Re: R-6 overdrive transmission

Posted by Peter Packard On 2010/10/6 23:58:58

G'day all, Jim is correct that the R6 has some peculiar aspects and that the cut-in and cut out speeds are determined by a centrifugal clutch arrangement. I wouldn't go so far as to say that the R6 is more fragile, as it shares the same epicyclic train as the R9 and R11 and was used on the torquey 320cid motor in 1939, it is just more prone to damage if lockout is attempted as per an R9 or R11 OD. The R6 has a throttle actuated automatic kick-down as per the R9 and R11, but the R6 cannot be easily locked out of overdrive after kickdown as can the R9 and R11. The R6 can be locked out of overdrive if accelerating very gently below overdrive engagement speed, or by stopping, engaging reverse gear, depressing the clutch and gently withdrawing the operating cable with the clutch depressed. I am using the R6 on a 1954-327 motor without any problems but I use a button on the dash to initiate kickdown. There are some overdrive aspects not widely recognised including using second gear overdrive to assist the brakes, if caught in the mountains or on a long downgrade in overdrive. Best regards Peter