Sour Grapes

RE: Sour Grapes

13/07/2011 09:26:43, MERI MX5 said:

No Titus, It shows what a great all round car the Mx is and us six speed owners can do something you cant?....Change from 4th to 6th!, My Peugeot has a 5 speed box and it cries out for a 6th gear!, My mate has a Ford Kuga Tdi 6 speed and it's very 'long legged' and a treat to drive, So obviously my next car will be 6 speed!, Have you driven a 6 speed Mx Titus? If the 5 speed is so good why does Mazda bother with the 6 speed? ...

Like a few other people, you appear to be suffering from the delusion that the 6-speed 'box offers taller gearing than the 5-speed - that the 6-speed car is like a 5-speed car but with an extra, more long-legged gear on top of the other five gears.

If that was the case, I would be delighted to have the six-speed 'box - except that a modern engine (even a high-performance one) with its fuel injection, electronic mamagement and variable valve timing is so flexible that it doesn't need a lot of intermediate gear ratios.

Both the 5-speed and the 6-speed gearboxes in the MX-5 are overdrive 'boxes - the direct drive is the second-from-top gear, and the top (overdrive) gear in both cases is a "step-up" (overdrive) ratio.  However the 6-speed box is a close-ratio 'box which means that the step-up (overdrive) ratio in top is LESS than for the 5-speed box.  In other words, the 6-speed car would have LOWER overall gearing (more revs for the same road speed) in top, if it were not for the fact that it has a different diff. ratio to compensate for this disadvantage.  

Close-ratio gearboxes are a relic of the old days when the only way to get a lot of power out of a small engine was to put a really wild camshaft in it, which meant that although the maximum power at maximum revs could be greater, at lower revs the engine wouldn't pull at all; so you needed a close-ratio gearbox in order to keep the engine "on the boil" - it virtually stalled otherwise.

We have moved on from that.  A modern engine like the one in an MX-5 offers the best of both worlds.  It not only develops a lot of power for its size, it also has lots of torque right through the rev range and pulls well even from low revs, which is why it can be driven comfortably around town in top gear.  It doesn't really even need as many as 5 gear ratios, let alone 6.  Manufacturers just feel that they need to offer more ratios for marketing reasons. 

Like small boys who are always fascinated by how many gears a bicycle has (more is always regarded as better), some gullible car buyers seem convinced that if a car has a gearbox with a lot of ratios then somehow it must be a "better"car - faster or more economical.

If the overall range of the gear ratios is no greater, then there is no advantage in having a grerater number of closer, intermediate ratios.  This is demonstrated in the case of the Sport version of the Mk3 MX-5 which has exactly the same 0-60 time, exactly the same top sped and slightly WORSE fuel consumption than the 5-speed version.  But gullible buyers regularly fall for the myth and marketing hype that somehow there is some magic, imaginary benefit to be had from having more gears.

You demonstrate the pointlessness of this by boasting how easily you can skip the intermediate gears. Exactly!

RE: Sour Grapes

Boasting Titus? Bit strong a word! I dont recall boasting, I merely said it was possible to skip the odd gear where roads or traffic situations permitted!, You've convinced me the 6 speed is rubbish!...I'm just on taking mine out now and replacing it with a 3 speed Ford Popular box from the 'sit up and beg' type? This will give me 60mph in 1st....90mph in 2nd...and 150mph in 3rd if my calculations are correct!