Originally posted by: Vic
First, no one should double-clutch a synchomesh transmission for upshifts. Anyone who actually double-clutches upshifts is a n00b poseur who probably watched F&F too many times.
More important that double-clutching is proper rev-matching. But on modern synchromesh transmissions used on the street, both techniques are most important for increasing the life of your clutch and transmission, and then ONLY for downshifting. Neither technique is really going to improve actual performance
for the street, but it will reduce wear and tear on the equipment.
On the track, proper double-clutching and rev-matching is crucial for improving vehicle stability at high speeds and under hard braking and cornering. Think of it... you're approaching a corner at 80mph and preparing to downshift from 4th into 3rd, where the engine rpm will increase (for example) from 4k to 6k. Simply slamming gears could easily lead to compression lock and unseat the vehicle's stability, leading to disaster. Here, proper downshifting techniques do improve performance, by allowing the driver to maintain a higher level of vehicle stability at higher speeds.
Originally posted by: chowmein
generally isn't double-clutching used for redline control downshifting?
Bingo.