DanS911

NEVER never give up John

Larry Herman

John, love the new Avatar, but don't agree on double clutching (or double de-clutching?). If you do it fast enough, you will match engine and wheel speed just fine. It does, however, take a lot of practice, and is not easily accomplished. So maybe your advice is better for the masses.

RedlineMan

Agreed Larry;

...On everything you said. D/D DOES work. It DOES take practice. It WOULD be better for novices (novi?) to learn single H&T. It also is unecessary unless you have a transmission problem, or you're driving vintage iron.

In the end, it is hard enough to learn the timing for one go through the sequence.

kwoksrus

Larry, in your earlier post you mentioned that you still double clutch. Can you describe the sequence? Just wondering if you blib a second time, after you have shifted to the intended gear?

Cheers,

Larry Herman

That's exactly how I do it, but the "blip" is a real push on the gas, running the motor up to around 6,000 rpm. I like to wait on the downshift, and go directly to the gear I want. It allows me to better concentrate on braking, and more time to do the downshift exactly when I want it to occur. If I do it right, when I let the clutch out, I am at around 5,000 rpm in my desired gear, and can continue with the last bit of braking, before I transition to the gas. That was with my old Carrera; with the GT3 add about 1,000 rpms to each number.

kwoksrus

Thanks for that Larry. At least I have not been doing it wrong all these years. But as John quite rightly pointed out, sometimes I can let the rev drops too much before clutching out. John's single clutch technique seem to be smoother in rev matching, but I feel uneasy staying in clutch whilst I blip the throttle. Just a habit thing I guess. Still, I will give it a go and see.

Stanley

RedlineMan

Hey Stanley;

What you have to realize is that the procedure I am talking about is over within a fraction of a second. Think of simply slapping the clutch down and back up. That is as long as it takes. If you couldn't hear the muffler, or see the physical motions, you probably wouldn't even know it hapened most of the time. Watch the "Lap of VIR" posted recently in this forum.

https://rennlist.com/forums/racing-and-drivers-education-forum/159123-in-car-from-vir-gt3-cupcar.html

That is how a H&T shift is done

Larry Herman

To echo John, the important thing here is to get the revs matched and to get the downshift done quickly. There is no one right way, and you should do what works for you. My way is more complicated, but it was something I learned on British cars, which had to be driven that way, and I have been doing it for 30 some years.

DGaunt

I might be asking for some disagreement here, but in my experience, there is enough drag in the clutch that blipping the throttle as Larry says--to 6,000 RPM and catching the gear on the way down, does spool up the input shaft speed enough to reduce the synchro effort by half or more. Try it.

Oh and on a 915, the synchros don't wear much, it's usually the operating sleeves that do. The most expensive part, naturally. If you see the two parts together and compare the void ratio ( lots of metal machined off the operating sleeve, comparatively little from the steel synchro, you'll immediately understand why.