Chasvhill

What is being described is not really double-clutching. It's just driving. As a true old fart...and ex-truck driver (no syncros)...I can tell you that double-clutching involves actually letting the clutch out between gears and spinning the engine rpm up. On older non-synchronizer transmissions this would spin the gears up to a higher speed. Then you press the clutch back down and slide the tranny into the lower gear.

Matching engine speed in the middle of a downshift is routine and you should get to where you do it almost unconciously. It leads to a smoother transition to the lower gear which is especially important if you are powering out of a turn. Heel and toe shifting is a variation on this practice.

guy321

I said double clutch, OR rev match in my very first sentence. I only described reving up later on as both methods require rev'ing the engine, and both are better than just downshifting and letting the sychros scream.

When I shift I clutch/disengage gear, release clutch/rev, clutch/engage gear, then release clutch and drive. It can't just rev match smoothly without double clutching for some reason.

-=Rowdy=-

I thought automatic transmissions just simply downshifted when you hammer on the throttle-I did not know they synchro "matched". It seems like a lot to do when you really need to downshift quickly. Although I understand rev-matching. I just don't see even doing it quickly is quick enough for passing someone.

I rev-match all day when downshifting to slow down, but I haven't when simply passing someone from 4th to 2nd or 5th to 3rd.

guy321

Sorry, you didn't mention auto in the first post You're right.. auto, just shift.

On a MT, even double clutching happens fast enough to pass someone. It doesn't take any significant amount of time.

HeelnToe

... and is probably unecessary these days with modern synchros. As long as the revs are matched, it slips easily from one gear to the next without pausing in-between. Why bother with that extra step?

I drop straight from 6th to 3rd all the time... I just make sure I blip the throttle as/before I release the clutch so the transition is smooth.

guy321

I don't think he double clutches his car.. You're right it's not needed. I do it because i do it more smoothly and I feel more comfortable.

DC does put less stress on the synchros also.

rowteree

ive actually done a little risky trick. Ive gone from 6th to 2nd at a few times. Revs were around 3K going around 60 and just I gently put in second gear and revs fly up to around 7500-8K. You would be amazed how it jerks your passenger's head. Wouldn't recommend doing it, but if you're careful and brave you might get a little punch out of it. Do something wrong and new tranny right there