SwayBar

That is not what I said, or, I did not mean to imply it. Since we're talking about braking, I intentially left out listing appropriate downshifting as it was implied.

heinrich

bla bla bla bla :P we all have opinions

heinrich

Btw Sway Brother ... there is no effect on our gearboxes, of double-declutching. None. Step on it once, step on it twice, same diff. Gears turn and are not slowed down any better by double-declutching.

James-man

My torque tube went from ill to terminally ill at my last track event. I have to believe that a contributing factor was engine braking, in the name of "rev-matching", so I find it hard to dissassociate the two.

I will say this, I apologize if I misread or misinterpreted your statements. Hasty reading and hasty typing occurs at the kids' bedtime and I suspect this was the case.

Jim bailey - 928 International

As long as there is no load not accelerating or engine braking the gears will disengage very smoothly if in doubt you can depress the clutch pedal but immediately let it back up while you come to a stop and wait to put it in gear. Everytime you push down the clutch the release bearing is put under very high loads as it bends all the spring fingers of the pressure plate to allow the friction disc/discs to move away from the flywheel. This also loads up the crankshaft thrust bearings but in the opposite direction of the automatic issue. Just more Blah blah blah... just drive it in a way that makes you smile !

heinrich

lol

RyanPerrella

who knew this would be such a hot topic.

Jim bailey - 928 International

Heinrich I believe that you are missing the point of double clutching , If you are downshifting and the engine is turning 3,000 rpm and you are going to a gear where the engine will need to be turning 5,000 rpm the torque tube , input 5 th gear are turning the 3,000 rpm buy reving the engine clutch torque tube and 5 th gear input gear to 5,000 rpm buy letting out the clutch in neutral. The gears are now turning about the same speed which they need in the lower gear. The syncros have little or nothing to do as the gears now turning compatible speeds when they mesh. If you listen to the big Semi tractors as they are shifting they are matching gear speeds. Syncronizers are used to make shifting easier for people who do not now how to double clutch

ErnestSw

Jim,
Far be it for me to correct THE BIG CAHUNA, but double clutching and rev matching are not the same thing. Proper double clutching is NECESSARY when you don't have syncronizers.

heinrich

I was about to say what Ernie said Jim. Double clutching in heavy trucks is used as follows:

Drive.
Clutch in, take out of gear (starts slowing gears)
Clutch out (gets gears running at idle)
Clutch in, put into gear (gets gears spinning up to new gear)
Clutch out (engages new gear)

John Welch

I tried coming to an intersection without the car in gear based on Jim's comments on an earlier similar thread. I didn't feel comfortable not having full control of the car as I was coasting, so I resumed downshifting. Luckily. A few weeks later, I approach a red light to turn right on red. As I am stopping, I hear the sound of locked brakes and skidding tires on wet pavement. Since I was still in gear, I was able to pull forward and give them the extra distance they needed. If I was in neutral, I would have been hit...

Dennis K

To slow the car down, use the brakes.

The reason to row through the gears on downshifts 4-3-2, is to be in the in the powerband when you get back on throttle, no matter when that may be. Being in gear also can help w/ rotating the car during turn-in. This is a much more subtle and secondary effect.

Re: what Ryan is saying, Michael Schumacher has an electronic differential in his Ferrari F1 car that he can adjust for % of lockup during acceleration and braking, separately. He has two dials on his steering wheel which he is often futzing w/ down the straights, altering the behavior of the car on turn-in and corner exit. He's notorious for wanting an unstable car on turn-in.

ErnestSw

This thread is turning into the department of redundancy department.

heinrich

Hey, Ernie just said : "This thread is turning into the department of redundancy department"

ew928

Waiting for Roger to dive in and ask:" What's a clutch?"

Ernest (NYC)