Autoxing my FB
 

I took my FB to autocross this weekend and was shocked by the amount of UNDERsteer i got out of it. I had good tires, and recently redone stock suspension.

Is there any suggestions for reducing it? I'd like to start going to autox a bit more, and the car isnt a daily driver for me, so I dont mind feeling a few more bumps

Re-speed coil overs, tokico illumina struts, sway bars, strut bar....i would upgrade all of the suspension if i was going to auto-x my car a lot.

There is no such thing as understeer. You were simply driving the car beyond it's limits. Some key things I know about road racing may apply to this but I can be certain as I don't autocross, but I always brake before entering the corner and if you need to rotate the rear end around to simply lift the throttle partially. Again These are my tactics for road racing and not necessarily on base with autocrossing

if you are braking a lot while turning its going to induce understeer....just keep practicing & you should get it....i have never autox'd...just like taking local twisties fast.

Mine acted the same way. I was little disappointed. Recently ordered all new bushings springs and shocks (OEM spec) from victoria british and removed the rear sway bar. There is quite a bit of body roll.

It's no secret. Lowering the car 1-1.5" and using a stiffer spring and shock rate along with a nice set of tires will be your best bet. Then spring for the big sway bars and brake kit.

Also lightening the car up as much as possible will help alot.

Good luck!

front sway bar.

ask kentetsu

The settings on a stock car are designed to be “safe,” so no one gets themselves in trouble. One way the factory does this is by setting the car so it does tends to plow in a corner if you come in too hot. There are tons of things you can do to alter this.

First, take the rear sway bar off. It tends to promote that plowing feeling in low speed turns (although it is helpful in higher speed turns). Next adjust in as much negative camber as you can get (do this by rotating the strut tops). Then, add tons of caster and a touch of toe out. The toe out helps the inside tire grab in a turn (this will make the car a bit squirrelly at higher speeds). I generally run about 4 or 5 pounds more of air in the front of the car then the rear. Next, learn to tune your tire pressure by reading your tires after a run. There a ton more things you can do with your suspension, but this will give you a good start. The next place to spend you cash would be on a bigger front swap bar.

Second, driving…We all hate to hear this but if the car is driven right, it will plow very little. Generally if we are coming into a corner too hot, we have to turn too hard and the car will plow. If you can get ahead of the turn, turn less (yet earlier) the car will not plow and you exit the corner much faster. This tends to be easier to say then to do and seat time is the real cure for this. Many clubs have autocross schools which are really worth their time. At my first autocross school, I was instructed by a regionally competitive Rx7 driver. I learned more in the day than in the year prior of racing.

Good luck racing ~

Slower into the corner = faster out of the corner
Friction used for braking cannot be used for turning.

Track time (with instruction if possible) is super valuble.

The upgrades will help but even if you throw money at it, if your driving style is not right it will only help a bit.

Good luck.

If it was your first time you were probably braking too late and going in too fast and just plowing through the turn. Next time try going into turns slower and progressively take it faster until you find the traction limit

Yep, just like all the others said, you are going into the corner too fast. It took me two years to get over that problem myself. Enter slower, and accelerate through the turn, using more gas to rotate the car if needed. You're just plain trying too hard. Slow down a little and think more about "driving" the course rather than just beating it into submission. :)

Ive raced stock suspension rx7's at autox events.

I rarely have had understeer problems except when first started out, its driving technique.

Brake before you turn, use the brakes hard as you can so you are using them for the shortest amount of time possible.

If you have to turn and brake, brake lightly and your speed better be correct.
dont turn the wheel further towards lock if your allready understeering, straighten it out a little.

On a stock suspension I had great results without a rear sway bar.

the stock strut tops can be adjusted for more camber by rotating the entire mount, max out your camber, itll handle way better.

I'm used to autoxing my Subaru. It understeers a bit, but always makes up for it by mid corner. I'll try disconnecting the rear sway bar next time and braking a bit earlier. So its the front sway bar that helps reduce understeer?

Generally, to get a better handling vehicle for autocrossing with a rear wheel drive car you want a larger front bar or no rear. For a front wheel drive car you want a larger rear bar.

man, only one person touched on it, TIRES!! Im telling you. for an autox car this is the biggest improvement you can make if your running some crap @$$ all season. Get something thats more geared for performance and is made by a reputable company. then track time. See if you can ride with one of the fast regulars. Im sure they will be happy to let you ride along, find out that has the same set up as far as rear wheel drive.
Slow is smooth, smooth is fast. it took me about 3 sesions to get that down. Even still my first lap is always a bit crazy as I get my adrenaline back down. Maybe I should try making it more. Damn field exercises

+1 for good tires.

Catatonik, where did you AutoX this past weekend? The MCO hasn't posted its schedule yet!

I'll be looking forward to swapping notes this year, since I'm in my 2nd season of autocross, and I've now got RacingBeat swaybars and a ReSpeed Rack and Pinion :)

Jon

stock alignment is 1 degree positive camber which causes understeer. get realigned with as much negative camber you can get. ends up being around .7 to 1.0 * neg camber. that alone really helped me out way back in the stock days.

+1 to what everyone else here said.

Everything has been touched on here but I want to add this, and really its what everyone has been already been saying: weight transfer. Try being smoother on your entries and exits. When you get it down you'll find that corners feel "easier" than before. Brake and throttle control is key here. Be smooth but dont be slow. Find your balance. Its gonna take time and practice.

Tires will make him faster overall, but they are not going to correct a handling problem.

I moved! I'm in Peterborough now, Jon!

I posted the vids on youtube. Just search PMSC Solo II, or PMSC RX7 :)


What tires are you autox guys running on the stock 13s?

You are too throttle happy, sliding=slow, look like you want to just have fun instead of going fast.

LOL! You're 100% right. It WAS fun... but my times were embarassing. I was beat by an 87 Prelude field car with 4 blown shocks. :wallbash:

Tires can really help, but they can bump you out of a class as well. It really depends on where (class wise) you want to race. Some clubs have a novice class, stock class, street tire class, and various prepared classes. Check out the rules for your club.

If you are going to race in a street tire class, check and see what rules there are. See if you can update/backdate to a 1983 LE wheel (which is 14”). This will give you some usable sticky street tires, like the Azenis 615. If you need to stick to the 13” rims there are no real sticky street tires available.

If you want to go to a real autocross tire you have options. DOT approved race tires or like Kumhos and Hoosiers, or even full on slicks (each has its set of car class issues). I run 215/50/13 Kumhos on 8” rims and I think they are great. They are easy to learn on and very forgiving. Work well when it is cool and stick when it is hot. I also have some Hoosier AS05s which would be great on a hot summer day, but like precise drivers )that is not me yet).

The biggest pain with race tires is having to swap rims at the track. It would be much easier to get a set of 14” rims and buy some Azenis 615 and call it good.

Sumitomo HTR200's are a sticky street tire used by many on the forums. Hoosier makes an R compund tire in the same size

i use kumho V710's and there great when they get warm but kinda soapy feelin when there cold and i usualy run between 25 and 30 PSI.

Way too low. Try something like 40 psi next time and see how it feels... ;)

In reference to the sway bar discussion, here's my thoughts on that:

Stock front sway bar: most feel you should remove rear bar. I'm not sure which way I liked it better, but ended up racing with the rear bar on most of the time.

Aftermarket front sway bar: When I installed the bigger front swaybar a couple years back, it was absolutely amazing how level the car would be when cornering hard. If felt much more precise and better poised under all conditions. However, I was experiencing quite a bit of understeer until I reinstalled the rear (stock) swaybar. Then things were much better.

Adjustable rear bar: Installed an adjustable rear bar (ISC maybe?) last fall, have it on the firmest setting, and love it. The car just carves right through the corners now with a definite precision. It's like it just "digs in" so much better. Although now that I think of it, a lot of that could also be attributed to the Bilstein shocks I put on the back end around the same time. lol.


Anyway, on to the mention of tires. I would advise you to hold off on buying expensive tires to race on until afer you fix your driving technique. Sumitomos are only about 50 bucks apiece, so if you burn them up by overdriving them you won't have to feel so bad. But if you treat a set of race rubber that same way, with the softer rubber compound the damage will happen a lot faster.

If you read at all, check out Bob Bondurant's book http://www.amazon.com/Bob-Bondurant-...9568123&sr=1-8

And more than anything else, seat time and practice. But you need the knowledge before you can practice it. I still have so much to learn, I know I've only scratched the surface, even after two years racing. Good luck man...

I have to agree with Kentetsu. I have used my FB for autox for a couple years now. I removed the rear bar just to see if I could tell a difference, and I did. I can't say it helped, though. I will likely reinstall it.
As for tires, I am using street tires. 205/50-15 Kuhmo SPT on 15 x 7 wheels. I find that 45-47PSI front and 42-45PSI rear works pretty well on this combo.
My suspension setup (if you want to call it that) consists of older ST springs (sagging a bit) and KYB GR-2 struts/shocks, and a homemade strut bar. Otherwise, all stock. Understeer is minimal, usually from braking a little late. Oversteer is a different story. Normally, I get mild oversteer that is easily controllable with the throttle, but it has got away from a couple times. I find that the LSD is a must. Without it, you simply cannot apply much, if any, throttle until the car is going straight, which is way too late.
The 1st two things to upgrade, is good tires and seat time. Tires need not be the best available, just new enough to still have some grip. My 1st season, I was using tires that were 10 years old. Can you say hard as cement?
Adjusting the loose nut behind the wheel is a slow and tedious process. Until you can make consistant runs, any car adjustments are totally useless. Once you can repeat your performance regularly, then you start adjusting the car, and be able to tell what each adjustment does.

Cool

I'm running Sumitomo HTR-200s from tirerack.com in 205-60-13

They don't count as "cheater tires" or "race tires" so I don't get extra points for them but they're a good tire. I don't know how the PMSC classing system works, but the MCO doesn't give me any points for them.

If you get points for them then you might as well go all the way and try to find a set of rims you can put Azenis on. They don't make them in 13s tho.

Jon

Thanks for all the help. Next event is may 25th, so I'll let you guys know how it goes.

V710 uses a lower pressure, you don't run a high pressure for those, street tires however, 40 would work great. I usually run my v710s at about 29front 31rear and adjust as I go along...

C'mon Firebird the Sumitomo just do not compare to the Azenis. They are not sticky or even in ball park. You did make a good point about Hoosiers being available to fit a stock rim.

How do you know which is the correct way?

I am new to the FB. I installed some new springs and i noticed my strut tops were both in different positions. Which is the correct way?

There is a notch on one of the 4 sides to the strut mount, where is it supposed to point towards in stock form? The front is my guess.

Which way do i turn them for the negative camber?

Thanks :)

Lil Red,
Unbolt the strut tops and rotate them until you find the side that moves the shock inward towards the engine the most. You will give you the most negative camber (or, the least positive).

Does that make sense?
JEB

thats what i thought/tried at first but it felt awful i get way more lateral traction with low pressure (and 25 - 30 is cold pressure they get to around 32 -35 by the end of my last run)i have some camber and that might be why. i guess its because it just feels better and it shows in my times

I believe the strut position you want is with the arrow pointing in, and toward the firewall. :)

That's how I have mine set. The SA had strut tops that were different. Those need to be pointed towards the front outside. The FB units are exactly opposite of the SA, so check them close. You can see the offset of the strut, when viewed from above.

Good to know Rogue. Thanks. :)

try setting them to 32ish for the first run and letting them heat up and rise to your desired pressure and dropping the pressure when it gets too high. For example on our RX-3 with kumho v710s (basicly the same suspension as an RX-7. It's fairly softly sprung with huge swaybars) We begin the day with 32 all around if the track is cooler, or 34 if it's already hot. We make our first run to decide on what pressure differential to run front or rear for balance (depends on the pavement and the course that day) and run that from there on out.

Not a lot of use in setting the tires low when they're cold and just letting them ramp up to where they should be, atleast in Autocross. Set them where you want them to be on run 1 or a little lower so they can get some heat in them quicker. You should be bleeding air out after most runs.

32-35 is a guestimate i do bleed them. i guess its my driving style, but these tires do have extremely stiff side walls it took me alittle over an hour to mount them on the wheels.

you can tell by looking at the strut tops.
or measure them. you want the most metal to the outside close to the fender.
that give max camber.

I run 35-40 psi but I run hankook z214's

I tried lower settings and the car just got sloppy.

With r compounds you go so fast your stock rear suspension will bind in hard corners, no rear bar helps in these cases but increases low speed understeer.
really tight low speed courses definatley put the bar on.
I just on hooked 1 link on that car to disable it. I could put it back on in a few min if it was needed.

try a victoracer v700 for your first r compound. it fits on the stock 13 inch wheel and is usually cheep plus will last 2 seasons or more.

handling adjustments
 

The following chart may help you sort out the car.
Hopefully it will format correctly. If not you can go to http://polybushings.com/pages/handlingtips.html

Adjustments To increase Understeer To Increase Oversteer
front tire pressure lower higher
rear tire pressure higher lower
front tire section smaller larger
rear tire section larger smaller
front wheel camber more positive more negative
rear wheel camber more negative more positive
front springs stiffer softer
rear springs softer stiffer
front anti-sway bar thicker (stiffer) thinner (softer)
rear anti-sway bar thinner (softer) thicker (stiffer)
weight distribution more forward more rearward

Yes. This guys original problem was too much understeer, which is why I do not understand why he is being told to get a bigger front anti-sway bar and remove the rear one. Removing the rear anti-sway bar softens the rear of a car. That increases understeer/ reduces understeer.

Suspension tuning is universal for virtual all cars:

http://www.ffcobra.com/FAQ/handling101.html http://www.msrlracing.com/setup_guide.htm http://www.s2000.org/articles/suspension/
http://www.rogerkraustires.com/TechS...verunder.shtml

The most likely cause of understeering as a beginner is driving into a turn too fast. Go by the old racers mantra: Slow in = fast out. This rule applies especially to our 1st gens. Your stock RX-7 is already a good platform to begin with. At less than 5 minutes of run time out there just go have fun and drive smooooooothly. Don't worry so much about modifying your car (like $$$ on parts, tires, etc...) yet. Ask an experienced instructor to ride along with you and you will learn alot. To those who have not yet autocrossed, try it. You'll be surprised at how slow you are!

Another thing I didnt see mentioned or I missed it. CG lock or a harness, keeping your own ass planted helps you keep control of the car as well. If you can spend the extra cash pick up a racing seat. And practice!! no point building a car that out performs the driver.

racerx7fb obviously didnt read everything.


Quoting myself

"With r compounds you go so fast your stock rear suspension will bind in hard corners, no rear bar helps in these cases but increases low speed understeer.
really tight low speed courses definatley put the bar on.
I just on hooked 1 link on that car to disable it. I could put it back on in a few min if it was needed."

I suspect I also mentioned he was probably entering turns to fast and braking at the same time. Rx7's dont really understeer much unless your doing something wrong.