TD in DC

I still think there is merit in learning how to DCHT even if I ultimately do not end up using it on the track or street. The main reason it is helping me now is that, with its smaller margin of error, it is forcing me to become more aware of my shifting. Remember, I am still very much in the grasshopper stage . . .

Larry Herman

I like my syncros, and since the brass ones in most of our trans's seem to wear out pretty quickly with track use, I find double-clutch downshifting to be a cost-saving skill. And I have not ever felt the requirement to perform lighting quick down-shifts, unless you want to row down through the gears and have a very close ratio six speed, like in the cup cars. BTW they have steel syncros to handle that abuse.

renvagn

Hi Ted,
I also did the Bertil Roos school and I am sure you will be fine. One caveat of the formula 2000 gear box was it did not require you to engage the clutch to take it out of gear.

So your sequence would be begin with braking, knock it out of gear, bring engine revs up, engage clutch, shift, let clutch out. I found reading the pre school manual was confusing and intimidating. In reality it was no big deal. You know how to drive and you'll be fine. You may want to ask them if the gear box will allow you to just knock it out of gear...... In addition, one of the more interesting points of a formula car is the need to be on the brakes into the turn to create down force allowing the car to turn in. In my turbo, attemping to decrease lag I am back on the gas ASAP, so the brakes on into the turn was different but easily and quickly adapted too.

mpaton

Pity to read such a denigratory post, and all the more so because it is WRONG!

It's not the straight cut gears that mean you don't need the clutch, it's the dog face selection of the gears. And if you have a dog box, it doesn't matter what the pattern of gear teeth is.

Furthermore, one reason (of several) to have straight cut gears in older gearboxes is to engare the gears by sliding them into mesh (not a constant mesh gearbox). If you drove one of those you would not only double declutch down through the gears, but also up!

Michael

FixedWing

On the "lighting quick down-shifts", I can see why this is unnecessary (since the downshift is usually taking place during an off-throttle period such as during the braking zone), but I personally feel more comfortable having the engine engaged as much as possible. Maybe this is just a crutch? But I feel that I have less control when the throttle is ineffective. I also like getting the downshift out of the way as quickly and simply as possible so that I can concentrate on other more important things. I think that's one of the reasons I like double-clutching -- it is fast and I only need to do it once rather than needing to row down through the gears (each time potentially upsetting the car).

Also, we seem to have been talking exclusively about track use. Tracks are by their nature repetative. We do the same thing over and over again. We can plan ahead. But driving on the street is not like that. Often we need to do unexpected things quickly. An example of this is trundling along in traffic in 6th gear when suddenly a passing opportunity opens up. Then it can be very useful to be able to double-clutch quickly down in to 2nd for the pass. The difference in time between double-clutching and using the syncros can easily make the difference between being able to take the pass and not.

One thing that continues to amaze me is how different our driving styles can be. Yet the we often have very similar results. Maybe driving is more of an art than a science?

Stephen

Geza

I add a second blip of the throttle before releasing the clutch after the downshift. First blip for gearbox engagement...second blip for engine engagement.

I'm with you. Even though it's not really necessary with a syncro gearbox, it's a skill that, IMHO, should be learned and used. There's nothing like coming into T1 at Summit Point in 5th, shifting directly into 2nd and having the shift lever just slide right in with zero resistance. Beautiful.

Also, on my commute, I have to shift into first twice while on a roll (to climb steep hills). Try shifting into first from 25mph some time without double de-clutching...it isn't pretty.

renvagn

Geza are you stopping in neutral with the clutch out blip for engine engagement??????

Capt. Carrera

With a good race box, I'm not even sure you need to clutch at all!

Geza

Clutch in.
Shift to neutral.
Clutch out.
Blip throttle (for gearbox).
Clutch in.
Shift to lower gear.
Blip throttle again if necessary (for engine/drive train engagement).
Clutch out.

Geo

Doesn't change the fact that clutching is not even required on a racing box. Double clutching is still an anachronism for drivers of cars with wire wheels while.

FixedWing

Shift faster. Without the need for the syncros that second clutch/shift action can be lightening fast. Then that second blip is unnecessary.

Stephen

FixedWing

I do it in my Turbo which has hollow spoke wheels. And I find it beneficial too.

Stephen

hinchcliffe

I was double cluthcing last night on my way home and it definitely seems smoother on the gear box in my daily driver '97 528i BMW.

kurt M

Ok I am Konfuzed.

Brake until car slows, clutch in, shift with rev matching blip to lower gear. Why the neutral stop and blip? The gear box is already turning.
Also you are, during the first part, coasting or under braking without throttle control.

Geza

The process I listed is double de-clutching (DDC). What you described is a conventional downshift where the syncros speed up the “input shaft” (while shifting into the lower gear) to allow for the smooth mating of the lower gear. In DDC, once in neutral with the clutch released, the “input shaft” is directly connected to the engine, allowing the driver to speed up the input shaft to the right RPM for the downshift with the first blip of the throttle. Now, the clutch can be depressed and the lower gear selected smoothly without using the syncros (to speed up the input shaft). The rest is just rev matching the engine speed to the drive wheel speed to make sure things are smooth once the clutch is released. Hope this helps.

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