Change final drive ratio...

Sep 02, 2005 75 Replies

But this might not help 0-60 time if the engine is peaky and need to be in the power band to produce the goods. Close ratios means that the power band can be better utilised.

However, 0-60 is as a performance measure is not ideal. In fact it is theoretically possible that a slower 0-60 car will cross the finishing line of a fixed length track before a faster 0-60 car. (even at full blast!). IMO we should try to get away from 0-60 time, bet it will never happen.

Our aftermarket exhaust is noisy in the 68 - 71 indicated zone, at 72 or higher (indicated) it's quieter. 72 indicated is ~67 GPS reported, so that works.

Yes it does, but the difference for most cars is changing from second to third or not. On a few, there could be a third to fourth. Using taller gearing can improve acceleration because the engine spends more time closer to maximum power.

As you say, this is a "problem" with using one benchmark for performance measurement. Shorter gearing makes it easier to keep the engine on the boil over a range of speeds but off the line stuff, it's not so useful.

If our Ka had slightly taller gearing it would probably be marginally quicker over the quarter mile. I'm approaching the quarter mile point above maximum power engine speed in third. Peak power arrives at 5,600 rpm and drops off very quickly; we cross the line just under 6,000 rpm in third almost at the limiter. It's not worth changing up... :-/

We already have, almost all manufacturers use 0 - 62 these days. :)

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Ahh you mean 0 - 62.15 mph ?

Ah the joys of the magnifying rear view mirror.

Sometimes...

I did see a lovely photoshopped image once, taken from inside a car looking at the wing mirror. Engraved on the mirror (For Murrikans, obviously..) was:

'Caution: Objects in the mirror are actually behind you'

Personally, I'm much more concerned about 40-80 times than 0-60, since that's what you want when accelerating onto a motorway; I very seldom need to floor the accelerator when starting from rest anyway.

Yes, and it's very unhealthy for the car anyway: Burning clutch, gearbox grind, CVJ wear, squealing tyres. Save your car and let the others do it.

It's not what I want, but I know what you mean, heh.

Not if you accelerate with mechanical sympathy of course.

Just my two pennorth. If you changed the diff to get around 2-3k revs at 90 instead of 4-5k you'd be roughly halving the gear ratio (doubling it? I dunno) in all gears. This would make 1st equivalent to at least 2nd and would mean slipping your clutch even more when starting.

I've read that 0-60 testers perform certain tricks, like moving the left foot sideways off the clutch.

Erm, but that's not the same as applying full throttle from rest...

They do that too. I guess that they must wear slippery shoes such that they can easily slide off the clutch pedal rather than lifting the foot.

Anything with a noticeable power band will probably accelerate quicker if you don't dump the clutch.

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