RX744CSP

iTrader: (4)

I run a 12A powered 1st gen autocrosser, and for me the correct answer is: it depends. Since my car takes a while to spool up and get moving out of a really tight hairpin turn at low speed, in that case I will try it at least once. I think that I have had to do that on 4 courses over 3 years. I remember one instance where it cut a full second off of my time.

Disclaimer: I am nowhere near National material. Yet.

tpdrx7

IMHO, the answer in a turbocharged car is: "it's course dependent, with an emphasis on leave it in second whenever possible"

At divisional events where turns are more sweep than hairpins second is the answer, but at local events where smaller lots require switchbacks and hairpins to keep the times up, in a car that does not pull anywhere near as strong as a N/A V8 low in the RPM range, using first is a viable option. I ran in one event earlier this year with FTS and I didn't get OUT of first gear.

Tomas

Houdini

iTrader: (3)

change to 4.7 gears and leave it in second. If you don't believe me, ask Andy Mckee, he just won SOLO II nationals and the Pro Solo Finale in SM2.

PureSephiroth

doesn't it help when you autocross in the saturn though
(saw ya at sparta)

RotaryAXer

iTrader: (4)

Worst autocross for me ever.

That was the first time I ever autocrossed it. In all honesty I think it was the best thing I had done in a while. It really is amazing what jumping into another car can do. I didn't down shift. (if there was ever a course that could use a down shift that was it).

The main reason I drove that car was so I could re-focus on driving and control and balancing the car. I achieved my goal. At the next autocross back the RX-7 I beat my co-driver for the first time ever. Car control is sometimes best learned in slow car.

DamonB

I've always felt it's more fun to drive a slow car fast than a fast car slow

jhillyer

This is entertaining. I want to see gyroscopic forces included. An upshift results in higher driveline inertia, increasing gyro effect, and in a common driveline layout this resists cornering the vehicle. When downshifting is combined with a need for deep braking, the stored driveline inertia can assist the exit.

Umrswimr

I really doubt that the rotational energy in the driveline has any effect on the cornering ability of a car.

jhillyer

The gyro forces are quite potent, naturally increasing with speed. Brake rotor and wheel mass also contribute gyroscopic effect, resisting yaw.

-Even for Chevy drivers.

Umrswimr

Ok, then. Prove it.

It'll take me a minute to dredge up high school physics, but I'll get there eventually.

Slacker7

iTrader: (2)

I think the easiest way to calculate those gyro forces is by using energy equations.... and that is a PITA. I doubt high school physics is sufficient to represent those forces. But hmm.. seems interesting.. I guess if your engine is transversely mounted like in FR applications it could help on left hand turns and hurt in right hand turns? Depending on the direction the rotation is?

Umrswimr

You definately don't want to use Energy equations... The force equations will tell you how much it takes to yaw the driveline, assuming you knew the driveline's I. F=Iw
From there it's just simple trig to get the force required to yaw it....

RenoCYM

The last autox we had I worked the station at the 180 degree hairpin (at the end of a long, very fast series of left-right turns) When I'd run the course in the morning I had motored through in 2nd, lugging out of the turn until I spooled up. My times were way slower compared to the Z06s than usual. So while I was working the corner in the afternoon I timed each car - from a point entering the turn to a point exiting the turn - to see if those who shifted down to 1st would get an advantage. There were lots of Subarus and a Mitsubishi 3000 GT, and a couple of Honda S2000s and a some fast EM cars. About half the drivers shifted, some down to 2nd from 3rd, and the others kept it in what ever gear they were in when entering the corner. The difference was anywhere from 1 second to over 2.5 seconds between those who shifted - faster - and those who didn't - slower. A lot of vairables there, I know, but that amount of time was just about the difference in my usual times compared to the Z06s and what I ran that day. There is no substitute for torque.

edmcguirk

Given the minimum turn radius of most cars, even a 1 cone hairpin turn shouldn't be traveled at much less than 25mph. That's pretty close to the top of most car's first gear.

In general you don't need first gear unless you are going slower than that. That's usually a sign that you blew the turn.

First gear is usually a last resort to save your run. It is almost always more valuable to find the right racing line and stay in second.

This was obvious at the Mazda Revitup this summer. I could not find the right line that would let me stay in second gear like the pros (automatic tranny) but when I downshifted to first, I gained almost a second on my time. That kept me in 54th place nationally but still nowhere near the pros.

(BTW I also have many other excuses for not doing better)
ed

elron90sc5speed

iTrader: (4)

I really think the issue of "to shift or not to shift", is really dependant on your own driving style
and what makes you comfortable on the track. Being comfortable in your racecar is almost as important as being smooth on the track. If you are comfortable then you will perform better than if you are trying too hard.
The bottom line is if you are comfortable heel-toe downshifting then you will most likley do better than if you don't.
Personally I will heel-toe sometimes but most of the time I find it unnecessary. It all depends on the specific course I am running.
I run at alot of events that have long "twichy" sections that are way to slow for me to run in second.
Find what is comfortable for you and don't be afraid to try new things. You may just find somthing you enjoy more.

(some of the courses I run at are so tight the only ones to make it out of first gear are the Fiat guys)