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Old 09-26-2014, 07:06 AM   #1
tortoise2 OP
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Melted Variator Sliders

Interesting excessive variator temperature issue on Vespa GT200 that had participated in the Sultan Sea Rally. ModernVespa and Reddits discussions.

Representative slider installation image . . .



Remaining metal cores after slider plastic melted . . .
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Old 09-26-2014, 12:51 PM   #2
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Heat seems to be the biggest problem with CVTs. I believe it is why my belt broke. There was melted rubber on the front pulley faces. I have seen several pictures of front pulleys that actually had cracks in the aluminum, most likely from excess heat. And it doesn't look like manufacturers do very much to help with the problem. My Yamaha had a huge plastic cover over the variator case, strictly for cosmetic reasons, which mostly blocked the vents.
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Old 09-26-2014, 02:04 PM   #3
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How the heck did it get that hot in there? Wow. DP Sliders used to be difficult to find, as there was just a couple of suppliers, and hard to get in the US. I wonder if they have been counterfeited, as they are readily found now.

I have a bud that used to have problems with his 50 cc Piaggio loosening the vairiator. I think that he was neglecting a thin washer, and was tightening the nut against the crank shoulder rather than the outer pulley. Looking at the pic of the blued crank end on the subject scoot, it doesn't look as if that could happen with that model, but it could be a factor.
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Old 09-26-2014, 02:31 PM   #4
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Quote:
Originally Posted by Dan V. View Post
How the heck did it get that hot in there?
Long durations of running at wide-open-throttle may have been a contributing factor . . .

"It was over 100F outside and I'd been WOT or near WOT from El Centro to Gila Bend save a few minute long fuel stop when needed."
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Old 09-26-2014, 02:32 PM   #5
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pinch stretch yank bounce

There seems to be much friction built right into the design of CVTs. The significant power loss is expressed as heat.
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Old 09-26-2014, 03:23 PM   #6
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My DR. Pulley sliders in my Honda Reflexes look like new after 20,000 miles. Most of my riding is at 60-70 mph.
Don't know what the issue was there, but something looks fishy.

After reviewing the photo links, I'd say he had the belt pinched when he torqued the nut. The outer face wasn't against the crank, meaning the nut wasn't really tight. There's no way all that damage was caused just by heat.

bikeridermark screwed with this post 09-26-2014 at 03:32 PM
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Old 09-26-2014, 03:38 PM   #7
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could be that the drive vent got blocked...also the gt/gts is known to have heat issues with the drive when prolong WOT and/or near 100*
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Old 09-26-2014, 07:38 PM   #8
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I've been using the same set of Dr Pulley Sliders on my '03 Silverwing for well over 40,000 miles with no signs of damage or wear. It must have been blast furnace hot in that variator to melt all that teflon, or whatever it is, in there. Yeah, like DaBinChe said, check the drive vent.

I'd contact Paul Wu (Dr Pulley himself) at http://www.UnionMaterial.com with your info & photos.
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Old 09-26-2014, 07:55 PM   #9
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Quote:
Originally Posted by tortoise2 View Post
Long durations of running at wide-open-throttle may have been a contributing factor . . .

"It was over 100F outside and I'd been WOT or near WOT from El Centro to Gila Bend save a few minute long fuel stop when needed."
I was on my way from Chandler to Gila Bend when my Yamaha belt shredded. I was riding WOT, as I had for 24,000 miles. Temperature was probably about 95F. The thing is, the plastic coated oem rollers still looked like new. The belt was almost completely ground up, the whole CVT case was full of runner dust.
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Old 09-26-2014, 07:55 PM   #10
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I replaced the OEM slider (roller weights) on my 06 Vespa GTS basically out of general principle at 20063 miles, as I was installing its 3rd drive belt (also OEM).
The orginal parts are in my spares supply, as they were still round, and without flat-spots or damage. I ride the bike in a spirited manner...

If you check my website found in my profile, you can see I routinely ride into 100+ degrees, many long days of 8-10 hrs, and have crossed Death Valley and Mojave National Preserve several times without incident.

My wife rocks a GT200L like the One in the post, and has accompanied me on that scooter on the rides I mentioned above, also without such a failure.

Im suspicious of those parts, and NOT the design of the CVT when outfitted with OEM components.
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Old 09-26-2014, 09:38 PM   #11
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I have to agree with oem components, especially internal engine and transmission parts. There are rare cases where oem parts are not designed properly, or manufactured properly, but that is the exception not the rule. When it comes to aftermarket scooter parts, the idea is usually to get more performance. More performance almost always comes at a price. Less reliability, durability, and longevity.

Stock variators are always aluminum. So are aftermarket variators. Common sense would seem to say that they should be made of something stronger and more durable. Rollers and belts could also be made much more durable. But they would also be more expensive. They seem to be built to absolute minimum specs.
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Old 09-27-2014, 04:47 AM   #12
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Hhmmmmm.

I have ridden my Piaggio X8 250 (same drivetrain as a GTS250 Vespa) at WOT for an hour and half, while also having 7% extra gearing, up and down rolling hills, and the sliders I used are still in there after over a year and more than 6000km later. I've done it a few times when riding home or late for work, but on this day in particular I was a bit worried so I checked them a bit later due to the high temps.
They were fine.

What temps I hear you ask?


I suspect other factors at play.........
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Old 09-27-2014, 09:24 AM   #13
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I've heard there are counterfit Dr. Pulleys out there from my mechanic.
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Old 09-27-2014, 01:26 PM   #14
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I've heard there are counterfit Dr. Pulleys out there from my mechanic.
There are more counterfit on the market than there are real ones. Genuine Dr. Pulley sliders don't melt. Unless the engine was very low on oil, or running very lean, the variator could not have gotten hot enough to melt a good set of sliders or rollers.
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Old 09-27-2014, 03:06 PM   #15
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Originally Posted by k-moe View Post
There are more counterfit on the market than there are real ones. Genuine Dr. Pulley sliders don't melt. Unless the engine was very low on oil, or running very lean, the variator could not have gotten hot enough to melt a good set of sliders or rollers.
I believe if this thing got that hot, the motor would have seized. there is more to this story than what we're hearing. Sliders don't melt like that. I still think the pulley wasn't tightened correctly, things got loose, and self-destructed. Look at all the rubbing in the photos.
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