There are many significant parts of your motorcycle system that make it operate on the road, and motorcycle transmission is undoubtedly one of them. Motorcycle transmission is one of the key components of your bike, and it has two primary purposes:
- It maintains the engine speed in the proper range regarding vehicle speed
- It lets the engine rotate free of the wheels while the vehicle is static
Every motorcycle rider should know how his transmission works and functions, but not everyone knows it. That is why we will teach you all the most important things that you should know about transmission work.
How does a motorcycle transmission system work? A motorcycle transmission connects and disconnects the motorcycle engine. It shifts energy out of the engine to the gear set. It is responsible for supplying the back wheel with power, which means that it is responsible for shifting energy.
Further in the article, we will explain transmission itself and everything related to it more in-depth, so stay with us because you don’t want to miss anything.
Table of Contents
How Does a Motorcycle Transmission Work?
A good way to know how a motorcycle transmission functions are to analyze a power flow diagram. With this diagram, we can see what happens to a motorcycle when it is in first gear:
- Engine power moves into the main shaft of transmission through the clutch.
- M1 gear is a fixed gear that rotates at the same speed as the main shaft.
- C1 gear, called freewheeling gear, continually interacts with M1 gear.
- C5 is a slider gear; the countershaft rotates when it interacts with C1.
- Power is transmitted from the transmission to the drive chain through the sprocket.
This power flow diagram represents what occurs to the transmission when we shift a bike in fourth gear:
- Engine power moves into the main shaft of transmission through the clutch
- M4 gear is a fixed gear that rotates at the same speed as the main shaft.
- C4 gear, called freewheeling gear, continually interacts with M4 gear.
- C2 is a slider gear; the countershaft rotates when it interacts with C4.
- Power is transmitted from the transmission to the drive chain through the sprocket.
The last power flow diagram represents what occurs to the transmission when the motorcycle is neutral.
- Power moves into the main shaft of transmission through the clutch.
- M1, M4, and C3 gears combine with freewheeling gears.
- The countershaft doesn’t rotate.
Motorcycle Transmission Specifics
As previously mentioned, a transmission does two significant tasks. But it is placed in a compact way to stay light and small. A stand-alone transmission attached to the motorcycle engine and driven by the outer primary drive can be found on many Harley-Davidsons. In contrast, a design in which the engine and transmission are one unit can be found on most other motorcycles.
Automatic Motorcycle Transmissions
The majority of motorcycles have a manual transmission through a hand-operated clutch and a foot lever. Automatic transmission is rear and is used in a couple of forms mentioned below:
- Electric motorcycles- it is not entirely automatic but doesn’t need manual shifting
- Continuously Variable Transmission (CVT) used in mopeds and scooters
- Honda’s Dual Clutch Transmission (DCT) uses full automatic mode
An automatic transmission has a similar function as a manual transmission, letting the motorcycle stop while running the engine. The rider doesn’t have to shift any gears like he would have to in the case of the manual transmission.
Motorcycle Transmission Parts
Many inner and outer parts are being used for motorcycles transmission to sustain the best possible RPM span.
- Input-main shaft: The engine drives it through the clutch pack, the transmission gets power through it.
- Output-countershaft: The main shaft runs it; a driveshaft or a sprocket is used to send the power of the output (countershaft) to the final drive.
- Bearings: They let the transmission shafts rotate accurately and free and are pressed against the external transmission or engine case.
- Gears: Motorcycle transmission has three gear types: slider, fixed, and freewheeling. Two permanently connected gears create a gear ratio, which means that a six-speed transmission consists of 12 gears.
- Fixed gears: are connected pieces of the main shaft or countershaft and spin at an identical speed.
- Freewheeling gears: rotate separately from the countershaft or main shaft. Protrusions are made on their sides, allowing interaction with a neighboring gear.
- Shift drum: Its purpose is to regulate the motion of the shift forks.
- Slide gears: Rotate along with the shafts
- Shift fork: It regulates the horizontal motion of the slider gears.
- Shift linkage: It combines the shift drum with the foot-operated gear selector. When the driver shifts gears, the shift linkage spins the shift drum, making the shift forks shift slider gears interact with their neighboring freewheeling gear.
Frequent Problems With Motorcycle Transmission
Although modern motorcycles are very high-quality products, some problems could still happen with their transmission system. These are the most common reasons about which most motorcycle owners complain:
- Jumping out of gear
- Difficult (hard) shifting
- Clunking sounds
- Neutral is hard to find
A qualified technician is able to distinguish the clutch problem and a transmission one since they both may represent similar concerns for a motorcycle owner.
Accessing a motorcycle transmission can take a lot of time and be quite a challenging process. Before opening the cases and accessing transmission segments, a technician will look for any other possible issue of the complaint and try to solve it if there is any.
What Leads to Motorcycle Transmission Problems?
1. Malfunctioning Shift Mechanism
A motorcycle shift mechanism is a crucial part of the entire transmission process. If there is a problem in the mechanism process, your motorcycle’s transmission could face problems.
2. Gear or Shaft Corrosion
Corrosion will likely happen on gears and shafts if you don’t take care of your motorcycle, which will lead to transmission issues. Corroded shafts and gears produce strange and unusual sounds and run clunky.
3. Bearings and Gears Worn out
Your transmission will fail if your bearings and gears wear down. If you want to diagnose if this is a reason leading to failing transmission, you will need to listen to sounds coming out of the motorcycle’s transmission.
4. The Tension of the Chain
If your chain tension is set incorrectly, it will also lead to transmission problems. Make sure that your chain tension is placed as it is suggested in your motorcycle manual. That way, you will avoid problems related to chain tension.
5. Worn Dogs
Worn and torn dogs can happen in cases where a rider doesn’t shift the correct way, a malfunctioned shift mechanism, or there are bent shifting forks. All of these states will lead to transmission problems.
6. Clutch Drag
Clutch drag can lead to gear clashing and rigid shifting and therefore cause severe transmission problems. Clutch drag happens when a rider presses the clutch lever, and the clutch doesn’t disengage entirely. This leads to rugged gear changing and produces clanking noise.
7. Low Level of Transmission Oil
Engine oil is a very important lubricant and has a significant role in lubricating the engine and clutch. Low oil levels can lead to transmission failure because the oil lubricates transmission components and prevents metal-on-metal friction, which could lead to serious issues.
Take a look at this nice animated video that explains how transmission works:
Final Thoughts
Transmission can be one of the most frightening driveline parts for motorcycles owners since transmissions are hard to access, complex and expensive. This comes down to a technician’s job security since they know how transmissions work and how to fix them.
Experience and practice are very important factors that enable a technician to spot and fix transmission problems faster.