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Inside The Bosch Xperience Mobile Technician Training

Robert Bosch LLC has been bringing technician training straight to the shop this year with its Bosch Xperience mobile tour, and when it rolled into The Swedish Solution in Orange Village, Ohio, a team of editors from Babcox Media had to check it out. In...

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Service Adviser Pay Program Tips That Work

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Mercedes-Benz: Installation guidelines for Smart Car front wheel bearing

The typical solution for replacing the front wheel hub on a 2008-‘13 Mercedes-Benz Smart Car is a front wheel hub assembly, including a front wheel hub and knuckle. However, with a wheel hub-only ­solution for the Mercedes Smart Car, like the one offered...

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Kia: Uncovering Unperformed Maintenance

While some vehicle problems will motivate the customer to make an appointment, an equal amount of Kia repair opportunities will be discovered as the vehicle is being serviced. If you’re not already doing so, always encourage your customers to keep...

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The Evolving Oil Change Market

The only constant in the oil change business is change itself, especially if you’re trying to maintain an inventory of engine oil for all makes and models of vehicles. Since Volkswagen began ­requiring application-specific engine oil in the mid-1990s,...

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John Heist Appointed Chairman of ETI's Mechanical Systems Group

STAR EnviroTech’s OE Account Manager, John Heist, has been appointed to the position of Chairman of ETI’s Mechanical Systems Group (MSG). He is also one of the newer members of ETI’s Board of Directors. MSG supports manufacturers of tools and...

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Snap-on Offers Top 14.2 Reasons To Upgrade To Latest Diagnostic Software Release

Keeping the diagnostic tools up-to-date is critical, because without the latest vehicle coverage, professional technicians simply cannot service as many vehicles in a day. Snap-on Software Upgrade 14.2 supercharges the Snap-on family of diagnostic tools...

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Tell Us Your Top 5 Tools and Win!

Send in your list of your five favorite tools and equipment that help you most in the shop, and you could be chosen to win a $25 gift card for Bass Pro Shops. From scan tools to flashlights, impact wrenches to on-car brake lathes or computer systems...

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Diagnosing Power Steering Loss on a 2008 Ford Escape

The vehicle in question is a 2008 Ford Escape with a 3.0-L engine. The customer complaints are as follows: The steering wheel will turn by itself; at times, usually when turning, the vehicle will lose all power steering assist; and occasionally, while...

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Cartridge Oil Filter Tips

Cartridge oil filters account for a large number of oil filter applications in the field. The chances of improperly installing a cartridge oil filter are greater than with a spin-on filter. The key is to take your time, inspect before installing and follow...

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The Case of the Missing Starter

I was called last fall by a client who owns a heavy-duty diesel shop to diagnose a no-cranking condition on his father-in-law’s 2006 Chevrolet Tahoe. Because his work is mainly with heavy-duty trucks, my client knew he was lacking both in tooling and...

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Home Brakes Twin-Piston Calipers: Are Two Pistons Better than One?

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generate more torque. More torque means more stopping power. Also, by using the floating caliper design instead of an opposing piston design, engineers are able to avoid wheel clearance issues and other robust design features of the floating caliper.

With a single-piston caliper, the footprint of pad is limited in some ways to the diameter of the piston. The diameter can only grow so large in relation to the rotor and brake pads. If the pad is too long, it flexes. When the pad flexes, it creates an uneven friction coupling on the rotor’s face. The uneven friction can create unwanted noise. If the flexing is sever enough, the friction material can separate from the backing plate. An example of this is the early Chrysler Neon. Also, there is a direct relationship between the diameter of the rotor and the diameter of the single piston caliper.

With dual- or twin-piston brake pads, the pads can be larger with even pressure distribution. A larger brake pad has several benefits. First, a larger pad will absorb more initial heat (less thermal shock). Second, a larger brake pad will have better wear characteristics and a longer life due to even pressure distribution. Third, a larger pad is able to absorb more unwanted noise and vibration because it is able to cover more of the rotor.

Another advantage is in the area of drag and fuel savings. With dual- or twin pistons, it is possible to have more aggressive piston seals that can pull back the pads more effectively after the driver removes his foot from the brake pedal.

SERVICE CONSIDERATIONS
Dual-piston calipers can be serviced in the same manner as single-piston calipers with a few exceptions.

  • Look for uneven pad wear. If the pads have tapered wear, it could mean a problem with the caliper. Tapered wear could mean that the slides are binding or that one piston could be exhort more force than the other, or both conditions could be present.

    The slides and bushings play a critical role on dual-piston calipers. If there is too much play, the caliper could rotate on the slides. This will cause uneven pad wear.

  • The pistons on dual-piston calipers may be difficult to retract. Both pistons must be pushed back at the same time and rate with special tools. If unequal force is used, it is possible to scrape the pistons against the bores. This can damage the finish and coatings on the pistons and bores. Also, it can damage the seals.

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Andrew Markel

Andrew Markel is an ASE Certified Technician and former service writer, and he brings this practical knowledge to the Brake & Front End team as editor.
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