secondary coil bind/pocket depth

[NOS-PRO]

Nice write up and as mentioned....us clutch tuners are here trying to help.

Have 3 helix's on my CMM at work here right now checking angles, ramp degrees from center bore and orientation . For the Stock SW helix, the ramps are pretty close for a die cast helix.

 

[NOS-PRO]

Here are some numbers.
This roller secondary has a spring pocket depth of 2.550" when at idle position, and when the clutch is fully shifted out ( sheaves spread apart at full shift), it has a spring pocket depth of 1.510"

Are you measuring full shift with a belt between the sheaves? A specific dimension? Or bottoming out the helix on the fixed shaft? I machined the hub of my helix and I'm way under at 1.409"

This was why I was taking .070" out of the spring pocket. (Which is what I did on the Vipers and Nytros)

 

[RTX]

Good info. maybe more should check it. .020 +" would seem to me to be a lot of variance on a permanent mould casting, but it is what it is. That is exactly what should be done...check your own machine. It is all pretty easy stuff to check, and as you can see here, maybe not all are exactly the same. Nobody has to rely on any "hearsay" with something like this....take a few minutes and check it rather than spend all winter asking and wondering or fearing something that may or may not matter on your own sled. I'm sure there will be some variances on one machine to another....but as the season progresses, I'm sure a few pics and videos will emerge to prove the zone of measurements that people are seeing. It is all good info for people.

Did you happen to do the physical test with the belt ( with the clutches assembled on the sled with no springs in them) to see how far your secondary really has to open when the belt is fully shifted on the primary? That is, of course, what is important in all of this.

just something to think about.
being that all these parts are cast, I would assume there is multiple molds.
with multiple molds come multiple variables in tolerance.
what you have on your sled is probably within tolerance, but its probably a little different than mine.
all those differences can and will add up at some point. just my opinion

 

[helix]

Nice write up and as mentioned....us clutch tuners are here trying to help.

Have 3 helix's on my CMM at work here right now checking angles, ramp degrees from center bore and orientation . For the Stock SW helix, the ramps are pretty close for a die cast helix.

The helixes are just cast and we see that often...on this one one of the things that is odd is this. The stock helix has ramps that have a bit of "twist".

If you use a Brand New set of rollers, put some smear of prussian blue lightly on the rollers, then roll the clutch with the helix bolted on, ...you will see that the roller is only touching on one edge of the roller...and as it travels down the ramp it ends up only touching on the other edge of the roller.

 

[helix]

Are you measuring full shift with a belt between the sheaves? A specific dimension? Or bottoming out the helix on the fixed shaft? I machined the hub of my helix and I'm way under at 1.409"

This was why I was taking .070" out of the spring pocket. (Which is what I did on the Vipers and Nytros)

You had to cut the center hub out of the helix and cut the spring pocket on the viper. From what I can tell, you do not need to cut this helix hub like you did on the old button clutch.
The distances that come from the factory are not the same at all, and the factory spring pocket is already deeper and the hub is at a different offset from where the helix bolts on to allow further travel of the belt.....it is possible that it may slightly touch in coil bid on some from the sound of things....but if it is it would be very slight and the clutch would have to be right completely pulled open until the center hub bottoms ( which the factory usually does not make them that way)

In the case of the depth of spring pocket I listed, it was wityh the clutch opened all the way with the center hub bottomed out. ....it should not have to go that far in reality on the sled when the primary is fully shifted, ...unless they have a center distance that is too long.

The pink spring back at the time i remember the controversy....lots could try it and squeeze a spring in a vise and show that it would compress actually more than that....and get closer ( shorter) than the 1.5" length....but as I had noted at the time, ...when you compress the clutch so that the spring is 1.5" long is when it starts to " act " as if coil stacked ...even though you could still see some light between the coils. The pressures would rise at a different rate.

 

[shagman]

You had to cut the center hub out of the helix and cut the spring pocket on the viper. You do not need to cut this helix hub like you did on the old button clutch.
The distances that come from the factory are not the same at all, and the factory spring pocket is already deeper and the hub is at a different offset from where the helix bolts on.....it is possible that it may slightly touch in coil bid on some from the sound of things....but if it is it would be very slight and the clutch would have to be right completely pulled open until the center hub bottoms ( which the factory usually does not make them that way)

In the case of the depth of spring pocket I listed, it was wityh the clutch opened all the way with the center hub bottomed out. ....it should not have to go that far in reality on the sled when the primary is fully shifted, ...unless they have a center distance that is too long.

The pink spring back at the time i remember the controversy....lots could try it and squeeze a spring in a vise and show that it would compress actually more than that....and get closer ( shorter) than the 1.5" length....but as I had noted at the time, ...when you compress the clutch so that the spring is 1.5" long is when it starts to " act " as if coil stacked ...even though you could still see some light between the coils. The pressures would rise at a different rate.

That is exactly how the sw is acting, even though you might not actually bind. You get close enough that the pressure rises and causes slipping. That is the biggest reason for the problems.


Sent from my iPhone using Tapatalk

 

[helix]

That is exactly how the sw is acting, even though you might not actually bind. You get close enough that the pressure rises and causes slipping. That is the biggest reason for the problems.


Sent from my iPhone using Tapatalk

Hey Shagman, maybe so. You could be correct.
I'm certainly not saying it isn't. I just posting some measurements.

As I had mentioned when I posted, the only reason I bothered to take the time to look up and post any of this is because I had the questions from people about " overdrive clutches" and "spring pocket coil bind" ...I went through my notes and dimensions and listed them. Thought people would want to see it if there was that much question about it.

A couple of the main points to be made are this,...the measurements clearly show that it is not the same case as on earlier button clutches and the spring pocket is already deeper than previous models, and that Yamaha did do what they said and built some overdrive into the clutches already.
Like NOS PRO has said, we are all just sharing information.

The real test is not guesswork though...it is a easy test to test your own and see how far the primary is pulling that belt down into the secondary when at full shift.
...if you throw in things like belt dimension ( some use other belts), center distance, etc it may be interesting to see.

 

[NOS-PRO]

Hey Shagman, maybe so. You could be correct.
I'm certainly not saying it isn't. I just posting some measurements.

As I had mentioned when I posted, the only reason I bothered to take the time to look up and post any of this is because I had the questions from people about " overdrive clutches" and "spring pocket coil bind" ...I went through my notes and dimensions and listed them. Thought people would want to see it if there was that much question about it.

A couple of the main points to be made are this,...the measurements clearly show that it is not the same case as on earlier button clutches and the spring pocket is already deeper than previous models, and that Yamaha did do what they said and built some overdrive into the clutches already.
Like NOS PRO has said, we are all just sharing information.

The real test is not guesswork though...it is a easy test to test your own and see how far the primary is pulling that belt down into the secondary when at full shift.
...if you throw in things like belt dimension ( some use other belts), center distance, etc it may be interesting to see.

That's the thing.....so many other things thrown into the equation... (different brand belts, clutching, even the same 8JP belts from Yamaha very .035" in thickness)

Makes a persons mind blow every day, but....that is why I/we like to help and share info

 

[helix]

That's the thing.....so many other things thrown into the equation... (different brand belts, clutching, even the same 8JP belts from Yamaha very .035" in thickness)

Makes a persons mind blow every day, but....that is why I/we like to help and share info

Exactly, lots of variables. Throw in things like belt variables and the fact that today someone posted that they have a pocket that is a bit less ???...could be close for some. What we have on these from factory for spring pocket depth, ... is pretty much what we used to cut the pocket to on the old button clutches for the same amount of spring. That doesn't mean there is anything wrong with cutting more if you want to.

 

[done dooin'_winder up]

The helixes are just cast and we see that often...on this one one of the things that is odd is this. The stock helix has ramps that have a bit of "twist".

If you use a Brand New set of rollers, put some smear of prussian blue lightly on the rollers, then roll the clutch with the helix bolted on, ...you will see that the roller is only touching on one edge of the roller...and as it travels down the ramp it ends up only touching on the other edge of the roller.

i had posted previously somewhere on magnified inspection of the cat rollers i had taken out after 40-50 miles if memory is correct. what i saw was an almost melted appearance on the entire outer 1/8" of one roller and what looked like tiny splits about 1/8" in around the entire circumference of another roller. HEAT? is heat also the cause of the flat spots? i added a 1mm shim at that point to get offset closer to center of spec. i used the ulmer rollers when i put it back together and put less than 200 miles on. i am waiting to hear the results of further testing to see if different spring or helix is next and will inspect the ulmers at that point when i pull it apart. we have 0 snow and temps nearing 50f for next 2 weeks.

 

[**sj**]

Where'd you put the shim

 

[done dooin'_winder up]

Where'd you put the shim

Me? removed 1mm from behind secondary and installed 2mm. 59.6 offset

 

[XP123]

So after reading between the lines I've come to the conclusion that the Yamaha engineers are smarter than what many give them credit for.

 

[justin1620]

Is it safe to say by adding a 1/16" helix shim will bring your belt 1/16" deeper into secondary at full shift? I have very minimal paint removed from secondary spring, looks to be a slight amount of coil bind, however I can see how far the belt has travelled to the bottom of the secondary and I'm very close to the hub with no shims. I'd like to eliminate this coil bind but I don't want belt to bottom out on secondary hub and blow a belt? On a side note I'm at 250 miles, original 8jp belt, primary clutch kit, cat rollers......just wondering if I should shim or not........

 

[DMCTurbo]

Ok who has a new spring for us? Anyone yet?