Truck fleets and owner-operators have been demanding relined brake shoes because of the cost of new brake shoes, especially for older vehicles. Adding them to your product offering gives you a broader breadth and depth of coverage, according to Pete Freeman, senior product manager, ArvinMeritor, Inc.
“If you are a dealer or distributor and you are not selling relined shoes, you actually are walking away from business you could be getting,” he says.
But be aware that not all relined shoes are equal and that you may want to look at carrying replacement shoes that have been remanufactured, not just relined.
Remanufacturing is a process that returns brake shoes to OEM specifications prior to delining.
“Distributors are moving away from relined brake shoes and toward remanufactured ones because the remanufactured product is as close to new as you can get at a competitive price,” says John Hawker, service engineer, Bendix Spicer Foundation Brake.
Remanufacturing is a process that involves several inspection points and quality control measures.
Understanding the process can help you assure your customers that they will get the mileage they need out of the shoes you sell them.
The first thing a brake remanufacturer does when it gets a used core is a visual inspection to check for wear and to make sure the core is suitable for remanufacturing. “We look for things like bent anchor pins, smashed roller ends, broken welds, etc.,” Freeman says.
Hawker explains that the cores also are inspected to see if they can be converted to a more modern version of the Friction Material Standard Institute (FMSI) number. He explains that over time, engineers make changes to the cores of shoes but the shoe still retains the same FMSI number. By inspecting cores, the remanufacturer can do the appropriate work to bring the core up to the latest standards.
Once a core has been deemed suitable for remanufacturing, it goes through a high-pressure washing operation to remove grease and dirt prior to being delined.
“When it comes out of the wash tank, all of the loose paint, dirt, oil and debris are off,” Hawker says. “And if it had some surface rust on it, where it started to oxidize under the paint, this washing process breaks that paint loose and actually removes the surface rust.”
Now the shoe is ready to have the lining removed. Freeman explains that the best way to do this is with a punch press machine as opposed to shearing the lining off. “Some people will take a blade and run it between the lining and the table of the shoe. This cuts the rivets out and shears them off, but the pressure can elongate the rivet holes and that can lead to loose rivets.”
Hawker added that a de-riveting machine pushes the center of the rivet so that it unrolls and falls out. This prevents the table from being damaged.
Next, the delined shoes are sent to a bead abrader to remove any of the paint, rust or dirt that did not come off in the washing operation. This process takes the shoe down to bare metal.
The cleaned shoe undergoes another inspection at this point. “You need to look for things like deep corrosion and pitting on the shoe table,” Freeman says.
Basically, this inspection determines if the shoe is suitable for the next step, which is coining. “We are evaluating the thickness of the table,” Hawker explains. “We need to determine if we will be able to flatten the table out to make the correct arc for the friction material. If there is too much rust, if it has been relined too many times or if there is not enough table thickness left, the shoe is scrapped.”
In addition, according to Freeman, you need to use stretch gauges and anchor pin gauges to make sure shoe stretch is correct and that anchor pin holes and roller slots are not worn excessively.
The webs, the structural parts of the shoe that are under the table, also are inspected at this point in the process. If they are stretched they need to be bent back into shape.
Shoes that are acceptable are now ready for the coining process. This process is designed to correct the arc of the shoe so that it is ready to accept new lining.
“Brake block is made to a certain arc or curvature, and is rigid for the most part,” Freeman says. “If the curve of the shoe does not match the curve of the block, when you go to rivet the block, you will crack it.”
After coining, another inspection is performed. “Once the arc is correct, there is no excess wear on the tables, the anchor pin holes are at acceptable tolerance and rivet holes are determined to be sized properly, the shoe is ready to be painted.
After the painting process, the shoes are ready to have new lining riveted on. At this point, it is important to make sure that both sides are riveted down evenly. “If you rivet one side of the lining down first, what will happen is you will have one side down tight which will cause a bigger gap on the other side. This can cause the corner of the lining to break off as you tighten it,” Freeman explains.
The brakes are then inspected again. According to Carl Swanson, product manager, aftermarket brake, Bendix Spicer Foundation Brake, the next step is to check table gap. “Any gap greater than a .006 tolerance between the shoe table and the friction material is unacceptable. It creates the opportunity for the lining to crack under stress.”
Rivet torque to rotate and rivet roll also are checked at this inspection. In addition, a visual inspection is performed to make sure the shoe was not scratched during the relining process. “Anytime you break the finish of the paint, you introduce the opportunity for rust jacking because water can get underneath the paint and start rust,” Hawker says.
Now the shoes are ready to be sold to your customers with some assurance as to the quality and life of the product.
Application Issues
Are remanufactured brake shoes appropriate for every application? Some experts say yes, while others say no.
John Hawker, service engineer, Bendix Spicer Foundation Brake, says no. “I do not recommend relined or remanufactured shoes in high-duty-cycle operations, like school buses or trash trucks.”
His reason? “You are using a piece of steel that has been stressed, flexed, bent and reformed. You are going to put it into a high-duty cycle, which will subject it to undue stress again. A piece of steel can only be stressed so many times before you start seeing degradation of the root product, the steel table or the webs.”
However he adds, “The marketplace will not accept my point of view. School buses are moving closer to requiring all new shoes but not trash trucks.”
Pete Freeman, senior product manager, ArvinMeritor, Inc., disagrees. “I can’t think of any application where you can’t use remanufactured shoes. However, if you are using relined shoes, you have to make sure that you use the same size shoe as the one that came off the vehicle and that you are using the correct friction material.”
He adds, “Unfortunately, a lot of customers look at relined shoes as a way to cut costs and they may be looking for a cheap solution so they will ask for a lower grade of lining than what was originally on the vehicle. This can cause problems.”
Rejected!
Not all brake cores are eligible to be remanufactured. The following conditions will eliminate a core:
- A broken weld
- A cracked table
- A cracked web
- A mushroomed roll pocket
- A mushroomed anchor pocket
- A table that is bent severely
- A corroded table
