Commentary: Getting Ready For Discs

Air disc brakes are a small portion of the market – so far. It’s a good time to learn about ADB maintenance.

February 2014, - Editorial

by Denise Rondini, Aftermarket Contributing Editor - Also by this author

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Have you been avoiding spec’ing your vehicles with air disc brakes because you think they are not seeing widespread use or because you have concerns about the cost of maintaining them? You may be surprised to find that the air disc brake market has actually grown 90% since 2005 and they take less time to service than drum brakes.

According to Gary Ganaway, director of marketing and global customer solutions for Bendix Spicer Foundation Brake, while air disc brakes represent only 10% of the Class 6 to 8 brake market, they are increasingly being spec’d, especially by owner-operators, fuel haulers and other safety-conscious fleets.

Even if your own fleet is not currently equipped with air disc brakes, if you work on vehicles other than those in your own fleet, it is time to take a look at mastering air disc brake service.

If you plan to service vehicles equipped with air disc brakes, you’ll need to make sure you are stocking the proper parts. Meritor suggests you add calipers, rotors and friction pads.

The good news with air disc brakes is that steer and drive axle brakes are essentially the same, Ganaway says. This allows for the same pad replacement kits to be used regardless of the wheel-end position for both tractors and trailers.

However, having the right parts on hand is not enough. Your technicians also need to have proper training in maintenance and repair. Both Meritor and Bendix Spicer Foundation Brake have resources available, including instruction videos and service manuals.

While rumors abound about the higher cost of maintaining and repairing air disc brakes, the reality is that they have fewer moving parts.

“Air disc brakes are a premium option for most platforms,” Ganaway says, “but also standard on a growing number of vehicles. While the service parts are typically more expensive, we see this offset by longer life, faster service times, and the avoidance of the need to periodically lube the brakes.”

He adds that once the wheels are off, it typically takes just 15 minutes to change pads on air disc brakes, compared to 60 minutes for drum brakes.

Air disc brakes are low-maintenance items, but Ganaway is quick to point out this does not mean no maintenance. Maintenance items include pad kits, guide pin/bushing kits, tappet boots and guide pin boot kits.

Meritor also says air disc brakes need to be inspected periodically, and that calipers, torque plates, pads and rotors should be checked for signs of wear and damage. In addition, it is also important to check for loose or missing screws.

Bendix recommends replacing pads an axle set at a time to prevent torque imbalance across an axle. While tappet boots should last the life of the vehicle, they are susceptible to tearing from road debris and therefore need to be inspected when the vehicle is in for regular maintenance.

While air disc brakes in North America do not enjoy the market share they do in Europe, they are increasingly being spec’d as many fleets look to reduce maintenance and extend service intervals. Now’s a good time to get familiar with properly servicing them so you’ll be prepared for the future.


  1. 1. Mike Pennington [ February 11, 2014 @ 06:32AM ]

    Quick-change cam brakes take about 20 minutes to change, not 60 minutes. And every shop in North America stocks cam brakes, springs, rollers, shoes with right friction, plus every technician is comfortable with this proven component.

  2. 2. Russell Vaughan [ February 11, 2014 @ 05:14PM ]

    They are constantly trying to compensate for drivers that don't know how to drive and know nothing about their equipment. I wish they had never come out with auto slacks either. It took away my choice about my trailer brake adjustment in bad weather. The industry has no respect and places no value on experience and long years on the job.

  3. 3. Michael Ashley [ February 11, 2014 @ 06:57PM ]

    After 20 years as an owner operator I use to poo poo the air disc brake system. They used to be horrible to work on and expensive. I have been in the fire truck repair business for over 10 years and I can tell you that the air disc brakes that are out now a days are unbelievable to drive and easy to work on.
    We get incredible mileage out of a set of pads.
    Don't be afraid!!!

  4. 4. Julie Garcia [ February 12, 2014 @ 07:49PM ]

    I'm in sales for the Fontana California Wabash National Branch, we are hosting an open house in May and I would be interested in having a rep come out to demonstrate or have information. If you have someone available to do some training on the disc brakes to our mechanics and other mechanics that will be invited that would be even better. If this could be possible please contact me at the e-mail address above. Our Open house date is set for May 15th, 2014


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