Harley 6 Speed Transmission Problems? Help Is Here, Trust Me

Almost every Harley enthusiast wearing a wrench as a badge of honor has faced it – the dreaded Harley 6 speed transmission problems. The irregular grinding noises, that sudden clunk-shifting, or even the fear of being left stranded in the middle of nowhere, can send shivers down your spine. Yet, this is where your love for Harley Davidson and your gritty DIY spirit come together. Rest assured, help is around the corner (and you don’t need to be a technical wizard to understand it).

This easy-to-follow guide will tackle your Harley Davidson 6 speed transmission problems step-by-step, turning the haunting problem into a source of empowerment. Whether you’ve just noticed the first signs or you’re knee-deep in troubleshooting, this is the down-to-earth advice you need, straight from a seasoned biker who’s been there, solved that. Let’s rev those engines back to life!

Table of Contents

What Are The Worst Harley 6 Speed Transmission Problems?

Here's a parts diagram for all Harley 6-speed transmissions. — Parts diagrams like this are a good way to gather an understanding of how the internals of a transmission work together. For more information, check out the provider: Zodiac Original Parts

There are several issues that riders have reported with the Harley 6-speed transmission. Here, we discuss four of the most common problems:

Whining Noise From The Primary

One of the most common complaints about the Harley 6-speed transmission is a constant whining or growling noise that seems to originate from the primary case. This noise often increases with the bike’s vibrations, causing discomfort to the rider.

What Are The Potential Causes?

There’s a myriad of potential reasons for this noise. Some speculate that Harley-Davidson is aware of the issue and that the noise can be traced back to the spur gear used in the 6-speed transmission. Others suggest that changing the spur gear to a helical one could solve the problem.

Related: Man o’ War Compensator Problems: Identifying Common Issues and Solutions

Complete Transmission Failure

This video is titled “Harley 6 Speed Transmission Problem”; however, you’ll quickly see that there were some shenanigans that led to this situation.

Another common issue reported by Harley 6-speed transmission owners is total transmission failure. This typically occurs when the transmission has clocked significant miles, with the most common breaking point being the inner primary bearing, not the gears.

What Can Lead To Total Failure?

A busted transmission could occur due to stress from letting your motorcycle lunge forward in sixth gear, which is past the 1:1 ratio in the gearbox per engine revolution. This puts unwanted pressure on the inner primary bearing, potentially leading to complete failure. However, there are other reasons as to why this can happen… (see video above)

This is a picture of the double roller bearing that makes up the inner primary bearing. — This is the primary point of failure we’re talking about – the inner primary double roller bearing.

Spontaneously Pops Out Of Gear

Some riders have reported that their Harley 6-speed transmission tends to spontaneously pop out of gear. This usually happens when shifting down from sixth to fifth or from third to second gear.

Why Does A Transmission Pop Out Of Gear?

While there are several potential causes for this issue, it mostly occurs as the transmission ages. It could also be due to a problem with the shift fork or gear engagement dogs.

Related: Harley Goes Into Gear But Won’t Move? Help Is Here!

Dragging At Low Speed

Another common Harley 6 speed transmission problem is that the transmission or clutch tends to drag at low speeds. This makes it hard to stay in the friction zone, leading to a jerky ride.

What Causes The Transmission or Clutch To Drag?

This issue could be due to using the wrong type of oil for refilling the transmission. It could also be a clutch problem or an issue with the compensator.

Internal Bearing Failure

In addition to the problems mentioned above, premature damage to the trap door bearings and the main shaft’s main ball bearing is another common issue.

Here's an example of the clutch hub bearing that goes bad in Harley Davidsons. — While (nearly) impossible to tell visually, this is a clutch bearing that has gone bad.

Why Do Bearings Fail Spontaneously?

Bearing failures could occur due to the clutch pack’s distance from the shaft support, which leaves the main shaft and clutch pack unsupported at the end. The primary chain’s tightness and the secondary drive belt both contribute to the stress on the main shaft bearing, leading to premature transmission failure and sometimes, an early rebuild.

When Did Harley Go To A 6 Speed Transmission?

Harley-Davidson introduced the 6-speed transmission in 2007 with the launch of the Twin Cam 96, a new Big Twin engine. The new transmission was featured in all models in the Harley-Davidson Dyna, Softail, and Touring product families.

Which Models Have The 6 Speed Transmission?

The 6-speed transmission was used in all Harley-Davidson models from 2007 onwards, including the Dyna, Softail, and Touring families. However, Softail was one of the most popular models affected by these transmission problems due to its unique rear-wheel suspension design. However, these transmission problems have also been frequently reported in the Milwaukee Eight series.

Related: Dyna Vs Softail: What’s The Difference?

Specifically, these issues are found in Milwaukee Eight 6-speed transmissions.

Which Are Most Affected By These Problems?

While the issues mentioned can occur in any Harley-Davidson model with a 6-speed transmission, Softail models have been reported to be more susceptible due to their unique rear-wheel suspension design. Many Softail owners reported experiencing transmission failure after reaching over 50,000 miles.

Related: What’s The Best Year Heritage Softail Classic? (Surprising)

Were There Any Related Recalls For The Harley Davidson 6 Speed Transmission?

In 2009, Harley-Davidson recalled approximately 13,400 Dyna series motorcycles due to issues with the 6-speed transmission in the 2006 models. The neutral light was coming on, even when the bike wasn’t in neutral, posing a significant risk as riders could release the clutch assuming the bike was in neutral, potentially causing serious accidents.

Harley-Davidson promptly provided remedies for the problem, offering to replace the necessary parts and even pick up the bikes for repair at no charge. Currently, the 6-speed transmission continues to serve bikers well, illustrating Harley-Davidson’s commitment to rider safety and satisfaction.

Wrapping Up

While the Harley 6-speed transmission has had its share of problems, it’s worth noting that these issues aren’t widespread and don’t affect all models or years. Regular maintenance, choosing the correct oil, and appropriately handling the transmission can prevent many of these problems. Remember, your bike is an investment, and taking good care of it will ensure it continues to provide you with a convenient and enjoyable riding experience.

Read next:
> Harley Bad Compensator Symptoms Get Revealed
> Harley Speed Sensor Symptoms Get Revealed (+Fixed)
> Does Harley Davidson Make Automatic Motorcycles? Yes And No

Frequently Asked Questions

What are the signs of problems with a Harley 6 speed transmission?

Signs of transmission problems may include hard shifting, a clunking noise when changing gears, slipping gears, or the bike jumping out of gear. You might also notice a grinding sound during gear changes or a delay in acceleration when you twist the throttle.

How do I diagnose a Harley 6 speed transmission issue?

Diagnosing a transmission issue typically involves checking the transmission fluid level and quality, inspecting for any leaks, listening for unusual noises while riding, and feeling for changes in the transmission’s responsiveness. It’s often best to have a professional mechanic conduct a thorough diagnosis.

Are there any recalls on Harley 6 speed transmissions for known issues?

Harley-Davidson has issued recalls and service bulletins for various models over the years. It’s important to check with a Harley-Davidson dealer or the National Highway Traffic Safety Administration (NHTSA) for any recalls specific to your motorcycle model.

What should I do if my Harley’s transmission is slipping?

If your transmission is slipping, it’s important to address the issue as soon as possible. Slipping can be caused by a variety of issues, including worn clutch plates, improper fluid levels, or internal transmission wear. A professional mechanic can diagnose and fix the problem.