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The Clutch


jps600rr
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I have a question about the use of the clutch in controlling the back wheel, if holding the throttle steady

helps the bike correct itself in a coner slide what effect does engaging the clutch have, if the clutch is used in its friction zone could we not regulate the power to the back wheel and control the slide with fine control?

Also what would be the effects on the bike dynamics, and ground clearance?

I am thinking of a rear slide not a front wheel slide.

 

To add to this I was reading an artical the other day that said if you get into a corner too hot, the throttle, or putting the bike in nuteral would work. (I think they mean engage the clutch.) but do not chop the throttle.

 

 

Sinice I ride on the street I have not created a real slide to test this theory of clutch control.

 

Any input would be apreciated.

 

Thanks. James.

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I find brake pads cheaper and easier to replace than clutch plates. I spoke at length on this idea many times but using the clutch becomes inefficient as well from a riding perspective and reduces a rider's control of the engine or go force.

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I have found on my CBR600RR that the off to on throttle reponse can be a bit abrupt,

instead of going completely off the throttle, sliping the clutch a bit when necessary

seems to smooth out the bike, it is usually only ncessary in very low speed turns.

Also holding the throttle open, and applying the brake gently keeps the bike very smooth.

 

It seems to be a common complaint from bike testers that the CBR's have an abrupt off to on throttle response, even at higher RPM's, but I have not seen an issue at the higher RPM's myself.

 

I agree that using the clutch at higher speeds most of the time is not good,

when I down shift too early, or if I don't like to the look of the road surface,

when shifting at higher RPM. I will let the clutch out in a controlled slow manner.

 

The track, and the street are different enviroments, and require a slightly different approach.

 

On the track using the clutch will cost you lap time, on the street using the clutch to modulate rear wheel power at the right time will keep you up right.

 

Thanks. James.

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One could spend a lot of attention using the clutch and to how much gain? Pretty much all the coaches at the school don't use the clutch up shifting, some don't even use it downshifting. I'd for sure have a hard time trying to modulate it going fast, nor would I want to take my left hand fingers off the bar. Don't know of any pro riders that do it (maybe some do, but I don't know of it).

 

On the trottle response being abrupt---is this a mapping issue? The ZX-6's are terrific, I'd assumed the Honda was pretty good, but maybe it's off?

 

Best,

CF

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I agree that not using the clutch at all is an advantage on the track, and this works well

when you can keep the bike in the high RPM's.certainly a 600

can be kept at very high RPM's. Riding like that requires space, and a known good surface.

 

Your comments are certainly directed to track riding.

 

Also the slipper clutch is standard on most bikes today, so clutch slippage is built in.

 

Part of my observations are that the sports bikes are realy designed for the track.

 

Thanks. James.

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I agree that not using the clutch at all is an advantage on the track, and this works well

when you can keep the bike in the high RPM's.certainly a 600

can be kept at very high RPM's. Riding like that requires space, and a known good surface.

 

Your comments are certainly directed to track riding.

 

Also the slipper clutch is standard on most bikes today, so clutch slippage is built in.

 

Part of my observations are that the sports bikes are realy designed for the track.

 

Thanks. James.

 

James,

 

Just to clarify, I use the same procedure for street riding, and riding in the dirt. Shifting up is easy, just rolling of the throttle for a moment. Down is only slightly harder, requires a little blip. It's harder on big twins, with big flywheels. Haven't ridden a Harley in a while!

 

Now, how about that throttle response on your CBR? One reason I ask, is for some is was the way the throttle cable was adjusted. I take all the play out personally, makes the transition easier for me.

 

Cobie

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Thanks Cobie for your input, I do blip the throttle but at low RPM the clutch makes it smooth, I will try it

without the clutch and see what happens.

 

Are you saying that it is possble to elimate most of the clutch useage apart from stopping?

 

Good input on the throttle, I take the free play out of the cable, and then roll on the throttle

smoothly when I feel the tension, but an adjustment here may help.

But that first crack open of the throttle is a very very small movement indeed on the CBR.

 

It's seems like a worth while investment to use your bikes at your school, and find out exactly

how the bike needs to be setup. Sinice I live in AZ that may be the best way to go anyway.

 

I need to check the school schedule to come work with you guy's.

 

Thanks. James.

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Thanks Cobie for your input, I do blip the throttle but at low RPM the clutch makes it smooth, I will try it

without the clutch and see what happens.

 

Are you saying that it is possble to elimate most of the clutch useage apart from stopping?

 

Good input on the throttle, I take the free play out of the cable, and then roll on the throttle

smoothly when I feel the tension, but an adjustment here may help.

But that first crack open of the throttle is a very very small movement indeed on the CBR.

 

It's seems like a worth while investment to use your bikes at your school, and find out exactly

how the bike needs to be setup. Sinice I live in AZ that may be the best way to go anyway.

 

I need to check the school schedule to come work with you guy's.

 

Thanks. James.

 

Yeah, come on out and play :) Will (our chief mechanic) has the bikes working very well, he really stays on that. But the clutch play thing can be a preference. Some like no play (like Keith and I), others like some play, like Will.

 

On some of the bikes the mapping for the fuel injection is not as good as it can be. The older ZX-10 was a little more abrupt, but the 6's are perfect.

 

As for the clutch, I virtually never use it after taking off from a start, and sometimes into 2nd gear. If you let the RPMs come down a bit, then you don't have to blip as much. That's correct for the track too, use the brakes to slow it down first. It can take a little practice, but can be done smoothely.

 

If you come out to the school, I can take you aside in the parking area and work on this with you, problemo.

 

Cobie

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  • 2 weeks later...

So cobie, what's the correct way to do the upshift and downshift without using the clutch? because i've got a bad esperienced using the clutch to do the upshift and downshift while riding more than 1000km journey.. my arm muscle was so much in sore an it was last for a month... hope you can explained more about this..

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For upshifting:

 

Back off the throttle enough to eliminate any lash in the drive train. At that point where there is neither acceleration or deceleration and everything is sort of "floating". (Especially inside the transmission.)

 

At this point there should be little or no resistance from the shift lever to shifting up. Then get back on the gas.

 

This is all done quite quickly. The entire process is faster than shifting up with the clutch though the exact timing will vary somewhat depending on the rate of acceleration or torque and revs just prior to the shift point. In other words, if one is not accelerating very hard there is already less lash on the trans/drivetrain to start with so less backing off would be needed. It does take some experimenting and practice.

 

Using the clutch essentially accopmlishes the same free floating lack of lash in the transmission by separating the tranny from the engine.

 

 

As for downshifting without the clutch:

 

It's sort of the same deal in needing to back off the gas and reduce lash but instead of just backing out of the throttle, one needs to incorporate a "blip" to match revs for the lower gear. It is quite a bit more difficult to learn to do smoothly in my opinion and I find it much easier to do on a two stroke road racer or dirt bike than a four stroke. (Probably because of the lighter crankshaft and flywheel rotational mass to create less drivetrain lash force in the gears to resist the shift.)

 

I definitely recommend mastering the downshift/blip while using the clutch before attempting to learn the clutchless downshift.

 

In any case, I don't generally use it on a four stroke motor except to impress myself or show off to a passenger in a car or truck. It just takes too much attention for me and I don't find that much is gained.

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Yikes! I typed a long reply and lost it :wacko:

 

Short version, Racer has described it fairly well on upshifting--simply roll off the throttle, and at the peak of the roll off upshift. The only real don'ts on this: Don't preload the shift leaver! Don't stomp on the lever, and if you miss a shift and get a false neutral, don't stomp on it until the RPMS come down.

 

Downshifting is matching the engine speed to the rear wheel, done with a blip of the throttle (small one), after you let the RPM's come down a little. Easier done using a little front brake at the same time.

 

Both of these are trained on our Control Trainer (that was the reason Keith made it). If you come out to the school, or we have it at one of the races, you are welcome to use it.

 

Best,

Cobie

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Yikes! I typed a long reply and lost it :wacko:

 

Short version, Racer has described it fairly well on upshifting--simply roll off the throttle, and at the peak of the roll off upshift. The only real don'ts on this: Don't preload the shift leaver! Don't stomp on the lever, and if you miss a shift and get a false neutral, don't stomp on it until the RPMS come down.

 

Downshifting is matching the engine speed to the rear wheel, done with a blip of the throttle (small one), after you let the RPM's come down a little. Easier done using a little front brake at the same time.

 

Both of these are trained on our Control Trainer (that was the reason Keith made it). If you come out to the school, or we have it at one of the races, you are welcome to use it.

 

Best,

Cobie

If you miss a shift (hit a false neutral) pull up (upshift.) It will go into gear much more easily than it will if you try to shift down. It can make the difference between going through a corner in the wrong gear vs. going through a corner with no way to get power to the wheel.

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I was in a big hurry yesterday as usual and...I guess I am again today..LOL...sorry.

 

I think the rider who understands how the mechanics actually work has a distinct advantage over simply trying to follow instructions but I will do the best I can in the short time I have.

 

For the clutchless downshifting you'll still need to reduce or eliminate the lash or backlash in the drivetrain. If you are slowing or braking for a corner there will be backlash or negative lash on the tranny. (Best words I can think of now)

 

Like backing off the gas removes accel lash while upshifting under aceleration, if you are decelerating you will need to add a bit of throttle to remove the lash in car/truck (or non-sequential tranny) mode where one must come out of gear and then match revs and enter new gear peferrably on the upswing of matching revs blip. However...

 

For a bike. if you are careful, you can begin to apply some pressure to the shift lever before you blip the throttle and the whole thing gets combined into one move. It takes very precise timing and attention so as not to come full on the gas before the gear shift. You have time the shift at that instant between being off the gas and on the gas. I can't say more now. Gotta go.

 

 

EDIT: OK, don't pre-load the shift leaver (sic).

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Oh, and being on the brake will also effectively remove lash or stress from the drivetrain . Good point Cobie. I hadn't even thought about that.

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To amend or clarify my previous posts...

 

There is a "sweet spot" in between being "on the gas" and "off the gas" where there is no pushing or pulling on the drivetrain either way. It is in this "sweet spot" when there is little or no pressure on the teeth of the transmission gears that they are essentially free to shift or slide over to engage the next gear. Same as when the motor is off and the bike is on the stand. Or when the clutch is engaged.

 

Simple enough, right?

 

Now, when a rider is off the gas, closed throttle, there is only enough fuel to turn the motor at idle speed. So the motor is being pushed or forced around more by the road than fuel and loads the transmission gears in the opposite direction from being on the gas. This is sometimes called "ENGINE BRAKING".

 

The lower the engine's RPM's while decelerating in gear, the less loading there will be on the transmisssion and the easier it will be to perform the clutchless downshift. You will still need to give a blip to the throttle to match revs for the next gear selection and you need to time that just as you come out of one gear and during the transition to the next. It may help to apply a little pressure to the shift lever first and then blip the throttle. When done right it is one continuous and smooth action.

 

It takes some practice to get the feel and master. It may also cause broken transmission gear teeth. Needless to say that will not make for a happy transmission. So, frankly, proceed at your own risk. Personally I don't consider this anything more than a novelty for riding on the street and of limited value on the track. I do not recommend trying it until you are an expert at downshifting like a master with the clutch. Chances are on the track you will end up doing it by accident in a wide-eyed moment of "whoa whoa" anyway. No need to rush it.

 

The truth is I didn't start downshifting without the clutch on motorcycles until I switched to two stroke GP bikes and I've never ridden or raced with a slipper clutch, so all of this may be somewhat less critical for those with slipper clutches, however, understanding the why of things helps me feel more comfortable and in control.

 

That's my opinion and it does not necessarily represent the opinion of the CSS and/or its staff. And they certainly have a proper program for learning it on specialized equipment at the school.

 

 

P.S. My gut agrees with Cobie that being on the brakes will help in and of itself but I'm not certain I know entirey why, yet. And it is snowing too hard to go experiment. I'm thinking perhaps it is simply a matter of helping to smooth out the the back-lash of gear engagement? Higher rev's, more engine braking again. Being on the brakes might help smooth out the pulses to not upset the suspension?

 

Generally speaking, the only time I intentionally used clutchless downshifting on a four stroke was when I wanted to catch a single gear and would be continuing upward on the throttle after the blip to immediately accelerate ...like because I got into a corner too hot and didn't have time to catch the last down shift before having to turn in, so, I'd grab the last one in a hurry at the apex sans clutch as I started to accelerate out of the corner. As opposed to banging four clutchless downshifts at the end of a straightaway. On the two stroke the back lash was minimal, just like the engine braking.

 

Anyway, I think Cobie read an early draft of this post. Perhaps he will enlighten me?

 

Questions? Comments? Thoughts?

 

Happy shifting!

 

Racer

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Previous post has been edited.

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  • 2 weeks later...

OR...

 

If a bike is equipped with a slipper clutch, the slipper clutch would be partially engaged under heavy braking with the rear wheel on the ground...hence, the downshifting will be easier because the clutch is already "slipping" and reducing engine braking forces on the transmission.

 

Only took me about ten days to think of that. Not bad considering I never rode with a slipper clutch...doh.

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  • 2 months later...

"Also holding the throttle open, and applying the brake gently keeps the bike very smooth."

 

I have a followup question on this .On my GSX600, if I let the throttle off completely, no matter how smooth I try to roll it back on, there is a definate thud in the responce. But experimenting with this idea of holding on a bit of throttle, and applying brake, it makes for a smoother transition out of a low speed corner. I have adjusted the cable to as tight as possible. I am having my dealer check the mapping as well.

Any thoughts from some of the more experienced on this? Is it something that a fairly new track rider should use? I am doing the two day camp at Barber on the 31st, so will be interested to see if the ZX6s have the same feel.

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"Also holding the throttle open, and applying the brake gently keeps the bike very smooth."

 

I have a followup question on this .On my GSX600, if I let the throttle off completely, no matter how smooth I try to roll it back on, there is a definate thud in the responce. But experimenting with this idea of holding on a bit of throttle, and applying brake, it makes for a smoother transition out of a low speed corner. I have adjusted the cable to as tight as possible. I am having my dealer check the mapping as well.

Any thoughts from some of the more experienced on this? Is it something that a fairly new track rider should use? I am doing the two day camp at Barber on the 31st, so will be interested to see if the ZX6s have the same feel.

 

Holding the throttle and then applying the brake---you mean the front brake? Or rear? If one has the front on, and keeps some throttle on, it can push the front.

 

The transition from off to on throttle should be smooth. Our 6's are great. Some riders are a little abrupt with their wrists, some have too much play in the throttle cable, sometimes the mapping is off. Cush drive being a little loose was one issue long ago on one bike. I personally like zero throttle play, just so it will not rev when twisting the front from lock to lock. This makes it easy for me to make that transition smoothly.

 

Are you going to have your bike at Barber--if so, you could have Will look it over.

 

CF

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"Also holding the throttle open, and applying the brake gently keeps the bike very smooth."

 

I have a followup question on this .On my GSX600, if I let the throttle off completely, no matter how smooth I try to roll it back on, there is a definate thud in the responce. But experimenting with this idea of holding on a bit of throttle, and applying brake, it makes for a smoother transition out of a low speed corner. I have adjusted the cable to as tight as possible. I am having my dealer check the mapping as well.

Any thoughts from some of the more experienced on this? Is it something that a fairly new track rider should use? I am doing the two day camp at Barber on the 31st, so will be interested to see if the ZX6s have the same feel.

 

Holding the throttle and then applying the brake---you mean the front brake? Or rear? If one has the front on, and keeps some throttle on, it can push the front.

 

The transition from off to on throttle should be smooth. Our 6's are great. Some riders are a little abrupt with their wrists, some have too much play in the throttle cable, sometimes the mapping is off. Cush drive being a little loose was one issue long ago on one bike. I personally like zero throttle play, just so it will not rev when twisting the front from lock to lock. This makes it easy for me to make that transition smoothly.

 

Are you going to have your bike at Barber--if so, you could have Will look it over.

 

CF

 

 

Cobie,

Thanks for your response. I will be doing the two day camp, so I will be using your bike. Mine is in the shop to check the throttle cable play, and mapping. I am sure I am guilty of getting back on the throttle way too late, and depending too much on some trail braking. I was refering to holding a very small amount of front brake, and very small amount of throttle, at the same time, to ease the transition back to a smooth acceleration out of the turn. Looking forward to learning more about this later this month.

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