Springs in a T-20 clutch

[lewis]

How much difference does a spring make?



How much difference will a spring in a T-20 clutch make. A LOT!! Since i am still new to the whole T-20 theater of operation and CVT clutches this is still a learning experience. While at Ash the Crush was flat and lost power severely in the many turns and seemed to labor in the straights. Ordered a new RED spring from Rec and tore down the clutch with fellow member RDR. This is the results.

The spring on the left is the one removed. The spring on the right is a green spring previously removed from another clutch. The green spring and the red spring are the same length but the red is much stiffer.

The left side spring could be compressed with one hand, other spring, no can do. Quiet a bit of difference between green spring and the mystery spring.

End result was quiet a bit of performance jump. I could tell a lot of difference in the way the machine performs.

While doing a few tight turns the engine DID NOT BOG...in just started spinning the wheels, with the old spring the engine would pull down and not recover.

Once i got to the straights the engine seemed to shift into a higher gear and start stretching out. This was noticeable. Still more testing to do but am pleased with the results so far. Just thought i would share this with all.

[racerone3]

glad to hear your making more progress! after i ran the crush in the free for all, i was thinking lighter weights in the primary. it felt to me like it was engaging about 600 RPM too low. what you've done to make gains seems much easier than reworking the drive clutch

[LarryW]

Good to hear its getting better. Great comparison and explanation of the driven springs. Thanks!

[George]

Keep going buddy!

[lewis]

glad to hear your making more progress! after i ran the crush in the free for all, i was thinking lighter weights in the primary. it felt to me like it was engaging about 600 RPM too low. what you've done to make gains seems much easier than reworking the drive clutch

The primary had just been rebuilt, Whipper and i had also changed it(Primary) thinking it was the primary that was giving trouble. Performace was the same. Was thinking of re-gearing but with the step up in performance with the T-20 clutch i need some more test and tune. Current gearing is 22 on sprockets and standard on T-20. Still have a lot to do but my time line is better. lol

[micmac]

Lewis,

I've been wondering a bit about driven clutch springs myself. I was having issues with my Hustler Warthog snapping drive belts. The last thing I did was change out the driven spring with one that I know came out of a 2 stroke machine. The one I removed was a shorter stiffer spring and the replacement two stroke was longer (more coils) and less stiff.

My theory is the stiff spring held off opening the driven while the drive was closing making the effective pulley distance too large even though the belt was loose statically. The lighter spring has worked so far but I need to run it more to call it fixed. So my question is are there two stroke springs (lighter for less torque but higher RPM) and four stroke springs (more torque clamping power and less rpms)

[lewis]

Lewis,

I've been wondering a bit about driven clutch springs myself. I was having issues with my Hustler Warthog snapping drive belts. The last thing I did was change out the driven spring with one that I know came out of a 2 stroke machine. The one I removed was a shorter stiffer spring and the replacement two stroke was longer (more coils) and less stiff.

My theory is the stiff spring held off opening the driven while the drive was closing making the effective pulley distance too large even though the belt was loose statically. The lighter spring has worked so far but I need to run it more to call it fixed. So my question is are there two stroke springs (lighter for less torque but higher RPM) and four stroke springs (more torque clamping power and less rpms)

Things i do Know: 2 stroke springs in the secondary do not work well if you have a 4 stroke. Springs will have to be matched to the type motor you have ....2 stroke/4 stroke. The weights and springs in the primary can be adjusted to perform as needed. There is quiet a bit of science and a little luck in my case to hit it right. I am not sure yet if i have it exact. Time as you have said will tell.

Now the fellows that have been working with this type equipment can tell you more and i do hope they chime in and if i have something wrong please speak up. According to the article that i read on this site belt tension is to be 1 1/8 and no more than 1 1/4. To me this seemed to be very loose but but it works. I went through a lot trouble to get proper alignment between both clutches but didn't get it perfect and still had to tweak it a little at the track with several of the pro's.

The secondary clutch will resist opening if a stronger spring is installed but i am not so sure it would break a belt. These things are tough, unless it was a old belt. The stiffer spring in the secondary will just hold it in for the sake of discussion in low gear longer until the engine rpm's get high enough to over come the pressure of the spring. I am thinking that if the secondary spring pressure is that high the primary would be held back and just would not open. Don't know what kind of spring pressure that would take to make that happen?

George just did a spring change(Secondary) on the Apache and he was performing great at Ashtabula. He seemed very pleased with it's performance.

Last part of the question: So my question is are there two stroke springs (lighter for less torque but higher RPM) and four stroke springs (more torque clamping power and less rpm)

When ever i get into George's machine i have to really rev, like any 2 stroke to even move and for a 4 stroke guy that seems very strange. So i would say that the 2 stroke(secondary) springs are stiffer to fight off the higher rpm's. This is where someone may need to assist me in my thinking. The 4 strokes can never achieve those type of rpm's.

I may have this totally wrong,.....but i hope not, and hope i helped if any.

As i said earlier this is all new to me but i must catch up or be last.........
Definition of Last: You weren't first!!!!

Didn't build the Crush purely for racing but sure is fun. Man i love the ride and the speed and the sound.

[micmac]

Lewis,

I hope this opens up some good discussion, as this stuff is a bit like voodoo magic to me. Another thing to consider is that the spring in the driven doesn't appear to be simply contract and expand. If you look at the Helix there seems to me to be a torsion or twisting component to the equation as well. I'd like to be able to tell the difference in the springs, hopefully one of the clutching gurus can chime in on the topic

Mike

[rdr]

sweettttttttttttttttttttttttttttt glad it worked lewis. cool

[jerseybigfoot]

The CVT does apply forces that stretch an can tear apart a belt. The trick is to create enough tension in the belt to eliminate slip and not overload the belt. The stiffer the spring in the driven end will require more tension on the belt to move down the sheave faces. You can add weight to the engine side clutch to give more squeeze to pull the belt up the dive end sheaves and down the driven end or you can reduce the driven end spring tension. If your are destroying belts and the alignment is correct i would reduce the weight of the drive end and the spring tension on the driven end.

[Tango42]

CVT clutch tuning

If you are going to be tuning your own clutches, I highly recommend grabbing a copy of Olav Aeen's clutch tuning handbook and reading it cover to cover. It covers mainly 2 stroke snowmobile apps, but is describes in detail how the system works and what effects what. Its been a huge help in getting a comet 102c setup on my superchief....I think Ive read it at least 3 times. (its also cost me more money, 'cause i'm tinkering more, trying to find every last horsepower ) I finally know why the superchief was labeled the fastest factory 6 wheeler.

You can find a download of it here......

olav aaens clutch tuning handbook Rapidshare Downloads Freshwap.Net

[lewis]

If you are going to be tuning your own clutches, I highly recommend grabbing a copy of Olav Aeen's clutch tuning handbook and reading it cover to cover. It covers mainly 2 stroke snowmobile apps, but is describes in detail how the system works and what effects what. Its been a huge help in getting a comet 102c setup on my superchief....I think Ive read it at least 3 times. (its also cost me more money, 'cause i'm tinkering more, trying to find every last horsepower ) I finally know why the superchief was labeled the fastest factory 6 wheeler.

You can find a download of it here......

olav aaens clutch tuning handbook Rapidshare Downloads Freshwap.Net

Thanks, that is where i was getting a lot of my info from and you are right it is mostly geared towards 2 stroke but the principles are still the same. Good posting!

[jpswift1]

I just learned A LOT about CVT clutching here, gentlemen. Thanks for all the information. Now I'm off to Recreatives to pick up some parts! I'll report back with my findings once I get the T-20 reinforcement bracing in my Hustler and run it again.