Hopefully I can clear up any misunderstandings about transmissions and how they work. During this shpeel I may use slang for some components, but don't worry, there will be an explanation that follows. If you see that have written something erroneously or left something out, please feel free to troll in the comments section below.
Introduction: GNOMES DON'T EXIST
Transmissions don't run off of voodoo or black magic. There aren't any gnomes swapping gears out every time you pull up on the shifter. But as with anything else in life, the fear is derived from not knowing or the unknown. Hopefully I can clear up any misunderstandings about transmissions and how they work. During this shpeel I may use slang for some components, but don't worry, there will be an explanation that follows. If you see that have written something erroneously or left something out, please feel free to troll in the comments section below.
Well... How the F@&# does it work?
Lets get some terminology out of out of the way. Most transmissions on metric bikes have whats called a "constant mesh indirect drive transmission." The constant mesh portion of that tongue twister means that the gears are always meshed together and constantly moving... yes, even in neutral. Indirect drive refers to how the power flow enters and exits the transmission. Meaning power from the crank turns the clutch pack, which is attached to main shaft (input shaft), the main shaft has gears on it that turn the counter shaft (output shaft) which contains your front sprocket (hopefully I didn't lose anyone). Most people know that this is how "it" works, but don't know the details. The gears that comprise the transmission are unique. Types:
- Fixed gears - either made to the shaft or held in place on the spline of the shaft with a cir-clip. Typically first gear.
- Slider gears - these are the gears your shifter forks actually rest and and what moves when you shift gears. These also have "dogs" on them to transfer power horizontally. Some transmission configurations have multiple gears on one slider gear. The fork would rest in between the two gears and slide them into the corresponding counter shaft/main shaft gear. Slider gears can also be free wheeling too.
- Free wheeling gears - gears that aren't on any part of the spline on the shaft. They contain "dog houses" that accept power from the slider gears' dog and transfer it from main shaft to counter shaft.
Direct Drive Transmissions: Primaries or GTFO
Direct drive transmissions are primarily used in Harley Davidson motors. It's pretty much the same as the indirect drive transmission, but with a twist. The power input and output share the same shaft. Since this blog is primarily directed at metrics, I will leave this section for a different blog. But I will show you a basic picture of a Harley Davidson primary.
Second Gear Failures: Wheelie Much?
Bump here's the bread and butter to your question. Second failures can be attributed to several different things. Improper or "power shifting" will cause second gear to fail fairly quick. You ask why? Well, the travel between first and second gear is longer than the rest. Since you're shifting through neutral to get to second gear, it wears on the dogs of the slider gear. Not to mention it wears on the teeth of the gear. Each time second gear misses the engagement, and you get that little grind or stutter sound, it wears away on the dogs. Eventually what you get is second gear "jumping" out and back into neutral. Other gears aren't treated as rough as second, but over time develop the same wear. What happens to them is that the transmission will jump out of a lower gear which results in a "false neutral" effect.
Wheelie much? I left this little bit for all you stunters out there. I love a good second gear clutch just like the next person, but it can be one of the most devastating things you could do to your transmission. It can definitely do some major damage if the transmission has some mileage under its belt. I've found parts of teeth and dogs (lol - that sounds funny) inside of oil sumps. I'm not talking little tiny pieces, I'm talking distinguishable parts of the gear. Customers, particularly stunters and wannabe drag racers, would come in with a completely grenaded second gear. This one guy actually rode his bike around with no second gear for a few thousand miles. Love it.
Other components get worn and can cause similar symptoms as a worn gear. The shift fork wears down just like all other parts in the motor. As they become thinner the transmission is more likely to jump out of gear. The shift drum is another one of those components. If it develops a rut or the "channels" gets to worn it may not want to shift in correctly. To prevent premature wear on the shifting mechanisms don't rest your ball of your foot on the shift. That a lot of standard riders do that because of the way you sit on the bike. It puts pressure on the shift drum which puts pressure on the shift forks.
***If you have any questions about this articles or would like to see something blogged let me know.***
Wheelie much? I left this little bit for all you stunters out there. I love a good second gear clutch just like the next person, but it can be one of the most devastating things you could do to your transmission. It can definitely do some major damage if the transmission has some mileage under its belt. I've found parts of teeth and dogs (lol - that sounds funny) inside of oil sumps. I'm not talking little tiny pieces, I'm talking distinguishable parts of the gear. Customers, particularly stunters and wannabe drag racers, would come in with a completely grenaded second gear. This one guy actually rode his bike around with no second gear for a few thousand miles. Love it.
Other components get worn and can cause similar symptoms as a worn gear. The shift fork wears down just like all other parts in the motor. As they become thinner the transmission is more likely to jump out of gear. The shift drum is another one of those components. If it develops a rut or the "channels" gets to worn it may not want to shift in correctly. To prevent premature wear on the shifting mechanisms don't rest your ball of your foot on the shift. That a lot of standard riders do that because of the way you sit on the bike. It puts pressure on the shift drum which puts pressure on the shift forks.
Wow, you really broke that down. I can't believe you can actually ride with such a severely damaged gear. I would think that the parts would float up and jam other things. Great piece man, I look forward to more of your work.