As a matter of interest, I had a mate who worked at the Government motor garages at Glebe. He once told me that back in the Police Cooper S days, the government bought a Cooper S, used it as highway patrol for three monthes or 40,000 kmh (which ever came first) and then auctioned them off.

He told me that they commonly renewed at least one set of idler gears during the service life of a police car. The reason ?? The police used to key start the car, clutch out in first gear and just roar after the violator as the motor fired up.


As for motor racing and hot cars - my ex-wife said to me once after I a motor racing incident in the race car for the third meeting in a row "Why dont you just go up on Gladesville Bridge and throw twenty dollar notesd at the boats passing underneath. It would be cheaper and more fun".

The difference between the A series drop gears is that the size of the shaft is smaller than the A+ plus, which is larger... Also some are different in lengths, for 3 gear synchro’s they are shorter on both sides and 4 gear synchro’s have one longer side… but I’m just taking a guess from what I remember..

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A+ Series Primary gears have 27 teeth from memory, a standard A-series 1275 Primary gear has 24 teeth. This obviously requires changing the other "Drop gears" depending on which primary you have. As for difference in ratios, I'm not sure.

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-Wasabi
1972 Clubman - Daily Driver
1962 850 - EW1 Powered

You can't mix and match the A+ and A transfer gears as the tooth profile and angle are different.
The different ratios are to enable some fine tuning of the overall gear ratios if there is no suitable diff ratio for your particular purpose.
Not an issue for road use.

RonR