In article <Pine.HPP.3.91.950913225631.1777B-100…@libws2.ic.sunysb.edu> Everett B Perry <epe…@ic.sunysb.edu> writes:
>What is the point of a close ratio tranny?!?!?! Does it give you shorter
>throws or a larger rev distance?
"Close ratio" is just that – the ratios are close together. As a
result, changing gears doesn’t result in as large a change in engine
speed as a regular transmission.
The advantages here are obvious – if you shift up just a little inside
the peak torque or power range, when the next gear comes on, you can
be right at the start of the range. This can make driving easier, and
it can also give you better acceleration.
The disadvantage is that you *still* only have as many gears as a
reguler transmission, except the ratios are all packed closer to the
size of first. As a result, engine speed at a particular road speed in
a particular gear (including fifth, typically) is higher. More noise,
worse mileage.
The above disadvantage was extremely apparent with A1 GTIs. Fifth gear
just wasn’t a cruising gear – the car really was a candidate for a
six-speed gearbox. Very similar ratios are used on the new GTI VR6,
but the engine power offsets the problem the Rabbit had – you can
cruise on the highway (110km/h) at a reasonable engine speed.
In the past, tuners have often offered "combo-trannys", where close-
and wide-ratio trannys are combined. First-third and sometimes
first-fourth are "close-ratio", and fourth-fifth or just fifth are
nice and tall.
–
Scott Ashdown
Engineer, MPR Teltech Ltd.
Burnaby, British Columbia, Canada.
ashd…@mprgate.mpr.ca