roymck Posted August 31, 2010 Report Share Posted August 31, 2010 What alternative ratios can be fitted to the TR3 Axle . Can the 3.45 to 1 TR6 ratio be fitted. Is the TR4 axle wider. And how strong is the axle? ..Thanks Roy Quote Link to post Share on other sites
Badfrog Posted August 31, 2010 Report Share Posted August 31, 2010 TR4 axle is one inch (per side) wider. Badfrog Quote Link to post Share on other sites
Alec Pringle Posted September 1, 2010 Report Share Posted September 1, 2010 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 Quote Link to post Share on other sites
Ashley James Posted September 1, 2010 Report Share Posted September 1, 2010 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 Quote Link to post Share on other sites
stuart Posted September 1, 2010 Report Share Posted September 1, 2010 (edited) Paul (UVC166) has a 3.45 diff in his 3a for long distance touring and that one certainly goes well Stuart Edited September 1, 2010 by stuart Quote Link to post Share on other sites
NickKerfoot Posted September 1, 2010 Report Share Posted September 1, 2010 Hi Roy I too have a 3.45 in my '4, put in by Moss about 5 years ago and still going strong. The car is pretty standard and still pulls well in all gears. It gives about 25mph per 1000 revs in o/d top (depending on tyres). Regards Nick Quote Link to post Share on other sites
Bob Smith Posted September 1, 2010 Report Share Posted September 1, 2010 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. Quote Link to post Share on other sites
roymck Posted September 2, 2010 Author Report Share Posted September 2, 2010 Thanks all for the replies , all my questions now answered.. Roy Quote Link to post Share on other sites
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