Nothing is as frightening as putting your foot on the brakes to slow down just to feel the brake pedal goes to the floor with no resistance, but why did it happen?
There are numerous reasons a vehicle’s brake pedal will go to the floor, from low to no brake fluid, brake line leaking or bursting, brake pedal rod linkage failing, brake pedal failure, brake master cylinder failure, and brake caliper failure.
This article will explain why the brake pedal goes to the floor.
6 Reasons Why Brake Pedal Goes To Floor
1. Low Or No Brake Fluid
Low or no brake fluid is one of the most common reasons the brake pedal feels squishy or has no resistance.
When it is low, the brake fluid can indicate that the brakes are close to the end of life and will need replacing and usually will also make brake noise or squeaking.
If the brake fluid is too low, the master cylinder can pull air into the brake system, and as we know, the air is compressible, thus removing the brake feel and leaving you with squishy brakes or no brakes at all.
If there is no fluid at all, it will be the result of the following:
2. Brake Line Leaking Or Bursting
If a brake line leaks, it can result in the brake reservoir being empty, or it can relieve the pressure you are applying to the brake resulting in the brake feeling spongy or not working.
The typical spots for brake hard lines to start leaking are at the fasteners or locations where clips hold them onto the body.
Over time the hard lines will chafe or rust at the fastener locations and, at first, will sweat and later on leak.
The soft lines in the wheel well of the vehicles are prone to burst of old age or rub through if there are clearance issues.
When this happens, the brake fluid will also be expelled in significant quantities, resulting in spongy or no brakes.
3. Brake Pedal Rod Linkage Failing
Between the brake pedal and the brake master cylinder is the brake pedal rod linkage that connects the two.
The only thing holding it in place is two clips, and in some cases, these clips can fail to result in the rod disconnecting, the pedal falling to the floor and no brakes.
The rod itself can bend or brake, but the chances of it happening is very slim, and with all the years of owning numerous cars from the ’60s to modern vehicles, it never happened with me or anyone I know.
4. Brake Pedal Failure
While the chances are slim, this can happen; the brake pedal is fatigued over the years of use, poorly repaired, or just a cheap replacement part.
Sometimes cheaper replacement brake pedal assembly can be manufactured from plastic or skinny stamped steel.
You won’t feel anything wrong in normal braking conditions, but it can bend or even break under high load.
Sometimes you also buy an accident-damaged repaired car without knowing that the previous incident damaged the brake pedal, maybe bent and fixed improperly, resulting in it bending again or snapping off.
Never cheap out on the safety aspects of the vehicle, please.
5. Brake Master Cylinder Failure
As the driver, the brake master cylinder gives you a mechanical advantage over the brakes, making pressing the brakes easier and resulting in better braking performance.
Inside the brake master cylinder are seals that were replacement parts in the olden days, but these days, dealerships and mechanics will replace the entire master cylinder.
These seals wear out over time and can start leaking internally; thus, the brake fluid can bypass the cylinder and leak into the brake booster.
Since the pressure is leaked past the cylinder inside the brake master, this will make the brake feel spongy, and if it leaks a lot even result in total loss of brakes when the pedal travels to the floor.
6. Brake Caliper Failure
While also very uncommon, a brake caliper can fail, leaving the brakes feeling spongy or giving no feel at all.
The brake caliper consists of the housing itself, the pistons that are moved by the brake fluid pressure, and the guide pins that help the caliper stay in line and optimally make the brake pad contact the disc.
On the pistons are oil seals that stop the brake fluid from bypassing the pistons, they wear out over time and can result in leaks and spongy breaks.
The pistons also have a rubber seal between the pad and the caliper housing to prevent contaminants from entering the machined surface where the pistons move in.
If the seal is broken, contaminants like dirt and moisture can get on the machined surface and wear it out or even cause it to rust, which can also cause the piston assembly to start leaking resulting in the brakes going soft or to the floor.
Final Thoughts On Brake Pedal Goes To Floor
While losing all brakes is not something anybody wants to experience, it is good to know what to look for when it starts feeling spongy, rather spongy brakes than no brakes.
Hopefully, you found this article helpful in diagnosing why your vehicle’s brake pedal goes to the floor.
What Should You Do If Your Brake Pedal Goes To The Floor?
First, stay as calm as possible and save time not trying to get the pedal at the idle position.
Immediately start downshifting to use the engine braking to slow the vehicle down, and slowly apply your handbrake if your car is equipped with a manual lever or pedal style one.
Be very gentle with applying the handbrake since it only stops the rear axle, and you do not want to initiate a slide or spin out.
While gently applying the hand brake and downshifting, you will be able to get your vehicle to a complete stop in a safe manner.
Once the vehicle is stopped, the best thing to do is get a tow truck to tow your car to the nearest workshop to inspect what went wrong and what to replace.
What Are The Symptoms Of A Faulty Master Cylinder?
The brake pedal will start to get more spongy over time, and there will also be a loss of brake fluid, later turn on the brake warning light.
The master cylinder has seals around the piston inside, which will wear down over time and cause an internal leak by bypassing the fluid past the piston and seals and leaking into the brake booster.
What Are The Symptoms Of A Faulty Brake Booster?
When the brake booster starts failing, the brakes will become harder and harder the press as it worsens.
The job of the brake booster is to use the vacuum produced by the engine to assist in helping the driver have a mechanical advantage over the brakes.