Clutching theory

[winter brew]

Yes....at rest. Keeping engine movement to a minimum will keep alignment closer towards full shift. I suppose a guy could align differently to be closer to perfect at full shift if he knows how much things are moving....but are they STAYING at that location or just moving that much momuntarily under load??
Heat generated at higher shift ratio's in the secondary....let me guess, a TEAM clutch??

 

[astro]

Yes....at rest. Keeping engine movement to a minimum will keep alignment closer towards full shift. I suppose a guy could align differently to be closer to perfect at full shift if he knows how much things are moving....but are they STAYING at that location or just moving that much momuntarily under load??
Heat generated at higher shift ratio's in the secondary....let me guess, a TEAM clutch??

Nope, a Paragon actually. Just added a 4 post Polar to the mix

 

[hivoltagesledhead]

Remove turbo lag with clutching

Getting a turbo to be "snappy" out of the hole is difficult, I've been told.
Can this be done with clutching so as to maintain the hole shot until the turbo spools up?

 

[devilrmk]

Negative angled helix will help. Custom ground weights helps some too.

 

[astro]

Polar is making me some ramps to compensate for that. It seems to manifest itself by loading the motor to much in the first couple of seconds when you pin it. Usually a slow climb to operating RPM.

 

[devilrmk]

I ground my own helix on mine. Works pretty good.

 

[clutch man]

what should one do. the sled goes up to the desired rpm and then steadly loses rpms. Basically the sled goes to 8200 rpms than settle down around 7600 rpms.

Should i got to a shallower helix?

It is time to get this going again. alot has not been coverd in here and some thing that our a bit off.
The # 1 rule in clutching the driven for falling off rpms in a climb do not fix it with the spring if it is over 200 rs. From 8200 to 7600 the ramp if to steep at the end and or the gearing it to high, 2.15 for 155 track 2.25 for a 162/163 track and a 2.33 for a 174 track now that is just a starting point on gearing there is alot that will play in there (your weight,snow conditions, elavation ect) remember gearing is a big part of getting the clutching right for where you ride track size and how you ride.
The #2 rule never change the drive clutch to match the driven. The driven just reacts to the torque of the drive and the load on the track. ( if you dont get full rpm at first change the drive clutch set up ) (if you get full rpm and then fall off change the driven clutch set up)

 

[thefullmonte]

Can someone explain to me why on a drive clutch spring, the manufacturer will say for higher peak RPM, increase the 1.25 compression rate, to lower peak rpm, decrease it. So if you increase it, then it's stiffer right? then won't it take more weight to overcome that heavy spring at the same rpm for full shift out? or more rpm with the same weight? well if i'm running 8100 and I need to get to 8300 won't a stiffer spring just keep the primary from full shift out? if I needed to get to 8300 and the belt is still 1/2 inch from the top of the primary then won't a spring with a little lower 1.25 compression rate allow the weights to swing all the way out?

Lets say your sled is turning 8000rpm, but you want it to turn 8200rpm. The 8000 rpm spring was a 140/330. So you change to a 140/340. Using the same weights the increased spring pressure will require (gain) more rpm to overcome that increased spring pressure. Everything else being correct, that would be the main reason to increase spring pressure.
You are correct in your thinking though. What you are describing are inadaquacies in current clutch and weight design. Standard weights (Polaris example) can easily fall short with increased spring pressure. They are limited by design. Although you may gain the rpm you are looking for you may not achieve full shift out.
The lower compression rate may also allow it to fully shift out, but you may fall short on peak rpm. Hence not making peak hp. It is a very delicate balance. This balance is often thrown off by todays modern high torque high hp motors.
Using Polaris primary clutch as an example. It exibits very poor belt squeeze at engagement. Not very noticable on a 440 or 600, but an 800 will slip that belt quite a bit. Which is why people go to an adjustable weight with more weight around the pivot. This provides more belt squeeze at engagement. Another option is to lower the initial spring rate for a smoother engagement. By doing this, a stock weight has less spring pressure to overcome and can give better belt squeeze, but it also lowers the rpm that you engage at.
Sorry, starting to babble. Another thing people do to offset this poor engagement performance is to bypass it altogether. This is why people are using the steeper initial angle helixes. This helix will upshift very quickly requiring little input from the primary. It works, but you all but sacrifice low gear by quickly shifting to where the primary is more efficient.
In a nut shell, spring pressure whether initial or finishing rate dictates the rpm needed to overcome that pressure by weights that are assumed to be correct for your application.
I hope that helped. :face-icon-small-con

 

[clutch man]

Can someone explain to me why on a drive clutch spring, the manufacturer will say for higher peak RPM, increase the 1.25 compression rate, to lower peak rpm, decrease it. So if you increase it, then it's stiffer right? then won't it take more weight to overcome that heavy spring at the same rpm for full shift out? or more rpm with the same weight? well if I'm running 8100 and I need to get to 8300 won't a stiffer spring just keep the primary from full shift out? if I needed to get to 8300 and the belt is still 1/2 inch from the top of the primary then won't a spring with a little lower 1.25 compression rate allow the weights to swing all the way out?

It is a mistake most people make when they our clutching, i have too it is cheaper to change the spring and not the cam arms, but is not the proper way to do it. When trying for more RPMS on the top change cam arms to a lighter cam arm. So if you our running a 68 gram cam arm at 8100 go to a 66 gram cam arm to get to 8300 in most newer higher torque motors now 2 grams up or down will get you about 200 RPMS up or down. Some fine tuning can be done with a the primary spring but should not be done to get more than 100 rs. you can put in a stiffer spring in the driven to get a few more rs too but not good to get more than 100 rs with a spring.

 

[Norway]

Ok another Q for this one:

Spinning 9400 - 9600 with 150/340 spring and 62gr supertips, bearcat seondary with 54/44 and green snopro spring.

Want to get more umph at takeoff and possibly lower the max rpm a little.
Have a 165/310 primary spring. Any bets on the results?

Also, think I' possibly running out of gear and consider going up a tooth or two on the lower sprocket. Now, since the secondary is supposed to be load sensing it should gear down/hold a lower gear when there is much resistance.

This gearing up will increase resistance/torque feedback, but will it backshift faster/better or just stay in a little lower gear all the time?

RS

 

[winter brew]

Ok another Q for this one:

Spinning 9400 - 9600 with 150/340 spring and 62gr supertips, bearcat seondary with 54/44 and green snopro spring.

Want to get more umph at takeoff and possibly lower the max rpm a little.
Have a 165/310 primary spring. Any bets on the results?

Also, think I' possibly running out of gear and consider going up a tooth or two on the lower sprocket. Now, since the secondary is supposed to be load sensing it should gear down/hold a lower gear when there is much resistance.

This gearing up will increase resistance/torque feedback, but will it backshift faster/better or just stay in a little lower gear all the time?

RS

Pure speculation here without knowing the sled, but IMO that green sec spring is pretty stiff for the amount of primary weight you are running and the helix angle....might try a softer sec spring and change nothing else.....or at least loosen that green as soft as it'll go. Ideally as little secondary spring as you can possibly get by with is ideal IMO.

 

[Reeb]

Pure speculation here without knowing the sled, but IMO that green sec spring is pretty stiff for the amount of primary weight you are running and the helix angle....might try a softer sec spring and change nothing else.....or at least loosen that green as soft as it'll go. Ideally as little secondary spring as you can possibly get by with is ideal IMO.

I suggest something along the lines of a Cutler Red.

 

[tdbaugha]

Also if there's anyone out there that can shed some more light on the Flyweight Profile, Mass Placement and the application of these concepts PLEASE SPEAK UP This is one area where I personally am just starting to understand in more depth and there are others here that are way more educated in this particular area and I would love to learn more as I'm sure others would as well.

Some areas that would be helpful in that discussion are how different mass placement effects shift profile for different applications. For instance Big Bore torque monsters seem to like more heal weight whereas turbos do not.

Lets keep this discussion moving and expand on things as much as possible, while making sure the basics are covered.

Heel and Tip weight is hard to explain. Think of turning a wrench, the further out you get from the pivot point, the more leverage you have. Heel weight(close to the pivot point) is more beneficial to the larger cc N/A motors because they have a fair amount of low RPM torque and horsepower. This low end power overcomes the heal weight. Tip weight(furthest from the pivot point) comes into play when you make a lot of peak power at high RPM. For instance, I talked to a guy from boondocker this weekend at haydays about clutching a turbo. They use a lot more tip weight because the turbo makes a lot of its power at the upper end of the RPM range. Did any of this make sense?

 

[milehighassassin]

I un-stickied this thread to try and have less stickies. I will link it to the opening thread on top but I am hoping there will be enough discussion in here to keep this going.

 

[pus1100]

Ok another Q for this one:

Spinning 9400 - 9600 with 150/340 spring and 62gr supertips, bearcat seondary with 54/44 and green snopro spring.

Want to get more umph at takeoff and possibly lower the max rpm a little.
Have a 165/310 primary spring. Any bets on the results?

Also, think I' possibly running out of gear and consider going up a tooth or two on the lower sprocket. Now, since the secondary is supposed to be load sensing it should gear down/hold a lower gear when there is much resistance.

This gearing up will increase resistance/torque feedback, but will it backshift faster/better or just stay in a little lower gear all the time?

RS

Rune,you can achieve this by moving washers on the supertips.take 2 washers from base and move to tip.increases rpm on takeoff and lower rpms on max rpm near full shift.supertips are great for fine tuning.how's that PFracing/ price combo spinning for you?

 

[westech]

Does this sound like clutching.

I posted the lower paragragh last season...struggled with clutching...ended up replacing the primary....had a bad roller on the spider...I thought it would solve alot of my grief but still seemed to loose rpm. Have some ideas thanks to this thread. Just looking for some input as I'm just starting to understand the basics of clutching. One thing I did notice though; I had been running the carlisle XS. I had a pretty worn out cat belt as a spare....what a difference it made! Was getting much better rpms(2-300) more. I could only make a couple climbs as the belt was loosing cords. Do belts really make that much difference? I should also note that on this ride which was the last ride of the season...I had cranked the secondary(RKT with 36/40 helix(I'll have to double check that) all the way and started to finaly see some back shift results. Also taken the primary from the 70 down to 68's. Seems like it may not be there yet...but I was finally starting to see improvement.


Went riding last week, things were good until I started pulling longer climbs. Noticed when the pull(rpm went down to 7000ish) got hard the engine seemed to go flat....not a bog but just not much there. Started trying to tune it out(It's an 05 with speedwerx pipe, y-pipe, mbrp can, sno-pro intake, RKT head and secondary and a boondocker box. Using an AEM air/fuel.) Found that at WOT it was good but if I let off in a climb and feathered mid to 3/4 throttle it stayed kinda flat. It's quite possibly not back shifting, but I did try to tighten up the RKT secondary, didn't change much. I'll try a stiffer primary (has 70g wieghts) with a yellow white spring.(I ran out of daylight) Elevation was around 5000ft. Tried adjusting fuel both ways....not much effect. Still learning to tune with the boondocker.I maybe don't understand the lo-mid-hi settings on the box...will have to do some more research. Anyway, not much there in the mid to upper unil WOT...when I would go wide open it engine would take a few seconds and then climb back up and run great. The engine tone would be different while lacking power too. Any thoughts? Never noticed this last year...since then came the y-pipe, sno-pro air, and RKT secondary. Also went from the 144 challenger extreme to the 153 powerclaw.

 

[KSH]

I posted the lower paragragh last season...struggled with clutching...ended up replacing the primary....had a bad roller on the spider...I thought it would solve alot of my grief but still seemed to loose rpm. Have some ideas thanks to this thread. Just looking for some input as I'm just starting to understand the basics of clutching. One thing I did notice though;] I had been running the carlisle XS. I had a pretty worn out cat belt as a spare....what a difference it made! Was getting much better rpms(2-300) more. I could only make a couple climbs as the belt was loosing cords. Do belts really make that much difference? I should also note that on this ride which was the last ride of the season...I had cranked the secondary(RKT with 36/40 helix(I'll have to double check that) all the way and started to finaly see some back shift results. Also taken the primary from the 70 down to 68's. Seems like it may not be there yet...but I was finally starting to see improvement.

I will make a comment on the belts.
Besides the difference in compounds in the 046, 060 and Carlisle. And there is a couple hundred RPM difference between the 046 and 060.
The next time you go belt shopping take a ribbon tape measure and dial micrometer. You will be surprised how much variance in tolerances there is.

Just try to buy belts that are the same measurements that way you are keeping one part of the clutching equation the same.

 

[milehighassassin]

I added the following to the first post:

I'm working on trying to consolidate some basic clutching info to post up just to give beginners a place to start. I've got a bunch of stuff down that should do such a thing, but was wanting to make sure it was all correct. Not only this but anything you could add would be great.

Namely something that I would like to get more info on is how the spring rates affect things. EX higher first number on drive spring = higher engagement, etc. Also how to fix slippage when using heat to determine which clutch is slipping more.

Anyways here is what I have. Let me know. Thanks!

Primary Springs​

• Use to control engagement
• Higher numbers = stiffer spring
• Higher first number = higher engagement
• Higher numbers generally = more weight needed
• Too high last number = incomplete shift
• Too low last number = too quick shift

Primary Clutch​

• Use to control RPM’s via weights
• Use to control engagement via spring
• If hotter than secondary belt slipping more in primary

Flyweights​

• Use to control RPM’s – more weight = less RPM’s
• Heel (close to pin) weight affects beginning of shift (slow speeds)
• Toe weight affects end of shift (high speeds)
• More heel weight = better low speed (crawling)
• More toe weight = better high speed

Secondary Springs​

• Use to control backshift
• Softer spring = more up-shift = more MPH
• Stiffer spring = better backshift
• Stiffer spring keeps clutch in “lower gear” longer

Secondary Clutch​

• Is torque sensing
• Use to control Backshift
• Up shift = clutch opening =increasing speed = shifting up/out
• Backshift = clutch closing =decreasing speed = shifting down
• If hotter than primary belt slipping more in secondary

Helix​

• Use to control upshift
• Shallower angle (smaller number) = faster upshift and slower backshift

 

[thewayout84]

"
Helix
• Use to control upshift
• Shallower angle (smaller number) = faster upshift and slower backshift
"

isnt the other way, shallower angle= SLOWER upshift and better backshift?
steeper angle= more upshift but slower backshift. Thats why you need a stiffer secondary spring if you choose a steep helix and still wants some backshift left.

 

[dgreet77]

"
Helix
• Use to control upshift
• Shallower angle (smaller number) = faster upshift and slower backshift
"

isnt the other way, shallower angle= SLOWER upshift and better backshift?
steeper angle= more upshift but slower backshift. Thats why you need a stiffer secondary spring if you choose a steep helix and still wants some backshift left.

Thanks for this; I'll go back and edit in the Clutching Basics thread, I had it that way then changed it. Sorry I suck at life. :focus: