Mintext testing ground



That the co-efficient of concordance amongst twelve motoring journalists trying to discover, through self-applied tests, the pads most suitable for the B.M.C. ADO16 series, should be compared to “six blindfolded women testing for best bitter” gives some idea of the divergence of opinions recorded.

The tests, which were carried out at the new Mintex proving ground at Sherborn-in-Elmet, Yorkshire, were to find the pad liner selected by both Lockheed and B.M.C. as most suitable for their range of family cars. Other than the correct pad liner, five other compounds were used on other pads, these being a selection of the many compounds tested over some months before final selection was made.

The test facilities consisted of a circuit of two straights of 900 yards connected by a loop at either end. A 2,200-yard straight for high-speed runs, and a water pit for wet recovery and rapid cooling of discs for cold braking. Tests carried out were left to the various pairs of drivers to devise for themselves, and to get consistent results the same sequence of tests were carried out on each run.

Six ADO16 variants were lined up, lettered A to F. Each had been fitted with different bedded-in front pads, while all rear drums were the same. After each half-hour’s tests, pads were changed so each test started with pads which had been bedded to the same degree.

A quick run through the various test results show A to have a poor co-efficient of friction when cold, building up to good as the discs got warm and beginning to fade when hot. The wet recovery was good. B’s co-efficient of friction was very good when cold but decreased slightly when hot. Wet recovery was fair. C was poor, improving slightly as it heated up. Its wet recovery was medium, but it caused the car to swerve on braking, and didn’t feel good at all. D was good when cold, but faded badly when hot. Wet recovery was poor, and was only of any use when quite cold. E was very poor when cold, snatching and jerky; it improved a little as it warmed up, but was on the whole very unsatisfactory. F was very even both when hot or cold. Its retardation not quite as good as the best results on B, but there was virtually no fade. Wet recovery was good, and high-speed braking even. This latter one we chose as the most suitable for use on ADO16’s and our results, fortunately, were the only ones to coincide with Mintex’s own tests. The morning’s testing was interesting and gave a very good idea of the differences of various pads on the same cars, also the thoroughness with which accessory manufacturers test their products.—M. J. T.