Clutch Won't Engage Under Hard Breaking?? - Wrist Twisters
 
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post #1 of 10 Old 08-04-2007, 10:05 PM Thread Starter
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Clutch Won't Engage Under Hard Breaking??

Anyone have a problem with there clutch not engaging / allowing you to down shift under hard breaking? E.g. crusing around 40-45 in 6th gear and making an emergency or hard stop and the clutch lever is pulled all the way in but I get no response from the gear shift lever.

I have to pump the clutch and/or try to find a spot in the travel of the lever for it to engage. It's a little scary if I have to move out of the way after hard breaking and I'm not able to.

I took it to the dealer and they said it was because the idle was to high, so they lowered the idle to ~1000 and now the bike just runs ruff in 1st / 2nd gear at parking lot speeds. And still has the same problem as I found out today.

Any ideas on what this could be? I'm taking it back, but I'd like to have some clue as to what it might be when I talk to the service guys.

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post #2 of 10 Old 08-04-2007, 10:06 PM
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loose clutch cable? but i'd have thought the service guys would have seen that.



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post #3 of 10 Old 08-04-2007, 10:47 PM
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unless something is very screwy with the actual clutch itself.. and you've checked all the adjustment barrel screws you can find, you should have a little freeplay,, as in complete freeplay with the clutch lever all the way out...

that is of course unless you have a hydraulic clutch,, in which case this sounds simply like air bubbles in the lines,, or the piston....

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post #4 of 10 Old 08-05-2007, 12:16 AM
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A motorcycle trans is different from a car's in several ways, and these differences are causing your problem. First, car gear engagement pegs, or "dogs" as they are called in the industry, are much narrower, have tapered leading edges, and are much greater in number than on a motorcycle for the simple reason that car transmissions use a synchronizer ring that brings the gears into a proper relative speed before the dogs engage, eliminating the necessity of the dogs to do all the work of speed matching. Second, cars use a non sequential shifter -- it is possible to shift from top gear to first in one move. Not so on a motorcycle: it is necessary to engage each gear in turn in order to get from 6th to 1st, and that difference makes it necessary to think about being in the proper gear for the speed you want to go under all circumstances, including panic stops. Let me explain. Motorcycle gear engagement dogs are few in number and usually rectangular in section to handle the shock loads of shifting without breaking or wearing out in short order. About 60% of the time when shifting the dog shoulders meet and have to rotate relative to each other in order to fall into engagement: this can be felt as the lever moving only part way, stopping, then moving the rest of the way when the gear engages. At speed this is of little concern, but if you are trying to shift down a substantial number of gears without releasing the clutch each time, eventually the shoulders will meet, the shifter will partially move and stop, and since the clutch is pulled in there will be no relative motion to engage the next gear down, and the whole process stops there. As an illustration, try to engage 1st gear without the engine running -- most of the time it won't engage until the bike is rolled a short distance to bring the dogs into engagement.
What this boilis down to is the necessity developing the habit of downshifting whenever slowing down: it doesn't take long to get from 6th to 1st (under 2 seconds) regardless of the circumstances.
There is no defect in the drivetrain, you just have to learn to play by it's rules since it won't play by yours.

Rob

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post #5 of 10 Old 08-05-2007, 12:34 AM
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Yea, what he said....And do it quickly!

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post #6 of 10 Old 08-05-2007, 08:18 AM
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Probably an unnecessary point, but I assume that in your panic stop, that the rear wheel is not locked up. Once the rear wheel locks, shifting is out the question, not to mention the engine coming to a sudden stop. Other than that I have never heard of something like this happening.

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post #7 of 10 Old 08-05-2007, 08:55 AM
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Yes this happend to me when i first started riding my 06 919.. If i was in a high ger and came to a stop with out downshiftting it would not down shift after i had stoped .. now i downshift as i stop every time. but all you have to do let the cluch out slow it will try to go a little then, then pull it back in and downshift .. if your stuck in nutral just let out clutch and bring rpm up a little pull clutch back in and she with down shift for ya.. the engin needs to turn for the clutch be able to work right...I am no expert but this works for me...




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post #8 of 10 Old 08-05-2007, 10:00 AM Thread Starter
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I figured I would hear that it was operator error, but I do downshift while stopping under normal riding and use the engine for braking in addition to the brakes.

This only happens when I'm grabbing both levers brake and clutch really hard to make a "panic" stop. No, I'm not locking up the rear wheel. It's not often, but I'd like to know that I can...

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post #9 of 10 Old 08-05-2007, 10:32 AM
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Rob and Mikey are very good at explaning things. We're fortunate to have those guys around.

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post #10 of 10 Old 08-05-2007, 10:41 AM
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Rob is right on the money with his explination. You will have even greater or should I say shorter panic stopping distances if you can get your body in the habit of doing all these things in an emergency situation. A bike decelerates much faster with the assistance of the engines compression.

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