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 type symptoms tend to be related to a hydraulic system leak.
- My brake lever/pedal feels hard and the brakes don’t work – These type 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 just 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 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) share 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 back-up system, makes good sense in theory.
In practice of course and in the heat of the battle, hitting a corner at full tilt, doesn’t leave a lot of time for grabbing plan B.
The brake circuits are either hydraulic or mechanically operated and commonly a mix of both.
ATV brake set-up – A typical set-up (I say typical because brake systems will vary) looks like this:
- Hand operated hydraulic brakes to both front wheel 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 brake).
Modern ATV’s however, will have four wheel braking from the hand lever and just both rear wheel braking from the foot pedal.
Other common ATV brake set-ups include:
- Hand operated hydraulic brake calipers front and foot brake to single rear brake caliper.
- Hand operated hydraulic front brakes 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 some foot pedal systems. A hand lever hydraulic brake circuit consists of the following components:
Brake Lever – Made from light weight 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 the 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 Rotors rotational energy into heat, as it slows the bike.
Brake Rotors – Metal disks fixed to each wheel hub and turn 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.
Some bikes may use a hydraulic foot brake to brake one rear wheel. The components of a hydraulic single rear wheel set-up 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.
Some bikes may use a mechanical drum brake setup on one rear wheel. The components of a drum set up includes 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 – 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 rusted adjusters.
Each wheel drum brake will have its own 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 which 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 afterwards.
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 just contact the drums.
You’ll find an adjuster inside each drum between the brake shoes. The adjuster is a screw that simply 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. 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 simply 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. This will tell if that’s the cause of the low fluid level. If it’s not, you’ll first need to check all components, connections and brake lines for any signs of dampness.
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 lines rubbed through
- Master cylinder seals
- Caliper piston seals
- Caliper bleed screws (Nipples)
Bleeding ATV Brakes
If you can’t find the source of the leak, go ahead and top up the fluid at the fluid reservoir. Use which ever type fluid recommend on the cap, DOT 3 or 4.
Gently work your brake lever, (as 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.
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. Gravity bleeding works a lot faster on vehicles with larger reservoirs.
A brake service vacuum bleeder kit works great on ATV’s or you can go the two man pump hold method.
A great MacGyver set up, is four clear plastic drinks bottles with four brake hoses:
- Fill reservoir and fit cap
- 1/4 fill each bottle with clean brake fluid
- Open each bleed screw and fit one end of the bleeder pipes (Clear pipe works best)
- Submerge the other end of the bleeder pipes below the fluid level in each bottle
- Pump to bleed system or alternatively allow gravity to bleed
- Keep an eye on your fluid reservoir level, it’ll need topping up
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.
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 remove one clap at a time and check 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 you brake calipers or fitted new ones, make sure they are on the correct side of the bike. Left hand caliper is different to right hand, hey, it’s an easy mistake to make!
A great way to remember is – The caliper bleed screw always goes to the top.
Worn Brake Pads/Shoes
Worn out brake pads/shoes will without 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 your 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 there bite, so although they may have lots of material still, they can give a hard brake feel. It’s a condition known as glazing, 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 course sand paper on a flat surface and run the pad across to remove the glaze.
Replacing brake pads is simple, brake shoes is quite 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 mounted in the brake handle assembly. It creates the pressure in the system, master cylinders fail regularly as they work pretty hard.
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 tell tale signs failure.
To quickly trouble shoot a master cylinder, you’ll need 3 hose clamps. Clamp each wheel on the circuit (usually 3 calipers) at the flexi hose (if possible).
Go ahead and check the brake feel now, if it’s improved, you’ve eliminated the the master cylinder as the source of the problem. I understand clamping the line won’t be possible for some systems.
If on the other hand, the brake feels the same, you’ve bled the system correctly and no leaks at banjo bolts, 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.
And you can 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 damages seals, pistons, brake lines and bleed screws.
Your fluid should be changed at least every 3 years to help maintain the system and prevent expensive brake overhauls.
Faulty Brake Caliper
Most ATV brake calipers use a floating caliper set up, it simple means the caliper is free to move side to side. Sliding bushings make this possible and It’s a good system but pron to corroded bushings, tis causes the caliper to bind and the brakes feel ineffective.
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 has corrosion and so 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 locks or brake tool. If the piston won’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 blockage. Go ahead and order a new brake line set.
ATV brakes are 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 ATV’s will use DOT 3 or 4 brake fluid.