Primary clutch oddity

[Shagnos]

But once you are balls deep in the secondary it can't go any higher on the primary.

 

[cannondale27]

But once you are balls deep in the secondary it can't go any higher on the primary.

Thats when you change belt length. Only then. Or gear

 

[Rich Kay]

Plus i'd rather have 8 1/2'' than 8 1/4'' anyways. Size matters when talking OVER-DRIVE clutches boys. This is one of those few times it matters...

"IF" the rest of the rest of the designed and geometry ( C/C , belt length, primary sheave travel to belt ride height ect.) permits it. Be careful.

 

[Rich Kay]

But once you are balls deep in the secondary it can't go any higher on the primary.

True ... But think about?? The sled (especially this one) with the power can continue to want to pull the belt up in the primary. One ya loose performance and things can go bad with all the forces fighting each other at that point.

 

[Rich Kay]

Thats when you change belt length. Only then. Or gear

X2!

 

[RJH]

First, it is a huge waste of energy...as an example....we could have used 7074 T4 aluminum for our jackshaft (in the day) or we could have gun drilled it. Inertia is more critical to (quick happening) than weight was....so it was determined we can machine down steel smaller OD them 7074 so steel with small OD was the fastest option

In this case, you are lugging around an extra 1/4" that has to start.

That is absolutely wrong. But...it has been tested for hundreds of hours so...shoud not worry.

I will machine mine to tuck my weights under more sometime this month and have a look at that.

It baffles me....and I have made clutch corrections since the 70's and nothing has really changed.
After our mod stock year ..all drunked up at the hotel celebrating....the Japanese engineers asked...why you sled so fast...what... impossible ...computer not wrong..you lie.
Let me be clear thou..I traveled with Yamaha engineers in the summer for weeks on end..brilliant men..their life was their job...you might be able to pick me out in the picture

The Doo Rev had the same issue but not the XP race sled??
Cat did a longer spring maybe 4 years back to stop the clutch from closing 100%

 

[Rich Kay]

First, it is a huge waste of energy...as an example....we could have used 7074 T4 aluminum for our jackshaft (in the day) or we could have gun drilled it. Inertia is more critical to (quick happening) than weight was....so it was determined we can machine down steel smaller OD them 7074 so steel with small OD was the fastest option

In this case, you are lugging around an extra 1/4" that has to start.

That is absolutely wrong. But...it has been tested for hundreds of hours so...shoud not worry.

I will machine mine to tuck my weights under more sometime this month and have a look at that.

It baffles me....and I have made clutch corrections since the 70's and nothing has really changed.
After our mod stock year ..all drunked up at the hotel celebrating....the Japanese engineers asked...why you sled so fast...what... impossible ...computer not wrong..you lie.
Let me be clear thou..I traveled with Yamaha engineers in the summer for weeks on end..brilliant men..their life was their job...you might be able to pick me out in the picture

The Doo Rev had the same issue but not the XP race sled??
Cat did a longer spring maybe 4 years back to stop the clutch from closing 100%

Thanks for the short story... cool stuff! and yes I could pic ya out of the group! Would love to hear some more.

 

[Sledroll]

First, it is a huge waste of energy...as an example....we could have used 7074 T4 aluminum for our jackshaft (in the day) or we could have gun drilled it. Inertia is more critical to (quick happening) than weight was....so it was determined we can machine down steel smaller OD them 7074 so steel with small OD was the fastest option

In this case, you are lugging around an extra 1/4" that has to start.

That is absolutely wrong. But...it has been tested for hundreds of hours so...shoud not worry.

I will machine mine to tuck my weights under more sometime this month and have a look at that.

It baffles me....and I have made clutch corrections since the 70's and nothing has really changed.
After our mod stock year ..all drunked up at the hotel celebrating....the Japanese engineers asked...why you sled so fast...what... impossible ...computer not wrong..you lie.
Let me be clear thou..I traveled with Yamaha engineers in the summer for weeks on end..brilliant men..their life was their job...you might be able to pick me out in the picture

The Doo Rev had the same issue but not the XP race sled??
Cat did a longer spring maybe 4 years back to stop the clutch from closing 100%

When was that picture taken as I think I was there !
Niagara Falls ?

 

[snowbeast]

It's a 1/4'' not 1/8''. Not concerned, just curious. If there is a "reason" for it, maybe everybody here just learned something new, but it makes no sense from a technical stand point. Now if it was a left-over part that fits & it can't go above it, then no harm no foul. Still very ODD!

steve its a dia. we are talking about,half the actual distance,its like .500 or half inch on a dia is only half of that,top and bottom of belt will only occupy 1/8 inch each for 1/4 total,ok.

 

[cannondale27]

What do they say about rotating mass? You are 100% right RJH. Couple hp there for sure.

 

[**sj**]

do we know it is intentional vs accidental? or just speculation?

 

[stevewithOCD]

steve its a dia. we are talking about,half the actual distance,its like .500 or half inch on a dia is only half of that,top and bottom of belt will only occupy 1/8 inch each for 1/4 total,ok.

Yes i understand that. 1/4'' total, 1/8'' per side or top. Still different than any other clutch i've worked on which is in the hundreds. IF it is extra then it's a waste. If there's a reason for it, then we'll learn something. Learning is fun...

 

[cannondale27]

do we know it is intentional vs accidental? or just speculation?

Speculation. In glass half full mood so I am going to say they did it for strength to fit all the parts on that sheave like was speculated before. I am sure it will get machined off real soon and then we will know.

 

[RJH]

When was that picture taken as I think I was there !
Niagara Falls ?

70's ..

 

[**sj**]

Hey guys , My thought is the outer sheave (which is the larger) in this case had to be in order to "contain" all the design of moving parts of the movable sheave and have the integrity??? There is ALOT of forces being generated within the movable sheave.

this makes sense..

if you look at the weight, change in the spider and the layout....it seemingly requires this "real estate" for it to all lay out..