Automotive Expert’s Analysis of Accident Conditions is Challenged in Brake Failure Case

    Court: United States District Court for the Northern District of Alabama, Eastern Division
    Jurisdiction: Federal
    Case Name: Bolt v. Ford Motor Co.
    Citation: 2019 U.S. Dist. LEXIS 44678


    The plaintiff crashed his 2002 Ford Taurus after the car kept accelerating even after he released the gas pedal. He claimed the brakes were unresponsive and did not allow him to slow down. As a result of the car accident, the plaintiff sustained brain, pelvic, and lower limb injuries. The plaintiff filed a suit against Ford claiming that the defective design of the speed control cable retention collar of his car caused the issues that resulted in his crash.

    Specifically under scrutiny was the 2002 Ford Taurus’s throttle control system, made up of a speed control cable and an accelerator cable connected to a throttle body plate. This body plate opened when the accelerator cable pulled as the pedal was pressed, generating speed and torque in the engine. Two springs closed the throttle body plate and turned the engine back to idle when the pedal was released.

    The speed control cable was part of the cruise control system. A servo pulled on the cable when the system was activated and a lost motion device connected the cable to the body plate. One end of the cable was bound by a ferrule, secured by two tabs within the cable retention collar. The retention collar, made of Nylon 66 polymer, was mounted on a bracket near the throttle body.

    The Automotive Expert Witness

    The automotive expert witness was an automotive mechanic retained by the plaintiff. The defendant, Ford, sought to exclude the expert’s opinion as unreliable and irrelevant. In his expert report, the automotive expert witness reported that his preliminary visual inspection of the vehicle showed that the speed control cable ferrule had been detached from a fractured retention collar. He further claimed that the throttle body plate had opened by 25-30% and that his discovery of slack in the accelerator cable had allowed him to exclude this cable as the cause of the throttle body plate being opened.

    The automotive expert carried out tests on another 2002 Ford Taurus to determine the effect of a broken speed control cable retention collar on the throttle and brake system. He used a cracked collar to measure how open the throttle plate would be when the cable was lodged against it. He determined that the vehicle would maintain 74 M.P.H. with the throttle body plate 29% open and that the vacuum assistance system could be exhausted by concurrently pumping the brakes.

    The expert noted that the results of his inspection of the speed control cable on the plaintiff’s vehicle were consistent with his testing of the exemplar vehicle. His ultimate conclusion was that the displaced cable in the plaintiff’s vehicle held the throttle body plate partially open, resulting in excessive engine speed and loss of braking capability. This, in turn, caused the plaintiff to lose control of the vehicle and crash into a tree.

    The automotive expert also, however, testified that he did not know the speed at which the plaintiff was traveling up the slope of the road or the grade of that part of the road. He further testified that he did not know how far the throttle body plate needed to be opened so that the plaintiff could travel up the inclined part of the road at 55 M.P.H., and that he could not say whether the throttle body plate would have to be opened more than 29%.


    The court noted that although the automotive expert’s methodology was sound, his assertion of the condition of the plaintiff’s car at the time of collision lacked a proper factual basis. The court discussed that although the expert testified that the throttle body plate would have to be at least 29% open for the speed control cable to become dysfunctional, a scientific conclusion would require consideration of the conditions at the time of the crash. The court found that the expert had not adequately accounted for the road grade and the plaintiff’s acceleration.


    The defendant’s motion to exclude the automotive expert witness’s testimony was granted.