Quote:
Originally Posted by mulberry
mister towed
can you say that in some sort of english for me to understand i have 1300 herald wots the best diff then ..
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Sorry if it was a bit over technical.
To make it simpler, the lower the number of the final drive the lower the revs will be at any given speed.
A standard Herald 1300 has a 4.11:1 differential. This means that the prop shaft has to go round four and a bit times to turn the back wheels round one full circle. The GT6 without overdrive came with a 3.27:1 differential so the prop shaft only has to go round a tad over three and a quarter times to turn the rear wheels once.
This'll give you more relaxed cruising, a theoretically higher top speed and better fuel economy
but, you'll lose some flexibility - the ability to accelerate from low speed in a high gear.
Obviously, those of us lucky enough to have the extra torque and power of a 2 litre six can run taller gearing and still vary our speed in traffic without constantly going up and down the gearbox, unless we fancy hearing that six cylinder roar.
With a Herald 1300 four pot you'll most likely have a 4.11:1 diff so at 60mph your engine will be turning over at 3,500rpm. Changing to a Vitesse 3.89:1 diff would drop that to 3,300rpm while a 3.63:1 from a 1500 Spitfire would reduce it even further to 3,100. With the Spitfire diff fitted though when the traffic slows to 40mph you'd only have 2,000rpm on the clock and with only 60bhp you'd probably need to drop a gear to pick up speed again.
As for which diff is 'the best' well, that really depends on your personal preference.