Reduce Understeer?

[Rustyfriend]

I raced in my first autocross this past sunday and overall i was happy with how it went, but there are a few areas that i feel need to be addressed.

 

first off, i was getting a lot of understeer with the front end. i would turn the wheel hard over to dive into a turn, and there was very minimal traction. tires were 245-45-16. not slicks. only suspension mods to the car at the moment are bigger sway bars front and rear, as well as a 4-pt. roll bar in the back. a front strut bar is in the mail.

 

any thoughts on how to improve traction in the front?

 

the only other major issue was single wheel spin in the rear, but we all know that the car would need the r200 lsd

[JMortensen]

How much money do you want to spend?

[Rustyfriend]

whats the list? i am usually pretty easily convinced to spend money and i plan to have the car for many years to come

[johnc]

Where to begin...

 

Look for the alignment settings sticky in this forum. The autocross/road race alignment numbers are what you need to hit to get the 240Z to turn-in better and stay neutral in a corner. The expense is making the suspension and chassis modifications to allow enough adjustment to get to those numbers.

 

At a minimum you'll need:

 

Stiffer springs

Better shocks

Camber plates

 

One point - driving style has a lot do with how the car behaves in a corner. This sentence:

 

i would turn the wheel hard over to dive into a turn, and there was very minimal traction.

 

...leads me to believe you're throwing in too much steering on corner entry and the tires can't keep up. Its made even worse if you're entering the corner too fast, and being on the brakes when you turn-in gives the front tires an impossible task.

[74_5.0L_Z]

Start with the basics and give us some more information:

 

What are your suspension settings? (Caster, Camber, Toe in front, and camber and toe in the rear)

 

Which sway bars are you running front and rear?

 

If this was your first autocross some of the front end push was probably driver induced. You may have been going into the corner too hot and trying to steer while still on the brakes. Its better to get your braking done in a straight line then turn the wheel as you remove your foot from the brake pedal.

 

Oops: Johnc beat me to the punch.

[JMortensen]

John's sticky on alignment:

http://forums.hybridz.org/showthread.php?t=126789

 

My sticky on the "usual" suspension mods:

http://forums.hybridz.org/showthread.php?t=114631

 

There is a lot more to suspension than just those, but if you know relatively little they'll get you headed in the right direction. There is really an incredible amount of info here, so if you come across anything you want to know more about, search it and you'll probably find related info.

[AK-Z]

driving behavior: enter wide if possible throttle steer just before the apex, if you have enough torque.

[Rustyfriend]

for the most part it is sounding like i was just simply coming in too hot. i guess i am too used to a fwd car.

 

i was braking before the turns, but it sounds like not enough. there is a lot of work i am going to be doing over the winter and i think a wilwood setup is going to be one thing on the list.

 

as far as my suspension settings--whatever came stock on a '77 280z 2+2.

 

for sway bars i believe they are 7/8" front and rear. brand is unknown because the front was on the car when i got it and the rear was hidden in a garage of a friend

[Silver Mine Motors]

what do you guys think about heel teo driving on the track? john? i've been introduced to the concept and it makes sence. what are your opinoins?

[260DET]

Never done autocross myself but with my 'not a S30' Z for circuit laps and tight corners the following driving technique shows promise, where it suits to have any braking completed prior to using the technique.

 

Come in a bit fast, back off momentarily on the throttle at the same time turning the wheel firmly into the corner, get back on the throttle immediately the car has turned in and drive out of the corner with as much throttle as possible.

 

The idea is to turn the car in quickly while the extra weight due to the throttle backoff transfer is on the front wheels. For faster corners trail braking may also help by holding extra weight over the front wheels while turning in.

 

Using weight transfer to get the car doing what you want is very satisfying as a driver, particularly when you don't get it right very often like me

[EMWHYR0HEN]

A 30 year old car with sway bars and wider tires isnt going to cut it IMO. Luckily your here at HybridZ so the info to help you improve is endless.

 

I have friends that only drive FWD and they had the same impressions with my car. With a FWD setup you have more grip during corner entry so different tecniques will have to be learned with a RWD setup. *trailbraking*

 

for the most part it is sounding like i was just simply coming in too hot. i guess i am too used to a fwd car.

 

i was braking before the turns, but it sounds like not enough. there is a lot of work i am going to be doing over the winter and i think a wilwood setup is going to be one thing on the list.

 

as far as my suspension settings--whatever came stock on a '77 280z 2+2.

 

for sway bars i believe they are 7/8" front and rear. brand is unknown because the front was on the car when i got it and the rear was hidden in a garage of a friend

[Rustyfriend]

that makes sense. this is my first rwd vehicle so it should be interesting. i am still a little confused though as to how trailbraking works. i also have an autocross this saturday at my school that will be more technical, so any pointers would be great.

 

i also should have a new steering wheel, front strut bar, and airdam in the mail

[WizardBlack]

Suffice it to say that different cars with different powertrain configurations require different behaviour, braking, throttle application and timing, etc. Just try what they're saying (consciously) and you should start to get a feel for how it works. I know how you feel as I came from all AWD turbo cars, so that was a tad different as well.

 

Heel-toe is very common, but focus on your braking, weight transfer, timing, steering first.

[johnc]

what do you guys think about heel teo driving on the track? john? i've been introduced to the concept and it makes sence. what are your opinoins?

 

Mandatory for proper downshifting while braking before a turn.

 

that makes sense. this is my first rwd vehicle so it should be interesting. i am still a little confused though as to how trailbraking works. i also have an autocross this saturday at my school that will be more technical, so any pointers would be great.

 

For your next event, forget about trailbraking or anything new. Here are soem basic tips:

 

1. After the start, get the car into second gear and leave it there for the entire run unless you have to upshift at redline. Don't worry about downshifting into first.

 

2. Look up, look ahead. Although you don't fixate one something, you should be looking at the second corner coming up most of the time.

 

3. Brake hard in a straight line before you get to the corner and if you left foot brake then trail up off the brake as you start to turn into the corner. If you don't left foot brake, don't learn on the course. Practice left foot braking in your daily driver car.

 

4. As you approach the corner apex start squeezing on the gas. As you start to unwind the steering wheel add more throttle. Be careful because a stock suspension Z can push under power in a corner. In a RWD car you can and should get on the gas sooner in a corner then in a FWD car.

 

The big difference in cornering between FWD and RWD is that in a RWD car you go into the corner a bit slower and get on the gas sooner.

[WizardBlack]

4. As you approach the corner apex start squeezing on the gas. As you start to unwind the steering wheel add more throttle. Be careful because a stock suspension Z can push under power in a corner. In a RWD car you can and should get on the gas sooner in a corner then in a FWD car.

 

One of my instructors said you should envision a string tied between your right foot and your hand on the steering wheel. Don't break the string and don't let it slack out on you. Probably pretty common tool for new drivers, but handy to help underscore your point for him.

[cygnusx1]

One of my instructors said you should envision a string tied between your right foot and your hand on the steering wheel. Don't break the string and don't let it slack out on you. Probably pretty common tool for new drivers, but handy to help underscore your point for him.

 

I think I had the same instructor....or one with the same analogy!

 

Less understeer?

-less front swaybar

-more front track width

-more front tire pressure

-come in slower

[mavisky]

Are your bars adjustable at all? How wide are your rear tires?

[Rustyfriend]

not adjustable, and my tires are 245-45-16 all around

[wheelman]

Listen to what Johnc said and don't start messing with things like tire pressures and sway bars or anything else until you have the basics down. Believe me it'll just confuse you, I learned this the hard way.

 

Once you are comfortable with when to brake and how hard, the turn in characteristics of tha car and timing of corners then you start adjusting things. Working on the basics first pays huge dividends later when you have the suspension setup optimized.

 

On a different subject, Wilwood brakes are not required for auto-x. They look nice but the stock brakes are good enough for the speeds you'll encounter on an auto-x course. You also don't use the brakes enough to get them so hot they fade. Good pads and keeping the fluid in good condition is the key.

I did the Toyota 4x4 caliper upgrade and replaced the rubber hoses with braided stainless and find it easy to lock the fronts flat spotting my expensive race tires. Unfortunately I got rid of my stock calipers otherwise I'd put them back on.

 

Wheelman

[zguitar71]

what do you guys think about heel teo driving on the track? john? i've been introduced to the concept and it makes sence. what are your opinoins?

 

 

If your car has the stock motor you probably have enough low end grunt to leave the car in second gear. It will help with traction with out an LSD and slicks and your driving will be smoother. It might feel slower but often feeling slower is really faster in the end. We run between 4 and 6 runs during an autox depending on turn out and time. If I am going to experiment with a new technique I do it towards the later runs. That way I have the course memorized and I can compare the new driving style to my standard style and time differences should be from the driving not learning the course. Before I modified my car I almost never went to first and it worked very well.