Larry Herman

Funny you should ask. The end of the straight at Summit is exactly where I was talking about. I would go from 5th to 2nd in my Carrera. I would get on the brakes and wait, and wait, and wait, and then downshift, turn-in and go. My downshift happened in the last 50 yards or so, but I really needed it to continue slowing. Otherwise, I'd overshoot my turn-in. When I was really on, I used to start braking just before the 300 marker.

JimB

The big advantage of working your way down through the gears is that you bias your braking more to the rear. It's very helpful on fast straights leading to slow corners, especially going downhill. Turn 5 at Road America and what ever the corner is at the end of the back straight at Road Atlanta come to mind. It's very hard on equipment but it certainly works. That's why you see the fast cup car guys like leh using the technique. I will do it in my 996 C class race car but only on special occasions like qualifying or when I need to go into one of those corners extra fast.
Jim

TD in DC

How does it affect braking bias? Also, in order to affect braking bias, you would need to disengage and engage the clutch slowly enough to get the desired affect, wouldn't you? Sorry for the stupid newbie question.

hacker-pschorr

The series of pictures in the middle is what happens if you don't blip the throttle properly in a 600hp vintage Corvette while downshifting. This is Canada Corner (turn 12) at Road America. He runs mid 2:30's here:
http://www.erik27.com/roadamerica/co...hris/index.htm

M758

I jump straight to the gear i need just like Larry does. My reason is that I feel I have slow feet. I can do a good job making one solid heel and toe, but can't seem to do it well 3 times fast or even twice fast.

For ME it is easier to do direct to the gear I need. I also learned heel and toe on the street where being in 5th and slowing for right turn at corner in second is quite common. Here you not in high revs at all, but need second on the way out of typically right turn. So I would brake and downshift to 2nd direct from 5th all the time. Of course on the street it was actually harder to do smoothly since you are not pushing as hard on the brakes and the pedals don't match as well.

I do feel if you can do it on street all the time and be smooth enough that passenger's can't feel it then you should very strong at the track.

Larry Herman

Todd, when you rev the engine up near redline, match revs and downshift, you get a large increase in engine braking effect. To try this, just run your car up to redline in 2nd or 3rd gear, and lift totally off the throttle. That is what you get. If you are under-biased with your rear brakes, it will help slow you down faster.

TD in DC

Ok, so in order to get the benefits of the rear bias, you would need to shift down through, and remain in each of, the gears for a relatively long period of time (i.e., 1000 times slower than Leh goes through the gears in his video), right?

Larry Herman

One of the reasons that Leh downshifts that way he does is because he can (his words, not mine). He is quite quick with the pedals, the cup car gear ratios are very closly spaced together, and steel syncros allow you to shift harder and faster. The other reason that he rows down through the gears is that he learned that way. Finally, if you drive a sequential trans, you have to shift down through each gear, so he always does it regardless of type of trans. I will have to see which method I like better when I drive a cup car.

chrisp

While watching the Infineon Nextel Cup coverage they showed in-car of Boris Said's footwork. I was intrigued when I saw that he is always deep into braking before he goes for the clutch. It was also amazing to see how quick his foot work was.

I am not sure why he waits so long...maybe it's something specific to the gearing in a Nextel Cup car.

Matt Marks

Remember - Nascar cars are 4 speed, so he has lots of time to make shifts as he has fewer ratios to go through, and they're farther apart.

JimB

Here is Leh's answer in a thread a couple of months ago when asked why he sequentially downshifts.

"In the cup car seems like the brake bias was more to the front so if u really needed it u could use the motor to slow down the car. Like when ur dive bombing someone. I dont use it to slo down the car eveytime i hit the brakes tho.

I think its just the way to do it. Makes the braking smoother. I dunno its just the way to do it. I used to skip gears when i first started. To me it jsut makes eveything go smoother when you sequential."

After reading this I tried it, but, only in very special situations.

TD, the sequence is depress brake, depress clutch, 5 to 4, blip, release clutch, depress clutch, 4 to 3, blip, release clutch, etc, etc. Obviously it's a pretty fast motion.

It actually makes a significant difference in how smoothly and quickly my car slows. I am not say that anyone should do this all the time and it might not even work in some cars. Also, there is no question it is hard on equipment. All I am saying is that there is a place for using your drivetrain to settle your car under braking and even aid in braking somewhat.
Jim

TD in DC

Interesting. So you get the benefits even when you are shifting very quickly. That was not intuitively obvious to me. I could see how it would make a big difference if you were using the same technique but waiting a second or so between releasing the clutch and then making the next shift, but it sounds like it works even at Leh speeds. I will have to try it some time (probably not at Leh speeds though ).

Carrera51

Using Summit Point as an example, I used to go from 5th to 2nd right before I got back on the gas at turn in. After doing this for many events, I started hearing an grind (second gear syncro wear I assume). Once in heavy rain I found that coming down through the gears resulted in the car feeling much better under braking, plus no more grinding. I've been using this method ever since and I just happen to like it better(apparently my 915 box does as well). It does require me to be quick and not ---- up the downshifts. Turned my fastest lap ever during the Summit Point club race last year so I guess it works for me. As others have said, this is a preference thing.

Capt. Carrera

• You only use the clutch when changing gears.
• You only change gears so you're in the right gear for the start of the next straight.
• You only use the brakes to slow the car enough for the corner.

You start braking. Now that the car has slowed, you need to pick a lower gear. Push the clutch in, shift, and while letting the clutch out, blip the gas. Repeat as needed.

One advantage of shifting down through the gears is it lessens the odds of over-revving the engine. If you shift from fourth to third a bit to soon, you may hit 6,500, or perhaps a bit more. Do the same thing going from fourth to second, and BOOM! Keep in mind, it’s only a matter of time before you screw a shift…

Rick Longano

If you watch Leh's video carefully you will see one wonderful example of professional racing technique in every respect, including sequential downshifting. Look carefully and you will see that Leh never pushes in the clutch until it's time to blip and downshift - as was stated before, it's easier to match revs that way AND minimizes any risk of engine stall by. Leh is 1 very gifted driver !

Rick Longano