Solved – 155. of All.: 1969 Ford Mustang Ferguson Formula

[grobmotorix]

Another rare photo of a Ferguson converted fastback Mustang:

[RayTheRat]

Please forgive a tired old man's failing memory & question.  I know I knew (frustrating as hell) what the trailing wheel was for, but can't recall it.  Was it a calibrated speedometer?  Slip angle detection?  Wheelspin detection?  None of the above?

Thanks,

[Wendax]

The fifth wheel, in Germany called Peiselerrad after its manufacturer, is a calibrated instrument for length measurement.

[Allan L]

The fifth wheel, in Germany called Peiselerrad after its manufacturer, is a calibrated instrument for length measurement.

therefore gave accurate speed data during acceleration testing.
They probably use GPS-derived data nowadays.