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diving deeper into belt issues

Doowithblue

Doowithblue

TY 4 Stroke Guru
Joined
Mar 17, 2016
Messages
864
Age
57
Location
Waterloo ON
Country
Canada
Snowmobile
07 Mach z x (sold)
18- RTX LE
I'm honestly not sure anyone has solved the real issue as of yet with belts blowing. I know it isn't simply offset. Something else is happening. This may have been discussed on another thread if so I apologize. Imo it's either the jackshaft twisting under load or mounts too soft once under hood Temps get warm. Everyone remembers the original TCL debacle. Could this chassis still be twisting under load and throwing out the parallelism? Perhaps a chassis dyno simulating a load with a camera focused at the clutches may tell the real story here?
 

Much of it could simply be that transmitting 200 plus horsepower through a 1.375 wide belt is just too much.
I'd like to see a 1.5 Mitsuboshi belt with the primary sheaves back at 14.5 degrees.
Or what about fan-directed air flow through the clutches much like the Rhino 700 and other ATV/SxS's have.
I also wonder if Yamaha has tested larger versions of the SxS clutches where the belt is always engaged and the initial engagement is inside the engine on a separate clutch. The belt life on those(almost identical to the Suzuki ATV belt clutches) is second to none.
 
I'm more or less thinking of something to fix what we've got rather than trying to Re invent the wheel. Btw my two belts that I have blown the clutches weren't really that hot. Nor was the belt.
 
Doowithblue said:
I'm more or less thinking of something to fix what we've got rather than trying to Re invent the wheel. Btw my two belts that I have blown the clutches weren't really that hot. Nor was the belt.
Click to expand...
The two times I blew a belt, I could not hold my hand on the primary. Also, both of them blew while doing top end pulls, one exploded at 123, the other at 120
 
Hmmm interesting.......I can honestly say that neither clutch or belt was hot on mine. Now I couldn't really feel the gates cause it exploded but the JP just snapped.
 
Some here are claiming 1,000+ miles on 240+hp, I for one am blowing belts (8JP) every 300-550 miles max and now carry 2 new spares wherever I ride. I break in religiously
I believe the belt has much to do with it as it absolutely obliterated to peices in all of my cases. My riding buddys sled has blown his belts withing 100 km of when mine blows and he is all stock.
Last one I blew was at mild acceleration, which was unnerving as it was no more than I would starting to cross a road.
Blow a belt crossing a road, no thanks, they better get this fixed now.
 
I'm no professional tuner,just Joe blow trail rider. I now have 2300 kilometers on the original belt from last year. 1100 this year on a PT tune and the belt still looks great. Don't know if the belt is a good one or am I just lucky. But some of us have had good luck. Sure hope I have not jinxed my self.
 
74Nitro said:
The two times I blew a belt, I could not hold my hand on the primary. Also, both of them blew while doing top end pulls, one exploded at 123, the other at 120
Click to expand...


whats your clutching, springs and rollers etc.
 
Every different combination still has the same common result. A blown belt. With the exception of a few. There are some bad combos out there that will certainly contribute to hot clutches but for the most part it doesn't appear to be clutching or even a millimeter here or there in offset.
 
I've got no skin in this game but have read just about every thread on this issue. I've had a couple beers too so here's my .02. There's only one common denominator and that's the Pro-Cross chassis. Doowithblue is on the right track. This would make a great TV series where expert engineers solve real world problems. This should be the first episode!
 
Doowithblue said:
I'm honestly not sure anyone has solved the real issue as of yet with belts blowing. I know it isn't simply offset. Something else is happening. This may have been discussed on another thread if so I apologize. Imo it's either the jackshaft twisting under load or mounts too soft once under hood Temps get warm. Everyone remembers the original TCL debacle. Could this chassis still be twisting under load and throwing out the parallelism? Perhaps a chassis dyno simulating a load with a camera focused at the clutches may tell the real story here?
Click to expand...

the tcl was a one sided brace...and after many braces to support the motor and jackshaft...its my opinion that these had little effects...in fact removing the tcl and motor mounts changed provided more relief for many...but in the end...the one thing that made the biggest difference is heat management.....therefore ... its kinda ironic that yamaha has More motor bracing than any turbo procross yet by far...

as a point of reference...the "green hornet" ...a 700 h.p. monster had no tcl or motor bracing...just different motor mounts...

going back to heat..our belt is narrower 1.380 vs 1.50 belt designed for a 180 h.p. sled and improved over 8 years of turbo experience....these are definate factors...

cool the belt ...and as long as everything is good...the belt will last longer...but again...250-290 h.p. will test the limits ...

will be working on some stuff...and resourceful guys like mike knapp is on it too..
 
Trust me we are too as this doesn't sit well with me or my peeps.
 
For what is worth, when I talked to Gilles Gagne he felt that the Sidewinder would have belt problems from the time he saw the cover come off it in Minnesota, and said so to the Yamaha reps.
He felt the angle and length of the secondary ramp was a problem, much as it was on the very first Vmaxx 4. I have been running a straight 45 with the stock spring for the whole season, 2000 miles, with zero problems on his recommendations. Many , many here have opted to go with the stock helix or an even shallower dual angle helix. Why? Is it because it is the cheaper, easier option? I am not sure, I can only post my results with what I am running.
 
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