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2004 Saturn L300

Question: What causes vibration breaking at highway speeds?

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Badger1969, 3.0L V6, Janesville, WI, November 22, 2011, 13:58
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There was cupping in the tires. I've had a four wheel alignment, replaced the front struts and springs, R&R sway bar links, and a new set of tires. The vibration occurs when breaking at 65mph. Slower speeds and extremely gentle breaking does not result in vibration. The vibration is felt through the break peddle and steering wheel.

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  • Answer #1

    mastertech6371 November 22, 2011, 19:08
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    warped brake rotors from overheating of the brakes.

    Roy

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    Badger1969, November 23, 2011, 05:44
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    Thank you

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  • Answer #2

    patrick mannion from Greg Solow's Engine Room, November 22, 2011, 20:58
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    Agree with Roy. When the brakes are applied to slow down the vehicle heat is produced. This heat may cause the brake rotors to warp or buckle. If the brake discs are warped even three or four one thousandths of an inch, the brake pedal may pulse and the vehicle may shake when the brakes are applied. If the brake discs are badly warped the whole vehicle may shake and cause the steering wheel to oscillate and shake from side to side under braking.To eliminate this unwanted vibration the brake rotors need to measured both for uniform thickness and “run out”. Run out is a measurement by rotating the brake disc and accurately measuring how much deflection the surface of the brake disc takes as the disc is rotated. The brake discs are brought back to uniform thickness and parallelism by machining the brake discs if there is sufficient material left to remove. If the brake pads have worn down to the point where they have damaged the brake discs the brake discs will need to be machined or replaced.

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    Badger1969, November 23, 2011, 05:45
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    Thank you

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