You are riding your motorcycle and your front brake keeps locking up.
It can be even more frustrating if your disc starts meshing with the front wheel or worse, the front wheel stops moving and, in the process, completely halts your bike.
So, what to do when motorcycle brakes lock up? Firstly, check the master cylinder reservoir, brake lever, brake fluid and the caliper.
Next, if brake fluid is old, replace it with a new one. Adjust the brake lever to provide enough free play. Remove the excess fluid in the caliper, if any.
And finally, clean the holes of master cylinder reservoir if they are clogged up.
Let’s deep dive into these action steps along with the reasons for motorcycle brakes locking up.
Why Do Motorcycle Front Brake Locks Up? Reasons
Let us look at the reasons why your motorcycle front brake locks up. The main reasons why your bike is in this situation is because of:
- Clogged up hole in the Master Cylinder Reservoir
- Excess brake fluid in the caliper
- Brake fluid is old
- Brake lever has insufficient free play
Before going into the details of the reasons for front brake locking, we need to have a basic understanding of how front brake mechanism works.
Whenever you apply the front brake by pulling in the brake lever on the right, you are essentially applying pressure to the disc located in the front wheel.
Front wheel braking is a disc brake system wherein the brake pads arrest the movement of rotating discs that are attached to the wheels as opposed to directly arresting the wheel movement just like the rear brake.
As you pull in the lever, the brake fluid from the master cylinder reservoir passes down the pressure all the way to the pistons located in the caliper.
The brake fluid pressure on the piston makes the component move towards the disc.
The brake pads which are attached to the piston comes in contact with the disc and stops the disc and hence the wheel attached from moving further.
Now that we know the basics of front brake mechanism, let us deep dive into the causes of front brake lock up.
#1 Clogged Up Hole In The Master Cylinder Reservoir
Inside the master cylinder reservoir, typically you will find two holes. These holes are significant for the movement of brake fluid, specially the smaller hole which is responsible for the return of the fluid that is released when you applied the brakes.
If these holes are clogged up, the brake fluid movement will not be smooth and the braking will become difficult. The smaller hole, if clogged up, can be very problematic as it will prevent the fluid from returning and as a result, you will see the front brake lever not returning as well.
#2 Excess Brake Fluid In The Caliper
This situation can arise whenever you have applied harsh or panic brakes. When you pull in the brake lever a bit too harsh, what happens is an excess brake fluid could have released from the master cylinder into the caliper.
Accordingly, this excess fluid will create additional pressure which is resulting in the caliper pistons not retracting back completely.
The brake pads will be in a semi-engaged situation and consequently, the brakes are still being applied on the disc.
In this situation, all you need to do is remove the excess fluid from the caliper system.
Once the excess fluid has been removed, the pressure eases off and the brake pads will release the disc and the brake lever will ease back simultaneously.
#3 Brake Fluid Is Old
Another possible reason why your front brakes are locking up could be because you have not changed the brake fluid for a long time.
If the brake fluid in your motorcycle is too old, more than two years old, then most possibly the braking fluid is the culprit here.
Here is a detailed post on how often should you change the brake fluid in your motorcycle.
The old brake fluid will not function properly and will not be providing an optimal performance in braking. So, all you need to do here is to replace your old brake fluid with a new one.
#4 Brake Lever Has Insufficient Free Play
Although this might be not be as common, but if the front brake lever has insufficient lever movement for free play, it could cause your motorcycle front brakes to lock up.
If there is an insufficient free play for the brake lever, there is a high chance that this condition has resulted in a blocked return port.
You need to add some more room for movement to the brake lever and check whether the lock up has been resolved.
What Happens When Motorcycle Brakes Lock Up?
Now that we know the causes for locking up of your front brakes, let us look into the symptoms and effects of this lock up on your motorcycle.
These effects of brake lock up include:
- Disc Brakes get jammed
- Front wheel will not rotate freely
#1 Disc Brakes Get Jammed
When there is excess pressure built up in caliper, the caliper pistons will exert force on the brake pads which in turn, will try halt the disc.
As a result, whenever you ride with a locked-up front brakes, you will feel the jamming up of disc brakes, preventing the easy movement of the motorcycle.
#2 Front Wheel Will Not Rotate Freely
This is an extension of the previous condition. When disc brake is being forced to slow down or stop due to the semi-engaged position of the brake pads, the movement of the front wheel will obviously not be smooth.
The uneven braking will eventually result in the front wheel not able to rotate freely thereby halting your motorcycle ride.
Things You Need To Do Motorcycle Brakes Lock Up
Here are the things you need to do when your motorcycle front brakes are locked up.
- Firstly, locate the root cause of the lock-up. Check each of the related components – Master cylinder reservoir, brake lever, brake fluid and the caliper, one by one.
- If the brake fluid is old, i.e. more than 2 years old, you need to change the fluid. Replace the old brake fluid with a new one.
- If there is not enough free play for the front brake lever, you need to adjust the cable to give some more free movement for the lever to move easily.
- If there is excess fluid in the caliper that is pressurizing the brake pads to semi-engaged position, all you need to is attach a small pipe to the caliper to remove the excess fluid. Slowly unscrew the nut and the fluid will flow out to the pipe. Once removed, tighten the nut back. That should resolve the brake locking situation.
- For clogged up holes in the master cylinder reservoir, use a small wire to unclog the hole. Once cleaned, the holes in the master cylinder reservoir will function properly and will automatically unlock the front brake.
Preventive Measures
In order to prevent the motorcycle front brake from locking up, you can follow certain preventive measures.
Firstly, change the brake fluid regularly in your motorcycle. A thumb rule is to change the brake fluid at least once in 2 years.
Next, while changing the brake fluid, do not fill the new fluid to the maximum. Fill it slightly below the maximum possible, so that there is no excess fluid pumped into the caliper pistons.
Lastly, regularly check for clogged holes in the master cylinder reservoir and ensure enough free play in the brake lever whenever you are adjusting them.
Summing Up
- The main reasons why the front brakes of your bike is locked up is because of:
- Clogged up hole in the master cylinder reservoir
- Excess brake fluid in the caliper
- Brake fluid is old
- Brake lever has insufficient free play
- The effects of front brake lock-up include:
- Jammed Disc Brakes
- Front wheel not rotating freely
- Here are the things you need to do when your motorcycle front brakes are locked up – check up on master cylinder reservoir, brake lever, brake fluid and the caliper. If brake fluid is old, replace it. Adjust the brake lever to provide enough free play. Remove the excess fluid in the caliper. Unclog the holes of master cylinder reservoir.
- To prevent the front brake lock-up, ensure that brake fluid is changed regularly – once in 2 years, and while changing the fluid, fill it slightly below the maximum.
Fellow Reader, what’s your moment of brake lock-up?
