How are you autocrossing and drag racing your A-4?

craig0ry · 04-27-04, 12:27 AM

I have an '84 Corvette and it is my first automatic I've owned, besides an old Chevy Blazer. I have my first autocross in the 'vette coming up this Sunday and I want to know what others have done in their automatics. Are you just leaving it in second? First? Manually shifting through? Leaving it in drive?

And on a side note, I am not a big drag racing fan. But I like to take my cars to the test and tune just to get a time for them. I am wondering what you guys have been doing to launch and get down the strip in your automatics?

Thanks a million,
-Craig

vader86 · 04-27-04, 01:12 AM

Leave it in D in both cases. Timeslips in the autocrosses dont really show any differences between manual shifting it and leaving in D.
Tricky thing about autox with an early C4 is the TC, its at 2K and youll feel like the car isnt responding when you slam the throttle.

You dont want to shift manually in a drag race. It will shift itself better.

craig0ry · 04-27-04, 01:32 AM

TC? Sorry, torque curve maybe? Don't know the acronym...

Thanks for the advice! I was thinking it might be a better idea to leave it in "2" so that it doesn't try to upshift me out of the power band?

Thanks a million!

c4cruiser · 04-27-04, 10:50 AM

Where you place the shift lever will depend on the course and speeds you may hit. Short courses with lots of turns, you may want to leave it in Low. Higher-speed courses (upwards of 60MPH) I would stay in 2nd. Being your first autocross, you want to get familiar with your car and how it responds to throttle and braking. Here's a page that you might find helpful:
http://www.tirerack.com/features/solo2/handbook.htm There is some very good information here for Novice drivers. Print it and take it with you so you can read it before you start out and during lunch. You will be too busy having fun and trying not to smile too much as you are waiting in grid!!

With an auto you have to watch for a couple of things. Coming out of a corner, be careful about applying full throttle if the selector is in 2nd as you may force a downshift into Low and break the tires loose which can lead to getting the rear end out sideways. This usually results in a spin and the death of many cones, much to the delight of spectators but may not make the courseworkers happy! Do all of your braking before going into a turn and apply throttle smoothly at or just after the apex. Another thing is to not let the trans upshift too quickly; too little throttle may cause an unecessary upshift and you will lose time. The trick is to be smooth, watch the line, brake before going into a turn and smooth but quickly on the power going out.

Make sure your tranny is full of fluid and the fluid is fairly fresh. Now would be a good time for a filter and fluid change. Your battery will have to be secure, decent tires, seat belts in good condition and no bad fluid leaks.

I run with a full gas tank; a half-tank or less can cause fuel to slosh around in the tank and the weight of the gas moving around can upset the rear of the car. Some people run with a 1/4 tank or less but you risk uncovering the fuel pump pickup and sucking air into the lines.

Hope you have fun!! Autocross is addictive and a great way to enjoy the car. I had to go out a buy a second Vette just for autocross and track days!!

craig0ry · 04-27-04, 12:56 PM

Thanks! I am already addicted to auto-x, I did it all last year in my little Toyota. But I have never raced an automatic before. The course is extremely short and very low speed, never above 35-40 mph, but it is very complex. I am thinking this would be a good course to leave the shifter in first for... ?

The tranny fluid was replaced within the last two years, all the seals and everything were replaced too. I am going to just check all the fluids, pump the tires up to 42 psi and I will let you know what happens

.

vader86 · 04-27-04, 10:06 PM

TC-Torque Converter

When it locks, all the power is sent thru the driveline, in 84-86 its set at 2000rpm, so the car wont jump until it gets to 2K rpm.

It'll feel like its not responding.

It wont shift out of your power band in a tight autox, leaving it in 2 wont do anything different.

Moonunit 451 · 04-28-04, 01:46 AM

Quote:

Originally Posted by vader86

Leave it in D in both cases. Timeslips in the autocrosses dont really show any differences between manual shifting it and leaving in D.
Tricky thing about autox with an early C4 is the TC, its at 2K and youll feel like the car isnt responding when you slam the throttle.

You dont want to shift manually in a drag race. It will shift itself better.

Hate to say it Vader, but I TOTALLY disgree with you on every point here

Try the autoX leaving it in 1st, if it's that tight you won't need more and you sure don't want to fight the tranny with all the other stuff you gotta do.

As far as the strip if the tranny shifts at the precise right R's already so be it, but that is not likely, agian, alotta stuff, happening very quickly. You gotta feel this stuff out IMHO

Skant · 04-28-04, 07:04 PM

The advice being peddled out by the top driver at the autocross I went to was to leave it in 1st gear if you possibly could. Unless it's totally obvious you'll get out of 1st gear on the course, leave it in 1st gear for your first run and find out if you hit the rev limitter.

If there's only one part of the track where you'd hit 2nd, then put it in 2nd for that section. Then back to 1st for the rest. Figure out at what point(s) you will shift the lever while you do your course walk. If there's just no good place for you to do it, then leave it in 2nd gear for the entire course.

Most courses can just be done entirely in 1st gear.

Put your car in 1st gear and just try it on the street. See what mph you hit the rev limitter at. This is useful information you aught to know.

- Skant

vader86 · 04-28-04, 11:54 PM

Quote:

Originally Posted by Moonunit 451

Hate to say it Vader, but I TOTALLY disgree with you on every point here

Try the autoX leaving it in 1st, if it's that tight you won't need more and you sure don't want to fight the tranny with all the other stuff you gotta do.

As far as the strip if the tranny shifts at the precise right R's already so be it, but that is not likely, agian, alotta stuff, happening very quickly. You gotta feel this stuff out IMHO

I'm speaking from personal experience here. My timeslips showed no appreciable difference in either autox or drag.

Mad-Mic · 04-30-04, 07:33 PM

this is what i do and i wouldn't recommend it to a rookie. i've put 30k hard miles on my auto vette strip and street. i run the **** out of her and manual shift it for what ever i need to do. if you know how to do it right the tranny will survive. if you don't it will die. to me letting the transmission shift itself when racing is asking for problems. the trans is not made to continually shift up and down and as much as you might think it is not in a regulated manner. it's all about line pressure. mine won't drop into 1st above 20 mph. won't drop into 2nd above 68 mph. i know my where i shift at and what the RPM's need to be when i pull down on it. 2.59 gear 40 mph and less 1st gear you can drop it down. NO GAS. once it catches you can nail it.same thing for 2nd gear. 75-80 mph 2nd gear let it catch then nail it. i actually tap the gas to get the line pressure up so it don't shock the clutch packs when i drop down a gear. my tranny is bone stock also and i've put 30k hard miles on her.

at the strip. i hold the brake bring the RPM's up to the point right before the car lurches forward and or starts spinning the tires then just nail it to the floor board and i shift at 4900 rpm consistantly. your CF car can and will pull to 6500+ rpm so be careful!

i know my 82 Z/28 with CFI i shifted consistantly at 6500 rpm and went thru 4 tranny's and a rear racing her

Moonunit 451 · 04-30-04, 10:29 PM

Quote:

Originally Posted by vader86

I'm speaking from personal experience here. My timeslips showed no appreciable difference in either autox or drag.

Not trying to start any problem here Vader

and I may be beating my car silley, but I picked up a half second at the drags manually shifting. Now I'm aware that the shift points can be changed, but I needed more than 4900 R's, which is where the tranny was shifting to optimize my ET's. Only been to the drags twice though, once stock and once with the new setup, all auto first ime out.

I figure a half second from 12.7's auto to consistant 12.3's and a fast of 12.257 with the new setup manually was pretty convincing. I took 12 passes, started manually shifting after 3.

There are all kinds of auto x courses out there, the ONE I have done, did not require me to be out of first gear so that's where I left it. I was only three seconds slower than the fastest time on my stock 16's with SP 8,000's. There was a lot of raised eyebrowes and talk going on that I was "claiming" to be a pure rookie

So, I admit to having limited experience.

Next up, maybe one one trip to the strip, then the Pony Express 130 in late June

The car suvives that and there might be a little more racing in my future

11's here I come

Jersey-vinny · 04-30-04, 11:36 PM

Maybe off base here because I drive a 4 + 3 but I always thought the most advantageous aspect of driving an auto at the drags was their consistency. Just leave it in Drive and let the trans shift on its own. Next run it should do the same thing. Drag racing in the bracket classes is about 2 things:
1. Good reaction time.
2. Hitting your dial - in.
Consistency is how you hit your dial - in. While I'm thrashing the gas, clutch and shifter, trying to be consistent, I envy you guys with the automatics.
Other opinions welcome.
VINNY

garycr14 · 05-01-04, 01:43 AM

I would tend to agree with Skant on this one, try it in 1st, unless you know it is a fast course, then put it in 2nd. The problem I have with my auto is sometimes it downshifts from 2nd to 1st while cornering, then has to shift back into 2nd right away, when I'd prefer it to just stay in 2nd. It certainly wouldn't hurt to start in 1st, and shift when you approach the rev limiter, quite often you think you'd be traveling faster then you actually are.

Have Fun!

Moonunit 451 · 05-01-04, 09:57 AM

Quote:

Originally Posted by Jersey-vinny

Consistency is how you hit your dial - in. Other opinions welcome.
VINNY

Good point, I must admit, my last time out I was at a test and tune looking for an ET. I also mentioned in the first post that if the tranny shifts at the right R's, I could be down with that, but I was getting quite consistant the last several runs and with a shift light could do even better with that. I know if I really wanted to bracket frequently to win it would take a lot of experience, and MONEY

Mad-Mic · 05-03-04, 02:51 AM

mine does not shift in D consistantly. sometimes at 4500 sometimes at 4800. i want to know the car is shifting at 4900 rpm on each pass or where i want it to shift at.

most bracket racers run electronics and have either electronic auto shifters or air shifters for pinpoint shifts that can be manipulated thru a delay box. although we are not racing full blown race cars this is why i shift to stay more precise.

and keeping it with in .005 on a dial and you hit a good reaction you can win

this was back 2 back runs after cool down. the car runs this consistant hot or cold and weather don't effect it's consistancy.