Posted May 23, 2006

Ask the Experts

I recently bought a used ATV. Everything is in pretty good shape and it runs great, but the brakes feel a little soft. They don’t work as good as I would like. Do I need new brake pads?
John Foreman
Kansas City, Missouri

Great to hear from you, John. The timing of your question couldn't be better. We are working on an old ATV with the same feeling to the brakes. Don’t take soft or spongy brakes lightly because having the ability to stop your ATV quickly is vital for you and everyone you ride with.

You mentioned brake pads, so we will answer your question using an ATV with hydraulic brakes.

Check the brake pads first. On many ATVs they may have an external indicator that you can look at to give you an indication of wear. We prefer to jack up the ATV and remove the tires and wheels to get a clear view of everything.

Use a good light to help you determine if there is sufficient pad remaining, or whether you need to replace the pads. If they need to be replaced, start making a list of what you will need.

Next, thoroughly inspect the master cylinder, each caliper, and all the brake lines for any evidence of leaking fluid.

If the brake pads are good and there don't appear to be any leaks, then the most common reason for a soft or spongy brake feel is air bubbles in the system.

When doing normal maintenance on our ATVs one of the most overlooked checks is the brake fluid.

You will normally need a screwdriver to remove the screws that hold down the master cylinder cover.

Remove the cover and rubber diaphragm and check not just the fluid level, but its condition. It should be clear and free of any debris. Brake fluid that is discolored should be thoroughly flushed out and the system filled with new, fresh fluid.

Refill only with the fluid recommended by the manufacturer. Many times the fluid type is stamped on the master cylinder cover.

Use a vacuum brake bleeder, if possible, to simplify the job of bleeding the brakes. If you don’t have one you can buy one. It will come in handy more times than you think.

But you can bleed the brakes manually if you have some help. A vacuum pump is much quicker.

You will need to bleed each brake caliper separately. Start with the caliper that is farthest from the master cylinder. Attach the clear vacuum hose from the bleed valve to the pump reservoir and another hose from the reservoir to the vacuum pump.

Pump the brake bleeder and loosen the bleed valve. Old fluid should flow. If it doesn’t, lightly operate the brake lever: you could have a clog in the lines or valve.

If you see any bubbles at all, no matter how small, you have most likely solved your problem. Watch the fluid level in the master cylinder closely, it can flow quickly. Close the bleed valve and move to the next caliper.

Clean and replace the rubber diaphragm and cover on the master cylinder and tighten the screws. Caution! Brake fluid will damage paint.

Pump the brake lever to get the pads touching the rotors.

Replace the tires and wheels and tighten the lug nuts to the proper torque specifications.

Now it’s time for a slow test ride. You don’t want to go blasting down the trail without testing your brakes at slow speed first.

Doug Morris is director of the All-Terrain Vehicle Association and has a lot of experience working on quads.

© 2006, All Terrain Vehicle Association