Ok guys I have seen a ton of things on here about Skidoo Clutching and so forth. Now will someone please explain to me a little more on tuning my Cat Clutches? Lets start with a couple of general questions.

1. What happens when we change the angle of our Helix? say going from a 5750 to a 6252 or a standar 55 to a 5750.

2. Secondary Springs, why do I run one or the others.

3. Weights in the Primary, what happens when I add more weight or take some out?

Any help is greatly appreciated!!!

Ryan

Well, the basic theroy is the same from the TRA to the other brands.

Primary spring functions the same: It is the force that acts against the primary weights. It is trying to keep the clutch OPEN, while the weights try to push it close.

Typically a stiffer 2ndary spring on any sled, will act more "revvy" and the biggest trend in clutching is lately is as stiff as a secondary spring you can find. This will allow for heigher effeciency, and usually uses a steeper helix. Even Cat has switched most sleds over to their Red spring, which is a pretty decent spring. Beyond that, Goodwin makes a very stiff one that is silver colored. We have been using angles in the 70s on F7s and ZR800s using this spring.

Weights - Now, in a flyweight clutch, weights act different that a Doo clutch. The weights have a tendancy to change RPM from engagement all the way to shift out with a flyweight clutch, where in a TRA it changes just the peak RPM. Remember, with a Cat or Polaris, you can get weights that weigh the same but are shaped different, which can greatly effect how the sled shifts. Cutler makes some great weights for the Cat clutches, and Polaris MOD weights work great also in a Cat (they are mid heavy, not tip heavy)

Originally posted by 800MXZ@Jun 3 2003, 05:02 PM
Typically a stiffer 2ndary spring on any sled, will act more "revvy" and the biggest trend in clutching is lately is as stiff as a secondary spring you can find. This will allow for higher effeciency, and usually uses a steeper helix.
It is important to note that while a stiffer secondary spring CAN offer better efficiency, it doesn't necessarily have to.

If the secondary sheave forces on the belt is enought to prevent belt slippage, a stiffer spring will only increase those forces and cause a drop in efficiency and hotter clutch temps, which is an efficiency killer.

What Dave is saying is that most models are shipped with some slip built in. Again, it's a compromise for all-around riding.

I will go through my clutches and let you know what I am running and see if you can give me any tips from there. I have a buddy that built my sled for his own liking and let me tell you the thing flys. This guy is the best AC tuner I know. He took his Stocker and Imp. Stocker to Haydays several years back and put a lot of the Big Boys on the Trailer (Bickford, Parquet, Etc.) I just want to gain a little more knowledge as to why you do certain things in certain situations. Thanks for the immediate help Dave and Cory, I will let you know what is in my sled and see if there is anything you can give me as to why it is there. Thanks again for the help!!

Ryan

this could take a while

ok my opinion on your questions....

1) changeing the angle of the heilx only, leaveing the spring alone will do two things, up shift time and back shift time. the greater the helix angle, the faster the upshift, and slower the back shift. if you had a 90 degree helix how fast would it up shift, instantly!! but the rpm's would have to go way down to below engagement rpm for it to back shift. like you mentioned, going from a straight 55 to a 57/50 would give you a better upshift until you hit the 50 degree part of the helix, with a faster top end back shift, compared to the 55. this is important, because a back shift is when you run hard on a snow packed trail and hit a drifted over spot where your sled will slow dramaticly. a high, one or maybe two angle helix will work good for drags of 500 foot, no back shift involved, but will be very untrailable.
for example i run a straight 78 degree helix in my t cat for 500-1000 foot, with spring changes, but we will get to that.

2)secondary springs; the secondary spring compresses as well as twists, since the helix twists on the buttons or rollers, so does the spring. both pound numbers are important. they give you a little help with the holes in the helix to pre load the spring with a little more or less pressure. you can't control the compression rate on the spring though. more preload on the spring makes it tighter by twisting it, and does help, but it does not change the compresion rate of the spring.

3)the biggy, weights;first and foremost the primary clutch serves one purpose, to adjust and control engine rpm!! this is done by the weights, their angle or ramp profile, where on the weight itself is the heaviest, the contact patch of the weight on the roller at a stationary position, due to a notch on the ramp or spider shims, and of course the spring. sound pretty simple, right? :D
ski doo ramps are stationary, and a arm with a roller on the end of it rides up the ramp profile, due to cintrifugal force (engine rpm) thus controling the rpm through the range. the ramps are changeable for the desired rpm curve, as are the pins, and arm itself. so, imagine a adjustable pin and arm controlled by cintrifugal force, rideing against a stationary ramp as the clutch closes.
on your cat, or polaris, or yamaha, the principle is the same only the components themselves are different. you have stationary rollers that the ramp rides along due to cintrifugal force. you have the ski doo ramp angle and arm and pin weight in one.your ramp, and it's weight and profile alone controls the rpm, the spring is involved too.
the spring is the buffer and controller of all this activity. it's rate will determine how fast or slow or to what delay this rpm change will happen.


i want people to think about this stuff and get it dialed. it sounds kind of complex, but when you figure it out, it is simple in a way.

here's the clutching goal, pin it from a stop, at 20mph your at the peak performance rpm of your sled. up to 100 mph the rpm never changed, primary clutch!!!! if you hit some soft snow in between, you didn't lose one mph, secondary!!!

sorry so long, if anyone has anything to add PLEASE do. if you do, post a new topic on any clutch component involved.

we need to help each other and this is what this forum and site is for. :D

Wow, I am still trying to soak all that up clutchman. Once I read it for the 10th time, I will reply and ask some more questions. That is exactly what I was looking for in a responce, not that Dave and the rest didn't help. Thanks for the help!!!

Ryan

soaked in yet? it's complex, yet quite simple when you figure it out. :D

Clutchman and everyone else who has helped, here is what is in my sled right now:

Primary: 10 / A Weights, Yellow White Primary Spring

Secondary: 6238 Helix, Black Spring with a White dot on each level in a straight line, with the Spring being set on its heaviest setting.

The sled is a Trail Monster the way it is, corner to corner it is hard to catch. Is there anything you can think of that you think would help this set up? These parts are on a 130 H.P. ZR 500. Thanks for the input!!!

Ryan