First track day, did not go so well. Need some suggestions

[Boy Blue]

So i just recently did my first track day in a car. It was allot of fun BUT... I seemed to be over driving my tires allot. So much so that I started chunking my left front. I put the tire pressure up to max. 50 PSI to give a harder sidewall. I lowered it later on in the day to 40 hopeing for better grip, that is when it started to chunk out. I was running Falken 512. 205-50-R15

The car also seemed to lean allot more than i had expected.
Suspension mods: TRD lowering springs and a TRD rear sway bar.

So my question is what do i need to do to the Yaris to help it on the track..

Tires for sure, need something more track oriented. anything else?

Here are a few pics from the track day.
http://i7.photobucket.com/albums/y297/revallot/IMG_0674.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0524.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0521.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0518.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0517.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0511.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0444.jpg
http://i7.photobucket.com/albums/y297/revallot/IMG_0442.jpg

[WolfWings]

First off, the obvious checks: Did you strip all the junk under the rear locking panel? If you did, put it back in. If you didn't, take it out. Change the weight distribution and see if more or less rear weight helps with your traction issues.

Second, yeah... go get some Hoosier A6's or something for dedicated track-tires if you're running in G-stock still. The 512's are great if you can't use R-compound sub-140-treadwear tires, but if you can, use the sticky meat.

[Lafiro]

True, 512's arent always that good for hard corners. I did that to many tims and eventually my tire went flat one night for no reason..... Inflated it and back to normal.... that was the strangest thing ever next to running over something and my tire making a poping sounds at 70mph..... stopped, saw a flat, drove 3 miles on the flat to the gas station, filled it with air to 40psi and it stayed at 40psi for 2 more days.

MADE NO Sense!!!! lol

[cali yaris]

If I read that right, you have stock shocks/struts? I have TRD sport shocks/struts, with the Tanabe DF210's and my car doesn't roll that much.

Also, +1 on removing everything from the rear. If you don't have time to take out the back seats too, at least fold it down and slide it forward -- move the weight forward as much as possible.

Finally, I had more tire pressure in back (40) to help move the back end around at the track, and I got pretty neutral steering?

Is your car under- or over-steering in the turns?
What was the ambient temp at the track?

[eTiMaGo]

I guess the tires play a bit part, I have Falken 512's too, from what I understand they are really good street tires, they do just fine in our tropical rains, but probably not quite at home on a track.

Lafiro, I'm guessing you cornered hard enough that it pulled the edge of the tire away from the rim, and let air out!!!

[Kaotic Lazagna]

hmmm, i also have the TRD struts/shocks, but paired with Tein S.Tech's. i don't appear to have a lot of body roll (i do have the Tanabe front strut bar too). however, i will start to understeer when i corner hard (OEM tires and steelies still). i would suggest getting some aftermarket struts/shocks.

[Boy Blue]

I did not remove the spare or any of the trays from the rear of the car...
I was running stock shocks.
The track temperature was warm, but not hot.
Not sure if I completely understand the under/oversteering thing..
Going into the corner I would push the car through, sliding on the tire till the apex of the corner, comming out I would be spinning and pushing through as well. (maybe my cornering speed was too quick?)

Is a front strut bar really going to make enough of a difference?

[blueskana]

I would get tires first, take it out, and see where you stand/what you feel your lacking. Your understeering, excessive exit tire spinning and line tracking will all be enormously affected by switching to a true UHP tire.
Another good reason for taking this step and then reevaluting is how much your ability/performance will be able to be "improved upon" in the driver department. Street tires leave you sliding and howling away, kind of a controlled clusterf*ck. The right tires will give you such a vast increase in control and feedback, you'll start to be able to see more clearly when both good and bad descisions are made and their outcome. Between predicatable traction charactoristics, tire pressure and weight distribution experimentation and techniques you'll be busy for a while.
Best of luck and enjoy!

[smokinyaris]

a set of nitto NT01's or toyo RA1's or R888's would be nice and a set of coilovers and may be up grade the brakes in the near future

[Kaotic Lazagna]

I would get tires first, take it out, and see where you stand/what you feel your lacking. Your understeering, excessive exit tire spinning and line tracking will all be enormously affected by switching to a true UHP tire.
Another good reason for taking this step and then reevaluting is how much your ability/performance will be able to be "improved upon" in the driver department. Street tires leave you sliding and howling away, kind of a controlled clusterf*ck. The right tires will give you such a vast increase in control and feedback, you'll start to be able to see more clearly when both good and bad descisions are made and their outcome. Between predicatable traction charactoristics, tire pressure and weight distribution experimentation and techniques you'll be busy for a while.
Best of luck and enjoy!

yeah, i would do that. forgot you already have your springs and wheel set up (that way you won't rub by getting too large wheels, then lowering the car). but yes, tires, i think will make a BIG difference (like how i'm understeering pretty bad with the crappy OEM tires).

I did not remove the spare or any of the trays from the rear of the car...
I was running stock shocks.
The track temperature was warm, but not hot.
Not sure if I completely understand the under/oversteering thing..
Going into the corner I would push the car through, sliding on the tire till the apex of the corner, comming out I would be spinning and pushing through as well. (maybe my cornering speed was too quick?)

Is a front strut bar really going to make enough of a difference?

understeering is when you turn the steering wheel to turn in, but the front tires lose traction and you end up going straight or not turning in as much. oversteering is when you are cornering, and the rear tires lose traction and you end up "fish tailing". if you're familiar with NASCAR terms, i believe understeer is being "tight" in the corners, and oversteer is being "loose" in the corners.

yes, i think a strut bar, when properly installed, will make a difference. furthermore, when we installed my TRD struts/shocks, we didn't get to put in the rear shocks, so i was still using the OEM shocks in the rear and the TRD struts in the front. i drove around like this for a few weeks. i'll tell you that when we finally installed the rear shocks, i immediately felt the difference. with the OEM shocks, understeer was more present than with the TRD shocks. now my problem, like i said earlier, is my OEM tires.

i think spring rate and strut/shock dampening will have a big affect on cornering abilities. too much spring rate in the front will cause understeer, while too much in the rear will cause oversteer (can someone confirm this?).

[Boy Blue]

Ok so Tires first then some new shocks and possible a front strut bar.
Thanks for the advise guys, I will have to start shopping for some parts.

How many track days will a set of track only tires normaly last?

[blueskana]

Depends on the specific tire, how hard you drive them, and the vehicle/set-up. On our car; a pretty long time! I know there are some track-monkey regulars on here who can chime in with specific tires they are using, suspension set-ups and expected tire-life.
Enjoy.

[cleong]

Carry a lot less speed into each corner entry. Your front tires have to do the task of steering, so don't try to make them do yet another thing in slowing the car down. Your tires are chunking badly because you are using your tires to scrub speed away in a corner. Very very bad - there is only so much that bit of tire contact patch can do. Do most of your braking in a straightline in the lead up to the corner entry and get the correct speed to accelerate the car out of it.

Setup wise you can change the camber of your car, it helps to give even treadwear across the tire.

However I've been down this road before - driving the car properly helps reduce much of the tire shoulder wear associated with track driving.

[cali yaris]

+1

"do all your braking before you turn"

So, with all the posts explaining over/understeer, which were you experiencing with your car?

[Boy Blue]

+1


So, with all the posts explaining over/understeer, which were you experiencing with your car?

understeering

[cali yaris]

ok, thanks

1. lighten the rear
2. stiffen the rear
3. use higher tire pressure in the rear.

All of these will make the rear end come around more easily and get you closer to neutral steering.

[blueskana]

+1 on the tire wear as well; how and where you are wearing/damaging/contacting the tires is a valuable insight into not only what YOU are doing TO the tire/car, steering input wise, but also how the TIRE is reacting. Once you start changing input, messing with pressure and weight, you can learn alot from what the tire is telling you... often giving you information you can't get any other way. You'll also get a feel for what the tires personality and limitations are, and with experimentation and a chance to drive other tires, be able to compare and compile experience on the the #1 component that connects you to the road.
Good luck.

[kurokoma-kun]

Guys, is there a formula for figuring out what tire pressure to use front/rear?

Someone told me do 4 lbs more in front to correct understeer, but y'all are saying increase in back...

[eTiMaGo]

AFAIK more pressure = smaller, less conformant contact patch = less grip. Hence, more pressure at the back will encourage the rear tires slipping.

[cali yaris]

Etimago's explanation is spot on. :thumbup:

[mojoyaris]

At the old autox track I used to run the car with a 40lb front and 42 to 44 lb rear. The newer track which is alot smoother I run 40 front and 42 back with coilovers set stiffer than usual in the rear. Tires are Azenis 615's 215, 45,16's.


For the road tracks I don't want as much oversteer. I run on even tire pressure and adjust the coilovers to stiffer in the front and about 30% softer in the rear.

[mojoyaris]

I did not remove the spare or any of the trays from the rear of the car...
I was running stock shocks.
The track temperature was warm, but not hot.
Not sure if I completely understand the under/oversteering thing..
Going into the corner I would push the car through, sliding on the tire till the apex of the corner, comming out I would be spinning and pushing through as well. (maybe my cornering speed was too quick?)

Is a front strut bar really going to make enough of a difference?

When I first took my car out to Autox I ran it on lowered springs, 17 in rims and ziex 512's (215 size). The tires surely chunked..........
To get the rear end around, I increased the rear pressure to 45 and the fronts to 42. To prevent the car from pushing I used the brakes and steering to unbalance the car on the next lap to get the back end up and around, but this also produces a bit more oversteer than you may want. ... but it's fun! If you want a neutral turn in and out, the best way is brake before the turn, not during the turn.

When you're getting wheel spin exiting out of the corner it's because, well you're gassing it too hard. An LSD to keep the power to the ground does help.

Hopefully this and the others will help you on your next time out.
Have fun!

[hoodlumcar]

High rear pressures are good, so stay on that track. Same thing with rear springs, I have used as high as 950 lbs/in in front drive cars that didn't want to turn.

Your big issue is front camber, as the photos show a lot of positive camber. This is where your chunking issues are coming from, and also your understeer, as it is making your contact patch smaller and making you corner on the sidewall. Ideally, there would be a much larger rear bar available that matches with a significantly larger front bar in order to get a good balance and control the roll issues of this car.

Adding weight to the front of the car will worsen your understeer issues. You want to move it to the back if possible, this is why a 911 wants to oversteer while a Mustang wants to understeer during steady-state cornering (it's also the reason that World Challenge touring cars have the driver sitting in the back seat). However, the amounts of weight we are talking about are not going to significantly effect the handling.

Also, slow in/fast out may help keep the tires on the car, but you are then going to be slow, not just because it means earlier braking zones and lower entry speeds, but because you are asking the car to do a LOT of work on the power, which is when it wants to push. Use brakes and entry speed to get the tail out at entry. Oversteer is your friend here. Don't worry about making it "too oversteery", because this car pushes so much that it would take A LOT of work, money, and time to get this car anywhere close to that. No one is going to accidentally find it with a set of shocks.

In a properly set up fwd racer you actually want to throw the car in while trail braking in order to get the back to rotate so that it is pointed when you go back to power. Also keep in mind that a good fwd car MUST oversteer off the throttle, because if it is neutral on the way in, it will be such an understeering pile of crap on the way out that it will not be worth driving (fwd cars come from the factory like this). Properly driving a car like this is a game of toss and catch. You throw it in, let it get sideways, then catch the slide with your throttle application.

If you have never driven a good front wheel drive race car, the first time you do you will think it is broken, as they just want to get sideways all the time. This is the only way they can be balanced when power is applied.

Good luck!

Mike

[hoodlumcar]

I just noticed that this thread is ancient. Damn hackers got me all confused and out of turn.

[cleong]

AFAIK more pressure = smaller, less conformant contact patch = less grip. Hence, more pressure at the back will encourage the rear tires slipping.

What I've found is that there is an optimal pressure range.

Sometimes more pressure (up to a point) gives better traction because of less contact patch and sidewall deformation.

[whoguy]

I agree with all the tyre pressure tricks and camber......

I reckon the best mod is to get some camber bolts and put more negative camber. To me, this had quite a big effect on reducing understeer.