Tech Stuff

Brake system tech: Plus safety issues for the customer — and your shop

 

For a thickness check, measure rotor disc thickness approximately 1/2-inch or so from the outer edge of the disc.
<p>For a thickness check, measure rotor disc thickness approximately 1/2-inch or so from the outer edge of the disc.</p>

Weber is president of Virginia-based Write Stuff. He is an award-winning freelance automotive and technical writer and photographer with over two decades of journalism experience. He is an ASE-certified Master Automobile Technician, and has worked on automobiles, trucks and small engines. He is a member of the Society of Automotive Engineers (SAE) and numerous other automotive trade associations. He has worked as an auto service technician, a shop manager and a regional manager for an automotive service franchise operation.

Should you encourage your customers to change their brake fluid? They may balk. After all, seldom is there any mention of this as a periodic maintenance service in many owner’s manuals.

European auto manufacturers are more adamant about replacing brake fluid than their American counterparts. Besides, European service is almost exclusively done at dealerships rather than at independent shops like we have in the U.S. European car owners also tend to be more fastidious about maintaining their vehicles. But brake fluid flush and fill intervals are now creeping into domestic maintenance schedules.

Brake fluid flushing was seldom done in the past. How many times have you performed the service on your own vehicles? Of course, we could ask how many times you have purged your water heater. For the most part, neither task has really been an issue. Nevertheless, we would bet that you have replaced a water heater at least once due to neglect.

The same could be said for brake system hydraulic parts. Without occasional service, components could fail. Some, like wheel cylinders, are cheap. Some, like ABS components, aren’t. Any contaminants that get into the ABS modulator assembly can cause expensive damage. Spending about $100 on a brake fluid flush and fill can save thousands on ABS repairs or at least hundreds on caliper or wheel cylinder replacements.

While a traditional micrometer (with flat anvils) is certainly adequate, for best results when measuring brake rotor thickness, a dedicated rotor thickness mic features both flat and pointed anvils.
<p>While a traditional micrometer (with flat anvils) is certainly adequate, for best results when measuring brake rotor thickness, a dedicated rotor thickness mic features both flat and pointed anvils.</p>

Water in the brake fluid leads to corrosion, but where does the water come from? After all, the hydraulic system is sealed — it is a closed circuit. The only time it is even open to the atmosphere is when the cap on the master cylinder reservoir is removed to add fluid. And you really should not have to add fluid unless there is a leak.

Since brake fluid is hygroscopic, water can also be drawn through the microscopic pores of rubber hoses and even the reservoir vent. Although there are corrosion inhibitors in the fluid, they wear out over time — up to 90% in as little as three years. The more depleted they are, the less moisture it takes to cause corrosion damage.

Tags: Brake service  Brakes 
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