I'm curious as to how many ppl feel that dbl clutching is a worthwhile affair in sport driving. My opinion (not that it matters) is that the mass of the syncros is low enough that the wear caused by aggressively using them is hardly worth the time required to dbl clutch. There's no doubt that dbl clutching increases shift time and its sole purpose is to reduce wear on the synchros which only happens when aggressively downshifting. When you are aggressively driving the last thing you are thinking about is wear and the first thing you are thinking about is speed and precision, therefore i see dbl clutching as a contradiction to sport driving. Am i wrong?

 

It's not really necessary, although it's a good trick to have in your book for smoothing out downshifts. Also when you get really good at it you don't necessarily take up much time.

If you watch pro race drivers' feet on tv while they downshift, mostly they heel-toe without double clutching.

 

Two things:
1) in racing, double clutching doesn't exist! Just takes up more time and who cares about syncs, the gear box is replaced regularly.
2) the best trick to find your rpm at any speed is to get a feel of the relative ratio of gears. The beauty if this is that the ratio is constant throughout all speeds; for instance:
Say you were at 60 km/h as previous example, and after downshifting, you found the increase in revs is 1800 rpm (as previous example) then when you down shift from third to second, always add about 1800 rpm!!! Your problem is solved! This is how it is done by the pros (me being trained by them)

As for heel-toe trick, try this for big feet: put your 'wide' foot half on brake, half on fuel (as if you are trying to fit your foot between the two pedals), so instead of heel and toe, you wigle your foot left, to increase braking, right to blip fuel. Works magic in my case and in case of emergency, i press hard ON BOTH but with clutch so all is safe!

 

so if im getting this all right double clutching is basically down-shifting? and when i do double clutch do i have to let go of the clutch while im in nuetral?

 

No double clutching is when you match the revs between the gears so it eases into gear and the weight doesn't shift to the front from the downshift.

 

a) it is when downshifting
b) yes you let the clutch go for a quick engagment at nuetral before you press it again for shifting.

 

so in the fast and the furious when vin diesal says to paul walker after winning the drag race "not double clutching like you should..." he was wrong?

 

defiant; I appreciate your keen remark, however, that is street getto racing and nothing to do with proper say Rally racing!! They use street cars with regular gearboxes and they do need to double clutch and rev match if they are to shift without destroying the gearbox.

Again, I assure you from self experience that proper racing does not involve double clutching. Then again, remember; if everything they say in movies is accurate and true, then we should all be RAMBOs!!!

 

The only reason to truly double clutch a street car using a synchro gearbox is if those synchros start to go bad. My '97 Legacy's synchros in 3rd and 4th gradually wore away, and it was grind city unless I double clutched. Then it was nice and smooth, no grinding.

Its a good trick to have in your book for situations like that, or driving really old cars with non-synchro gearboxes. Otherwise, simple rev-matching is all that's necessary. That's the bottom line.

-Mirror

 

Practice, practice, practice. When learning to rev-match, like you are doing, forget trying to use the brakes at all (heel-toeing). Just keep blipping the throttle on downshifts, and as time goes by it gets more natural as to how big of a blip to give it.
Once you feel comfortable with that, then you can work heel-toeing with the brakes into the equasion.
Cheers,
-Mirror