It’s a hair-raising ride, taring into a corner, only to find you have no brakes. While exciting, it’s not an experience I’d like to repeat.
Common causes of ATV brake problems include:
- Brakes need adjustment
- Air in the brake system
- Worn brake pads
- Damaged brake controls
- Faulty master cylinder
- Faulty brake caliper
In this post, you’ll learn all about the most common ATV brake problems and how you can fix them. I’ll also share some insider hacks for fast brake system troubleshooting and some really valuable maintenance tips.
Common Brake Symptoms
You can tell a lot about the possible cause of a problem by the way a customer describes their issue. Common brake system complaints include:
- My brake lever/pedal feels soft and the brakes don’t work – These types of symptoms tend to be related to a hydraulic system leak or air in the system.
- My brake lever/pedal feels hard and the brakes don’t work – These types of symptoms tend to be related to brake pad and caliper faults.
ATV Brake System
I don’t want to get waste high in the weeds here, so I’ll outline in basic language how an ATV braking system works. It’ll help with diagnosing and repair work later.
ATV braking systems vary, depending on the make, engine size, and year of your bike. But all ATV brakes are broken into two separate braking circuits.
What’s a brake circuit? A circuit is a fully independent brake system that (in most cases) shares no brake system components.
On a typical ATV, the independent circuits are:
- The hand lever operated brake circuit
- The foot pedal operated brake circuit
The system is designed so that if one circuit fails, the rider has a backup system, which makes good sense. The brake circuits are either hydraulic or mechanically operated and commonly a mix of both.
ATV brake setup – A typical setup (brake systems will vary) looks like this:
- Hand operated hydraulic brakes to both front wheels (calipers) and to one rear wheel caliper and,
- Foot operated mechanical lever to remaining rear wheel with drum brake, (or, foot operated hydraulic brake to remaining rear wheel with caliper).
Many modern ATVs however, offer four-wheel braking from the hand lever and just both rear-wheel braking from the foot pedal.
Other common ATV brake setups include:
- Hand-operated hydraulic brake calipers front and foot brake to a single rear brake caliper.
- Hand-operated hydraulic brake calipers front with a single rear rotor carrying twin calipers. (One operated by the hand lever circuit and the other by the foot pedal).
- Hand-operated with mechanical cable & drum brakes front and back, this is a base model set-up.
A single rear axle brake indicates the lack of a limited-slip differential.
ATV Hydraulic Brake System Components
All ATV hand-operated braking circuits are hydraulic, as are most foot pedal systems. A hand lever hydraulic brake circuit consists of the following components:
Brake Lever – Made from lightweight corrosion-resistant alloy and incorporates brake fluid reservoir with fluid level sight glass. It also houses the master cylinder. Some incorporate a hands-free brake holding control.
Brake Master Cylinder – The master cylinder lives in the base of the brake lever housing and is serviceable. It creates fluid pressure within the hydraulic system.
Brake Lines – A fluid-resistant rubber pipe covered in braided steel.
Brake Pads – Brake pads are what slow and stop your ATV. They are a special high friction material, which converts the rotational energy into heat as it slows the bike.
Brake Rotors – Metal disks fixed to each wheel hub and turned with the wheel.
Brake Calipers – Calipers are the business end of the braking system. The caliper applies force to the brake pads proportional to brake lever pressure. The caliper is fixed to the wheel knuckle and, together with both brake pads, sandwiches the Rotor.
Brake Fluid – Brake fluid is what makes the whole system possible. The fluid is designed to resist compression, so pressure at the hand lever is immediately transferred to all calipers evenly in the circuit.
DOT 3 and DOT 4 (Department Of Transport) are common fluid types, but your brake fluid reservoir cap will specify which type to use.
Not all brake fluids are compatible, see chart.
Some bikes may use a hydraulic foot brake to brake one rear wheel. The components of a hydraulic single rear wheel setup include:
Brake Pedal – Steel pedal pivoting on a bushing, mounted on the chassis.
Rear Brake Master Cylinder – The foot brake master cylinder is mounted close to the foot pedal and is often mechanically operated by a short steel braided cable.
Master Cylinder Reservoir – The small plastic transparent reservoir bottle is mounted close to the master cylinder and supplies brake fluid via a rubber hose.
Brake Line – A single steel braided brake line from the master cylinder to the rear (r/h usually) wheel.
Rear Pads – Most models will run the same pads front and rear.
Rear Rotor – Rotors front and rear tend to be identical.
Calipers – Calipers tend to be identical front to rear, but be mindful they are always different left to right.
Brake Fluid – As per front reservoir.
Drum Brake System
Some bikes may use a mechanical drum brake setup on one rear wheel. The components of a drum setup include the following components:
Brake Pedal – As per the above.
Control Rod/Cable – Adjustable mechanical lever connected from brake pedal to single rear (r/h) wheel brake assembly.
Brake Shoes – Shoes are a serviceable high friction material located on the brake assembly, used to slow and stop the bike.
Brake Assembly – The assembly is fixed to the rear axle and is stationary. It houses the shoes and brake adjusters.
Brake Drum – A metal drum that turns with the wheel and fits over the brake shoes and brake assembly. As the brakes are activated, the shoes push against the inner wall of the brake drum, slowing the bike.
This may seem like it’s too simple to be the solution, but it’s the first item I’ll check when a customer complains of poor brakes.
If the brakes are drum brakes with a mechanical cable/ rod set up, they can be easily adjusted. You may, however, need a wire brush and WD40 to help loosen the guaranteed to be rusted adjusters.
Each wheel drum brake will have an adjuster. Some adjustment at the hand lever may be possible, but it’s better to do the major adjusting at the wheel adjusters first.
The adjusters will have a lock nut that needs to be backed off before turning the adjuster clockwise to tighten the brakes. Adjust all drums a little and test, repeat until you have good brake performance.
Over-adjusting any single wheel will result in brake grabbing. Remember to tighten your adjuster lock-nut afterward.
Brake Shoe Adjustment
If your adjusters are already well adjusted, you’ll have to roll your sleeves up a little further and remove the wheels and brake drums. Inspect the brake shoes and adjust the shoes so that they contact the drums.
You’ll find an adjuster inside each drum between the brake shoes. The adjuster is a screw that pushes the shoes further away from each other.
Adjust the shoes too much, and you’ll struggle to get the drums back on, or they’ll drag. Not enough adjustment and the shoes won’t contact the drum.
Air in Brake System
There’s no adjustment on a hydraulic brake system, that said rear master cylinder rods typically have adjustments to take up foot brake pedal free play. Hydraulic brake system faults tend to revolve around air in the hydraulic brake lines. A common symptom is a spongy feel from the brake lever and poor or no brake bite.
Your front brake reservoir has a sight to check the level and the rear reservoir is clear, so a quick visual check will reveal any issue with low fluid levels.
A low fluid level could mean your brake pads/shoes are worn, or it could mean a more serious situation – A hydraulic brake fluid system leak.
If you have a low fluid level, check for pad wear. If the pads are worn, replace and check the fluid level again. If the pads are not worn, you’ll need to check all components, connections, and brake lines for any signs of dampness. We suspect a leak in the system.
Brake fluid is oily, so you shouldn’t have a problem spotting a leak unless, of course, the bike is wet.
Common brake fluid leaks include:
- Reservoir cap seals
- Copper seals at the Banjo bolts (brake line to caliper union)
- Brake lines rubbed through
- Master cylinder seals
- Caliper piston seals
- Caliper bleed screws (Nipples)
Bleeding ATV Brakes
You have a few options when it comes time to bleed the brakes. But before bleeding, we’ll need to top up the fluid. Go ahead and top up the fluid at the fluid reservoir, remember your rear brakes is likely a separate reservoir, positioned towards the rear of the bike.
Use whichever type of fluid is recommended on the cap, DOT 3 or 4, remembering it’s best not to mix fluid and some types can’t be mixed.
Gravity bleed set-up
Go ahead and open all bleed screws and place a cloth around each, allow gravity to push the fluid down the lines. This is messy and may take a while. Gently work your brake lever (careful it splashes) to move the fluid into the brake lines. You may find holding the lever open a touch (I use tape) helps the gravity bleed process.
Gravity bleeding works a lot faster on vehicles with larger reservoirs.
One man bleed set-up
See the brake bleed tools I recommend here on the ATV tools page or you can go the MacGyver route.
The MacGyver setup is a clear plastic drinks bottle with some brake hose:
- Fill reservoir and fit cap
- 1/4 fill bottle with clean brake fluid
- Fit one end of the bleeder pipe to the caliper bleed nipple (Clear pipe works best)
- Submerge the other end of the bleeder pipe below the fluid level in the bottle
- Open the bleed screw
- Pump to bleed system or alternatively allow gravity to bleed
- Keep an eye on your fluid reservoir level, it’ll need topping up
- Repeat on all calipers on the brake circuit
With the system bled, you’ll need to clean around your bleed screws and reservoir cap. Build some pressure and check the whole system for leaks.
Other brake bleed options
A brake service vacuum bleeder kit works great on ATVs, or you can go the two-person pump hold method.
System Won’t Bleed
If you’re having problems building or holding brake pressure, you may have a master cylinder, brake line, connection, or caliper fault.
Check all connections (including bleed screws) and components for weeping fluid. If fluid can get out, then air can get in.
Troubleshooting Soft Lever
With a fully bled system, go ahead and clamp all brake caliper flexi hoses using hose clamps. Check brake lever feel. It should now be firm (if it isn’t, see master cylinder below).
Now go ahead and remove one clamp at a time and check the brake feel. Repeat on all wheels until your brake lever feels soft. A soft brake indicates the problem wheel circuit. Check brake hose for bulging or trapped air in the caliper, leaking bleed screw, or leaking brake line connection.
If you recently removed your brake calipers or fitted new ones, make sure they are on the correct side of the bike. The left-hand caliper is different from the right-hand. Hey, it’s an easy mistake to make!
The caliper bleed screw always goes to the top.
Worn Brake Pads/Shoes
Worn-out brake pads/shoes will, without a doubt, leave your ATV difficult to stop. But worn pads will make a hell of a racket when they’re worn down to the steel base plates.
Unless your muffler is missing, you’ll have certainly noticed the noise. But if you are in any doubt, you can usually check brake pad material depth by simply looking through the wheel. Shoes are a little harder. You’ll need to remove wheels and drums.
Glazed Pads – Old pads lose their bite, so although they may have lots of material still, they may offer a hard brake feel. It’s a condition known as glazing, the best fix is to replace the pads, or you can try cleaning them.
You’ll need to remove the pads and, wearing a mask, sand the friction surface to remove the glaze. Lay coarse sandpaper on a flat surface and run the pad across to remove the glaze.
Replacing brake pads is simple. Brake shoes are a bit more work and can be a pain in the jacksie. So if you haven’t tried any DIY maintenance previously, as a rough guide – Replacing brake pads will be 3 out of 10 for difficulty but shoes, about a 7.
Damaged Brake Controls
If you’ve had a collision recently, a brake hardware issue is a likely place to start looking. If you’ve been into the drink and parked your bike up for a time, corrosion can accumulate on the rear foot brake pedal bushing. A frozen rear brake pedal is common as they are rarely used compared to the hand lever.
Plenty of WD40 will fix the issue.
Faulty Brake Master Cylinder
Your master cylinder is, as you know, brake handle assembly integrated. The master cylinder creates the pressure needed to push the pads against the rotor.
A spongy brake feel is a symptom of air in the system, but it could also be caused by a faulty master cylinder. A leaking master cylinder will be easy to diagnose, but often the master cylinder will show no telltale signs of failure.
To quickly troubleshoot a master cylinder, you’ll need three hose clamps. Clamp each wheel on the circuit (usually three calipers) at the flexi hose (if possible).
Go ahead and check the brake feel now. If it’s improved, you’ve eliminated the master cylinder as the source of the problem.
If, on the other hand, the brake feels the same, and you’ve bled the system correctly with no leaks at banjo bolts, etc., then you’ve diagnosed a faulty master cylinder.
Master cylinders are pretty durable but can fail prematurely because of old brake fluid. The old fluid carries contaminates like rubber and metal particles. Add water to the mix because brake fluid is hygroscopic (attracts moisture), and the moisture creates corrosion inside the brake system.
Metal partials, rubber particles, rust, and water damage seals, pistons, brake lines, and bleed screws. Your fluid should be changed at least every three years to help maintain the system and prevent expensive brake overhauls.
Faulty Brake Caliper
Most ATV brake calipers use a floating caliper setup. It simply means the caliper is free to move from side to side.
Sliding bushings make this possible, and It’s a good system but prone to binding when bushings wear, which results in ineffective braking. So go ahead and check that your brake caliper has free movement across the Rotor. If not, remove, clean, and lube the fixings.
So you already know the problems old fluid can cause. And caliper pistons bear the brunt of corrosion. A frozen caliper piston is common.
A symptom of a frozen caliper piston is a hard brake lever feel and no brake bite. A frozen caliper means the piston inside is corroded and can’t be fixed. It will need to be replaced.
How to check for a frozen caliper? – Remove the caliper from the bracket, and try pushing the piston back. You’ll need a channel lock or brake tool. If the piston doesn’t budge, try opening the bleed screw. If the piston still won’t move, then it’s seized and will need replacing.
If it did move, you’ve found an issue with the brake hose. The internal lining may have come away from the line and created a blockage. Go ahead and order a new brake line set.
Are ATV brakes soft? A soft brake feel indicates air or contaminated fluid in the Hydraulic braking system. Try replacing the brake fluid and purging the air from the system. Most ATVs will use DOT 3 or 4 brake fluid.
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- About the Author
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John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.