Why do bike suspension oil leak?

Every rider has to face this situation and that also several times. Bike suspension oil leak can make your heart sink. Firstly, there will be traces of oil around the fork seal, and then over time, it will turn into an oil spring. It is always better to replace the seal when there are traces of oil over it.

Oil traces will be easily visible as the dust particles stick over the oil.

If you do not replace the seal in time, then the leaking oil will reach the brake calipers and hence decreases the brake efficiency, or in the worst scenario, you have to replace the calipers.

So, before reaching any conclusion or solution, you should discover the cause of the oil leak and the working of the fork seal.

Working of fork seal

You might be aware of the function of a fork. Forks are suspensions that absorb shock, which means the oil inside them controls compression and rebound.

These fork suspensions are a huge technological advancement. We are using shock absorbers from the time vehicles are manufactured. Vehicle suspensions were simpler at the earlier times. Spring suspensions do not need oil, but their shock-absorbing properties are not that effective.

Today almost every motorcycle uses fork suspension, mainly over the front wheel. These fork suspensions have oil within them, which controls the compression and rebound. For this oil within the fork, an oil seal is used. This seal comes in between the inner and outer fork tubes.

Why does fork seal leak?

There could be a lot of possibilities due to which oil leaks through a fork seal.

• The first possibility is that the seal might be old and has got stiff and rigid. A rigid seal will not work much effectively, and hence the oil will leak whenever the suspension compresses.

• The second possibility is that dust particles have lodged in between the seal and fork tube. These dust particles will create a space between the seal and fork tubes, and this will cause oil leakage.

• The third reason is that your bike’s fork tube may have some imperfections. These imperfections may arise due to hard riding. The possibilities for fork tube imperfection can get even more when you ride off-road. Off-road riding puts a lot of pressure on the fork tubes.

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What to do if a fork seal leaks?

There are several solutions for a leaking fork seal depending upon its causes.

• Most of the fork tubes are provided with dust cover to prevent dust from falling into the oil. 

If the leakage is due to the accumulation of dust particles, you can resolve the issue by cleaning the seal.

But there’s a drawback of this method. When you clean the seal, some of the dust particles may fall into the suspension oil. Now, these dust particles will cause further damage to the fork tube.

• If you clean the seal and leakage is still prevalent, then you can try Seal Doctor. The usage of Seal Doctor is simple. Lower the dust seal and insert Seal Doctor into the leaky seal and then twist it 360 degrees. After this, pull down the Seal Doctor, and it will remove all the dirt. This way, you can clean the dirt from your seal.

A plus point of removing dirt using Seal Doctor is that it pulls out the dirt and eliminates the risk of any further damage.

• The last thing you can do is, replace the fork tube. If you have already followed the other two solutions and still the oil leaks, then you have to change your fork tube. Fork tubes may have dents or bents somewhere due to which oil leaks. Another possible reason for the fork seal leak is the presence of scratches over the fork tube. Due to these scratches, the oil will leak.

Conclusion

All these are possible reasons due to which fork seal leaks. Fork tube replacement is required less often; usually, replacing the seal works out.

Always remember to put back the seal correctly after cleaning. If not replaced properly, the oil will leak immediately after the installation of the fork seal. Also, clean the fork seal thoroughly; even a speck of dirt will result in seal leakage.

The chances of fork seal leakage due to dust increase if you ride over a muddy path. In this case, you can use fork seal covers to protect it from dust.

Your bike fork oil seal gets stiff over time. This stiffness causes oil leakage.

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