Slipping secondary

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befarrer

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Aug 26, 2021
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I bought my 99 Yamaha VMax SX 600 triple last March. I had what seemed to be an intermittent issue where my secondary clutch acted like the spring broke. The snow was wet and heavy, riding in fields, the belt would start to slip, then get worse where I could not move. I opened up the hood, and the belt is way down on the secondary, so I move the belt back up, and nothing, can't move. It did this twice today, after the first time, I made sure My spring wasn't broken, then tried again, did 1km in the snow, then it acted up again. I rode around in the yard for half an hour later, and it was fine, going out into the deep snow every now and then. My belt is new this year, with 180km on it, the secondary has a brand new stock Yamaha spring in it, set to 90 degrees wrap which is stock, clutch moves freely as it was cleaned with new spring and belt 180km ago. I took a video of what's happening, keep in mind, the sled does not move, and the secondary does not spin more than 1 turn. To me, this looks like a weak spring in my secondary, but it's brand new. Any suggestions? Picture is how my belt sits after stopping/unable to move, most times, it works fine, last week I did a 36km ride with no issues.

Here is video:
drive.google.com

PXL_20220123_230602436.mp4

drive.google.com drive.google.com

I should add, clutch buttons are new, has a Bendix helix too, secondary is a black / red Yamaha.
 

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74Nitro said:
Can you take the secondary apart and post of video of you putting it together?
Click to expand...
I forget what holes I used right now, but to install the helix, I had to rotate the helix about 1/4 turn clockwise to align it with the 3 studs that hold it on. When I had it apart yesterday on my trailer, I tried using hole 9 on the helix, but I couldn't twist it far enough to align the studs, so I used hole 6. My helix is a Bender 9960, which is apparently a 51/47, the sled has 13,400km on it.

Just measured my offset, from back of primary fixed sheave to back of secondary is 17mm. I don't have the offset tool. Clutch center to center is 268mm.
 
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74Nitro said:
Can you take the secondary apart and post of video of you putting it together?
Click to expand...
Video link of disassembly and reassembly. Clutch has not been apart since first video was posted. I loosened and tightened bolts before and after video. Holes 3 and 6 were used.


drive.google.com

PXL_20220124_142105810.mp4

drive.google.com drive.google.com

Also took pics of clutch parts after video was taken.
 

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I just wanted the video to see if you were twisting it. And you are.
I think the helix must be too steep, but you can try tightening the spring even higher.
Stock belt?
 
did a bit of reading online, and I'm going to try to find a helix with an angle closer to stock as mine seems steeper than it seems everybody runs, which could affect belt squeeze, and/or I may look for a stronger secondary spring. Another thing is my belt is a high torque belt, which is likely harder than stock, requiring a stronger belt squeeze, so I may get a stock Yamaha belt. My work schedule makes it difficult to order parts as I can only order or pick up parts on my days off every other week. I also live in the city so I have to haul my sled somewhere to test. Hopefully tomorrow, I can find something then test it this weekend and report back.
 
stock 8dn is what most people run for a belt as it wear great and lasts. might be that the set up in your sled is for an 8dn and the aftermarket belt is messing up how it works.
 
The belt that was on it was a standard Dayco, I put the XTX high torque (i.e. hard) belt on it as it was the only one they had.
 
Nothing on the helix, is CNC machines, says Bender Racing on the outside and 9960 engraved by hand on the inside. Not much info online, but from what I found it's a 51/47.
 
i can usually get an 8dn belt for under $100 including tax here in canada from my dealer. tried dayco on another sled and it blew up. 8dn went on and it made 3 seasons of abuse before it failed. on my 4 strokes i usually get 2-3000 mi before one fails.
 
befarrer said:
Nothing on the helix, is CNC machines, says Bender Racing on the outside and 9960 engraved by hand on the inside. Not much info online, but from what I found it's a 51/47.
Click to expand...
Sounds about right. Probably great on harder pack snow.
Is the primary in good condition. Check the surface of the weights, make sure they are not developing grooves. Primary spring not broken?
 
74Nitro said:
Sounds about right. Probably great on harder pack snow.
Is the primary in good condition. Check the surface of the weights, make sure they are not developing grooves. Primary spring not broken?
Click to expand...
The primary spring is brand new stock Yamaha, replaced at the same time as the secondary, weights are smooth and rollers are smooth and rotate freely. I added the second set of rivets to my weights, I tried looking for a stronger secondary spring or a shallower helix, but everyone has to order one, I wrapped my helix at 110 to see how that works, I picked up an 89L belt, was $110 at dealer with a discount. Hopefully go try it out tomorrow. I adjusted my engine alignment, the mag side was too far forward, set offset right to 15mm and center to center to 268.5 or as best as I could eyeball without the proper tool. I might pick up a set of 5 Polaris or Arctic Cat secondary springs that are for sale used today if they will work, just to see if they make a difference, they are cheap enough.
 
I would tend to stay with the 8DN belt.
Good move wrapping the spring tighter.
How much weight in rivets did you add to the weights?
Maybe too much?
The sled should rev 8500-8700 on a hard pack surface during a wide open pull.
 
I had stock weight arms with what I believe a 2.4g steel rivet in the outer hole. I added another 2.4g steel rivet to the other hole in the center position, I have no hole in the inner position. I ran it on the stand today, going WOT my RPMs hung at about 8600rpm while shifting out. Should hopefully be able to test it tomorrow. I do not have the stock helix.
 
befarrer said:
I had stock weight arms with what I believe a 2.4g steel rivet in the outer hole. I added another 2.4g steel rivet to the other hole in the center position, I have no hole in the inner position. I ran it on the stand today, going WOT my RPMs hung at about 8600rpm while shifting out. Should hopefully be able to test it tomorrow. I do not have the stock helix.
Click to expand...
Ok, really leaning towards that helix being too steep.
 
Took it out yesterday, seems to be better. It has been warm here and raining, so the snow in the field was hard and like driving on groomed trails, but it seems to pull harder now. With the added weight in my primary, I pull about 8500rpm all the way to 120km/h. I'm going to keep looking for a different helix still closer to the stock 47 degree angle.

Rode with some other guys for a few fields, they were suprized at the speed of my Vmax, I was able to keep up or out run some. One guy was on a newer ski Doo 850 e tech Summit, he was suprized I was keeping up with him. We weren't racing, bit just flying across the fields.
 
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