Heavy duty clutch spring - Harley Forum

03fxst · #1 03-29-2009, 09:15 AM

Hey folks
Has anyone installed the heavy duty clutch spring unit that comes with the Screaming Eagle big bore kits now. I friend gave me one and suggested I slip it on while I have the primary cover off. I've been re-reading the article on the Barnett Scorpion spring kit in Chris Maida's 101 Twin Cam performance projects. He gives a great breakdown on how the springs change the pull on the lever and the resulting pressure on the clutch pac. He says the lighter Scorpion springs increase lever pull to 24 pounds and clutch pressure to 320 pounds while the heavier springs need 42 pounds of pull to drive 390 pounds into the clutch pac. Stock is listed as 18 pounds of pull delivering 248 at the spring. So, how much of an increase will I get out of the Screaming Eagle spring? And Frisco I already here your voice of wisdom so before you ask me I'll answer, no I haven't had clutch slippage just rear tire spinning. But the new spring was free, the primary is off, I have 40 thousand miles on the stock clutch and more than 90 foot pounds at the back wheel soooo maybe beafing up the spring is a good idea.

Thanks

03FXST

frisco-rigid · #2 03-30-2009, 03:32 AM

Ha ha 03, hmmm, I think

I was simply going to remind you that I run the softest springs at the softest point of adjustment possible in my old 4spd's on the 93" and the 120" with absolutely NO slippage and total tire-spinning lock-up for hole-shots..
The springs in the 93" shovel are a couple hundred thousand miles old..

Far be it for me to dis-agree with whatever Chris said but you've heard me say this before,,,, these super strong clutch springs & new super packages are bunk and only there to separate guys from money..

The heavier the clutch is the more diff it is to feather out power in sensitve situations like heavy traffic & rain & cornering slowly in sand gravel etc etc etc..

Heck, it's free, use it..

rjrivero · #3 03-30-2009, 01:01 PM

Weather or not it's necessary, well, that's up to you. But another option is the AIM Variable Pressure Clutch that replaces the Clutch plate. It's available here:

AIM Corp*::*VP Clutch Series

I have one in my V-Rod (Prior to the introduction of the Slipper Clutch) and at 140HP and about 100 ft-lbs of torque, it doesn't slip, on the street, or the strip.

03fxst · #4 03-30-2009, 04:38 PM

Hey Frisco
I hear you, as always. Can't and won't argue with your experience. But you gotta take a little ribbing because you bare so much of the blame for turning me loose on this stuff. I just love wrenching on it. Never thought of the traffic and I do the bumper to bumper grind every morning but the gravel in my driveway might be a bigger issue.
I'll check out that AIM link RJ, thank you. If it can hold those horses it can hold mine easily.
The real question I have now though is if this new spring is really any heavier. I compared it to mine and can not see any differece in thickness or shape. Did Harley go to a lighter spring some time after '03 and now offer the older one that was once stock as a performance upgrade?

03FXST

frisco-rigid · #5 03-31-2009, 03:08 AM

Hey 03

Thank you

That is exactly the kinda blame I bear with joy..

One of the biggest reasons I go to these forums is to convince guys To Do It themselves and how to wade thru the BS..

Go ahead on Baby