Checking brake fluid levels is one of the common servicing steps taken during motorcycle servicing.
However, the brake fluid is only topped up during servicing. An entire draining and refilling with a fresh and new brake fluid is necessary after some time.
So, how often should you change your motorcycle brake fluid? The thumb rule for changing brake fluid in a motorcycle is every 2 years. This is because brake fluid absorbs water and moisture overtime and also deteriorates in quality due to the heat generated in the braking system, as time passes by.
A detailed description of the change interval, why the braking fluid needs to be changed and how it should be changed is discussed in further sections of this post.
Motorcycle Brake Fluid Change Interval
The ideal change interval for brake fluid in a motorcycle is 2 years. This is mainly because the brake fluid absorbs water and overtime the water content in the brake fluid will start corroding the metal components associated with the braking system.
Also, this 2-year interval is not for brake fluid top up. The top up should be done whenever required by checking the brake fluid levels during every motorcycle servicing time.
By changing motorcycle brake fluid, we mean draining the entire brake fluid existing in the motorcycle and refilling it with the new fluid.
While the exact period of interval to change the brake fluid in your bike might vary depending on the riding, bike model, usage and the quality of braking fluid, the general thumb rule is to replace the brake fluid in your motorcycle every 2 years.
Why Brake Fluid Should be Changed?
The first and foremost reason why brake fluid must be changed in the motorcycle is because brake fluid absorbs water. They are hygroscopic. As a result, many metal components associated with the braking system will start corroding once the brake fluid start absorbing the moisture from air.
That’s why, to prevent too much water entering into the brake fluid in the motorcycle, the brake fluid must be changed every 2 years.
Second, the quality of the brake fluid deteriorates overtime. The constant heat generated in the braking system, especially due to anti-lock braking (ABS), will impact the brake fluid.
The heat generated will gradually breaks down the fluid and the brake fluid characteristics change over a period of time. Sometimes, the characteristics change is so drastic in the brake fluid that it won’t apply brakes at all.
Third, as the brake fluid ages, more contaminated particles enter the brake fluid. As the contamination increases, the performance of the brake fluid decreases. As a result, the braking performance deteriorate overtime as well.
For these reasons, the motorcycle brake fluid must be changed regularly every once in two years period.
Brake Fluid Top Up in Motorcycle is not Enough
Brake fluid top up is when you fill up the shortfall fluid levels over the existing brake fluid. Usually how this occurs is – you go for motorcycle servicing and the mechanic checks the brake fluid levels. And the fluid levels are low.
So, on top of the existing old brake fluid, the mechanic or the service shop guy fills the new brake fluid to make up for the shortage. The existing brake fluid is not drained out, rather it is kept as it is. And only a required amount to fill the fluid to the brink, the new brake fluid is used.
Now, while this method of topping up the brake fluid is okay to make up for the shortage in brake fluid levels, the entire fluid must be drained out and refilled with a new one when you are going for changing the brake fluid.
And that change interval should be every two years for the motorcycle brake fluid. Make sure, while changing the brake fluid, the existing fluid in the motorcycle is entirely drained out and refilled with a new one.
Why Brake Fluid Top Up is not Sufficient
As to why brake fluid top up does not fulfill the purpose, well, the old deteriorated brake fluid is still in the braking system. The performance won’t drastically improve if the new brake fluid is only topped up to fill up the shortage.
The moisture and the water content absorbed by the old brake fluid will still exist in the braking system. The contaminated particles that have infiltrated the fluid is going nowhere unless drained out. And the performance of the old brake fluid which has deteriorated won’t change.
Adding new brake fluid only to fill up the shortage in the brake fluid levels will not change the performance and functionality of the braking system.
As long as the old and existing brake fluid still remains in the system, the braking performance won’t be improved drastically. In addition, after some time, the existing old brake fluid will actually deteriorate even further in quality.
That’s why, after the 2 year period is up since the last brake fluid change in the motorcycle, you need to change it again. No matter how many times you have topped up the brake fluid in several motorcycle servicing.
How to Change Motorcycle Brake Fluid?
To change the brake fluid from the motorcycle, you can always drain the fluid from the system completely and then refill with a new brake fluid. While this is the most common-sense method to go about it, as you might have guessed, this approach is messy and time consuming.
Here’s a much a simpler method and one that’s just as effective.
You will need a length of hose, preferably clear and one that fits your bleed screw; a container to hold the used fluid, also called catch can; brake fluid; common tools; and plenty of clean rags.
First, fasten the hose to the bleed screw, just as you would if you were preparing to bleed the brakes. Go through the pump and bleed procedure as if you were bleeding the brake.
Now, keep a close eye on the master cylinder, whenever the brake fluid drops to the add mark, top off the cylinder with the new fresh brake fluid.
Continue this process for several times. After several cycles of pump and bleed, you should see clean and the fresh brake fluid coming out.
Repeat this procedure until only the new fresh fluid flows.
Essentially, instead of draining out the old fluid and then refilling with new and fresh fluid, what we are doing here is we are topping up the fresh fluid at the same time of draining the old fluid.
Once repeated for enough cycles, the fresh fluid will completely replace the old brake fluid. And bingo, you are all set now, and the brake fluid is replaced.