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Harley Davidson Transmission Problems? Help Is Here

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So you’re having some dreadedful transmission problems in your Harley? Don’t despair; help is right on the corner. Trust me, you’re not alone. Before diving in, let’s kick back and acknowledge that every machine, even one as iconic as a Harley, will have its quirks. And it’s no secret that transmission problems are among the most daunting. But fear not, fellow biker. We’ve turned every bolt and checked every fluid in our quest to understand and solve these issues. Prep your wrenches and snag that old rag — we’re about to lay out everything you need to know about your Harley’s transmission problems.

With a robust mechanical background and a way of breaking down complex repairs into simple steps, we’ll share practical advice, relatable stories, and hard data to hit the road running. Remember, there’s nothing that the spirit of camaraderie and a little know-how can’t fix. Let’s roll up our sleeves and get to it, shall we?

Navigate to your specific transmission type:
Harley 6 Speed Transmission Problems? Help Is Here, Trust Me
Harley Davidson 5 Speed Transmission Problems? Help Is Here!

What Are The Most Common Harley Davidson Transmission Problems?

I like to use parts diagrams like this to get a greater understanding of how the parts work in relation to each other, inside the transmission. This is, of course, a breakdown of a 5-speed Harley transmission.

There are five major transmission problems that a Harley Davidson owner may encounter:

  1. Clutch Slippage
  2. Difficulty Shifting Gears
  3. Sputtering or Uneven Acceleration
  4. Grinding Noise in the Transmission
  5. Degraded Oil Seals (Leaking Primary Fluid)

Each of these issues has certain symptoms and potential causes, which we will explore in the following sections.

Clutch Slippage

Clutch Slippage is a common issue that affects the transmission of Harley Davidson motorcycles. It occurs when the clutch fails to engage and disengage the engine from the transmission smoothly, resulting in a hard driving experience, especially uphill or in stop-and-go traffic.

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

Possible Causes

Several factors can cause clutch slippage:

  • Tight Clutch Cables: If the clutch cable is too tight, it can cause the clutch to slip. Clutch cables should have some slack to engage and disengage the clutch smoothly.
  • Worn Out Clutch Disks: Over time, the disks can become thin and glazed, making it difficult for them to grip the flywheel. This Can cause the clutch to slip.
  • Power Upgrades: Clutch slipping problems can start after Stage II upgrades or other power upgrades. It is recommended to get a stronger spring to address this problem.
  • Clutch Lever: In some instances, the clutch lever can rest with the clutch partially engaged, which would wear the clutch prematurely leading to slipping. In others, the clutch lever is not positioned correctly to fully disengage the clutch. In either case, it’s recommended to frequently check the position of your clutch lever. If unfamiliar, it’s worth learning how to do a clutch adjustment for this reason alone.

Related: Harley Hydraulic Clutch Problems? Here’s What to Know & Do

Gear Shifting Problems

Some Harley Davidson owners report issues with their gear shifters. Common Harley Davidson shifting problems include the shifter becoming stiff or difficult to move, the gears not shifting smoothly, or the bike getting stuck in one gear – or not going into gear at all.

Related: Motorcycle Goes Into Gear But Wont Move? Do This

On the last point covered above, here’s a video titled “Harley 5 Spd Transmission Won’t Go Into Gear”.

Related Components and Potential Issues

Several components can influence gear shifting problems:

  • Shifter Adjustment: One way to fix gear shifting problems is to adjust the tension on the shifter. This can be done by loosening or tightening the shifter cable.
  • Shifter Springs: Shifter springs can weaken or break over time. These will need to be replaced to fix the issue.
  • Pawl Adjustment: The pawl is a small part that engages the gear; if it’s not adjusted properly, it can cause shifting problems.

Sputtering or Uneven Acceleration

Harley Davidson motorcycles are known for their power and performance. But what happens when your Harley starts sputtering or hesitating when you try to accelerate?

How To Tell When It’s The Transmission

Several factors can cause this problem, and the best way to diagnose the issue is to check these potential causes:

  • Carburetor Adjustment: One possibility is that the carburetor needs to be adjusted. This is a relatively simple fix that can be done at home.
  • Spark Plugs: Dirty or worn-out spark plugs can cause acceleration problems. It’s essential to replace the spark plugs with ones specifically designed for Harley Davidson motorcycles.
  • Faulty Sensors: Bad TPS (throttle position sensor) or MAP (manifold absolute pressure sensor) can also cause acceleration problems.
  • Leaky Tanks: Leaks inside the tanks may also contribute to acceleration problems. Cracks or holes in the tanks can cause fuel to leak out and air to get in, leading to engine problems.
  • Faulty ECU: A faulty ECU (engine control unit) can cause a variety of problems, including sputtering and hesitation when accelerating.

Grinding Noise In The Transmission

One of the most alarming harley davidson transmission problems is a grinding noise coming from the transmission. This noise is not part of the Harley’s signature rumble and should be addressed immediately.

What Can Cause This Grinding Noise?

Several factors can cause gear grinding noise:

  • Worn-Out Bearings: Worn-out bearings can cause a grinding noise in the transmission.
  • Dry Drive Belt: A dry drive belt can cause gears to grind against each other.
  • Tight Primary Chain: If the auto-adjuster runs the primary chain too tight, it can cause gears to grind.
  • Damaged Gear Teeth: Worn or damaged teeth on gear teeth themselves can cause a grinding noise.

Related: Harley Davidson Drive Belt Replacement Cost (and When?)

Degraded Oil Seals (Leaking Primary Fluid)

Here's an example of primary fluid leaking from the transmission of a Harley-Davidson.
Here’s a common location where the primary will begin to leak.

One of the most common issues Harley Davidson owners face is leaking primary fluid, caused by degraded oil seals.

How Often Does This Happen?

Oil leaks can occur due to various reasons. The most common cause is a faulty gasket or seal. Harley Davidson uses high-quality parts, so these gaskets and seals should last long. However, they can degrade over time, especially if the bike is not properly maintained.

Does Anything Make Primary Fluid Leak Prematurely?

Improper installation is another potential cause of oil leaks. If the seals are not installed correctly, they will not be able to properly seal the transmission, and oil will be able to leak out. Harley owners who attempt to do their own repairs or who take their bikes to inexperienced mechanics are more likely to experience this problem.

Pops Out Of Gear When Riding

Another common problem is when the motorcycle jumps out of gear while riding. This can be frustrating and dangerous, so getting it fixed as soon as possible is essential.

This issue usually arises due to worn mounts or loose linkage, a damaged shift fork, bad shifter bearings, or a weak spring in the shift rail. To fix this issue, start by inspecting the shift drum and detent mechanism for any signs of damage. Also, check the shift lever adjustment and ensure it is slightly loose.

A Note on The Shift Forks

Shift forks in a transmission play a crucial role in gear selection and engagement. If a transmission is popping out of gear, a shift fork is one of the more immediate culprits. Here’s how:

  1. Wear and Damage: Over time, the forks can wear down or get damaged. This wear can prevent the fork from fully engaging a gear, causing the transmission to slip or pop out of gear.
  2. Improper Alignment: If a fork is not properly aligned, it might not engage the gear completely or correctly. This misalignment can lead to the gear not holding and subsequently popping out.
  3. Interaction with Gears: The shift forks move the collars that engage different gears. If the fork or the collar is damaged or worn, it can lead to incomplete gear engagement, causing the gear to disengage or pop out under load.
Here's an example of a Harley shift fork, a primary cause of having trouble shifting gears.
Here’s a picture of the little guys if you haven’t seen them before.

Related: Harley Davidson Clutch Replacement Cost: Complete Overview

This video titled “Why Harley 5 Spd Trans Jumpts Out Of Gear” goes more into depth on this problem in particular.

Wrapping Up

Remember that Harley Davidson motorcycles are built to last but are not immune to problems. The five transmission issues discussed in this article are some of the most common problems that Harley owners have to deal with. If you are having any of these Harley Davidson issues, it’s important to take action as soon as possible. Ignoring the problem will only worsen it, and it could eventually lead to serious damage to your Harley.

Read next:
> Harley Bad Compensator Symptoms Get Revealed
> Harley Speed Sensor Symptoms Get Revealed (+Fixed)
> Does Harley Davidson Make Automatic Motorcycles? Yes And No
> Red Light on Harley Speedometer: Causes and Solutions

Frequently Asked Questions

What are typical signs of transmission problems in a Harley Davidson?

Typical signs include trouble shifting gears, a noisy transmission especially in neutral, slipping gears, leaking transmission fluid, and the motorcycle refusing to go into or stay in certain gears.

How can I troubleshoot transmission issues on my Harley Davidson?

Troubleshooting should start with checking the transmission fluid level and condition. Look for metal shavings or debris, which could indicate internal wear. Also, listen for unusual sounds and pay attention to any changes in the transmission’s behavior during gear shifts.

What common issues can cause transmission problems In A Harley?

Common issues may include worn out gears, damaged shift forks, bearing failures, or problems with the transmission belt or chain. Clutch issues can also manifest as transmission problems.

What should I do if my Harley Davidson transmission is leaking fluid?

If you notice transmission fluid leaking, it’s important to have it inspected as soon as possible. Leaks can lead to low fluid levels, which may cause serious damage to the transmission if not addressed.