Harley Transmission Noise - Here’s What Can Lead to Problems

Harley Davidson motorcycles are incredibly durable, powerful and simply made to last. However, these iconic motorcycles are not exempt from natural wear and tear over time and can sometimes face problems.

Harley's signature rumble of the engine may be music to a rider's ears but can be a clear sign or symptom of trouble when it is replaced by other strange and unusual noises. 

Noises are usually the first sign of most transmission problems, generally caused by bad bearings, broken set of gears, or even damaged shift forks. Anyone with a Harley Davidson Motorcycle knows that the transmission is one of the most important key parts of your bike's drivetrain and requires considerable attention.

Here are three of the most common noises an owner of a Harley Davidson motorcycle may encounter that are clear indications of impending transmission problems. 

Constant Growling/Low Grumbling Sound

If you have been riding a Harley for a while, you may have experienced such constant growling or even a low grumbling sound coming from the transmission when it's running. These types of sounds are normally associated with bearing failures and should be attended to immediately.

Having bad or worn-out bearings will produce a growling noise when the transmission of your bike is turning.

When a bearing wears out or fails, it directly affects the transmission shaft. Since the bearing is worn-out and cannot support the transmission shaft the way it is normally supposed to, the transmission shaft ends up moving slightly out of position. As a result, the gears do not mesh properly.  

This cause and effect of the transmission shaft moving out of position due to bad bearings not only creates the sound but also puts excessive wear on the gears that are related to this function.

So, to fully solve this issue and avoid more add-on damages, it may be necessary to replace both the bad bearings and the affected set of gears. Do keep in mind that replacing a bad bearing and the gear set will require you to disassemble the entire transmission of your Harley.

Fortunately, there are a few simple techniques to determine exactly which bearing is the main cause of the problem. If you hear the noise with the clutch lever extended while the transmission is in neutral, then it is the main shaft bearing that has gone bad and needs to be replaced.

For the countershaft bearing to be at fault, the noise will be heard when the clutch is engaged with the transmission in gear.  

If you happen to hear the noise all the time when the engine is running, regardless of the clutch position, then it is your clutch hub bearing that may need your undivided attention.

Just remember that Harleys are bikes that are equipped with chain-driven primaries and can make similar noises if the chain is set too tightly. Therefore, don't forget to first check your chain tensioner before you jump to any conclusions and start tearing up into the clutch hub. 

If you have been riding long enough, you know that bearing failure due to bearings wearing out is a very common issue. Unfortunately, the leading cause of bearings getting worn out and losing their value is your standard wear and tear from everyday riding.

Although we cannot fight nature taking its toll, we can prolong the inevitable wear and tear through better maintenance, applying sufficient lubrication, and avoiding excessive load by not riding too hard or for too long.  

Clunking Noise

Transmission issues with Harley Davidson Motorcycles can be a little confusing and somewhat tricky to figure out at times. Especially for new Harley riders, it is very common to get it mixed up between an actual problem and a normal characteristic of your bike. The famous clunking noise coming from your Harley is the perfect example of such a scenario.  

When shifting into gear from neutral, your Harley most likely makes a loud clunking noise. From conducting focus group studies with their customers, Harley Davidson as a company came to an understanding that Harley riders love hearing the loud clunk when shifting the transmission to first gear.

So, to please their customers, Harley engineers designed it into the bike to make that clunking noise when going from neutral to first gear.  

Although the clunking noise is normal due to the design, it may also be a sign of trouble in some other situations. It is indeed normal and very common to hear a clunk sound as the power of the motor is met with the resistance of moving such heavy bikes as Harleys.

However, excessive clunking noise can also be the cause of something as crucial as having broken transmission gear.  

If you happen to hear any loud clunking sound while the transmission is in a particular gear, it could be the result of broken or missing teeth on one or more gears.

It is more common to hear the clunking noise in such cases during acceleration, but it can also be heard during deceleration in some cases. Either way, if the cause of the noise is due to broken gears, you will need to act fast for a solution before you end up in a much more catastrophic situation.

Broken teeth floating around in the engine can be a nightmare that you will definitely want to avoid. It can cause a tremendous amount of damage and could even lock up your Harley's gearbox.

Unfortunately, similar to replacing bad bearings, it is also necessary to disassemble the transmission to replace the broken set of gears.   

The main cause of gear failure is due to wearing down from constant usage. Even though it is bound to happen at some point in your riding journey, you can help extend the lifespan of the gears with good quality maintenance. Using the right gear oil designed specifically for those large Harley engines is a great way to avoid premature wearing of the gearbox.  

Transmission Pops out of Gear

If you are hearing your transmission popping out of gear, that can be a sign indicating that your gear dogs are worn out. As slipping is associated with the clutch being worn or out of adjustment, popping out of gear is most often caused as a result of worn "Dog Teeth" on the gear in the transmission.

Having bent shift forks can also be considered a reason in this situation as they too can cause your Harley's transmission to pop out of gear. 

For gears to engage, they need to slide on the transmission shaft with dogs on one gear engaging with slots on the adjacent gear.

However, if the dogs and slots are worn down or too rounded off, the dogs will tend to slip or bounce out of the slots when the engine RPM increases. This failure to engage will cause the transmission to pop out of gear and go into a false neutral.  

False neutral occurs basically due to an incomplete or unsuccessful gear shift. To accomplish a complete or successful gear shift, the gear dogs first have to release or separate completely from the previous gear and then engage in the next gear.

But if it cannot engage to the next gear, the upshifting of the gear fails and the transmission pops out, getting caught in between the two gears.  

When there is an incomplete gear shift, the shift forks also encounter excessive pressure from the transmission popping out of gear. Delaying to take action can and most likely will cause the shift forks to get damaged.

If that is the case, then you may end up having to replace the worn-out gears, damaged shift forks, and possibly even the shift drums.  

For most normal and frequent Harley riders, you are already aware of your bike's performance and know what to expect from your Harley. You know how to recognize when something is not right and understand the importance of getting to the bottom of the problem.

So, when you can hear and even maybe feel the transmission popping out of gear, you already know that there is a problem in hand and your Harley needs a check-up.  

Conclusion

Listening to the noises coming from your Harley's transmission while running is the easiest way to diagnose a transmission problem. These alarming noises can originate from several different areas both inside and outside of the transmission. Therefore, it is important to be able to recognize the different noises that may sound like trouble and take the necessary steps toward a solution as soon as possible to minimize the damage.    

The three different types of noises discussed in this article are some of the most common sounds that are associated with your Harley's transmission problems. Unfortunately, noises coming from the transmission usually indicate a series of serious issues.

So, diagnosing and repairing these types of problems generally require having to disassemble and replace parts such as bad bearings, worn-out gears, damaged shift forks, etc.   

Ignoring transmission problems will only make matters worse and much more costly in the end. If you sense that something is wrong with the transmission of your Harley, immediately take your bike to a qualified mechanic for a proper diagnosis. Remember, it is always much easier and cheaper to have to replace one particular part rather than the entire transmission.