Shifting

Started by FastBoy, January 01, 2003, 12:37:51 PM

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TZ_Boy

Quote???Mechanical advantage is found at the shift pedal, at the shift mechanism behind the clutch and on the drum itself.  I was wondering what your engineering diploma says.  Mine says Bachelor of Science in Engineering from The University of Iowa.  Although I did not get to take the class "dynamics and kinesiology of a sportbike transmission", I did read the textbook. ;D
Iowa, I thought there was just Corn in Iowa?
The shift mechanism behind the clutch is the shift drum!

BC61

QuoteI think we are getting closer to understanding each other.
From reading your reponse I don't think you truly understand "blipping". The intent of blipping the throttle is to match revs between a lower gear and higher gear to prevent unbalanceing the rear wheel during down shift.

How about an example.  Let's say that you are in 6th gear and doing 100 mph, off the gas and slowing down.  If you give it just a little bit of gas, you don't start accelerating.
There is about a 4,000 rpm difference in gears. How are you going to match the revs of a lower gear that requires approximately 4,000 more rpm to run the same speed without the clutch?

You have to give it enough gas to overcome the deceleration before you start accelerating again.  that split second where you go from deceleration to acceleration is when there is no load on the tranny.
Blipping is not about unloading the tranny to shift. It's about rear wheel control, reason why you don't need to blip with a slipper clutch. The slipper cluch absorbs the shock of not matching engine revs between gears.







tcchin

Blipping on trailing throttle for the purposes of downshifting can be accomplished without  accelerating by virtue of the fact that the drivetrain has lash in it. This means that the lower gear is selected and fully engaged before the drivetrain can fully reverse its load condition and before any drastic changes have been made to the engine speed. Granted, this is not a technique for the hamfisted, and should probably be avoided if one is inclined to attempt to upshift without changing either the throttle or clutch positions.

BTW, bweber, shame about that Orange Bowl, eh?

BC61

There is no need to blip the throttle with a slipper clutch.

BC61

QuoteI think it is obvious that when you upshift under full power, you should roll off the throttle as you engage the clutch as not to rev the engine. With dexterity and practice this becomes second nature and you don't even think about the movements.
I am not telling anyone to leave the throttle pinned, pull the clutch in to the bar, slowly depress the shift petal, and drop the clutch as you roll down the front straight.  Lets be reasonable ;).

Never said full throttle cluchtless shifting was best technique but it is do able and does have it's place.

bweber

Hawks at the Orange Bowl, it was nice for the first half, but I knew it would not last.  I think someone paid off Brad Banks.  It was like watching Ronnie Harmon Fumble the ball in the Rose Bowl in the 80's!

The mechanism behind the clutch I was referring to is the arm that attaches to the shift shaft, that attaches to the shift rod, that attaches to the shift pedal.  That arm grabs the drum and rotates it to shift gears.  The drum has spiral cut groves to move the shift forks according to the position and rotation of the drum.

I know. You don't need to blip the throttle whith a slipper clutch... That is what I said, twice! This makes three times.

BC61

#42
Quote

I know. You don't need to blip the throttle whith a slipper clutch... That is what I said, twice! This makes three times

It seems others still don't grasp the concept. ::)

Thingy

QuoteI think we are getting closer to understanding each other.
From reading your reponse I don't think you truly understand "blipping". The intent of blipping the throttle is to match revs between a lower gear and higher gear to prevent unbalanceing the rear wheel during down shift.

How about an example.  Let's say that you are in 6th gear and doing 100 mph, off the gas and slowing down.  If you give it just a little bit of gas, you don't start accelerating.
There is about a 4,000 rpm difference in gears. How are you going to match the revs of a lower gear that requires approximately 4,000 more rpm to run the same speed without the clutch?

You have to give it enough gas to overcome the deceleration before you start accelerating again.  that split second where you go from deceleration to acceleration is when there is no load on the tranny.
Blipping is not about unloading the tranny to shift. It's about rear wheel control, reason why you don't need to blip with a slipper clutch. The slipper cluch absorbs the shock of not matching engine revs between gears.


I agree with you completely that blipping the throttle is intended to match engine speed to wheel speed.  That doesn't mean it is the only reason for doing something, does it?  I thought you were trying to understand why you blip with no clutch.  ONE reason is to unload the tranny.  It doesn't mean it is the only one.  

I agree with all of your points in your last post, except the 4000 RPM part.  My bike does not have gears spaced that far apart and I do not blip my throttle 4000 RPM when downshifting.

Regardless, I think we are both on the same page.  I think we are now describing the same thing, just differently.

You are talking about matching the engine speed to the wheel speed.  I am talking about matching the the DRIVE gears speed in the tranny to the DRIVEN gears speed in the tranny. (and also unloading the tranny, while we are at it)

So, are we describing the same thing but still not answering your question?  
-Bill Hitchcock
GP EX #13
Double Bravo Racing
'01 Ducati 748

Tuck your skirt in your panties and twist the throttle!

Thingy

QuoteI know. You don't need to blip the throttle whith a slipper clutch... That is what I said, twice! This makes three times

It seems others still don't grasp the concept. ::)


See, you understand Brian.  I was IMing Brian about this.  Brian and I understand each other.  You and I just can't seem to understand each other. :)
-Bill Hitchcock
GP EX #13
Double Bravo Racing
'01 Ducati 748

Tuck your skirt in your panties and twist the throttle!

TZ_Boy

#45
QuoteThe mechanism behind the clutch I was referring to is the arm that attaches to the shift shaft, that attaches to the shift rod, that attaches to the shift pedal.  That arm grabs the drum and rotates it to shift gears.  The drum has spiral cut groves to move the shift forks according to the position and rotation of the drum.
.
The arm is the shift shaft.  The arm also provides the shiftshaft with mechanical advantage. :P

sdiver68

Just one question...

My Ducati 996 has an Evo Slipper Clutch.  Should I blip the throttle on downshifts?  ;D  ;D  ;D
MCRA Race School Instructor

ceesthadees

I want sdiver's budget. His clutch costs more than my trailer!