Texas Two Step Taco

I can see you are a friend who is a clutch player. Very interesting and thank you for that information. Have you ever used the steel clutch plates?


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Desmo Bulto indogtrination
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So this is what I used Supertech “Walmart” conventional 10w-30 and it does not have JASO Ma or Ma-2
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Do you not need to use JASO-MA oils in these? We're talking wet clutches, right? Don't want to get into one of those famous internet debates about oil, but seems the additives in conventional automobile oils will make a mess of your clutch grip.
 
The dog is cute. The oil, not so much.

Irk is right that you want an oil that doesn't include the friction reducing package of additives. I have tried many different oils from zero visosity aircraft oils to expensive European race oils and I come back to that Honda trans oil as cheaper and just as good.

And to John's point, I try to get more thin plates in to set the clutch pack height rather than a few thicker ones and I always use plates with friction material at the outside and none close to the hub for the same reason plus less are means higher effective plate pressure. See what alternative plates are available. Modern clutches use relatively thin plates compared to older designs.

The only clutches I have problems with are Barnett plates which are sticky when cold or TZ dry clutches that break at least one plate with every hard start.
 
Do you not need to use JASO-MA oils in these? We're talking wet clutches, right? Don't want to get into one of those famous internet debates about oil, but seems the additives in conventional automobile oils will make a mess of your clutch grip.

Once again I need to toss the manual because it doesn’t cover the changes in oil. It said conventional oil and since I haven’t been in one of the “you are an idiot for not knowing that everybody knows you are suppose to use JASO-ma in your wet clutch dummy debates I just used the cheap off the shelf oil but what would you expect from a guy who only uses one petcock? Now I know we need to use JASO-Ma or Ma-2.

Now we have plenty of dyno time so I am intrigued in which one will make more horsepower Honda tranny vs JASO-ma Ester superclalifragiloilicious. We will see...flog me I deserve it.


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And soon you will be our tribologist in residence.

But look for alternate plates from other bikes to see if you can get a more effective clutch pack or adapt a Banshee lock up. They are cheap compared to a full custom set up. And if it can't be made to work, you can sell it again.
 
I just use the Rotella in my wet clutch bikes, because it's JASO-MA and cheap. $60 for 5 gallons at Wal Mart, Rural King and Tractor Supply. A bit more expensive at the auto houses.
 
I just use the Rotella in my wet clutch bikes, because it's JASO-MA and cheap. $60 for 5 gallons at Wal Mart, Rural King and Tractor Supply. A bit more expensive at the auto houses.

5 gallons wow sounds like you are a man of conviction. Lol!


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Barnett nos plates top, metal nos bultaco plates bottom, borrowed lock up.


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OK, here's everything I found with my clutch testing rig, some of which I found a bit surprising.

I tested a dozen or so different oils - motorcycle oils, ATFs, non-friction modified engine oils, diesel engine oil, CVT oil, hydraulic oil. Nearly all the oils gave very nearly the same results; the CVT and ATF oils were at the bottom of the list, followed by pretty much all the others apart from the motorcycle engine oil which had a clear lead over everything else. The one I tested was a Castrol synthetic 4T oil; I expect other brands would give similar results.

In general, higher viscosity oils held better than low viscosity oils - something I wasn't expecting. This was particularly so with plates that had a smaller surface area. The exception was the worn factory plates that didn't like the thick oils. The obvious tradeoff with viscosity is cold drag.

I tested several types of plates - new factory plates, worn factory plates, Barnetts, Honda style plates with cork facing, Honda style plates with cellulose facing, plain steel plates I had laser cut in two different thicknesses.

The factory Bul plates appear to have a massive area, but they are embossed at the factory in a process that leaves hundreds of little peaks on them and this reduces the effective area by a lot. Out of all of the plates the new Bul plates were second lowest in holding power.

The worn factory plates gave the lowest hold. As the little peaks wear down the area goes way up, and it appears they then hold a thick film of oil between the plates that reduces the friction very significantly. Worn plates simply will not hold. Grinding grooves in worn plates restores some of the grip but not all.

The Barnetts use a Kevlar facing that seems to work well - they gave more holding power than the new factory plates. These plates work well in lower revving engines but are problematic as the rpms and power rises. To keep the plate thickness similar to stock the facings are bonded to a very thin backing plate, and I found with my air-cooled engine I could kill the Barnetts in an hour or two on the dyno. The thin drive ears would be badly beaten up.

The Japanese style plates were better again. They have a larger inside diameter and a small contact band. The cellulose facing gave a slightly better hold than the cork but there wasn't much in it. On the dyno however something strange happened - the cellulose plates worked perfectly for a while but then suddenly lost their grip. There was no visible fault with them, they just went slick for some reason. I switched to the cork facing and these ran without problems. The thicker aluminum backing held up to the torsional battering fine. The combination I ended up using was cork faced plates (modified Kawasaki plates from ProX) with thinner steels I had cut out. I use this combo in all my engines, however if they later prove to be too weak for the LSR engine I'll go to all steel.

Plate thickness is important - obviously the thinner the plates the more of them you can run. At first I thought that going too thin would be problematic and the drive ears would get beaten up. But that proved not to be the case - regardless of plate thickness the drive ear total thickness remains the same and even with 1mm steel plates the ears survived just fine.

The strongest grip by a large margin was given by the custom steel plates. These had a very narrow contact face and a large effective radius. In actual riding they tend to be a bit savage on the take-up but it is something you can adapt to. Even with the stock thickness they gave a big improvement and with the thinner plates they are even stronger. I think these could handle 100hp, should I ever get to that figure (highly unlikely). They are very cheap to get laser or waterjet cut but you need to be careful to use dissimilar grades of steel for the inners and outers. My initial set used plain mild steel for both and while they tested fine on the rig they would gall and bite in actual riding. Nickel plating one set of plates fixed this, at least until the plating wore out. One set of plates need to be made from a tough manganese steel or similar (Waukesha 88?) to avoid this. The ProX plates are working for me at the moment and have a nice smooth take-up, but if need be I'll switch to an all-steel pack.

All these tests were done on a Pursang style clutch which is smaller than the Bandido unit but uses the same type of factory plate, so everything should apply equally. One key difference though is the chain drive setup on the Pursang makes it easy to change the primary drive ratio to reduce the torque loading on the clutch and gearbox.
 
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OK, here's everything I found with my clutch testing rig, some of which I found a bit surprising.

I tested a dozen or so different oils - motorcycle oils, ATFs, non-friction modified engine oils, diesel engine oil, CVT oil, hydraulic oil. Nearly all the oils gave very nearly the same results; the CVT and ATF oils were at the bottom of the list, followed by pretty much all the others apart from the motorcycle engine oil which had a clear lead over everything else. The one I tested was a Castrol synthetic 4T oil; I expect other brands would give similar results.

In general, higher viscosity oils held better than low viscosity oils - something I wasn't expecting. This was particularly so with plates that had a smaller surface area. The exception was the worn factory plates that didn't like the thick oils. The obvious tradeoff with viscosity is cold drag.

I tested several types of plates - new factory plates, worn factory plates, Barnetts, Honda style plates with cork facing, Honda style plates with cellulose facing, plain steel plates I had laser cut in two different thicknesses.

The factory Bul plates appear to have a massive area, but they are embossed at the factory in a process that leaves hundreds of little peaks on them and this reduces the effective area by a lot. Out of all of the plates the new Bul plates were second lowest in holding power.

The worn factory plates gave the lowest hold. As the little peaks wear down the area goes way up, and it appears they then hold a thick film of oil between the plates that reduces the friction very significantly. Worn plates simply will not hold.

The Barnetts use a Kevlar facing that seems to work well - they gave more holding power than the new factory plates. These plates work well in lower revving engines but are problematic as the rpms and power rises. To keep the plate thickness similar to stock the facings are bonded to a very thin backing plate, and I found with my air-cooled engine I could kill the Barnetts in an hour or two on the dyno. The thin drive ears would be badly beaten up.

The Japanese style plates were better again. They have a larger inside diameter and a small contact band. The cellulose facing gave a slightly better hold than the cork but there wasn't much in it. On the dyno however something strange happened - the cellulose plates worked perfectly for a while but then suddenly lost their grip. There was no visible fault with them, they just went slick for some reason. I switched to the cork facing and these ran without problems. The thicker aluminum backing held up to the torsional battering fine. The combination I ended up using was cork faced plates (modified Kawasaki plates from ProX) with thinner steels I had cut out. I use this combo in all my engines, however if they later prove to be too weak for the LSR engine I'll go to all steel.

Plate thickness is important - obviously the thinner the plates the more of them you can run. At first I thought that going too thin would be problematic and the drive ears would get beaten up. But that proved not to be the case - regardless of plate thickness the drive ear total thickness remains the same and even with 1mm steel plates the ears survived just fine.

The strongest grip by a large margin was given by the custom steel plates. These had a very narrow contact face and a large effective radius. In actual riding they tend to be a bit savage on the take-up but it is something you can adapt to. Even with the stock thickness they gave a big improvement and with the thinner plates they are even stronger. I think these could handle 100hp, should I ever get to that figure (highly unlikely). They are very cheap to get laser or waterjet cut but you need to be careful to use dissimilar grades of steel for the inners and outers. My initial set used plain mild steel for both and while they tested fine on the rig they would gall and bite in actual riding. Nickel plating one set of plates fixed this, at least until the plating wore out. One set of plates need to be made from a tough manganese steel or similar (Waukesha 88?) to avoid this. The ProX plates are working for me at the moment and have a nice smooth take-up, but if need be I'll switch to an all-steel pack.

All these tests were done on a Pursang style clutch which is smaller than the Bandido unit but uses the same type of factory plate, so everything should apply equally. One key difference though is the chain drive setup on the Pursang makes it easy to change the primary drive ratio to reduce the torque loading on the clutch and gearbox.

Wow that is a lot of testing. How long do you think it takes for a bultaco clutch to get to the correct temperature to take advantage of the heavier viscosity in say 10w-40?

Also how much are you using? My bull manual originally said 300cc and I have crossed that out and have 200cc written down because Lynn Mobley told me to use less once upon a time.

I would think with one burn out we are not going to be at temp to take advantage of a 10w40 and may need to go to finding a straight 30w or 40w.

What is the heaviest viscosity that you have tested?

I have a good friend who has a water jet so making our own plates won’t be a problem.

Also do you know why they put the T and L on the stock Bultaco Clutch plate and did that compromise the clutch or help?

Do you think the thumbs up logo would compromise our plates? :)


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And soon you will be our tribologist in residence.

But look for alternate plates from other bikes to see if you can get a more effective clutch pack or adapt a Banshee lock up. They are cheap compared to a full custom set up. And if it can't be made to work, you can sell it again.

It makes me happy to know you are using Honda transmission fluid in your Yamaha...lol. Glad I waited on the AJR clutch and straight cut gears to ask what clutch plates and basket they adapted.


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Wow that is a lot of testing. How long do you think it takes for a bultaco clutch to get to the correct temperature to take advantage of the heavier viscosity in say 10w-40?

Also how much are you using? My bull manual originally said 300cc and I have crossed that out and have 200cc written down because Lynn Mobley told me to use less once upon a time.

I would think with one burn out we are not going to be at temp to take advantage of a 10w40 and may need to go to finding a straight 30w or 40w.

What is the heaviest viscosity that you have tested?

I have a good friend who has a water jet so making our own plates won’t be a problem.

Also do you know why they put the T and L on the stock Bultaco Clutch plate and did that compromise the clutch or help?

Do you think the thumbs up logo would compromise our plates? :)


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Don't get too hung up on viscosity, just use a 10w40 or whatever you can get in a synthetic motorcycle oil. The difference in holding power isn't enough to worry about and a multi-weight will have less cold drag.

I don't know what the Ts and Ls mean apart from making it impossible to bore the middle out of them without making them too weak.

I use about 250ml of oil - I don't think it's critical.

Given the larger size of the Bandido clutch I don't think you'll have too much trouble getting it to handle 40 - 50hp. A good place to start would be a set of Barnett outer plates paired up with a set of thinner inner plates. The thinner inners would probably end up at 1 or 1.2mm thick - whatever you need to allow room for an extra pair of plates. I think this would hold fine but even if it didn't you still have the option of carefully boring out the Barnett outers. Use as much spring tension as your hand can reasonably handle.

A thumbs up logo anywhere on the clutch is worth a tenth and 5 mph.

Somewhere I have a listing of the common bike clutch plate dimensions - if I can find it there may be something there that can be easily adapted, as with the Pursangs.

You'll get it working - everyone that starts to get serious power from a Bul ends up playing this game.

PS Desmo looks almost unbearably cute!
 
Whoa that is a serious knowledge dump on clutches! thanks for sharing John its always great to get info from people doing real testing.

I have run into a similar problem on a project bike of mine (stock clutch cannot handle doubling the power) I have been considering grafting a clutch basket from a 2013 zx636 as the dimensions are very similar, The 636 clutch has ramps built into the hub and pressure plate that create additional clamping pressure when higher torque is applied. The harder it's stressed the harder it grabs.

Would it be possible to graft a late model clutch here? keep up the testing!

-Vic
 
I meant for this bultaco application. Im reasonably confident i can make it work for me but it will take some machining and welding.

You just solved another problem I am having. Using a roll pin instead of a cotter pin. How? Well I went to AJR to see how there clutch basket was constructed and noticed this. Machining, welding, and DTT all things are possible. Would love to follow your build.
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I meant for this bultaco application. Im reasonably confident i can make it work for me but it will take some machining and welding.

OK, I don't really think it's necessary given the size of the clutch and the power level. And if you can adapt later style plates then you virtually have a new clutch anyway.
 
I think I found the perfect oil for my bultaco. JASO ma2. Good enough for a Panigale’s power.
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