[gsxr6racer]

Couldn't it be just as abusive to use the clutch improperly?? Say on a downshift you are a green rider (not to pick on anyone, just as an example) and you don't understand the logic of rev matching. Say like my wife, and you jam it down a couple of gears and drop the clutch? Is this not worse/more abusive than me down shifting wihtout the clutch but matching revs? I do shift with and without the clutch on both up and down shifts depending on my mood. If I am matching revs properly is it not about the same thing as using the clutch? It was in my mind...

[The CyberPoet]

Couldn't it be just as abusive to use the clutch improperly?? Say on a downshift you are a green rider (not to pick on anyone, just as an example) and you don't understand the logic of rev matching. Say like my wife, and you jam it down a couple of gears and drop the clutch? Is this not worse/more abusive than me down shifting wihtout the clutch but matching revs?

No. It's not as abusive to use the clutch, even when used poorly.

It's a matter of where the excess energy goes. When you use the clutch, even poorly (too fast, too slow, seriously mis-matched revs), the majority of the excess energy from the mismatched speed of the parts passes into the clutch plates and turns to friction (which in turn becomes heat, just like in the brake pads when you squeeze the brakes). This heat gets carried away by the engine oil when the clutch opens again.

When you don't use the clutch, that mismatch gets absorbed the other parts of the system -- parts that aren't designed to take the shock or at least not the majority of it (such as the gear faces, the wrist pins for the pistons, the chain's O-rings, the cush drive at the rear sprocket, the sprocket teeth).

More-over, the concept of matching rev's while downshifting clutchlessly in a sequential-engagement transmission is a misnomer. Since there is no "neutral" between gears in a sequential-engagement tranny, there really isn't any point at which the revs can simply fall away or rise during the actual shift, meaning that 1k of RPM differential (or whatever the spread is at your particular RPM) suddenly engaging generates energy that has to go somewhere... Back to that list of parts that takes the hit. Since tranny gears are usually made of softer metals than crank, conn rods, output shafts, etc., they tend to take the majority of the abuse, with some of it then cascading outwards through the system in both directions (towards the engine and towards the rear wheel).

Cheers,
=-= The CyberPoet

[gsxr6racer]

No. It's not as abusive to use the clutch, even when used poorly.

It's a matter of where the excess energy goes. When you use the clutch, even poorly (too fast, too slow, seriously mis-matched revs), the majority of the excess energy from the mismatched speed of the parts passes into the clutch plates and turns to friction (which in turn becomes heat, just like in the brake pads when you squeeze the brakes). This heat gets carried away by the engine oil when the clutch opens again.

I realized this when I went to bed... didn't think that out completely did I. I completely follow what you are saying and I agree there is no way to not abuse the transmission without using the clutch. What I described would abuse the clutch and possibly cause a slide but would not affect the transmission at all. I still shift without the clutch from time to time, can't help it now, it's one of those bad habits now!

[MinnGreenGT]

OK, so call me a bit confused. I've been reading Lee Park's "Total Control: High Performance Street Riding Techniques" and I just finished reading Chaper 10: Shifting.

The following image was created by combining pages 65 & part of 66 for the purpose of readability... Click the Thumbnail to see a "readable" version:


He writes:
"The basic upshifting technique involves preloading the shift lever by pressing your foot down with just slightly less force than that needed to engage the next gear. Next, quickly roll off the throttle approximately 25 percent of its twisting range. When this happens, the torque force on the transmission will temporarily unload, and the preloaded shift lever will now snick into the next gear. For regular shifts at less than full throttle, a simultaneous, light stab of the clutch will help ease this process."

He then goes on to point out:
"For full-throttle "speed shifting," no clutch is necessary. In fact, it's actually harder on the transmission to use the clutch in this type of situation than to just let the loading forces do the job."

According to this text, under full throttle acceleration, using the clutch is actually harder on the tranny... so really the answer should be "acceleration dependent". Right?

[The CyberPoet]

OK, so call me a bit confused. I've been reading Lee Park's "Total Control: High Performance Street Riding Techniques" and I just finished reading Chaper 10: Shifting.

According to this text, under full throttle acceleration, using the clutch is actually harder on the tranny... so really the answer should be "acceleration dependent". Right?

Three things come to mind:

(A) Is Lee Parks an engineer at Suzuki? No, he's a self-admitted rider who came up through the racing ranks from ice racing on RM80's to WERA endurance racing and 125 GP class racing (see www.leeparksdesign.com/aboutus.asp). This means he carries a racer mentality when it comes to shifting (no value judgement there -- I'm sure his skill set is great and he can probably out-ride me any day of the week, but it also means that he's inevitably used to having such repairs on a regular basis as a result of his use of bikes).

(B) Even the article you posted says to use the clutch in down-shifts, which is where I was placing the heavy emphasis (because downshifting sans clutch is the most damaging). He even states that for upshifting at anything shy of WOT [Wide Open Throttle], the clutch should be engaged momentarily with upshifts, which is what I generally recommend (momentary clutch engagement). Add in that most street riders don't ride WOT on a regular basis -- that's usually left for the track

(C) He mentions that some bike's transmissions are not designed to handle clutchless up-shifting without modification. Is the stock Suzuki transmission design shared by the GSXR & GSXF series perhaps included in this list (and omitted because he doesn't know otherwise)?

Cheers,
=-= The CyberPoet

[MinnGreenGT]

CP - thanks for addressing my post!

(A) Is he an engineer? Nope (quite the contrary from his writings). Good point... although I'd have thought that at least one person he consulted would've at least mentioned this. Guess not. But definitely a good point!

(B) Clutching Downshifts - YES! I definitely agree that no matter who you are or what you're riding... you had better be clutching the downshifts (unless you want to end up with a closer inspection of the pavement).

(C) Transmissions. Although I see your point about his lack of specifics when mentioning boxes not designed for clutchless up-shifting... I personally feel that his point is clear as to which brands & kinds of bikes would not respond well to this type of maneuver.

Again... thanks for your response - it defintely shines a better light on the text!

[TurboMike]

And from the Poet's reply:

E) he doesnt have to rebuild his own tranny

D) he doesnt have to pay for his tranny

F) he has a team of mechanics rebuilt it to better n' new after each race

[gsxr6racer]

(B) Clutching Downshifts - YES! I definitely agree that no matter who you are or what you're riding... you had better be clutching the downshifts (unless you want to end up with a closer inspection of the pavement).

I don't think that is the big concern, I can clutchless downshift all day as smoothly as I can with the clutch. I think I am not doing my tranny any favors if I do it, that's all.

[gibwar]

So now we're talking about clutchless shifting hookers

Clutching Shifty Hookers?

=-= The CyberPoet

I suppose it is bad that when I originally read this title... I thought it was crotchless shifting? ...

[Paladin]

I've tried the clutchless shift by blipping the throtle and a smooth shift up. I always use the clutch on downshifts. Smooth shifting is something I strive for in every case.

[md86]

(B) Clutching Downshifts - YES! I definitely agree that no matter who you are or what you're riding... you had better be clutching the downshifts (unless you want to end up with a closer inspection of the pavement).

Broke SOMETHING (thought it was the cable) on the way home one night and had to get home with no clutch . I didn't meet the pavement . NOT something I'd wanna make a habit of , though . Takes a little more effort to figure out how to do it than upshifting .