Yamaha clutch alignment ?

Barisax

Being a total newbie to golf cart repair and maintenance, many questions of operating theory and function come to my mind. Today, while disassembling the drivers axel and hub for replacement, I noticed the driven and drive sheaves were at opposite ends of their motion.
So, I’ve been pondering the working and position relationships of the drive and driven movable sheaves.
So if the driven movable sheave is at its widest position w/ it’s spring compressed fully, should it’s position be in the same plane as the driving clutch?
If not then how can the best alignment be achieved? With various shims behind the drive and driven clutches? Does it even matter? As I look at the two
Clutches the belt can be seen to lie crossing the plane of each, and yet no strange wear is found on any of the faces of the sheaves. I have never observed them running through the stopped to full speed range, would that be a reasonably observable process?

BGW

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mikeasis

yes the "clutches" will be opposite in that one starts open then closes while the other start closed then opens fully. The two "clutches" are actually a constant velocity transmission. Think of it as a 18 speed bicycle the rear sprocket set starts out all the way at the top then you shift it down to gain speed but loose torque. the front gear set starts out down low then shifted into high.

cgtech

Also, there are no "adjustment slots", as none are needed. Would only allow for improper adjustments to be made to motor/axle trying to solve other problems. Consider the original motor and axle arrangements "set in stone", as they need to be left alone. Unless you put totally different motor or axle in there, that would be a different story.

meimk

On a Yamaha "neutral" is a balancing act, so safest to put the rear on stands so the tires don't touch the ground. Lift the seat and watch how they play against each other as engine speed rises. The front (drive) clutch has weighted arms inside it that force the sheaves together as RPMs increase. As that happens the rear (driven) clutch is forced open to let the belt drop down in the V as the drive clutch takes up more of the belts diameter. Watch it work and you'll see what I mean.

CP241

Watch this.




https://www.youtube.com/watch?v=uCEvBGT8twM

Barisax

Thanks for the explanation of theory and the video link. Very helpful responses tjat are greatly appreciated! Fixed sheaves in parallel planes: check! I think I understand now.
The smooth and even operation of the video clutches is an awesome sight. I have to see this on my cart, when reassembled, to find out if my cart clutches move as smoothly as the ones in the video.

CP241

inspect the sheaves for any signs of waves or wear. The insides of the sheaves should be ruler flat.

Yamaha's don't have a "neutral" but there's a spot between forward and reverse that acts like a neutral. But as stated, put the rear on jack stands before testing operation just in case it slips. you should be able to rev the engine and watch them work. plowmans website has some videos as well showing clutch operation that may be useful for you, and how their clutch performs better than the factory

Barisax

It was really enlightening to observe the clutches moving smoothly while the cart was jacked and secured. While The drivers rear wheel was off , and the hub and axel were out for replacement because of spline failure, the secondary was replaced due to real dished out faces, and very worn helix slides and deeply worn ramps. I got an inexpensive secondary with a heavy spring, because of the hill climbing around the sand blows and steep lakeside hills around here; it made a difference in the speed of climbing that was formerly quite slow.
Thanks for the information about how to analyze the variable ratio drive: It was something that I just never thought about before.