Help - Search - Members - Calendar
Full Version: Help me win at autocross
914World.com > The 914 Forums > The Paddock
Pages: 1, 2
crash914
ok, I need help. currently I am about 3 to 5 seconds off the pace in my local club events. I know most of the time is due to the driver. I think that there is some time in the car also as it is mostly set up for the long track.

Here is what I know so far, if more info is needed..ask...

73 914, blue. bolt in cage, just the 4 plates plus the seat belt for tie in points.

stiffly sprung, Koni yellows, I think 250 lbs in the rear and 21 or 23mm torsion bars in the front.

Delrin bushings everywhere, I have needle bearings, just not installed.

lowered, see pictures for height. 4 inches in the rear to the bottom of the engine mount bar, 4 inches in front to the bottom of the front floor pan.

205 50 15 tires, not sure of the wheel width, 4 lug.

my tires are about 8 year old khumo v710's that have been in the garage and have 4 autocross days on them now.

air pressure I have been running, 22lbs front, 20 rear. see pictures for chalk. looks like I am using all the tread.

Camber is close to -2.4 degrees front and rear. Front toe is 0, not sure about the rear, perhaps 1/4 inch toe in.

Motor is 103 by 80, nickies, split cam, le200 heads, tangerine header, 6800 rpm redline, 11:1 compression, so plenty of grunt.

Megasquirt with twin throttle bodies.

Transmission is open diff, with a flipped 5th gear for 3rd and standard 5th.

no camber plates,

See pictures in the following posts..




crash914
Video of the loose nut....I had a good run until the cone jumped out in front of me....

https://www.youtube.com/watch?v=54uULzcLg4s
koozy
1- Lose as much weight as possible (car and driver)
2 - Toss the old tires and get some Hoosier A6 tires under there (wide as ya can fit)
3 - Get some toe out in front
4 - Get the car corner-balanced and make sure you are not running the car too low (a-arms and axles need to be parallel to the ground when static)
5 - Lose more weight (if it don't make ya go faster take it out)
6 - You need to know what the spring rate is up front to balance the suspension so guessing on T-bar size won't cut it.

That should make a HUGE difference
crash914
I know about the weight thing...I did corner balance some time ago...I am going to do it when I replace the bushings.

I did forget...no money...got to be done on the cheap...this is still a street/track car...

I am about 1900 lbs now without driver.

I agree about the tires...old rubber...but, no money!
The car is pretty balanced, I can throttle steer very well. I did get lots of understeer when taking that sharp left in the video, but was just too hot into the corner. Otherwise, both ends let go pretty much the same....
Is my air pressure too low?

working on the driver weight....got another 25 lbs to go...
thanks!
koozy
If you machined the Delrin bushings properly and lubed them prior to install they should work fine. Bearings will be better but properly installed Delrin is light years better than rubber.

I just watched the video. You are coasting too much. If you are not on the gas you should be on the brake. Those tires are probably worse than soft compound street tires at this point. You are overwhelming them with little to no effort. Also, you are in third gear where you could probably be in 2nd most of the time. Find some fast drivers and ask them to get in and instruct you a bit. Then, seat time is your friend.

The "no money" thing will keep ya from the pointy end of the field, if for the lack of competitive tires alone.

Good luck in your adventures.
mskala
I sure as hell don't know everything, but:

1) It looks like there are several places there where you are coasting up to
the braking zone, when you should be full on the gas and then hard on the brake
(these look like straights in the video, if not then my bad, but you will still need to
push the limits more)

2) I'm in favor of hands at 9 and 3 (ish) and if a corner gets too tight, you leave
the outside hand in position (but it can't grab), take your other hand off, move it
across and pull the wheel the rest of the way. This way you will always know where
the wheel is. Easier to show than to explain.

If you are that far back as far as times you're getting vs. your goal time, then keep
those tires if they haven't aged out while you improve.
koozy
Also, this book is money well spent.

Secrets of Solo Racing: Expert Techniques for Autocross and Time Trials

http://www.amazon.com/Secrets-Solo-Racing-...s/dp/0962057312
koozy
Hand technique is explained in that book. Get a tire money jar and throw $5 every chance you get. Do a side-job or something. Tires are critical in this game.
koozy
Also, tire pressure should be slightly higher in the rear than the front due to weight differential. I would swap those tire pressures front and rear
Alice
QUOTE(koozy @ Jul 1 2014, 06:35 PM) *

Also, tire pressure should be slightly higher in the rear than the front due to weight differential. I would swap those tire pressures front and rear


What about a new set of good race shoe s ?
crash914
all good info. Thanks!
I know I need rubber, but I figured it would be worth 1 second or so...not 5..

As far as 3rd gear, you are right. this was a long 911 course, FTD was a cayman with a 42.something. I was 47.x

the previous courses, I tacked out at 6500 rpm several places..thus the pull in 3rd gear. I was about 4500rpm in 3rd. Remember it is a flipped 5th gear.

I did have on my lucky autocross shoes.

Since I have a full set of Shine suspension bearings, I am going to install them...then I will know my T-bar size and sway bar.

I do really like the idea of a solo instructor...thanks for looking at the videos....I learn a lot from everyones videos also.

I will post the link to the FTD video of this event..you can see the difference. I wish I knew how to do a side by side...that would be awsome....thanks all...
crash914
Here is a link to the FTD...

FTD run
koozy
You said top 10. What was the tenth place time?

In your case the tires would be worth more than one second. Sticky street tires would give you a full second over the stones you have on there now. 8 year old race tires have gassed out years ago but are fantastic for learning car control since they give up so easily.
ChrisFoley
Your car is already too low for good suspension movement.
The lower CG won't make up for loss of contact patch from the wrong dynamic camber.
You don't really need toe in at the rear for AX. Some toe out at the front will help turn-in.
wobbletop
Keep your hands at 9 and 3.
Get new tires.
Be more aggressive... go for ride alongs with guys that are faster than you.

www.youtubedoubler.com btw
crash914
All good info...my street tires are 10 years old also....so at least the soft rubber is stickier.

I plan on running these tires this year and will look at wheels and tires for next year...practice, practice and burn them up..

I did have a fuel problem during some of the last runs, my inlet air temperature sensor was flakey and was reading -40 degrees to 140 degrees. Really threw off my AFR.

I really get no body roll. this car is STIFF. the front A arms are just lower than horizontal...but the suspension doesn't move...

could I bee too stiff?
naro914
Tires, tires, tires... yes, tires can get you more than 1 second. Difference between my soft 'street' tires and A6's is more than 4 seconds. You will be amazed at how well A6's grip. My first time using them, I couldn't hold the steering wheel I went through the turns so fast and held so many G's.

Using !6's, I can usually compete for or are within top 5 of FTD in our region with nearly 100 cars running - some purpose build SCCA or full track cars. Without them, I am middle of the pack...top 30 or so...

And NO COASTING....gas, gas, gas...brake brake brake. One or the other...never neither.
drgchapman
As a driving coach, I find the most time can be made up by working on the driver and his habits.......
Check out evolution driving school, very good instruction for autocross.
crash914
ok, see this thread is helpful already!

Chris, what do you recommend for ride height? A-arms horizontal?
I have our next ax mid July...hopefully I can have some of these ideas in place...

I am currently top 20, around 16 to 18th. this years goal is top ten, then for next year......I might have to run with the big dogs...just for fun. my problem is my motor pushes me out of any stock or improved class...I have to run modified..its all good though.

I would like to go to one of the driving schools...I feel that would be the biggest bang for the $$....
thanks all...
Woody
Everyone touched on some really great points. I don't have much to add except try to keep it in close to the key cones such as sweepers and slaloms. Here is a couple of vids from earlier in the month. I had a bunch of trouble going into the sweeper because I couldn't heel toe with my new shoes and it cost me a bunch of time.

https://www.youtube.com/watch?v=TE4QWNzKhys...Wm8bK1V5SXqdhrQ

Keeping it in close.

https://www.youtube.com/watch?v=o5LXqWb2YAY...Wm8bK1V5SXqdhrQ
naro914
Couple quick videos:

https://www.youtube.com/watch?v=N0E67YE7Js4



https://www.youtube.com/watch?v=523pRL0QETI


Looking at them back to back, they look like pretty similar layouts, but the second ran 1/2 of the course twice...

I don't do 9 & 3...I shuffle steer... A LOT as you can see. First video I got 3rd from FTD, second one I got 2nd..

and yes...no need for 3rd gear in your videos. Keep it in second. All the power is at the higher RPM range..
crash914
NICE! I like the low camera angle..



QUOTE(Woody @ Jul 2 2014, 01:49 PM) *

Everyone touched on some really great points. I don't have much to add except try to keep it in close to the key cones such as sweepers and slaloms. Here is a couple of vids from earlier in the month. I had a bunch of trouble going into the sweeper because I couldn't heel toe with my new shoes and it cost me a bunch of time.

https://www.youtube.com/watch?v=TE4QWNzKhys...Wm8bK1V5SXqdhrQ

Keeping it in close.

https://www.youtube.com/watch?v=o5LXqWb2YAY...Wm8bK1V5SXqdhrQ

mskala
Me on saturday. Our courses tend to not have super tight corners or you
would see the steering technique. I was second only to a modified GT3RS.

If your car is super stiff, but the pavement is smooth enough, that is not a
bad thing. I'm using 180lb springs as my car is a street car, and it rolls all
over the place.


https://www.youtube.com/watch?v=PABjDKH_Upw
crash914
If I remember, you were always smooth and fast at devins...
The course here is usually bumpy, with good pavement and then loose choppy stuff...
they are mostly set up for the 6 cylinder crowd...I like a tighter course..
jhadler
Herb,

I'll address this in two parts: The steering nut, and then the car.

First and foremost... SEAT TIME, SEAT TIME, SEAT TIME. You need to get a lot more time behind the wheel to catch the front runners. Don't sink investments (that you have admitted you don't have) into the car until you are finding the limits of the car everywhere on the course.

As for the car... TIRES. The rocks you're on will be great for learning, but are probably keeping you back at least a second, maybe two. Don't take this to mean you should go out buy new sticky race tires right now. The only that will do for you is make you go broke. Old rock race tires are GREAT for learning on, and you need that. New drivers on fresh race rubber quickly discover how intolerant race tires are to mistakes. And it is not uncommon for a new driver on fresh race tires to destroy a $1000 set of tires in one weekend.

A common error for new drivers is to go too fast in the slow parts and too slow in the fast parts. Others have touched on the GAS GAS GAS issue. If you are not using as much throttle as the tires can handle, you should be on the brakes as hard as you can, for as little time as you can. And from the video I can only hear a few places where you're really getting hard on the gas. For that course, it (full throttle) should be audible in many more places. Oh, and use the full rev range of the motor, you're short shifting too much. That's the going slow in the fast parts. You're also going to fast in some of the slow parts. When you dive in too hot, the car will push, not turn, and then your first instinct is to turn in harder, and then you get even more push. Slow down when you need to go slow.

Autox is about TIME, not SPEED. Spend as little time in the slow turns as you possibly can. This means: enter controlled, get out fast. If you go in too fast, you will push, and spend even more time there trying to get around the turn.

An age old saying from racing applies: "Better to go in slow, and come out fast, than to go in fast, and come out dead.".

And now the car:

As noted, you've got rocks for tires. And that'll hold you back on time, but you've also got a lot of prep in the car while still running on 205's. The front runners in most regions will have made an investment in getting as wide a tire under their car as they can. Usually this will mean widening the fenders to accommodate larger wheels and wider tires. A stock bodied 914, is limited to 205's, and that will also limit how far up on the time sheets you're going to be able to get. Want top times? Gonna have to pay if you want to play.

Suspension:

You don't seem entirely sure of what's in there. Suspension is everything in autox car prep. Engine is a *distant* second, again this is about TIME, not SPEED. Make sure you know what you have right now, and get it working as well as you can.

Bushings - Mentioned before, but delrin alone may actually be a hindrance if not properly installed. You need the suspension to free of binding.

Springs - You use "I think" in describing your spring rates. You really should know what you've got. If you've really got that much spring in the car, especially if it's as light as you claim, you may very well be over-sprung. Too stiff, and the car will not behave well. Even more so if you don't have the sticky tires to get the suspension working.

Sway bars - no mention here of what, if any, sway bars you have. This will make a really big difference in how the car is set up.

Shocks - Koni Yellow are fine. Set 'em for now and then forget 'em. Don't mess with settings right now, it'll only make the learning curve steeper. Learn to drive the car you have. Then start making small changes, one at a time. You'll find that once you're really getting the car to the limit -everywhere- on the course, small set up changes can become much more noticeable.

And now ALIGNMENT.

You mention -2.4 deg camber front and rear with no camber plates. I'm skeptical. It takes some work to get that much negative camber in a 914. You also make no mention of caster in front. Caster is king. More is better. Caster is dynamic camber. The more the wheels are turned, the more negative camber they gain. Toe is okay, a tiny bit out in front. Neutral to a tiny bit in at the rear.

Corner balance the car, you may find you actually need to raise the ride height a little. That's okay. Too low and you get funky behavior of the suspension (bind, bad camber curves, etc).

I think that'll be good for starters...

Oh did I mention SEAT TIME, SEAT TIME, SEAT TIME??? Drive every chance you get. Ask to ride with other experienced drivers. Ask them to drive your car. You'll be SHOCKED at what an experienced driver can do behind the wheel of your own car.

And HAVE FUN!!!

-Josh

crash914
Thanks Josh...good info..
I do now have flairs on the car...tire width is no problem. I am running keiser wheels but need to get the back space measurement.
Front sway bar is 22 mm. Stock rear sway bar. I put the coil overs on the rear, but just don't remember the spring rate. Did I mention I had the car off the road for 8 years? I did not do the cage, T-bars or bushings...done by previous owner so I need to dig deeper.

oh yea, I am having fun...competing with myself. I am finding the gopro the best tool to see actually what I am doing when.
Lots more to learn for sure...you all are great coaches....
jhadler
QUOTE(crash914 @ Jul 2 2014, 04:35 PM) *

Thanks Josh...good info..
I do now have flairs on the car...


Are they sparkly?? Sorry, just a bit of end-of-the-week humor. I find myself sometimes a stickler for spelling. Flares are for race cars, flairs are for TGI Friday employees... biggrin.gif

QUOTE

I am running keiser wheels but need to get the back space measurement.


4-7/8" or 5" backspace is the maximum the tub can take without excessive rubbing, and even then it might be too much. What width wheel? Do try to find a VERY GOOD tire tech for mounting race tires on those wheels. Keizer's are stupid light, but they're also quite fragile. A gorilla of a tire tech can EASILY destroy one of those wheels with too much grunt in the wrong place...

QUOTE

Front sway bar is 22 mm. Stock rear sway bar. I put the coil overs on the rear, but just don't remember the spring rate. Did I mention I had the car off the road for 8 years? I did not do the cage, T-bars or bushings...done by previous owner so I need to dig deeper.


Aha! Loose the rear bar right away. Unless you've got a limited slip, you're going to find that the best set up will have a strong front bar, stiff spring rates front and rear, and no rear bar. The rear bar is only going to get you wheel spin right now, and with the spring rates you're running, it's not doing you much good anyway.

QUOTE

oh yea, I am having fun...competing with myself. I am finding the gopro the best tool to see actually what I am doing when.
Lots more to learn for sure...you all are great coaches....


Have fun!

-Josh
infraredcalvin
Don't make any changes to the car.

Have one of the fast drivers drive your car , I'll bet they'll make it within a 1-2 sec of your target time with no changes except the driver. If you can ride with them in one of those runs, even better. Watch their lines/technique, etc. all great comments above, but learn how to drive first, constantly tweaking your car while you are trying to learn is just going to extend your learning curve. Take notes, videos, review them.

Once you get close to those times, then start making tweaks 1 at a time - make a small tweak, see what to does, another, then test... You'll get an idea of what changes have the maximum effect for your driving style.

Good luck have fun!
koozy
I agree, working on driver skills is the single most important thing you can do. But, I caution you on doing it in a car that has basic setup flaws. These are simple fixes that can have you learning how to drive better and reach your goals faster instead of learning how to drive around basic setup problems.
crash914
The car is fast and easy to drive...very neutral.
In the last video autocross I ended up at 21st out of 63 cars...I am about 2 seconds off 10th and 4 seconds off 1st...long way to go.

So for the next event, loose the rear bar, increase tire pressure to 30/32, chalk and see if I am using all the tread. Raise up the front of the car slightly and see if there is any weight transfer improvement.

last but not least...keep my foot on the floor...I am now looking for a led solution that I can wire up. green for on the gas, red for on the brakes....should be easy to see in the video..
thanks all...
crash914
Here are a couple of pictures...I even show the flairs! They are quite special.

Click to view attachment
Static shot of ride height

Click to view attachment
Click to view attachment
Click to view attachment

Suspension is stiff...these are with the rear roll bar attached and low tire pressure.
I can see that I am off the cones and turning/braking late...


mskala
I don't remember any recommendation to go to 30/32 tire pressure, only to avoid
having more pressure in the front than the back. For reference, I was running the
V710 up until this year, at 24psi all around, and my car is heavier than yours.
crash914
I was looking in some old threads about the V710's....they were from 2005 about the same age as my tires...

I think that my pressure is too low now at 18/20 as my rankings have slipped. think that I will try a higher pressure next time..
I will chalk to see where I am. Perhaps the chalk sent me down the wrong path...My first event was run at 24 everywhere based on what you were doing...going to try it again..thanks
koozy
Chalk will get you nowhere with those tires. Chalk is used on bias ply tires to determine rollover but in single run autocross you can easily see this without chalk.. Radials such as the V710 do not tell you much when chalking due to their construction. Forget about the chalk. Set the tires at a known, neutral tire pressure such as the suggested 24/26 front/rear and see how that feels. Toss the rear bar on a shelf in the garage.
crash914
got it! oh and have fun!

Has anyone ever seen a throttle/brake light indicator for Ax?
I will try to hook up something to my megasquirt for the throttle, I guess somewhere above 80% and to my brake light switch....that way I can see when I am on the gas/brake....It would be nice to find something already in production....
koozy
QUOTE(crash914 @ Jul 8 2014, 08:08 AM) *

got it! oh and have fun!

Has anyone ever seen a throttle/brake light indicator for Ax?
I will try to hook up something to my megasquirt for the throttle, I guess somewhere above 80% and to my brake light switch....that way I can see when I am on the gas/brake....It would be nice to find something already in production....


Your money is better spent on tires.

You can hook a light up to the brake switch and set it so you see it on the video. That will help but only if you remember to apply it on the course next time you drive. Everyone learns a little differently. You may benefit tremendously from that. Though, once you get the hang of it you will know by looking and listening when watching the video, little red light or not. Look at them enough and you will know.

Just set the basics on the car and drive. There ain't no smoking gun here. Drive the piss outa that car. Judging by that video, you ain't doing that yet.
koozy
When is your next event?
crash914
the next events are July 19th, Next Saturday and then Sunday July 27th...I will by driving balls out....no doubt about that...
Racer
As a Potomac member I will chime in with some other things..

1) The lot is hard. Low grip. imho, if you are not on the knife edge of slip angles, you will not carry any speed.

2) For me, AX is an on/off switch.. don't feather shit.. just bam on and bam off.. gas, brakes etc.

3) I found running same pressurs front/rear was the best place to start. imho, 20 is too low. I always preferred 26-28 all around.. sometimes even 30 all around.

4) would love to take a ride and help out if I can get to an event this year.

The new cars have tremendous advantages. Bill C or Vrankovich in their Caymans are very good drivers in a nicely set up car. 275+ width R comps or Hoosiers will make anyone fast. As mentioned, new soft 205-50 rubber would drop 2 seconds for you. The new cars also have a rev advantage (say 68-7500rpm.. means less gears needed.. less errors in shifting too..

Seat time is the best advice... get more and more.. Run Chesapeake and Potomac events.. maybe SCCA (badly classified) and Capital Driving Club too.
crash914
Thanks Dave! you are welcome to drive anytime...I know I won't be as fast as Bill or John, (we are in the same class!) so I just want to be top 10. I am running both chesapeake and potomac events as they are pretty close to me..Not ready for the others yet until I get new rubber..next year!
Swing by and say hi!
herb
crash914
Latest runs, crappy cell phone video.

Ok, looks like I still spend too much time coasting and am braking late and on the throttle too early...



https://www.youtube.com/watch?v=U9E5_3dCO28


tire pressures were 30/32 I did drop to 29/31 but went slower. I guess I will start higher next time.

Front ride height was bumped up so my control arms are horizontal.
Rear sway bar removed.

Overall, the car felt very good, still a little loose in the rear. The front stuck like glue.
Mostly loose on throttle.

thanks for watching....
koozy
Looks much better. There are places you will NEED to coast a bit. Don't let that bother you. In some places it is the faster way around. When you learn better throttle control you will be on throttle in the coasting spots but slowly, and controlled. I would say the loose rear is too high of tire pressure. I suggest going lower before going back to the higher pressures. In my opinion, your pressures are 5 pounds too high.

Do you have the ability to lower the rear ride height?
koozy
Coasting is ok, sometimes. This is my run from Saturday. Though, mostly it is a feathering of the throttle when ya need to.


https://www.youtube.com/watch?v=zBBhj3Cybjw


koozy
I looked at your video again. You need to get used to the brakes. Get where you are going, in a hurry, and stomp on those brakes. Find where they lock up and learn the threshold just before lockup. This way you will have more confidence to charge into corners.
crash914
Thanks Mike,
I think you are right. Looking at my g data, I am pulling much more in turns then on decell. I am still used to the street tires that lock up too easy. I never locked up the fronts and I think I can still keep more speed through the corners. Throttle, I am just about maxed out. I did go to 3rd again as I was on the rev limiter halfway through the straight. It seems to help me to brake and downshift. I just seem to be able to put it together better.

I do have coil overs in the rear. you think I should go lower? I can also stiffen up the front bar. I am about 3/4 soft now.

Thanks agin..
ChrisFoley
Keep adding front bar until you don't like the understeer.
koozy
What size front bar do you have and how old is it?
crash914
front bar is 22mm...how old? it came with the car...I would guess early 2000's

somehow I misread Marks post on tire pressure....looks like mid 20's to 30 should be the ticket...next event next sunday...
koozy
Yea, I'd start with trying to maintain 24psi front and 26psi rear before doing anything else to the car. Start there and bleed down as the tires warm up and the pressures go up. This will likely tame the wild rear end. Then, when you get used to that, a couple of events worth, you can fine tune with the bar if needed. Start saving for tires for next season. Even if it is a jar with pocket change and a five dollar bill every once in a while. Start now and you won't find yourself without competitive tires next season. We'll get ya in the top ten, eventually. How many seconds off of the tenth driver are you now?
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2024 Invision Power Services, Inc.