Calling Clutch Gurus... Primary Spring/wieght

[mountainhorse]

I hate to admit it but I'm a bit confused about primary clutch spring pressure and the weights.

What is the difference between these two scenarios... given the same design to the weights 9not heelclickers or other wieghts that you can change position on0

All other items are the same.. secondary and gearing.

I am also assuming the the weights are properly matched to the spring force

1) Lighter weights on lower force primary spring.

2) Heavier weight on a higher force primary spring.

What are the differences in how the cluch system performs with the two different weights/sprigs above?

 

[eddy]

Weights

We have had this discussion a few times and the answers are all over the place!

Some folks tell me there is no difference as long as the rpm is correct for the application. It makes no difference how you got there.

My intuition based on tuning experience is the light/light set up lets the secondary dominate the shift. The heavy/heavy lets the primary dominate. This is given the secondary is not changed.

 

[thefullmonte]

I'm not really a clutch guru, but here it goes. Light springs obviously tend to give a low engagement. They will also allow the weights to try to shift out sooner. In other words your weights will overcome spring pressure at too low of rpm putting your clutches in an inefficient ratio for the rpm you are turning. Backshift will also be sluggish.
Stiffer springs will require more rpm for the weights to overcome the spring pressure. Usually this will give more positive grab on the belt. Too stiff of a spring and your weights will never shift out completely even though you may be overrevving.

Sorry, just reread your question. With both setups being perfectly matched. I would have to say that you would get less backshift from option 1 along with more belt slippage. Option 2 would give better on/off throttle characteristics as it would backshift and hold rpm better.
This is a good question and I can't wait to see other replys. There should be some people on here who can explain this very well.

 

[4Z]

Depends upon the secondary set up. But it all comes down to a balancing act.

If you take a good running setup on a Polairs twin with a button secondary and replace it with a team, you will have to increase the weight in the primary to make the secondary operate within the "balance". By doing this the chance that the existing primary spring my not be up to the challenge to keep the motor responsive, you may have to stiffen up the spring.

Now the good running team set up in the primary won't work with a cat roller. They require less primary weight and spring than a polaris button secondary.

Too much primary spring and primary clutch won't "grab" the belt in a effective manor.
Too little spring and the motor will not be as responsive.

Too much of both spring and weights, the secondary will struggle.
Too little of both, again the secondary may struggle.

I hope that I was able to help confuse folks.

 

[mountainhorse]

Guys,

Thanks for the replys..

I am talking the situation where everything BUT the Primary spring and weights have two different charcteristics.

1st situation.... High force spring with heavier wieghts, MATCHED to each other

2nd situation..... Low force spring with lighter weights, MATCHED to each other

What are the differences if the same secondary and gearing are used with BOTH above?

===================

How do you find PRIMARY weight and spring combo (again the secondary and gearing are constant and considered set up correctly).

Will engine braking on a down hill be "Hold" better with heavier springs and weights?

 

[ItDoAble]

I am definately no clutching guru, but I did some testing yesterday with the exact thing you're talking about. Here are my seat of the pants 'riders' observations.

I first tried a light spring / light weight setup. Engagement low and very smooth. It held RPM on long hard climbs in ~1 ft or fresh pow. The biggest thing I noticed was the shift reaction. Grab a handfull of throttle and the sled just didn't 'jump' .. no wow factor. Backshift was slower, too. If your primary riding is slow boondocking in tight trees, playing in meadows (or trail riding), with a occasional hill or gully thrown in, this would be a great setup. It's very forgiving, and you'd probably be more in control and have less stucks.

Then tried a heavier spring / heavier weight setup. All other things stayed the same (secondary / weight type / conditions / max RPM / etc.). Engagement was higher and more harsh. Held RPM on a climb same as lighter setup (but higher up the hill). Clutch reaction time was much faster. Pop the throttle and the sled would now 'jump'. It also 'pulled' a lot harder on a climb. Faster track speed perhaps (felt like it). Backshift was alot faster/harder when you let off the throttle. More 'wow' factor. If you like riding agressively (big hills, exploding out of gullys, jumping, 'ripping' it up) then this is the setup. It's not as forgiving, tight boondocking will be more difficult and you'll probably get stuck more, hit things more often.

As you've already asked, maybe some of the experts can explain the tech details of why these two setups react so differently..

 

[Scott]

NOT a clutch guru here at all...but you also have to factor in the torque of the motor and it will overcome too light of a set-up.

 

[winter brew]

Good question. What I feel the biggest difference in your 2 scenarios is the lighter weight/spring settup is more "reactive", it will feel a bit snappier, and is also more readily controlled by the secondary, also since it takes a measurable amount of time for the secondary to effect the primary you will see more fluctuation in RPM in load/unload conditions (like a bumpy hill climb). With the heavy weight/spring settup the RPM will remain more stable, track speed typically the same to higher, but less prone to losing track speed as the secondary has less influence over the primary...if that makes sense....also, a little less snappy feeling but in reality will probably accelerate a bit harder.
Keep in mind this is if you change nothing else.

 

[mountainhorse]

ttt