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Secondary Spring question

A

auto2665

Extreme
Joined
Oct 29, 2012
Messages
70
Location
Bitatitti,NE
Can someone explain how the twist or degree(70,80,90....) of the secondary spring effects the clutching? for example, how will my clutching be affected if I change my twist from 6,2=80 to 6,1=70? I cleaned my clutch over the summer and when I put it back together I had a helluva time getting it back to 80 so I left it at 70. I'm sure with another hand it would be easier but I didn't have one. Anyhow, what will I notice if I left it like this?
 

I see the numbers on the helix but where do you see the other numbers?
 
Can someone please post a picture of the location of these numbers on the secondary clutch. I cannot seem to find them for the life of me.
 
Well you can't see them with helix bolted on.
With helix off looking at outer side of clutch that helix bolts to use flashlight and you will see numbers.
Unless you have the only non numbered secondary alive.
 
you will notice a different RPM shift.
 
The Yamaha secondary clutch has 1 - 2 - 3 inside the pockets where the spring and helix goes. The helix will have 0 - 3 - 6 - 9 and this determines how much twist the spring will have and force for shifting.

Like the percentages listed above.... 6-2 = 80%. All you are doing is taking the number from the helix, adding to the number on the secondary and basically putting a 0 at the end. Result is the tighter the twist, the more force it takes to make the secondary shift.

Now, if you have really crappy traction (drag racing or want the track to bite more) then lower your percentage to 3-3 (wouldn't go lower than that othewise you slip the belt and just heat up the clutches).

If you are doing off trail where you need to have very quick backshift or keep the rpms wound up more (kinda like holding it in first gear longer), then you want more twist like 6-2 or 80%.

Adding a steeper helix angle to the equasion will also help with traction without sacrificing to end performance.

If you can get your hands on the clutch tuning book from Olav Aaen.....the clutches are something else and clutching comes down to a science. Trust me I read it twice and still learning.... :)
 
If you had it at 80 last year and now only have it a 70 this year, don't go charging into any tight corners until you understand how it back shifts now. It will back shift slower (less drive train braking and weight transfer) at 70 than it did at 80. Backshift helps you get into and through a corner by "shifting down" quickly and transferring weight to the nose of the sled giving the skis more traction and tighter steering. Too much back shift and you get too much pressure on the skis making it hard to steer causing you to push through the corner. Too little backshift and the skis turn easily but don't have any traction and you push through the corner as well. Like Nos Pro said, find the Aaen clutch tuning manual a read it and then re-read it and you will be miles ahead on clutch knowledge and tuning.
 
You didn't say if you tried to put the clutch together on a work bench, or on the sled. It is a lot easier if your alone to install the clutch on the sled. You can slide the two sheaves on the jackshaft and then install the spring, then line up the helix with the correct number. Than just twist and use your body weight to push in. Just keep the three nuts close.
 
I have found that if you stick the belt between the back of the sheave and the block or frame, it keeps the sheave closed together to easily bolt back together.
 
That's a good book for sure. I read it as a young teen. Should probably read again. Off the original topic I know, but can someone explain why compression only secondary clutches have different helix angles? Since the spring doesn't twist at all, what purpose does the helix now serve? It seems they could just use a straight ramp system like on the primary.
 
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