Clutchless shifting


Technical information and Q&A applicable to all years and models of Goldwings
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propstop
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Motorcycle: 1983 GL1100A Aspencade

Clutchless shifting

Postby propstop » Sun Nov 08, 2009 11:46 pm



Does it hurt a bike to shift into a higher gear without using the clutch?



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Re: Clutchless shifting

Postby WingAdmin » Mon Nov 09, 2009 8:01 am

It depends.

Are you able to match engine speeds exactly? If you are, then it shouldn't hurt anything. If you aren't then every time you shift, you're taking a bit of metal off the transmission gear dogs as they grind a bit bringing the engine speed up (or down) to match the wheel.

When you use the clutch, and you shift gears, the appropriate gear is slid into place on the countershaft. Three metal posts, or gear dogs, slot into three slots into the gear next to it. If the mainshaft (the shaft with gears that is normally connected to the engine output by the clutch) is already at the correct speed, these dogs fit right into the slots. If not, then there is a bit of pressure, and potentially, grinding, as the gear dogs rotate past the slots they should be fitting into. However, all they have to do is to bring the rotational speed of the mainshaft up or down to match the countershaft, and there isn't a lot of mass there, so it happens fairly quickly, and without much drama.

Countershaft, showing dogs and slots
Countershaft, showing dogs and slots


However, in a clutchless shift, the mainshaft is still attached to the engine by the clutch. So if there is any disparity in the rotational speed of the mainshaft and the countershaft (when the new gear is engaged), not only do the dogs have to bring the mainshaft up (or down) to speed, they have to deal with the entire rotational mass of the engine - and that's QUITE a bit more than just the mainshaft. The result is worn dogs - the little "posts" get rounded shoulders. The problem with worn dogs is that they tend to be more likely to "pop" out of their slots, and this is what is happening when you find the transmission suddenly pops out of gear - perhaps when you didn't get it entirely into gear.

Clutchless shifting is useful on the racing track where shaving a few hundredths of a second off a shift time can make a difference. On a big bike like a Goldwing, with its big engine, I really don't see the need, nor would I recommend it.

propstop
Posts: 17
Joined: Wed Aug 19, 2009 10:27 pm
Location: Louisiana
Motorcycle: 1983 GL1100A Aspencade

Re: Clutchless shifting

Postby propstop » Mon Nov 09, 2009 9:07 am

The only time I have been shifting clutchless is from 3rd to 4th and 4th to 5th. The shifting is actually a lot quieter. Thank you for your response and I will take your advice. I was just being lazy, but I sure wouldn't want to hurt my lil darlin!

edgrimly
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Location: Michigan
Motorcycle: 81 GL1100

Re: Clutchless shifting

Postby edgrimly » Mon Feb 15, 2010 11:24 am

Clutchless shifting in racing does not save any seconds. The clutch is actually more abused in racing as feathering the clutch will give the bike a short surge of power from the engine revving up when the clutch is pulled in and then dumping the clutch to release that power to the rear wheels.
There is no real difference between shifting the bike with the clutch engaged or disengaged if done correctly. It is actually easier to shift incorrectly when using the clutch then when not. The force on the gears tends to keep them in gear unless you have a wear problem. Once the force is released (and no counter force such as engine braking when throttle is completely closed) the gears will easily change from one position to another. This is the exact same thing that pulling in the clutch does. It relieves the pressure from the gears so they can change position. Damage to the engagement cogs can occur when the gears do not slide fully into the new gear position and the POP out of position back into a lower gear. This will wear the edges off the cogs and promote poor engagement. The only way to fix this is to either file the cogs and slots or replace the gears.

Some bikes have known problems with the engagement between gears. Some years of the Honda Nighthawk have engagement problems into second. 2003 Yamaha Raptors actually break the second gear due to weak design, etc etc... Second gear is the touchiest change due to the massive amount of torque and dramatic change in gear ratios. Personally I use the clutch from first to second and no clutch for the rest of the shifts. This requires no load on the gears (neutral throttle setting, no accel or decel) and a firm shift so there is no partial engagement. In drag racing shifts are generally made with the clutch as you can relieve the pressure on the gears for the shift without letting off the throttle and keeping the engine revved into the powerband for more power every shift. Chances of a misshift in this situation is much higher then a gentle slight release of the throttle and a shift.

There again, this is only my opinion after 35 years of riding and 30 years of working on bikes.




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