Hi Guys, have had a few inquiries lately about coil binding on the secondary, and from a quick browse of the forum I see it mentioned. It is probably important to remember that everyone here is sincerely trying to help get good info to fellow users on a new model sled with a new clutch.
During development of helixes we do test things like spring pocket depth, etc.
In case some are on their first Yamaha, here is a brief rundown of why some of these more experienced Yamaha clutch tuners are cautious of the issue.
RX-1/Apex:
The regular old yamaha button clutches had always used smaller springs until the 4 strokes came along in 03. The 4 strokes often came with with this spring with a pink dot ...the pink spring would shift to a full tight position in stock form, but many of the yamaha guys would machine the clutches for overdrive. If they machine the primary for overdrive would not allow any more overdrive unless they also cut down the center hub of the helix ( we made ours with the hub already cut down a bit more than .100" to save them the trouble) on thoise button clutches.
....with the overdrive cuts, the spring pocket would try to close tighter to get the over drive...but ...you still couldnt get the overdrive because the pink spring would stack coil to coil and still not allow the overdrive.
Tuner guys would do a few different ways to resolve it. They would add washers under the helix to increase trhe depth of the pocket distance...or they would machine the spring pocket deeper, ...or many, would simply use a spring that had a bit less wire ... (a lesser number of total coils) so that a fully compressed spring was not as tall.
The pink spring that came in all those 4 strokes would compress to approx 1.5" before it started to touch and act coil bound a bit. You could compress a spring in a vise and get different lengths of coil stack that sounded a bit less, but when held properly in a clutch and compressed, it was at about 1.5 that it started.
The old button clutch had a coil pocket depth of around 2.42" when opened up at idle position...and the depth of that pocket was approx 1.44" when in overdrive with a cut helix and shifted all the way.
...as you can see, when you have a spring that starts to act funny at 1.500" compressed height....and a clutch that wants to compress to 1.440" ....there is not enough room. Thus some .060 washers or a pocket cut would allow you to use that spring. Many used other springs instead, like the YMR spring we have, but some like the stock spring and that is what was necessary to do it.
Sidewinder
Enter sidewinder with a new roller secondary clutch and clutches that were supposed to be "overdrive" clutches.
The new roller secondary clutch does indeed have a deeper spring pocket, but is it enough for full shift and some variances in belt width etc?
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"
There is no need to cut the center hub anymore, although we added a very slight (0.5mm) relief to allow for belt width variances)... as the secondary was designed from the factory obviously for more overdrive.
The new stock secondary spring is what I have been calling gold ( it has a gold/yellow spot on it)...I dont even know what yamaha refer to it as, but it is the stock sidewinder spring. This spring is similar to the yamaha pink one that they previously used in 4 strokes, ...as it is also the same 6.0 mm wire, and it is also the same 5.53 total coils in design. ...so it would have pretty similar fully compressed action when it gets close to coil bind....that being around 1.500" ...the spring pocket is 1.510"....pretty close.
As you can see, it is pretty close, and at complete full shift...with some of the variables it is probably right at the edge.
It may be good to also realize, that in most applications, the primary does not pull it right down to that limit anyway.
It is close. It is probably also fine for most the way it is.
I'm not here to claim any different than anyone has found, I'm just puting some numbers to it for those who may want to know. Based mostly on my hillbilly pencil notes that I have all over the place.
The thing is, that you dont have to take my word for it.
Although we have lots of depth guages and a CMM, etc around here....you do not need any of that to just check it yourself. You can take the helix off and take the spring out...get some playdough or putty from your kids and put it in the spring pocket and bolt the helix back on.... and cycle the clutch with no spring in it and measure it for yourself. In twenty mins you can draw your own conclusions.
Sorry to ramble,
Hopefully this helps someone.
During development of helixes we do test things like spring pocket depth, etc.
In case some are on their first Yamaha, here is a brief rundown of why some of these more experienced Yamaha clutch tuners are cautious of the issue.
RX-1/Apex:
The regular old yamaha button clutches had always used smaller springs until the 4 strokes came along in 03. The 4 strokes often came with with this spring with a pink dot ...the pink spring would shift to a full tight position in stock form, but many of the yamaha guys would machine the clutches for overdrive. If they machine the primary for overdrive would not allow any more overdrive unless they also cut down the center hub of the helix ( we made ours with the hub already cut down a bit more than .100" to save them the trouble) on thoise button clutches.
....with the overdrive cuts, the spring pocket would try to close tighter to get the over drive...but ...you still couldnt get the overdrive because the pink spring would stack coil to coil and still not allow the overdrive.
Tuner guys would do a few different ways to resolve it. They would add washers under the helix to increase trhe depth of the pocket distance...or they would machine the spring pocket deeper, ...or many, would simply use a spring that had a bit less wire ... (a lesser number of total coils) so that a fully compressed spring was not as tall.
The pink spring that came in all those 4 strokes would compress to approx 1.5" before it started to touch and act coil bound a bit. You could compress a spring in a vise and get different lengths of coil stack that sounded a bit less, but when held properly in a clutch and compressed, it was at about 1.5 that it started.
The old button clutch had a coil pocket depth of around 2.42" when opened up at idle position...and the depth of that pocket was approx 1.44" when in overdrive with a cut helix and shifted all the way.
...as you can see, when you have a spring that starts to act funny at 1.500" compressed height....and a clutch that wants to compress to 1.440" ....there is not enough room. Thus some .060 washers or a pocket cut would allow you to use that spring. Many used other springs instead, like the YMR spring we have, but some like the stock spring and that is what was necessary to do it.
Sidewinder
Enter sidewinder with a new roller secondary clutch and clutches that were supposed to be "overdrive" clutches.
The new roller secondary clutch does indeed have a deeper spring pocket, but is it enough for full shift and some variances in belt width etc?
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"
There is no need to cut the center hub anymore, although we added a very slight (0.5mm) relief to allow for belt width variances)... as the secondary was designed from the factory obviously for more overdrive.
The new stock secondary spring is what I have been calling gold ( it has a gold/yellow spot on it)...I dont even know what yamaha refer to it as, but it is the stock sidewinder spring. This spring is similar to the yamaha pink one that they previously used in 4 strokes, ...as it is also the same 6.0 mm wire, and it is also the same 5.53 total coils in design. ...so it would have pretty similar fully compressed action when it gets close to coil bind....that being around 1.500" ...the spring pocket is 1.510"....pretty close.
As you can see, it is pretty close, and at complete full shift...with some of the variables it is probably right at the edge.
It may be good to also realize, that in most applications, the primary does not pull it right down to that limit anyway.
It is close. It is probably also fine for most the way it is.
I'm not here to claim any different than anyone has found, I'm just puting some numbers to it for those who may want to know. Based mostly on my hillbilly pencil notes that I have all over the place.
The thing is, that you dont have to take my word for it.
Although we have lots of depth guages and a CMM, etc around here....you do not need any of that to just check it yourself. You can take the helix off and take the spring out...get some playdough or putty from your kids and put it in the spring pocket and bolt the helix back on.... and cycle the clutch with no spring in it and measure it for yourself. In twenty mins you can draw your own conclusions.
Sorry to ramble,
Hopefully this helps someone.
Good info. Thanks
Turbor
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Very good and informative post! thanks!
pretty slim margin at .10 right...would shimming the helix make sense then?
whats your thoughts on the 8dn then?
whats your thoughts on the 8dn then?
welcome
.10 is .10. Better than the other way. I would imagine shimming for those who don't believe it would be the way go, but is sound like we are good, barely.
Hi SJ,
I guess everyone may come to their own conclusion on the clearance. Most may never shift that far anyway because the primary may not pull it open that far . if you used a longer belt it certainly wouldn't although if you dont pull the secondary open as far with a longer belt you may lose a mph or two). There could be things like belt dimensions, gears and variables that come into play as well. I guess one point of the conversation is that they ( Yamaha) did indeed change the depth and it is not the same as a older button secondary clutch. The sheave with the three posts on it that the helix is attached to is the same part number....the helix and sheave with rollers is new. the spring pocket depth between the two new parts is different.
I'm really just giving the depths and numbers for people to consider, rather than just a generic statement. With the variables in play it may be close to slightly getting coil stacked for some...it certainly isn't the same as before though. It may also be important to realize this:....when at higher torsion settings a spring can sometimes "act" like it is getting close to coil stacking. If someone wants to machine some room in there, it is not likely to hurt anything. From what I've seen I wouldn't go overboard, as it is not the same as the old ones.
You could always do the old "physical limits test" .... take the springs out of both of your clutches and reassemble the clutches with no springs...put the clutches back on the sled, ..and put the belt on and hold the primary fully shifted and see how far it actually opens the secondary ( with your OWN belt, clutches, and center distance)...does it really fully open the secondary?.....
It is what you have to do when you build a open mod or race sled...the truth can be told real quick. In less than a half hour you could do it and prove to yourself your own situation and never have to ask question it again or have to second guess it.
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On another note regarding the new spring itself, when i mentioned that it was simlar in dimension to the pink it is, in the fact that it is the same number of total coils and the same wire diameter. ...thus it has similar compressed stack height. That would also mean similar "torsion forces"....but it does have different "side pressure " forces since it is a longer free length. With a torsion spring you have to consider both types of forces when comparing springs. I'll have more info on some comparisons on lots of springs soon. I'm waiting to finish some new samples that may be applicable for some. Just didnt want to mislead you to thinking I said the springs were the same.
dsimonRX1
Pro
So I'm shimmed .060 without issues thus far. I checked the secondary set this way and it will not completely bottom out, but it gets closer than without the shims. What is the possible negative to running this way? I'm thinking of trying the Dalton 35 helix. I'm running the Dalton weights and TD ecotrail setup.
ROCKERDAN
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Nice write-up Dale..
probably no harm in it, and since you are running a straight helix you arent changing anything that way by lifting it up.
Soupy
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Had my secondary apart tonight so I took some measurements. The fully collapsed spring pocket on mine is 1.48 inches. Just thought I'd let ya know.
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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.
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Will look at this really soon as I have time this weekend. .. thanks for the info...
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Soupy
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I did not. Haven't had the primary apart yet. Seems to me that it would be very hard to mock up with such a stiff belt but maybe I don't know the trick either.
On another note I found a cracked web on the secondary too.
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