Have you noticed oil dripping from your bike’s front forks lately? 

This issue is more common than you may realize and can cause many problems if not addressed properly.

The issue in question is called a “front fork seal leak” (or just a “fork leak”), and in this blog post, you’ll discover more about it – specifically:

  • What a front fork seal leak is
  • 3 bad things that happen
  • What causes a front fork leak to happen

What Does It Mean to Have a “Front Fork Seal Leak?”

At the front of your motorcycle are the front forks, which are part of your suspension setup.

As such, the front forks are there to absorb any bumps in the road to maintain a smooth ride.

Inside the fork tubes are powerful springs, and between each inner and outer fork tube, there’s a small rubber ring.

This rubber ring is also called a “front fork seal” – and if it ruptures, the front fork oil will pour, or rather “leak” out – creating our dreaded “front fork seal leak.”


Why does this area need to be sealed?

The purpose of having front fork seals is so that:

  1. No dirt enters the inner fork area
  2. The front fork oil stays contained inside the fork tube

In other words, the front suspension simply would work without them.

Just like any other kind of oil, the front fork oil acts as a lubricant so that the front forks (or specifically the fork springs) move smoothly when they compress and rebound.

So, with a front fork seal leak, the front fork oil is no longer inside the fork tubes, which, in turn, can lead to all sorts of nast side effects.

3 Bad Things That Happen With a Front Fork Seal Leak

1. Accelerated wear-and-tear on your suspension components

It might sound like I’m repeating myself – but that’s because this bears repeating:

No oil, no lubrication. No lubrication increased wear-and-tear on your suspension’s internal parts.

Worse still, with the fork oil all gone, putting weight on the front end would cause metal-on-metal grinding that quickly destroys bearings and bushings.

2. Braking problems

On top of having no fork oil inside your fork tubes, a fork seal leak also introduces more problems – with your brakes.

Perhaps it sounds absurd – how could a leaky front fork seal cause issues with your brakes?

It’s not like they’re linked together, right?

No, they’re not – but remember all that front fork oil that used to be inside the fork tubes?

That fork oil has to go somewhere. And since the fork seal is at the bottom of the fork, the oil will pour down toward your brake caliper.

Inside your brake caliper, you have your brake pads. If they get fork oil on them, it might affect their ability to stop the bike when you apply the brakes.

If the brakes start to feel “spongy,” and you know that it’s not because your brake fluid needs changing, it might be time to check your fork seals.


3. Rusting and deterioration of the lower fork ends

Front fork oil may not be particularly corrosive (at least not when compared to brake fluid), but it can still attract trouble.

This trouble comes in the form of the dirt and dust that now sticks to your lower fork ends – all because the fork oil is no longer where it’s supposed to be (i.e., inside your fork tubes.)

It’s essentially like the brake problems we just covered, except it might not be as noticeable initially.

Why Does a Front Fork Seal Leak Happen?

So, as you can see, a leaky front fork seal is a big deal. But why does it happen?

There are several reasons, and by far, one of the most common ones is aging and wear and tear.

It’s not just tires that wear down with age and use – the same thing happens with fork seals.

And when you think about what they’re exposed to regularly, it’s not hard to see why.

All that vibration and force caused every time the suspension rebounds will eventually break the seal down.

Granted, it takes a lot of time and just as many kilometers/miles traveled, but at one point, the seal will rupture.