Stop for Maintenance, Part 2

No matter how religious a shop is with preventative maintenance (PM), brake systems will eventually have to be replaced. Randy Petresh, vice president of technical services for Haldex Brakes, says the problem with brakes and tires is fleets are constantly wearing them out, so replacement...

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No matter how religious a shop is with preventative maintenance (PM), brake systems will eventually have to be replaced.

Randy Petresh, vice president of technical services for Haldex Brakes, says the problem with brakes and tires is fleets are constantly wearing them out, so replacement becomes a high maintenance expense.


When the maintenance issue does come down to replacement, Chuck Eberling, principle engineer in vehicle systems group for Bendix Commercial Vehicle Systems, warns technicians to follow the original specifications for the brake systems as possible.

"As far as lining and component replacement, you want to be certain-and all of Bendix's manuals state this-that mechanics are replacing like for like with respect to foundation brake material being utilized for a given application," he says.

Tom Runels, manager for drum brakes for Bendix Spicer Foundation Brake, persuades technicians to constantly refer back to the manuals for specific component indications.

"Our expectation would be that the OEM equivalent materials would be used, whether it is linings or bearings, air chambers-anything that would be replaced on the brake would be OE equivalent-otherwise they are not within the approved specification," he says.

Kurt Hornicek, director of medium heavy vehicle technical services for ASE, says "Our policy here at ASE is that whatever the OEM or component manufacturers recommend during any type of repair or diagnostic procedure, that's our standing," he says.

Mike Caggiano, product line director for specialty products at Bendix Spicer Foundation Brake, said that although a brake system can still function if individual components are replaced rather than the entire system, it isn't ideal.

"In a perfect world, when you go in and do a brake job, you would change all the parts. It's getting it as close to the original equipment as possible. Go in and replace everything, however na?ve that may be," he says.

"We recommend that they change brake shoes, springs, pins and clips, (and) if you are going to change the drums you look at your bearings, your seal and all of those types of things," Caggiano continues. "Slack adjusters and spring brakes, while they are wheel end-related, they don't normally need to be changed with every brake job-they are looked at a little bit differently, they are a little bit outside of the normal wear items."

Hornicek reminds technicians that they need to know what to look for. "Brakes are still the number one issue year in and year out," he says.

"Check to see if the automatic slack adjusters are properly maintained. If they are not maintained properly, then the brake will go out of adjustment," he says.

Hornicek advises that there are various ways to check brakes. "One, make sure the brake is in adjustment. If it isn't, let's say you do a brake job including the initial set up, you've got to just make sure that the brake is set up properly," he says. "It really depends upon the manufacturer you use."

Preventative maintenance for brakes is unlike other components where technicians can use diagnostic tools to find the trouble codes.

According to Hornicek, "Most brake inspection is visual. If you are doing an initial installation, for example, you put on a set of shoes, there used to be one where you did a torque wrench and torque check on it to see if it would move. It is pretty bullet-proof overall," he says.


"So when you are looking at maintenance, you do the same thing to the right side as you do to the left side, and you change everything out at once," Caggiano says. "Although we all know in practice, that doesn't happen."

"We would ask that if they change shoes or pads then they change the related hardware. Brake systems are designed to be fault tolerant and extremely reliable under such diverse conditions and lots of levels of maintenance. Maybe that's why the industry doesn't maintain things as well as they really should because they have found that they get reasonably reliable performance when they sometimes run a little short on their maintenance calls," says Caggiano.

Eberling reinforces that whatever you do to one side you do to the other. "It would also probably be a good idea to check ABS sensors to make sure they are in proper adjustment as they are doing the brake job."


As the bulk of the maintenance continues to be done in-house, here are a few things to keep in mind, according to our experts.

Kevin Pfost, technical service at Bendix Spicer Foundation Brake, says, "An important thing when you acquire a new truck, whether it is brand new or it is acquired as a serviced used vehicle, check the brakes upon receipt of the vehicle just to make sure that everything is there and that it is working."

"There are many things that are apart of the brake system that are set up upon first installation, like a slack adjuster. It's the preverbal kick of the tires before you take it out on the road on both new and recently purchased vehicles," Pfost says.


Bendix Spicer Foundation Brake's Caggiano said, "The one thing that comes immediately to mind is the myth that the automatic slack adjuster is automatically adjusting-it needs to be set up properly and it needs to be maintained."

Andrew Hess, marketing manager of hydraulic parts for Bendix Spicer Foundation Brake, wants to remind fleets, "Most guys who work on trucks are very well trained; however, in smaller shops where it isn't as controlled of an environment, they may receive a driver complaint concerning a truck and notice that a slack adjuster is out of adjustment. They may be tempted to manually adjust the slack adjuster into its correct operating range and send the truck its way.

"The problem with this approach is that, usually when an automatic adjuster is out of adjustment, it is due to some other issue in the foundation brake. If you just manually adjust it back to the correct position, the problem is going to present itself again. So, you have to do a little bit of analysis when you see something out of adjustment, because generally that's an indication of a problem with another foundation brake component,"says Hess.


There are always indications that can be measured to evaluate the wear on the components. Whether it is listening to the driver's complaints to diagnose a problem, or physically getting under the truck to take a look, no amount of effort will be wasted when proper maintenance and replacements schedules are followed.

Petresh's take on brake systems is that it is crucial to reinforce strict PM practices. He also reminds fleets to utilize items like organizations, technical manuals and other publications. Component providers and professional associations put a lot of resources into producing these materials, which can often be wasted because no one takes advantage of them.

ASE's Hornicek encourages fleet shops to take advantage of the technical manuals offered by various company websites. Many of these manuals are free of charge and will download instantly. The following websites offer technical service information and brake maintenance tips: Literature Center Products and Services Commercial Vehicle Systems North America