N80

I have trouble downshifting from 5th to 3rd in my unmodified 07 Enthusiast. Even 5th to 4th doesn't seem to feel natural. 4th to 3rd no problem. Most trouble at VIR and Roebling at the end of a long straight. Sometimes get it right, sometimes miss the gear altogether.

Yesterday I was watching a video of Mike Skeen driving Crawford Anderson's Z at VIR in 2010. Google it, its worth a watch. Anyway he downshifted twice at the end of a long straight. 5th to 4th then 4th to 3rd. It seemed to work quite well.

I've had instructors advise against it. Anyone else do this? Any reason why not to do it?

dkmura

iTrader: (64)

It really depends on how good your heel-toe skills are and if you can hold max braking while blipping the throttle to rev match. Without this, the syncros will be working hard to make the 5 to 3 shift work.

MicVelo

What exactly are your instructors telling you? To NOT do 5-4 then 4-3 OR 5-3 direct?

From the vid (not familiar with VIR or RR) but on a long open track like that, I see NO reason not to go sequential as Skeen does. Tighter tracks (like Sears 7-180 right approached from slight uphill straight) yes, but on that road course, sequential makes for smoother transitions and is easier on equipment.

However, dkmura is absolutely correct on the heel/toe comment and while there's little reason for a 5-3 (in my estimation), if you HAVE to cuz you're late braking another competitor then you just need to get your foot and hand work in sync.

It's OK to miss a shift occasionally - just gives you just cause to get out there and practice a lot more.

Nice vid, BTW.

Mic

mhoward1

There is a compromise solution. You can actually go 5th to 4th to 3rd without ever lifting up off the clutch. This will align the shifts better with the gates and the guides, but at the same time does not put as much emphasis on getting Hill toe correct. This way the only throttle blip you need to be concerned about be the one right before letting the clutch up once in third. In truth though, there's enough breaking zone in turn one at VIR and turn one Roebling Road that you can concentrate more on doing a slower smoother clutch release versus doing the throttle blip. That way you can be completely on the throttle as you go in because both of those can you can use a fairly aggressive application of the throttle once turned in.

N80

So you are saying: start braking, clutch in, 5th to 4th and then 4th to 3rd with clutch in the whole time, heel toe, clutch out, then throttle on? I guess this just lets the synchs do their job sequentially rather than all at once?

As far as instructors, no one ever told me not to do it in the car, it was something I heard in the classroom once.

My heel-toe skills are decent. My biggest problem in the Z is hitting the right gate with the shifter.

Anyway, I'm going to try it whenever I can get back to the track, probably this summer. CMP is my home track and I never get into 5th there so it will have to wait until I can get to VIR or RR again.

dkmura

iTrader: (64)

Try holding threhold braking, then clutch in, BLIP THROTTLE by rocking foot to right, then moving from 5th to 3rd in one clean motion. Release clutch and if car rocks back you didn't rev high enough. If the car rocks forward slightly, then you revved too high.

Some schools will insist double clutching for each shift is the way to go for maximum smoothness (and they may be right), but I find the single clutch, rev-matching downshift option for multiple gears works fine for me.

JMII

My instructors always said to use each gear going down so you don't shock the transmission and allow the syncros do their job. However if you can heel-toe properly everything should be smooth. I can do on the street but can't on the track because I'm too busy trying to brake as best as possible.

In general the Z's tranny is so notchy I fully understand the problem with the gates, half the time it feels like its refusing to go into the gear I want. I've owned Honda's before and they practically shift themselves... so smooth and flowing. However the Z's action is very mechanic, almost rifle-bolt like, it seems to require really positive, hard, perfect throws - then it either snaps in or jams Drives me nuts! I'm on my 2nd transmission, first one ate third gear My second is the improved CD0009 and it still grinds 3rd and 5th when cold Never had such a crappy manual box before. My Hondas (Civic S 1500 and Prelude Si) were so smooth I could shift them without the clutch by just timing it right - lift, push towards the next gear and it would just slide in with light, constant pressure. Its like the gears grabbed and pulled it into gear automatically. The Z feels like its fighting you most of the time

mhoward1

Yes.

In truth though, Heel toe is a tweak technique vs a foundation one. It does gain you some smoothness in the braking zones, and easier on the equipment. But modern day syncros are pretty good anyway.

What is more critical is the smooth application of "On Brake", "Off Brake", "Clutch engage", Clutch Disengage", "Throttle on", and Finally "Throttle off".

Many people really work on smooth Brake on, and smooth throttle on, but they are harsh on everything else, especially brake off. Any action that causes a s significant weight shift will have a lot more effect that anything rev matching will gain you. A good threshold brake with the clutch in and then a smooth single release will be better than a couple of good shifts.

The data clearly shows that good corner entry speed, followed by early throttle application will gain you the most, no matter that the turn type or track.

Bottom line, that's what I would focus on (The 90% gain) smooth pedal and steering actions, and once that is great and repeatable, then focus on the other 10% items like heal and toe.

MicVelo

That's a da*m good point!

N80

I read about smooth brake off in Ross Bentley's book. Made myself do it. It makes a big difference. It seems to me that the Z tends to understeer and if you pop the brakes off suddenly you're unloading the front tires right at turn in making understeer worse.

Smooth brake off (with a little trail braking in the tight turns) really helps my stock Z turn better.

JMII, I agree. Coming down from 5th (into 4th or 3rd) I don't get a positive 'feel' for where it needs to go. I feel like I need to look down at the gear box.

mhoward1

Yeah, Mr Bentley, Mr Krause, and I spend a couple of hours over dinner one night talking about that and what looking at the data vs what you feel works. One other thing the data shows is where to spend your time. Let's take a look at turn 1, and a 2:08 lap vs a 2:06 in almost identical cars.

Entry speed on car 1 - 135.9
Entry speed of car 2 - 135.6

Total brake time
Car 1 - 3.9
Car 2 - 3.7

Entry speed
Car 1 - 46.9
Car 2 - 45.7

Time on throttle (from S/F line)
Car 1 - 10.58
Car 2 - 10.70

Corner Exit Speed
Car 1 - 75.7
Car 2 - 71.5

Top speed before the brake at 3
Car 1 97.8
Car 2 89.3

Total time from the start of braking for T1 until the braking in t3:
Car 1 - 20.01
car 2 - 20.55

SO even though Car two gained .2 seconds in the braking zone, the higher entry speed and the 1/2 second sooner on the throttle gained car 1 almost over .5 second and 10 MPH. Multiply that by 17 corners. On the longer straight after t11, the difference was almost a full second and 16 MPH.

Being sort of the data business for a while, I have gotten to see literally thousands of laps in data, and pretty much every track in the US. Its funny to see what we think works, and what really works.

I think a better tool in the tool box is left foot braking. Especially at your home track of CMP. Wit that you can possibly gain a full .5 seconds in the t11-t13 combo. You can not do it in T11, but you can set yourself up for it in T12. That means you can go into heavy into T12, and then be on the throttle almost immediately. That's a corner that really rewards an early throttle because you can set the car early, carry more speed all the was until T14.

N80

Excellent data!

I have not been able to left foot brake in my car. It is part lack of practice and lack of coordination but the biggest problem is that there just doesn't seem to be enough room in a Z to get my big left foot over there.

Does anyone else left foot brake in a Z?

mhoward1

The biggest issue with left front braking is foot control. We train our left foot as an on off switch. Getting it to be a rheostat instead takes a lot of practice. The good news is once you get it right, your shifting actually gets a lot better too.

In the Z to pull it off, keep your right foot square on the gas pedal, and use the left 1/2 of the brake pedal. That should give you enough room. I wear size 12 wides, I think if your foot is smaller, then you can be square on both pedals.