Landracing Forum
Tech Information => Technical Discussion => Topic started by: robfrey on February 23, 2014, 11:52:39 PM
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Is anybody having issues with their wet or dry motorcycle clutch slipping under high loads?
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Do you have a bike in mind? I'm not taking any chances on my build. I've added a locker and a Barnett clutch pack to the Z1 clutch.
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A centrifugal lockup will hold turbo torque, stiff springs will hold quite a bit too. What engine? Dean
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As I have noted many times on this forum.........if you have a clutch problem, contact Barnett Tool and Eng. in Ventura CA. they make outstanding products and clutches all the way back to the 1950's ...OR they can make you a special one-off custom clutch...............
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We have had great support from BT&E for both the Kawasaki drag bikes, used the kevlar clutch with a slider, and the Bockscar Lakester. Always very good people to deal with. If you use a lockup clutch there is a learning curve. Understanding what it takes to unlock it at speed :-o can be an interesting adventure.
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MTC make lock up pressure plates for most anything and they work.
Good Luck,
Gary
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Our company can apply a 280grit metallurgically bonded carbide coating to the steels that will probably double clutch torque capacity with that being the only change. Extremely cost effective if it would work. Looking for racers that are looking to experiment. Forum member free for now. We could go rougher if need be but I dought if it will be necessary. We will also purchase the steels if you don't have any extras around. I feel pretty good about this potential application. Anybody want to try?
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It was very nice to meet you and see your car at the GNRS. Stainless is on his way home from the NWR. I will see if he can send you a Suzuki set. We could run our turbo motor on his dyno and see if we can blow something up :cheers:
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It was very nice to meet you and see your car at the GNRS. Stainless is on his way home from the NWR. I will see if he can send you a Suzuki set. We could run our turbo motor on his dyno and see if we can blow something up :cheers:
Super!
Lookin forward to seeing those parts.
If you want to get a better understanding about what we are doing here, visit www.carbinite.com
Please send parts to:
Carbinite Metal Coating
Attn: Rob
463 Brownsdale Rd.
Renfrew, PA 16053
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Rob,
Several years ago I tried sandblasting my steel plates in a CB350 race bike with a new set of aftermarket friction plates (not Barnett). The new friction plates lasted one weekend. I am not convinced that the aftermarket friction plates were not a little too thin to begin with, as I later realized that the CB350 clutch bottoms out long before the workshop manual claims, so that may have contributed. On my BSA B50 clutch with strong aftermarket springs and stock plates, I got about 9 or 10 runs before I lost my drive. Disassembling them revealed that the friction plates were not worn out, but the steel plates had burnished slick. So it seems that a proper roughness, perhaps 280 but I would guess maybe 600 might work well. But if the steel plates are too rough, the friction plates may wear out prematurely. Also, will the rough steel plates "clean" during use or will they clog up? It might be a good idea to add radial grooves as well to allow worn clutch material to escape.
I have just rebuilt my current clutch using Surflex (?) plates and adding an additional friction and steel for this year, as well as adding a new lower 1st gear. I do have some old steel plates, but they are rust pitted. Can you still process them? If not, I will try to source some good spares, pretty easy to find, and get back to you.
Tom
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My clutch slipped terrible last year. After the BUB event I bought a centrifugal lock-up, but I never had a chance to run it.
I have lots of steels around and would be happy to Guinea pig some. I will have the new engine on the dyno this weekend and have lots of other testing to do.
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A centrifugal lockup will hold turbo torque, stiff springs will hold quite a bit too. What engine? Dean
Dean,
like you, i misread this thread the 1st time thru.
robfrey is a vendor
... Looking for racers that are looking to experiment.
...Our company can apply a 280grit metallurgically bonded carbide coating to the steels that will probably double clutch torque capacity.
also like you, i see the solution for slipping clutches is not rocket science
1. make sure you have good condition frictions & steels, correct stack height
if it slips
2. use heavier springs
if it still slips
3. install a lock up
IT WON'T SLIP
There is surely something i don't understand here, but the thought of bonding any grit on the steels gives me the willies; seems like it would tear up the fibers.
robfrey,
please educate me.
karl
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I would be more comfortable experimenting with a 2 stroke where the trans/clutch oil is separate from the crankcase than with a 4 stroke even if its oil is filtered before going thru the rods/crank/cams etc. Microscopic ceramic particles if not trapped by filtration could be a source of worry. Just my thoughts, I am in no way saying their process would not hold fast to the steels. Robfrey, please understand, no disrespect to you or the process intended.
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Karl, for street use, I agree that the 280 grit would greatly accelerate clutch wear but I think race use where clutch maintenance is common place, I think it will be ok.
Clutch life will be very effected if clutch us slipped a lot. I don't know what is the commonly used shifting method for most LSR bikes so please excuse my ignorance.
Koncrete kid, we are trying to achieve the surface finish you got from sand blasting but with much more longevity.
If we can get clutch material to pack up on steels it will be a good thing. At least that is what the brake pad manufactures say which is a similar application.
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Rob: As long as I've been racing LSR bikes I've had it told me over and over to learn and perfect clutchless shifting. If you (or anyone else here) doesn't know it -- here's the story (as far as my not-that-technical brain knows it):
Bike transmissions are by a large of the type where all sets of gears are always engaged, and shifting gears really shifts between various of those sets. That can happen when the pressure of the engine trying to spin the drive side of the clutch (which is coupled to the driven side) is relieved momentarily. An easy way to relieve that pressure is to pull in the clutch lever, but another way is to relax the throttle for a short time. That removes some/all of the engine pressure/torque from the input side and allows the gear set to change. Power shifters (on bikes) accomplish this by interrupting the ignition for some few milliseconds (50 - 150 or in that range), and shifting by hand takes a minor amount or release of the throttle for about as quick as your hand can do the job.
The benefits of clutchless shifting include much less time off-power and the fact that the clutch is not disengaged/re-engaged, and that means the clutch see far less wear from slipping at a high-torque level. If the clutch, in other words, was well hooked-up -- it'll stay that way from one gear to the next. Clutch wear is reduced greatly.
Well done - it sounds dang near like a Lenco (car) transmission - that is, instantaneous.
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Slim,
This is good news for texture coated clutch steels. Sounds like the only wear will happen at the start. I'm feeling better about this.
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Rob,
I'm interested in working with you and have sent you a PM.
David
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Rob I think this could be a great application for the motorcycle engined 4 wheel streamliners. If they received a push-off to get up to speed a bit to engage the clutch without slippage I think it could really extend clutch life. I am very familiar with Slim's comments about clutchless shifting, I use to road race a 500cc Ninja and you didn't pull the clutch in unless you absolutely had to, with 55HP I had to keep those gerbils spinning at all costs! Does anyone manually clutchless shift the cycle engined streamliers or does everyone use air shifting?
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it took us quite a few years to get the clutches sorted on the twin engine 'liner.... at 2200lbs when she comes on boost it'll blow away the clutches even with lock ups on both motors... we worked with Mike at Barnet and he supplies several thicknesses of linings and stiffness of static springs, then we had to work on lock up weight... if it hooks up too much it'll snap a final drive chain or rip the trans right out of it..... solo bikes usually don't have this problem because of the weight.... took a while but we got just the right amount of clutch chatter in 2nd and 3rd....rapid clutch ware is not good on a bike motor as the material will plug up the oil pump pickup.... drag racing Busa's have this problem 2 sets of plates and ya gotta drop the pan or you'll loose a rod bearing....
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A change in the primary ratio which spins the clutch faster takes a twisting load off of it. The final gearing needs to be changed, too, to make up for the alteration in the primary ratio.
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We just did a set of aluminum drive plates for speedway bike over in Great Britton. I was not wild about coating the aluminum pieces as the bond strength is not near as good as steel but he stepped up so we did it. I will let you know what the outcome of the testing is as soon as I know it.
Clutch oil is not shared with crankcase on this application which is good.
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Just to throw a wrinkle in this discussion, being motorcycles are wet clutch and use a common sump for the engine oil and transmission (excepting H-Ds and designs with separate trans like 2 strokes), what effect does the viscosity of the oil create? To make an extreme example, if you use a 50 weight oil vs a 10 weight, does this have any change? I would think the thinner oil would work better for minimizing slip, since it would be better able to squeeze out? The idea is to not have an oil film between the steels and friction plates the way I understand this? I hope that I am explaining this right.
Since an oil film would reduce friction, would oil with lower film strength enable higher torque before the clutch slips?
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I agree, I would think a lighter oil would allow clutch to bite faster and harder.
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Here us a short video of what I've been trying to describe.
http://youtu.be/aEw6gyHQ_Wc
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Coating only one side?
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No, just demoing the difference .