New belt shredded in less than 10 miles..why? By looker (Read 7,571 times)

[looker]

Thanks Alley,
what does the 30/32 denote, is it the angle? How can I measure that? The 3 belts I have just have the length and width printed on them, although the 842 belt I just bought is listed as 842 20 30.
If indeed the belt in Dr. JR's first link is the same one as I had and is a 32 how come I did'nt have the same problem for the 2500 miles it was on the scoot?

I put a straight edge on the pulley faces of the variator and the clutch and they are all perfectly flat.

Happy thanksgiving,
Mike

[looker]

That's what I've been thinking, the 845 belt (yep,on scoot for 2500 miles) would have settled itself in to fit the pulleys, we're only talking about 2 degrees difference. So if the new Gates belt was indeed a 32 it should have gone in and worked without problems?

I guess I'll only know for sure once all the parts have turned up and I put another new Gates belt on (I have 2 new ones now) and see what happens.

Cheers Dr. JR,
Mike

[looker]

Today I finally managed to get out on the scoot for a ride since this happened. It's been stuck in the garage and I've been tinkering around with it and doing some other little jobs too.

Good news is it that it seems to be running perfectly again ;D

Was out for just under an hour and covered about 25 miles on local roads (just incase it happened again), with speeds from 30-50mph.

Clutch pulley assembly was given a good clean out and re-greased, new clutch fitted with 1000rpm springs, new 1500rpm contra spring, new drilled bell, new 115mm variator, and a new Gates 842-20-30 belt fitted.
She runs as sweet as a nut now, very smooth and no more juddering at very slow speeds. It used to do that a lot before, I'm guessing it was mainly down to a warped bell.
Stopped after about 35 minutes and felt the trans cover, rear was warm to the touch and it was quite easy to hold yer hand on there, front was a bit hotter but not enough to totally burn ya.
A complete change from when I had this problem.

Now all I need to do is have a play with the rollers to find that sweet spot when riding. It pulls away great at the moment with 12.5g, but runs out of steam pretty quick and is always pulling high revs. I had 14g in there before this all happened which was good for cruising, but lacked a tiny bit on pull away. My next weight to try is gonna be 13.5g, I'm hoping that will be about right for my riding needs.

Cleaning and re-greasing that clutch pulley assembly will now be part of the scoots maintenance, and I would suggest that everyone does it at least once even if only to know you've got some decent grease in those bearings

Many thanks to everyone for their thoughts and ideas when this happened, you all helped a great deal and the tech section here was also an enormous help.

Mike

[Cruiser]

Congratulations on fixing your problem, Mike. If your 14 gram weights are still good, you might want to replace half of the 12.5 gram weights with the 14 grams to get an average weight of 13.25 grams. Just make sure to alternate the 14 and 12.5 weights around the variator to maintain balance. This will give you a result very close to all 13.5 gram weights.

[looker]

At the moment I have 3x11g & 3x14g rollers in there to get the 12.5g. I'm gonna put all 14g in next as I have 6 of those in good condition and see how it goes as I've got a 1500rpm contra spring installed. Then I'll get a set of 13g rollers and mix them to try the 13.5g set up, or if I like the 14g I might try a set of Dr Pulley sliders in 14g.
Before I started to find out how all this CVT tuning worked, the scoot had 14g as standard from new, and when I ordered some service parts a while back the rollers that were supplied came as 11g. I did'nt know about different weights back then. From new the scoot had quite a good cruising speed but lacked acceleration, when the rollers were replaced it had good acceleration but the top end died out a little,so I'm now trying to reach a happy medium. All good fun, just need to fit the test rides in between all the rain we're expecting

Cheers,
Mike

[Alleyoop]

A longer belt MAY not melt do to less stress on it when it climbs up the Variator and pulling the Clutch pulleys apart so that it goes down in the Clutch plates. Depending on the length the belt can climb up the Variator BUT not all the way down in the Clutch pulley also it could go down so far in the Clutch Plulley that it is riding on the Contra Spring which will tear up your belt. Also if any of the Pulleys hang Clutch or Variator it will usually teat up a belt.
In addition a cheap manufactured belt may not be able to take the heat and stress that your pulleys put on them. So it is really hard to say what caused a belt to get destroyed. Best you can do is get a good quality belt the right size and it should be ok unless something breaks in your cvt.
Alleyoop

[looker]

Earthman,
air filter was removed from the trans cover a looong time ago, also did this to help 'enhance' air flow to the cover inlet,
www.scooterdoc.proboards.com/index.cgi?board=150cc&action=display&thread=2596

As Alley says, I'm sure a cheapo pattern belt would fail before a good make of belt, but this happened in a very short amount of time/mileage to a Gates belt


Alley,
I can't see how a belt riding too low would make contact with the contra spring as the spring is not between the pulleys but between the outer face of the outside pulley and the inside face of the clutch pad assembly, at least it is on mine.

Not forgetting I had an 845 belt on there for 2500 miles with no problems.

In my case I'm convinced this happened due to overheating of the torque sleeve due to piss poor grease being used in the assembly that had little or no heat resistance properties and it broke down into a black gooey mess in a very short space of time.

Now that the scoot will get a bit more use, weather permitting, I will keep a close eye on the entire CVT assembly, maybe stripping it down on weekends to check everything still looks kosher.

Mike

[Alleyoop]

Looker,
Your correct, the contra spring is on the inside of the outside pulley, got confused there Getting old sucks
Alleyoop

[looker]

Yeah, youth is wasted on the young ;D

Tried the 14g rollers today, way better, much more pleasurable to drive, no more revving the nuts of the engine all the time and it's settled to around just under 5000-5500rpm for all but high cruising speed. I think it's just shy of it's best rpm working range though so I'm gonna try swapping out 3 of the 14g for 13g and give the 13.5g weight a go. Will hopefully allow it to rev a little higher as at the mo it's staying at about 6000 at wot untill the road speed picks up some.

Also changed back from the 1500rpm contra spring to the standard one as I did'nt like the way it seemed to be pinching the belt. Maybe it's just because it's a new belt and it's wearing in?
I dunno

Cheers,

Mike

[Alleyoop]

No, I think you did the right thing by changing back to the standard contra spring. With stronger Contra Spring it does require more rpms to get the Clutch Pulley to open, therefore I can see how it would wear the belt more as well as more stress and heat created.
Alleyoop

[LUKE]

"New belt shredded in less than 10 miles..why?"

answer: China

sign,
earthman