Clutch Springs

[GSJimbo]

Using the softest clutch springs Schnitz sells and a lock up clutch my dragbike still sort of leaps off the line, clutch seems to grab rather than slipping a little, do they make any softer springs?

[brveagle]

Not being an a$$ or anything, but maybe you should work on your launches rather than trying to have a slipping clutch. Don't you want it to jump off the line? I know that a good 60' time is the key to a successful 1320 time.

[Ironriot]

Not being an a$$ or anything, but maybe you should work on your launches rather than trying to have a slipping clutch. Don't you want it to jump off the line? I know that a good 60' time is the key to a successful 1320 time.

No not really. You want a nice uneventful launch. And a slipper clutch is the name of the game in dragging a motorcycle. Usually adding a slipper clutch yields a better 1/4 mile time

[Billy Ricks]

No not really. You want a nice uneventful launch. And a slipper clutch is the name of the game in dragging a motorcycle. Usually adding a slipper clutch yields a better 1/4 mile time

It's about keeping wheel spin to a minimum.

GSJim, how many springs on your pressure plate? I have a set I removed from my bike recently that may be softer than stock due to age.

[lecroy]

GS, I fully understand what your going through. My bike makes very little power off the line and I have a lot of weight to get moving. The 10" slick adds to the problem.

I tried slowing down the clutch release arm. This was a bad idea. I tried dropping the static pressures way down, resulting in many burnt plates. 3 springs, spacers... I played this game of balancing the gap, static force, centrifugal force, launch RPM and gave up. I put a data logger on the bike and then I could see what the clutch was doing. This was a big help.

In a nut shell, if I slipped the clutch too much, then I needed enough arm weight to make sure the clutch would hold the power when it came on. This meant more arm weight. But the arm weight is a function of input shaft speed and once the bike would start moving all this arm weight would bog the motor.

My fix was to buy an MTC multi-stage clutch. With this clutch I can set the trip point where the centrifugal force kicks in. I am still learning better ways to make it work with my bike but I am night and day different than where I was. Not saying that this clutch would solve your problem. Its more difficult to set up right and costs a lot more.

Hope you get it solved.

[GSJimbo]

my two step might need to be adjusted, not in line with the clutch engaugement, I have gone down from two step rpm from 7800 to 6800 and no change , it launchs hard and hooks up, and hard to keep straight, when I do get a good launch 60 foot is 1.35 @ 9.90 et @ 135mph I think I can do better with a smooth launch (a little clutch slip). I'm using 40lb. springs....Thanks for any input.............

[RacingJake]

Are you running any weights on the arms??

[GSJimbo]

yes, two washers on each arm

[rosco15]

When I was running the lockup I was running some springs out of totally different bikes to get the right combination. I had springs from 14 lbs at installed height all the way up to 52. Whatever combination I needed to make it work is what I used. I have them all color coded with a graph so I know what springs I need to go up or down in 2 lb increments. I wonder if you approached a small local bike shop and see what kind of old springs they have on hand for you to use. For the clutch engagement I was told to set it so the 2-step turns off just as the clutch starts to drag and begin rolling forward. Make sure you have a little slack in the clutch cable. 1.35 60' is pretty good. The MPH seems high for 9.90. I'm running in the 9.60's at that kind of mph.

What does the rpm do as you leave the line? Is it dipping real bad out near the tree.

[RacingJake]

I'd reduce the weight, maybe use just 3 arms or none?? and see if the bogg goes away. I'd run the least amount of weight on the arm's as long as the clutch doesn't slip down the topend of the track. With too much arm weights she might be locking up at launch.

[GSJimbo]

I got the shift rpm set at 9600 and the shift light comes on real quick, not to far past the tree.......

[rapidray]

Jimbo, take the bolts, nuts, & washers OFF of every arm & put a nut & bolt ONLY on every other arm. NO washers & only every other one! You will be surprised how much better it will be, I GUARANTEE it! Let me know how it works & call me at 714-356-7845 if you have more questions. Ray.

[rosco15]

I used to put a tap recorder in my pocket so I could listen to the motor and hear what the clutch was doing.