Texas Two Step Taco

teazer

Well-Known Member
DTT BOTM WINNER
I like that approcah. Machine off some of the friction material and see how that works.
 

John Murray

Member
Yes, like that.

Here are some pics. First is some worn factory plates:
clutch1.jpg


Next is from L to R, cork Japanese plate, cellulose Japanese, Barnett

clutch2.jpg


Finally laser cut steel inner (slotted), l/cut steel inner (unslotted, used), l/cut steel outer
clutch3.jpg


Notice how the original factory plates have a big, wide contact surface; this was pretty standard practice up to the late 60s to early 70s. Now of course all the manufacturers use a narrow contact band right out at the edge and these work much better.
 

Texasstar

Can't is a four letter dirty word
That AJR set looks very good..
So does the straight cut gears ;) thank you for the visual and the evolution of the clutch. As you said before then the outer contact patch has greater grip than the inner. I wonder how the measured that?


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Texasstar

Can't is a four letter dirty word
Yes, like that.

Here are some pics. First is some worn factory plates:
View attachment 226910

Next is from L to R, cork Japanese plate, cellulose Japanese, Barnett

View attachment 226911

Finally laser cut steel inner (slotted), l/cut steel inner (unslotted, used), l/cut steel outer
View attachment 226912

Notice how the original factory plates have a big, wide contact surface; this was pretty standard practice up to the late 60s to early 70s. Now of course all the manufacturers use a narrow contact band right out at the edge and these work much better.
I am curious. What made you decide to go back to steel plates?


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John Murray

Member
I am curious. What made you decide to go back to steel plates?


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I didn't - I'm using thin laser-cut steels with Japanese style outers. But if future power increases (nitro?) require it I can go to a full set of thin steels. The full steel set had enormous holding power, so much that I had to delete a couple of plates before I could make it slip and then adjust the readings accordingly. I was very surprised by this - the friction coefficient seems to be more related to how well the surfaces can maintain a thin, uniform oil film than anything else and the dry material COF has little or no relevance.
 

John Murray

Member
..As you said before then the outer contact patch has greater grip than the inner. I wonder how the measured that?


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Torque is simply force x distance, so increasing the distance from the contact patch to the shaft centre increases the torque capacity for a given value for friction. In practice, the greater pressure (from the smaller area) gives a thinner oil film and more friction per cm2, so this along with the increased radius gives a stronger clutch.
 

Texasstar

Can't is a four letter dirty word
I didn't - I'm using thin laser-cut steels with Japanese style outers. But if future power increases (nitro?) require it I can go to a full set of thin steels. The full steel set had enormous holding power, so much that I had to delete a couple of plates before I could make it slip and then adjust the readings accordingly. I was very surprised by this - the friction coefficient seems to be more related to how well the surfaces can maintain a thin, uniform oil film than anything else and the dry material COF has little or no relevance.
A friend of mine said he had the same result with steel plates and that they were damaging his clutch basket so he went back to turning Japanese.


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John Murray

Member
A friend of mine said he had the same result with steel plates and that they were damaging his clutch basket so he went back to turning Japanese.


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I use an early style clutch basket, all steel and made in one piece with the sprocket. Very tough and doesn't get beaten up like an aluminum basket.
 

Texasstar

Can't is a four letter dirty word
Torque is simply force x distance, so increasing the distance from the contact patch to the shaft centre increases the torque capacity for a given value for friction. In practice, the greater pressure (from the smaller area) gives a thinner oil film and more friction per cm2, so this along with the increased radius gives a stronger clutch.
In Texas we call this grabbing the bull by the balls. Nitro the evolution of all great motorcycles. Have you seen Clem Johnson’s Vincent Rapide


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Texasstar

Can't is a four letter dirty word
I use an early style clutch basket, all steel and made in one piece with the sprocket. Very tough and doesn't get beaten up an aluminum basket.
Mine is steel and that is one reason why I wanted to get it to work instead of going directly to AJR. Teazer says it is all about optimization.


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John Murray

Member
Mine is steel and that is one reason why I wanted to get it to work instead of going directly to AJR. Teazer says it is all about optimization.


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I agree. I think the Barnetts could be made to work. As Teazer said machine off the inner half of the facing and see how they go. If need be you can always use thinner steels and an additional plate later. BTW, how old are your Barnetts? All the ones I've seen have Kevlar facing, the one in your photo looks like cork or something similar.
 

Texasstar

Can't is a four letter dirty word
I agree. I think the Barnetts could be made to work. As Teazer said machine off the inner half of the facing and see how they go. If need be you can always use thinner steels and an additional plate later. BTW, how old are your Barnetts? All the ones I've seen have Kevlar facing, the one in your photo looks like cork or something similar.
That is a good question. This is the first set we fried on the dyno and they only way 1.3 lbs. for the set.
IMG_8507.jpg



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teazer

Well-Known Member
DTT BOTM WINNER
John, Nice listing. Thanks. What is the OD of those plates you showed?

Tex, RD350 and TZ are 12 tab and 132mm OD. RS125 are 12 tab and 125mm, CB160/175 are 10 tab and 125mm. Hope you can see something in John's link that works at a lower cost than an AJR clutch
 

John Murray

Member
No OD numbers are given, just says that they are shown actual size. I'm sure one of the manufacturers (Vesrah?) has a better listing that gives all the dimensions, I just have to find it.
 

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