kwoksrus

I have a 993 C2 manual and am new to the tracks. Appreciate it if you guys can help me with the following questions regarding gear shifting:

1. If I am in 5th gear coming down the straight and approaching a 2nd-gear corner, should I shift down in 5-4-3-2 sequence or can I just engage 2nd before the turn. Seems to me that one can save effort and braking distance by jumping straight to 2nd, especially if you are double declutching.

2. Is double declutching still the way to go in modern cars? Why?

Thanks.
Stanley

ScottMellor

1. Skip shifting is a very personal preference. Some of us have a little trouble maintaining a rock-steady braking pressure during the throttle blip portion of heel-toe-process, so a skip shift reduces the number of blips. The downside is, if your speed sensing cababilities are not VERY advanced, it is possible to let the clutch out too early in the lower gear and, at the least, upset the balance of the car or even spin. Also if you make a serious error you might over-rev the engine. Bang! Ka-Ching!!
You have to decide if the upside is worth it to you.

2. Double declutching is generally not considered necessary on a modern street car, because the synchro systems are just more robust and work better.

38D

1. I think you will find two schools of thought here. One that says go thru all the gears (5-4-3-2) and the other that says go straight form 5-2. I think the main disadvantage of going 5-2 is the potential to over rev your engine. Assuming your can heel/toe effectively, I don't think there's much difference in wear & tear on your synchros. I would ormally go with the 5-4-3-2 approach.

2. Double clutching is not necessary on any synchromesh gearbox.

Fred R. C4S

FWIW

I once attended a driver's shool taught by Derek Bell, 5 time Lemans winner. He advised shifting directly from 5th to 2nd. All those shifts in between are cause additional wear and tear on your driveline components. He remarked that brake pads were far cheaper than clutches, synchros, and driveshafts.

One tip, get a few colors of very narrow colored tape used for making charts. Back in the days before PC's this was a common item. You can find it today at hobby craft stores. Take a bright color, like red, and place a small piece on your speedometer at the speed you reach at 5500 rpm in 2nd gear. A quick glance at your speedometer out of the corner of your eye will confirm that you are at a safe speed for a 2nd gear downshift. You can move the tape closer to 6000 or 6500 rpm speeds if you want to be closer to the edge.

Cheers,

oldtimer

Hi Stanley, interested that you are needing to use 5th gear , maybe your tracks have got much longer straights than the ones here in UK. Beginners here can simply go round in 3rd gear when learning ( in a 964/993/996 the engine pulls fine) and rarely advance to speeds that need more than 4th. If you stick to going no higher than 4th , going down to 3rd is a simple fast push, and then 3rd to 2nd is the only one you need a measure of shifter skill for - the fewer the steps you take the better to allow more time for other things like braking down to the right speed and hitting your turn-in point right. I find 911 pedals a bit awkward for double declutching when combined with heeling and toeing , but if you have the skill to do it , its a good way of synchronising engine speed and wheel speed so that you dont get a tyre chirp/back end shudder when you re-engage the clutch in 2nd gear ... specially if its wet

RedlineMan

Hey Stan;

Being a great fan of Mr. Bell, and an adherent to that advice about components wear, I myself would likely just go straight to second. You do need to be fairly proficient at H&T to do such things, and have a good sense of timing in order to pick the right moment for the shift. If you are not good at it, I might consider 5-3-2. 3rd is usually a very long gear, and so would have a wider range for engagement than 2nd.

You do not need to double declutch a synchro box... unelss it has been abused/worn out and needs synchros!

Anyone getting rear tire chirps when they complete an H&T shift needs to do some serious practicing on proper technique. There is no room nor reason for this. I heard a guy in a Boxster a couple weeks ago at Lime Rock doing it. Lap after lap going into Big Bend he chirped the tires in the same place, and he was a signed-off driver. I wish I was his mechanic!

If you think you might need a tune up on your H&T shifting, I might suggest my article dealing with the subject. It might prove useful.
http://redlinerennsport.homestead.co...18HeelToe.html

Bob Rouleau

Stanley - In your car the 5 to 2 shift is safe because if you make a mistake you will get 4th instead. The danger is letting the clutch out too soon of course. Double clutching is not needed but a blip to match revs as you release the clutch to prevent a lurch is the right thing to do.

Going from 5th to 2nd suggests a pretty long braking zone. My personal choice is to "row" the gear box, i.e. 5,4,3,blip 2.

I hold the clutch in while I am braking and moving the levers through the gears. I don't let it out until I have the car in 2nd and then only after I blip to match revs. I do this for two reasons:

1) It ensures that I'll get the gearbox inthe correct gear without balking which sometimes happens if you try to go through the gates diagonally.

2) It helps ensure that I do not let the clutch out in second too soon and over-rev the engine.
Regards,

ScottMellor

Bob, I like that!
Kind of the best-of-both-worlds approach.

aam993

Does it mean that you push the clutch in with still a lot of braking to go? I was doing the same thing at my last DE(long braking zone), but my instructor told me that that is bad:
- you might unstable the car by releasing the clutch;
- you might need to be "in gear" in case something goes wrong in the braking zone.

Thanks.

M758

Not sure if it is the "best" way, but I too "skip" gears on downshifting. I will go from 5 to 3 or 5 to 2 to 4 to 2. My reason is that I am not fast enough at heel and toe to hit each gear going from 5th to 2nd. I can however match revs well in 2nd once per braking zone.

So this is what works for me.

Bob Rouleau

Alexander -

I begin my braking without touching the clutch - as I get near the corner push in the clutch and move the lever through the gears until I get the one I want. Then, I heel and toe to blip the revs to match speeds. Doing so means I have the clutch pressed a few seconds longer that going directly from 5th to 2nd but I avoid balking the gear box.

Best,

Bob

aam993

Interesting. Thanks, Bob. I understand now.

Larry Herman

I prefer to go straight to the gear that I need. It allows me to concentrate solely on the braking during the most critical phases; the initial application, build and maintenance at threshold. Then my downshift comes late in the braking phase, as I am getting ready to ease off the brakes. I also double clutch (spent my youth in British cars) because I still like the rhythm of the engine and pedals. Call me old-fashioned.

Skip Wolfe

There is a great video on another thread of Leh driving a GT3Cup at VIR that has some great footage of him running down through the gears.

Video (right click and saveas):
http://gscdownloads.com/GT3cupatVIR.wmv

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

trumperZ06

With a big V-8 (lots of torque), I very seldom need to go down 3 gears! I try to get the braking done before down-shifting.

Example: Coming off the back straight at Road Atlanta, I'm in 5th gear going over the top, accelerating down-hill until ~ 2nd marker, then HARD ON BRAKES, wait until 1 marker, then downshift to 3rd... allowing car to "settle" before left turn.

I've been "schooled" the same way! Brakes are for braking, tranny & clucth repair is way more expensive than pads & rotors.