double clutching

Richard,
There is no reason that double clutching would hurt your full synchro tranny. Is it absolutely necessary? No, you seem to already know this. It is a lot of fun and will still help the car.

Once you get the hang of it, it will become 2nd nature and will make you more aware of what your engine is doing.

We teach it at the track but only after students have a solid grasp of the basic skills.

Haus

Thanks in_d_haus. I get a kick out of fooling around in my Prelude, but if my 325i ever gets here from South Africa, I didn't want to do any harm to my new car. Maybe I'll try some real heel and toeing on the Prelude before my car comes in. On second thought maybe not, I need it for a trade in.

richard said:

Is there any harm double clutching with modern syncromesh transmissions? I find it kind of fun to try to match revs on downshifts. However, I'm not that good at it...can that be harmful?

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Better than single clutching and matching rev's.

I admit sometimes I single clutch and rev match when I should be double clutching and rev matching. When single clutching and rev matching, I really hear the syncros at work, so I am sure single clutching and rev matching must add wear.

Re: Re: double clutching

From a technical standpoint, what would the differances be from double clutching/rev matching?

CD-55 said:

Better than single clutching and matching rev's.

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Double clutching is different from rev matching, although many think they are the same.

Double clutching is when you clutch in, put the car in neutral and clutch out. Then, you clutch in again, select your gear and clutch out. What you do in between is up to you. Typically that would be matching revs. When you single clutch, the synchromesh is working hard to prevent you from ripping your tranny apart. Double clutching takes the synchromesh largely out of the equation.

hth

Nick325xiT 5spd said:

Double clutching is different from rev matching, although many think they are the same.

Double clutching is when you clutch in, put the car in neutral and clutch out. Then, you clutch in again, select your gear and clutch out. What you do in between is up to you. Typically that would be matching revs. When you single clutch, the synchromesh is working hard to prevent you from ripping your tranny apart. Double clutching takes the synchromesh largely out of the equation.

hth

Click to expand...

Yep, and it slips into gear slick as butter!

Dave, if you're cornering hard, the force of the transmission engaging is important. Remember: This force gets transmitted to your wheels. Back when I drove my E36 325i, the ONE and only time I allowed the synchros to take a down shift HARD and fast, I almost felt as if the parking brake had engaged in a turn, found my tail end coming around and had to work awfully damned hard to regain my line. It was this experience that interested me in rev-matching. If you're easing gently off the clutch, then you're not saving time, you're wasting it, increase wear and tear, etc.
When I first started, rev-matching took forever. I wanted to do it precisely. Now, I just hammer the throttle for a moment until the revs start climbing. Ideally, I like to get the car revved a little higher than where I actually want to be before I let the clutch out. Smooth, takes maybe 1 second longer than granny shifting and has yet to send me into a spin. :thumb: If you learn to heel-toe, it takes LESS time than granny shifting, because you've matched revs while still braking. This way, you don't have to wait for the car to rebalance itself and for the drivetrain to sort itself out after a massive shock.

Dave 330i said:

Double clutching and blipping have to take longer because you are doing more than just clutch and shift (less things to do=faster at doing it). I dont care if the shift is smooth like butter. In racing who cares about wear and tear? I am concern about maximizing my speed through the turn.

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As Nick states Double Clutching (rev matching) does make the car smooth, and speed through a corner is ALL about smooth. If you are doing things that upset the car you will never be the fastest through a turn.

Racers care very much about wear and tear. If you hammer your car you are out of the race... you don't get any points for that (or pay)

The whole reason people developed Double clutching (rev matching) was to save the equipment. and make their downshifts better, upsetting the car less.

Dave, I'd suggest taking a driving school. They will teach you the reasons with real examples of why these things are done. You do not want to waste any effort in a race car, double clutching is just one way to improve your times.

Haus

oh brother.

i understand a priori how someone would say that heel and toe and/or double clutching is "slower" and yeah, that's not the fastest way around the track.

but if you are truly driving the car at the limits of adhesion and do not care to match revs thereby unbalancing the car or blowing a shift....well, good luck.

short of SMG, the fastest way around the track is to drive smoothly. and that means rev matching and heel/toe and doubleclutching.

it means you get on the gas faster. and that's the point. either you're on the gas or you're braking. there isn't supposed to be any in between.

Re: oh brother.

blackdawg said:

i understand a priori how someone would say that heel and toe and/or double clutching is "slower" and yeah, that's not the fastest way around the track.

but if you are truly driving the car at the limits of adhesion and do not care to match revs thereby unbalancing the car or blowing a shift....well, good luck.

short of SMG, the fastest way around the track is to drive smoothly. and that means rev matching and heel/toe and doubleclutching.

it means you get on the gas faster. and that's the point. either you're on the gas or you're braking. there isn't supposed to be any in between.

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YUP! good point 'Dawg, BMW programmed the SMG to double clutch and rev match on downshifts. This came right from the F1 software. We won't even get into trail braking...

Dave,
I'm not slamming you here, please don't get me wrong. I'm just passing on information I've learned in driving schools.

If you think about it the act of double clutching seems like a total waste and it also seems like it would take longer than granny shifting.

But you have to look at the added benefit to the car (wear and tear) and the dynamics involved with turning (effect on the contact patch) to really see the benefit.

I thought I was a hot driver, even cocky about it, till I took my first driving. It humbled me considerably! I realized that I was just damn lucky. I also watch people going through corners at speeds I thought were impossible.

I've been to many driving schools since and am planning more. It is the cheapest and most effective "mod" you can do to your car.

I can now keep up or do better than cars that are far and away better than my little 325 because I drive better than the other wheel jockey.

I'm not blasting you buddy, just passing on something I learned the hard way.

I enjoyed meeting you at the 'fest.

Ok?
Haus