustable variables (i.e. belt delfection, heal weight, tip weight, helix angle, spring rate…..etc) they will all have an impact on performance in different ways. Belt deflection will impact you affective gear ratio and possibly the ability to achieve full shift out……which equates to acceleration and top speed.

 

[Shaneway59]

I don't think it has anything to do with your belt being to tight. I am running mine with only one shim in the secondary and it is just enough that the belt barely turns at idle in neutral. That is the way I like it, makes shifting easy. The rubber one your bearing would be because it is NFG and was not turning.

I didn't say my one way bearing wasn't turning, it turned both ways like a 2 way does.

 

[RTB]

Something I noticed in your video is that you have a tungsten weight and washers on your launch arms. This is what happened to my clutch with that much weight on the small arms. This is what's left of the axle. No sign of where the arm went after exiting the belt box. View attachment 5134 View attachment 5135

Yes thanks for the feedback. I have since removed the tungstens off the small arms.

I was experimenting trying to get the primary to grab the belt better on partial throttle take off's. The extra weight on the stage one arms does help but is a potential hazard as you have pointed out. I changed out the 45/35 helix for a 50/40 helix and it seems to help a little bit, but mostly only really noticeably in low. I still have a soppy, belt burning, take off in high range at partial throttle and it is getting aggravating. High stall, low stall, springs in the primary, does not seem to matter. Next thing I am going to try is to go to a stiffer initial rate secondary spring (KSS lime green). It is 8 lbs stiffer initial than the PSS Gold I am running right now. If that does not work I am pretty much out of ideas.

If I punch it straight to the floor it takes off hard. Nearly pulls the front tires in high, does pull them in Low..... But trying to take off normally in high range on a smooth hard surface it is almost like my belt is wet, I can't stand it. I have to get rolling in low and switch to high at 5mph unless I want to smoke my belt. Running out of things to try, that is why I posted it all up here to get some feedback so thanks.

 

[KRIS]

I don't think I am getting a full shift. If I draw a line on my primary with a sharpie and take it out and run it as fast as it will go in low until it hits the rev limiter (about 38MPH on the speedo) there is still a quarter inch of marker at the top of the primary sheave. I don't think it is in the tuning though. I have weight on the tip and it pulls about 7950rpm until it stops shifting than goes to the rev limiter. I think it is my sheave getting hung up on the two way bearing. I don't know what else it could be. I have tried many different weight and spring combinations as well as the 45/35 helix it came with and the 50/40 helix I have in it now.

Unless you have low range sport mode bypass you'll probably never see a full shift in low range. Only because they are restricted on power and the throttle blade will actually close at 38-40 mph.


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[LBSwank]

We need to have a clutch tuning jamboree!!

 

[RTB]

Unless you have low range sport mode bypass you'll probably never see a full shift in low range. Only because they are restricted on power and the throttle blade will actually close at 38-40 mph.


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I have sport mode in low bypass.

The top speed thing I am not all that concerned about. If I could get this thing to engage positively/properly in high range without having to put a 75 lb orange spring in the primary and two tungstens on the stage one arms I would be a fairly happy camper right now. It is functioning pretty well aside from that and the issues noted in the videos posted.

 

[heavysledz]

I have sport mode in low bypass.

The top speed thing I am not all that concerned about. If I could get this thing to engage positively/properly in high range without having to put a 75 lb orange spring in the primary and two tungstens on the stage one arms I would be a fairly happy camper right now. It is functioning pretty well aside from that and the issues noted in the videos posted.

Have you checked to see the condition of your bushings on your primary. If you have any binding, it will not engage properly but under full throttle acceleration, you may not notice it since you are putting a lot more force on the clutch to close.

 

[KRIS]

the primary clutch is 1/4 inch smaller that factory.... they will not have the top end speed of stock... measure it!! lol

This is true but the STM closes further and in turn pushes the belt out further. The QSC primary is the smallest diameter primary on the market but it has more mph than stock.


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