Clutch Spring Tuning

[bigcheesestick]

So the wait for parts begins...

The new clutch comes with three sets of springs 1,000, 1,500, & 2,000 RPM. My guess is these springs (the three small ones, not the big "Contra spring") ONLY effect what RPM the clutch first engages on take off. Is this right?

Anybody have experience with swapping these around, and what worked best for daily use?

[90GTVert]

:welcome2: and nice avatar! lol


The clutch springs do mostly affect your initial launch and when you get off and back onto the gas. For 4 strokes, usually it doesn't take a stiff (high rev) spring to get good performance, since they make pretty good low RPM torque usually. I'd prob start with the 1,000RPM or softest springs first and see how you like that.

[bigcheesestick]

:thumb: Thanks, it comes with the 1,000rpm springs already installed. = EASY!

When I took the old one further apart I found more cracks in the same shoe, and that they hadn't drilled it like the other two. More concerning is that with the springs off like it is in the picture it was everything I could do to move the shoes! They're that tight on the shafts!

Dry lithium would probably be ideal, not "oil". Still, it's amazing this thing ever worked at all! And more amazing that it seemed to be working perfectly fine up until it started making a little noise, and I found bits of metal laying in the bottom of the CVT.

[rocketdog]

On a 4 stroke it kinda depends on what you want to do with it. If you need to cruise around a parking lot, at low rpms, I would suggest a 1000 spring or stock. It's a balancing act. The contra spring pushes against the variator weights. Give or take.

RD

[Goosey]

Good catch there. Balance is nice.
When i took my clutch apart I found a layer of grease all around the clutch bell. Makes you wonder, like you said. How did it ever work at all.

[Fox]

I've seen clutches like that before. Some of those Chinese Factories must use cheap pot metal to coat the plates. No resilience whatsoever. The heat and pressure make it brittle and it flakes off. It can't hold up to rapid expansion and contraction not to mention the G-forces involved.

GO CHINA! :chinese:

[bigcheesestick]

Well, this is the "After"

Larger pads than stock, and installed yellow springs.


Resurfaced the variator, and original clutch bell. The original Gates "Power Link" belt looked fine, and only has 800 miles on it, so I reused it. Put a film coat of grease on the center shaft the variator slides on, and repacked the grease in the driven pulley roller bearing.


Cut an inch off the front of the cover (oval shaped part where filter was) to make R/R MUCH, MUCH easier, and "vented things a bit" to improve cooling.


Actually is was about 5 "adult beverages", and 2 hours of drilling, dremeling, and filing to get the cover to this point.


After a quick test ride (been sicker than a dog) I DEFINITELY feel the 1,500 rpm springs actually engage at 2,100rpm, and disengage as I coast to a stop. There's a lurch forward when coasting down to about 5mph as the clutch disengages and it's freewheeling.

With the grease, and obviously better balanced clutch the CVT runs MUCH smoother. But on the short little ride I took I did notice it feels like one of the clutch shoes is grabbing just a second before the other two, so there's a slight "double hit" on take off. Probably just needs a little break in time...

I think a 1,500rpm contra spring lies in my future though. The stock one seems to be gearing up a little quicker than it should IMO.

[90GTVert]

Well I think it was worth your time invested, cause it sure looks good. Not really sure what to tell you on the clutch shoe engagement. I guess either do like you said and hope it breaks in and quits or take it apart and have another look if you feel like something is wrong.

BTW, from what I can see it looks like a very nice fox you've got beside that scoot. If you ever care to share, there's a Mustang thread here... ;D
49ccscoot.proboards.com/index.cgi?board=generalchat&action=display&thread=14

[bigcheesestick]

DANG! Good eye! And thanks. I took the scoot out and did a few hard launches and the clutch is working fine now.

I'll check out the stang thread to. This is her though. '92 notch, 5 speed

[Goosey]

I did a DOH there when you said you cut off the part where the filter was. I can't tell you how many times I messed up the kick start spring working that end in, just cut it off! Simple and brilliant

[vvtr]

that's a very neat setup you have built - looks very clean and functional.
wish i could keep mine clean like that lol!

[bigcheesestick]

Thanks guys. I wouldn't even try a dremel or anything fancy to cut off the oval shaped part on the front of the CVT cover. I used a hack saw & then a large file to smooth out the cut. Super easy, takes about 5 minutes.

[90GTVert]

Good looking car. I really like the star type wheels on foxes. I've got drag lites like just about everyone else, cause I didn't know there were 4 lug wheels like Weld's pro stars out there back then.

[bigcheesestick]

Got about 40 miles on the clutch now and it consistently engages at 2,100 rpm, and disengages as you coast down to 12mph. When I'm off the throttle any slower than that it's freewheeling with the 1,500 rpm springs in there. Took a little getting used to, but I like it.

[bigcheesestick]

Scratchin my head over the next mod to try... EVERYBODY jumps right to using lighter rollers in the variator. But wouldn't it make MUCH more sense to skip the variator and instead put a heavier contra spring on? Wouldn't I be right in saying you'd get the exact same performance change, with less chance of belt slippage, more likely you'll get full travel on both pulleys, and even at a lower price???

I'd guess going 2 grams lighter in roller weight would net you about the same rpm as installing a 1,500rpm contra? Right? But installing the spring would include the other benefits to.