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Blown Belt

bleedyamaha said:
I just want to get to the bottom of why belts are grenading I ran a 8dn on my Viper for for 2 years with zero issues. Guys threw turbos on there Vipers and wham 8jps were exploding. Not saying other belts were blowing cause they were but the 8jp seems to be a problem child with turbos.
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Check your clutch offset. Make it as close to 61.1 mm as possible. Your manual shows how to check it. Don't rely on your dealer. Techs tend to just say it's within spec. 61.1 mm.....


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That's crossed my mine. Thanks Shagman. Do you recall where the instructions and measurements are posted? FAQ?
 
shagman said:
Check your clutch offset.


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Shag remember how happy we all were with 8jp till about 500mi and WFO? Something changed in those belts with miles. Put new on and everything was just fine for another 500. Went through 3 and then moved on myself.
 
cannondale27 said:
Shag remember how happy we all were with 8jp till about 500mi and WFO? Something changed in those belts with miles. Put new on and everything was just fine for another 500. Went through 3 and then moved on myself.
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Your saying on your viper? How many miles where you getting on the 8dn
 
Joe ltx-le said:
Your saying on your viper? How many miles where you getting on the 8dn
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Turbo viper 1200 miles and toss them. Don't like blowing belts. Gates carbon same thing. Never blew one.


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Joe ltx-le said:
Your saying on your viper? How many miles where you getting on the 8dn
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Yes on the Viper. Which is nowhere near the power you guys have but for me the 8JP would just start melting or something around 500mi. Never blew one but Terrible black smears and dust. Change belt and good for another 500. 8DN on there now has at least 2000mi. Don't even think about it or clutching anymore. Just ride it. I often am over 95 and on occasion over 100mph. So not in your realm. But not for lack of trying!
 
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Many never had 8JP issues on Vipers also. I saw many running that belt get just as fast results as me and others but I moved on and never went back. 8DN Yamaha or Dayco XTX5033 is all I run and lately too cheap to even buy the Dayco so running 8DN only.
 
cannondale27 said:
But what does deflection or belt height adjustment have to do with belt blowing or speed for that matter. I guess if way off it could heat belt up on launch but after engagement it is doing nothing at all.
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Set your belt deflection over the sheaves and my rollers are ALL off the helix. When I set it at a 1/16 or more (under sheaves)they all touch and can't move any of them. This 6/1 and stock belt. STM straight 38. Observations with my sec and OSP ADJUSTER.
 
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jonlafon1 said:
Set your belt deflection over the sheaves and my rollers are ALL off the helix. When I set it at a 1/16 or more they all touch and can't move any of them. This 6/1 and stock belt. STM straight 38. Observations with my sec and OSP ADJUSTER.
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Sounds like it's out of useable travel if the rollers aren't touching. If that's the case 8dn length would be worse. Obviously the rollers would take a hit on engagement. Do you think it's causing issues?
 
Everyone I have checked and made the clutch offset around 61mm has been good since.
 
cannondale27 said:
Sounds like it's out of useable travel if the rollers aren't touching. If that's the case 8dn length would be worse. Obviously the rollers would take a hit on engagement. Do you think it's causing issues?
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8DN would be worse IMO.(I blew 2 8DN length belts) GATES CARBON. The one thing that keeps coming into my mind when I think about these blown belts and the way I blew two of them IS > mine both blew when I was hard on it let up and then got back on it SOME. Its like the belt is hanging up and or getting JERKED hard (slammed into rollers?) When you get back on gas.. Guy said it was rolling hills( my first blown belt I hammered it over a small hill pulled skis down it , let off gas for a second then got back on gas and BANG. Last one was hard on gas on grade let off for a bit then next burst BANG! These are not WFO hammers either.. I really think the softness of the Gates Carbon has something to do with my two blown belts also.. Sticky belt getting hung up? I was running both belts over the top of my secondary sheaves at least a 1/16.. Both were longer belts 8dn length so guy has to run them up higher. But I have a 8JP with 650 miles on now that's been good and looks great.. Really like the straight 38 helix also.. I would really think a 35/38/35/39 or even 35/37 would be my ideal, BUT I will run the straight 38 the rest of season
 
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The other question I was wondering what guys think is this.. Does the higher helix angle back shift better and keep the belt deflection/tension more consistent through out the whole RPM range and stop some of the hurkey/jerky(IMO) stuff that contributes to blowing belts???? (or have I lost my marbles).. I know Coil bind is also a major issue (my secondary was machined for it).. Just seems to me since I have gone to a slightly higher helix angle(and 6/1) the clutching feels and act more fluid and responsive. (NOT LAZY, which was how it felt with stock helix).. I know this isn't a great example BUT I ran my sled a little on a stand and WATCHED the belt work through the secondary with different helix and stock spring wound to 6/1 and it just seems more responsive(opening and closing better and faster and more consistent with the primary.. Which keeps the belt tension more consistent?? Just blabbing out loud and trying to see if my observations are what other guys see or think.
 
jonlafon1 said:
The other question I was wondering what guys think is this.. Does the higher helix angle back shift better and keep the belt deflection/tension more consistent through out the whole RPM range and stop some of the hurkey/jerky(IMO) stuff that contributes to blowing belts???? (or have I lost my marbles).. I know Coil bind is also a major issue (my secondary was machined for it).. Just seems to me since I have gone to a slightly higher helix angle(and 6/1) the clutching feels and act more fluid and responsive. (NOT LAZY, which was how it felt with stock helix).. I know this isn't a great example BUT I ran my sled a little on a stand and WATCHED the belt work through the secondary with different helix and stock spring wound to 6/1 and it just seems more responsive(opening and closing better and faster and more consistent with the primary.. Which keeps the belt tension more consistent?? Just blabbing out loud and trying to see if my observations are what other guys see or think.
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Cripes this sounds just like the Cats back in 12 and 13. Remember belt whip? I know my RR was first mod I did. Bikeman Torsional. The on off brake and on the gas clunk from secondary not keeping up with primary and rollers off the Helix was unrideable to me and I thought how the heck do these Cat guys ride these things? Everyone I asked said that clunk was normal and person just had to ease into throttle after hard on brake. My response is Bull. That's not how I ride. Its no wonder the drivetrain and belts blow with a hit like I experienced. It was way worse with clean scuffed clutches and a new belt. 8DN being hard should help. But length hinders if your findings are legit. Any hard belts with 8JP length? Or could go Bikeman route and way stiff springs in Primary and secondary but would be clutching from scratch.
 
cannondale27 said:
Cripes this sounds just like the Cats back in 12 and 13. Remember belt whip? I know my RR was first mod I did. Bikeman Torsional. The on off brake and on the gas clunk from secondary not keeping up with primary and rollers off the Helix was unrideable to me and I thought how the heck do these Cat guys ride these things? Everyone I asked said that clunk was normal and person just had to ease into throttle after hard on brake. My response is Bull. That's not how I ride. Its no wonder the drivetrain and belts blow with a hit like I experienced. It was way worse with clean scuffed clutches and a new belt. 8DN being hard should help. But length hinders if your findings are legit. Any hard belts with 8JP length? Or could go Bikeman route and way stiff springs in Primary and secondary but would be clutching from scratch.
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Okay someone knows kind of what I feel and think about the clutching before my helix change.. I have not lost my marbles! Thanks Canondale for saying belt whip that's what I was trying to describe. And IMO the laziness of the stock helix and spring and or even roller issues, and spring bind combine to = belt whip = BANG goes belts
 
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