How do you down shift when multiple gears need to be dropped

[Tim Comeau]

Yes, it does make for good discussion and some learning, too!
By 2 separate functions, I meant that they are 2 distinct needs for the driver(in the brain).
1. I want to slow down.
2. I want to drop a gear so I'm ready to accellerate.

I never use the tranny to slow the car down.
You'll never hear my engine "chasing" the tranny.
By that I mean hearing the engine revs increase to catch up to the tranny speed when you release the clutch. If that happens, it would mean the driver didn't tach it up sufficiently and/or didn't time the release of the clutch properly. If you can hear the engine chasing the tranny it means you're adding a braking force to the rear tires, right? If you're already at threshold braking that would cause momentary lock up of the rear tires.........woops! Even worse, if you're trail braking at the time, "Game over."

I'd love to see the data on brake pedal pressure during downshifting. I don't sense that there's any "significant "change in my pedal pressure, but as a driver trying to get the most out a car, I wouldn't want there to be ANY, right?
Other than the possible slight lessening of the decelleration, my braking is uneffected by downshifting. It doesn't take any longer because I'm downshifting, nor do I feel downshifting distracts me from effectively using the brakes. But the data would tell the real story. Strap on that MyChron data logger, Mr. Benbow?

I'm still failing to understand how a driver would know how much to tach it up when shifting from 5th to 3rd.
You push the clutch in, take it out of 5th, go to threshold braking for 2-3 seconds, put it in 3rd, ...........then how much do you tach it up before releasing the clutch? Would you look down at the speedo and guess the revs per mph? I suppose if you let the clutch out slowly it can blend a little easier to make up for errors in revs?
If I run through the gears, I know to tach it up about 500-800 rpm between gears. I don't look at the tach, I know what this sounds like. So the tranny is actually almost always in gear, though the clutch is in.
The up side to this method is that if someone spins in front of me in the braking zone, I can accellerate immediately (because the car is in gear with the revs matched, I can let the clutch out at any time and hit the throttle. If you have to dart left or right suddenly while braking, and you have no throttle to make the rear end stick, you're in danger of becoming part of the mess.
As with most "techniques", there's more than one effective way of doing things. Some video of the differing techniques would be awesome!

[kary]

Tim, regarding how do you know how much to tach it up. What I do in the case of turn 3 at the speedway is the following:

1. In high RPM's full throttle in 5th gear.
2. Entering the brake zone, usually the second marker when no traffic in front me I begin the brake by just setting the brake to gently shift the weight of the car forward.
3. Now I put on full braking almost to lock up (nice to have anti-locks here).
4. I look down at my speedometer to see when I am approaching 70 mph. I am usually coming down from 135 mph or 140 mph in this example but it does not take long to brake down.
5. At the same time or very near the peek at the speedometer looking for 70 mph, I push in the clutch and shift the gear to 2nd gear. A few seoonds have passed prior to this for the braking. Since I have a nice LSD I like to allow the lock up on the ramp down to help out in the slowing and in 5th gear it is not that big of a strain on the car.
6. While the last two steps are happening, I am loosing speed from 70 mph. The top end of my 2nd gear is 63 mph. I normally target turn 3 at about 50 to 55 mph. I like to take that turn 3 at a fairly high RPM for the torque and then get back into 3rd very soon after making the turn in.
7. That said I now blip the throttle up to about 5000 to 5500 rpm which is about right for second gear at the 50 to 55 mph speed.
8. Engage the clutch. BTW, I am now off the brake and am about to turn in.
9. Turn in and get on the gas.


That is how I do it, but patenice is required to not down and re-engage the clutch too soon. I know I have come close or even breached on over rev's early on when learning to do this, but so far the motor has been tough enough to take it, but then that is a 993 motor

Also, one at each track, depending upon the tires I use, I am trying to figure out just what the sequence is for each corner and what the exact timing would be. One of the trick section at SOW coming into the high speed chicane took me the entire first day to figure out and master how I could get through it fast with out giving up speed (read time).

Just my two cents on a topic that I think has shown some very interesting information for all to think about.

[Mike]

I'm still failing to understand how a driver would know how much to tach it up when shifting from 5th to 3rd.

If I run through the gears, I know to tach it up about 500-800 rpm between gears.

It is a sensitivity you develop through repetition, same way some become skillful at left foot braking.

Tim you mention during rowing down you always blip the same RPM.
I vary the RPM I blip the throttle based on what speed my car will engage the gear. For example T-1 at Big Willow the downshift from 5th to 4th the car is near top half of 4th gear so it requires a higher rpm blip. I imagine this is true for you too.

Back to Fontana…
I guess I do it like Kary. At Fontana before I skip gears I complete a session of laps rowing down at all corners. Then I'm ready to start thinking about deleting shifts. Regardless if I row down or skip shifts at T-3 my car is going to engage 2nd gear at the same location, same car speed and at the same RPM. The experience gained from rowing down all the gears in practice helps me judge how high a blip will be required. Still I don’t claim to be an expert at skipping gears and in traffic my gear skipping rhythm can be compromised. In that case I will default to rowing down.
In the braking zone while in traffic and looking for passing opportunities for immediate acceleration rowing down works best.

CB, Driving Faster is one of my favorite books, mine is on loan to Mark Tyler so I could not reference it.
Another book, Twist of the Wrist can be interesting too.

[MikeD]

Like Mike said. I think it is different depeding on the situation. When I am just cruising around during a relaxing TT I might skip a few gears (after I get a feel for the proper RPM). But in a high intensity race I might row just to make it more methodical so my braking, turn-in, down shift can become subconscious and I can focus on the 4 guys immediately surrounding me trying hard to kill me .

Tim: You can take a mathmatical approach to your downshift problem. From 5th to 2nd you can simply multiply (500 * 3 = 1500) - (800 * 3 = 2400).

Kary kind of touched on this. But if I have an 40/80 LSD. How do I take advantage of it if I do not row through the gears, leaving the transmission engaged as much/long as possible?

Now that I have this LSD I am trying to train myself to leave the drive train engaged as much as possible and ONLY depress the clutch for a very brief time (just for the shift). Is this wrong?

[Jim Knoke]

watch the 'ring video:
http://www.dgtalpimp.com/m3_gtr_nurburgring.wmv
a few thoughts:
this is worth watching more than once.
note the corner workers!
how many times does Hans get in 6th gear?
how many miles was that?

[Chris Benbow]

OK I'm a convert.
THAT VIDEO IS SO COOL that I don't care about braking efficiency anymore I just want to drive like Stucky does
You'll notice that he doesn't left foot brake either.

[kary]

watch the 'ring video:
http://www.dgtalpimp.com/m3_gtr_nurburgring.wmv
a few thoughts:
this is worth watching more than once.
note the corner workers!
how many times does Hans get in 6th gear?
how many miles was that?

Jim, I have seen this many times, though Hans is using a sequential gear box which always require "rowing". Maybe I missed something in your post?

[MVZ944T]

I read somewhere that skipping gears in a downshift sequence can ruin the syncro's, so right or wrong, I try to hit all the gears.

[Jim Knoke]

Kary, I don't think it is a sequential gearbox. Upshifts can be either "up" or "down." I think it is a conventional 6-speed. BTW, I don't hit all the intermediate gears in downshifting either, but I'm not HS.

[kary]

I am not sure aboiut HS, but he is not using a clutch on those down shifts, is he? I can't seem to see his leg moving.

[Tim Comeau]

So the question remains...who among us can host some video? My website will be able to in the near future, but not yet.

[kary]

Tim, depends upon how much space the video takes up. let me know the size and maybe I can host it for you.

[Tim Comeau]

I can edit the video into clips of any size. What's my target?
Can you upload windows movie maker files?
Thanks, Kary!

[ttweed]

Hans is using a sequential gear box which always require "rowing". Maybe I missed something in your post?

No, he is not using a sequential box in that video, he has a racing "dog box" with straight cut gears (no synchros) in that car. They do not require the clutch to shift, either up or down, just a slight lift of the throttle on upshifts to unload the gears (or a slight blip of the throttle on downshifts), but they still use a conventional "H" pattern for shifting.

The obvious clue to this is that in a sequential box, the lever acts only in a single plane, forward and back, and he would always be pulling the lever on upshifts and always pushing it on downshifts. A 5-4-3 downshift sequence, for instance, would require two successive pushes on the lever, and a 3-4-5 upshift sequence would be two successive pulls. You can see clearly that he is rowing thru an H pattern still on both up and down shifts (alternately pushing forward and then pulling back for the next shift in the sequence), just not "de-clutching" to do it, as you would with a conventional synchro box.

TT

[kary]

Hans is using a sequential gear box which always require "rowing". Maybe I missed something in your post?

No, he is not using a sequential box in that video, he has a racing "dog box" with straight cut gears (no synchros) in that car. They do not require the clutch to shift, either up or down, just a slight lift of the throttle on upshifts to unload the gears (or a slight blip of the throttle on downshifts), but they still use a conventional "H" pattern for shifting.

The obvious clue to this is that in a sequential box, the lever acts only in a single plane, forward and back, and he would always be pulling the lever on upshifts and always pushing it on downshifts. A 5-4-3 downshift sequence, for instance, would require two successive pushes on the lever, and a 3-4-5 upshift sequence would be two successive pulls. You can see clearly that he is rowing thru an H pattern still on both up and down shifts (alternately pushing forward and then pulling back for the next shift in the sequence), just not "de-clutching" to do it, as you would with a conventional synchro box.

TT

Ok, I buy that but still, straight cut gears and never using the clutch has little to do with this discussion where we use our clutches to shift. If we did not have to use a clutch I would probably "row" through the gears as well, but the reality is we need to use the gears with a clutch action. So again I am failing to see what HS video has to do with our discussion?