Torque converter belt jumping/ slipping

[karl]

Done got a problem. Too much torque. At like below 20mph if you hit the gas
the belt climbs up the driver and slips back down and just aint having it.
After its moving a bit, the belt grabs fine and it moves stupid scary quick like.
It's not gear ratio, the used the same clutch , sprockets, tires, ect with
a gx270 and it worked fine. The 40 series just does not appreciate the
extra 11ft/lbs of the 459cc.

Any ideas? the 44 magnum driver does not run inboard, and yes it
has a genuine comet belt. I took apart the driver and cleaned it up, and dry lubed it.

 

[BaconBitRacing]

Well I'll be, this is quite the case. @panchothedog, @Denny, any ideas? Since I've never worked with one of these I'd think it's just getting too much power through it.

 

[Denny]

Maybe try a heavier spring on the driver to delay the upshift some? That’s my only idea.

 

[JimD]

Wow, the Wright brothers certainly could have used you at Kitty Hawk. Very nice design and you got it to work. Hard to tell but the belt looks to be pretty loose. I also don't see the bushing on the driver. The clearance under the belt should only be the thickness of three business cards is what you try and shoot for. Everything else looks to be correct, ramp on the driven is on the correct side. As Denny suggested a stronger spring may work, just take one out of a "SS" clutch you have and cut it to length, about 7 5/8" measuring to the end of the outside of the loops. It is a lot stronger than a driver spring and you can see if that works. I would only do one spring change and see if it helps, leave one of the original springs in the driver.

 

[Snaker]

Done got a problem. Too much torque. At like below 20mph if you hit the gas
the belt climbs up the driver and slips back down and just aint having it.
After its moving a bit, the belt grabs fine and it moves stupid scary quick like.
It's not gear ratio, the used the same clutch , sprockets, tires, ect with
a gx270 and it worked fine. The 40 series just does not appreciate the
extra 11ft/lbs of the 459cc.

Any ideas? the 44 magnum driver does not run inboard, and yes it
has a genuine comet belt. I took apart the driver and cleaned it up, and dry lubed it.

Not sure if I get your drift but, one thing I pick up on is the upshift then downshift on accelleration.
If you punch it and it upshifts some, then downshifts some, that could be the TS (Torque Sensing) feature kicking in.

TS is reactionary.
Throttle, then rpm, causes upshifting.
TS senses the increased load and try's to resist more upshifting or force a downshift (backshift).
If the TS overpowers the driver flyweights, then you get the backshift.
That is necessary to keep weaker engines from dogging down under heavy loads.

The TS feature is helix ramps, its all about the angle.
So, if I understand your problem, and everything is the same except for a stronger engine, you may be feeling something that was always there, but now its more pronounced.
If so, your stronger engine may not need so much backshifting.

So, if that's the case, a weaker contra spring (the scooter world calls the driven pulley spring the CONTRA spring and I love the term. so descriptive) may help.
A different ramp angle helix could possibly help also, but I'm not sure what's available for these systems.

A free possibility would be to check for contra spring position holes and use the hole lineup that winds the spring up the least amount.
Maybe even drill a new hole if feasible. Some have talked about this, but I don't know if its wise or not.

 

[karl]

Thanks for the input guys. Ill play around with it some more and report back.

Not sure if I get your drift but, one thing

It kinda feels like the chain is skipping. But it's the belt slipping, but its not smoothly slipping, if that makes sense

 

[Thepartsguy]

Thanks for the input guys. Ill play around with it some more and report back.


It kinda feels like the chain is skipping. But it's the belt slipping, but its not smoothly slipping, if that makes sense

Put someone else in the drivers seat and you hop on the mini.... have them drive down a straight road at a moderate and constant speed. you follow on the mini and watch the belt and chain well the whole system actually work under load. You will immediately see if the belt is crooked. the pulleys can look straight as an arrow your not gonna know until you follow it and verify the belt is actually straight. Edit: bonus points on the way back switch bikes and verify alignment on your bike under load.