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Hi Roy,

 

there's nothing to stop you fitting the 3.45 crownwheel and pinion set, although I'd suggest you'll need a fair increment in power and torque to make it worthwhile. The Girling axle is reasonably strong, sufficient to take a substantial increase in engine output - it was the earlier Lockheed axle that was a weak link in the chain, prone to snapping halfshafts.

 

Cheers,

 

Alec

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You can gear cars up much more than you might imagine. My Bristol 400 (2 litre 100 BHP) is a bigger, heavier car than my TR3A yet I have an overdrive on it, it reduces the revs by 25% and gives me a 3.5 to 1 top gear that it pulls quite nicely, but with less accelleration than top gear, which at 4 to 1 is much too loo low. My son's business Richard James is regularly fitting 3 to 1 axles to Bentley MKVI, R Types and sometime Silver Dawns that started life at 3.7 to 1, so, in my opinion a TR would pull a 3.5 to 1 axle which I believe is the equivalent of overdrive top.

 

A Rolls-Royce 20 HP from the nineteen twenties is over 3 litres, weighs two tons and develops 50 BHP, nothing could be slower or more gutless, yet owners put 25% overdrives on them. They don't do any slower or faster, but they cruise without making so many distressing noises!

 

Ash

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Paul (UVC166) has a 3.45 diff in his 3a for long distance touring and that one certainly goes well ;)

Stuart

Edited by stuart
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Roy, The use of a 3.45:1 ratio over the usual 3.7:1 ratio gives an approx 7% reduction in engine revs for the same road speed. I have such a unit fitted in my 3 and I do not notice any problems with acceleration - you need not have any concerns if you decide to go that way, but remember that your speedo will no longer be accurate.

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