i don't know if this has been discussed or not here before, but is there any way to do a skidpad test, without going out and buying something like a g-tech? i want to see what my individual mods (i.e. strut bar) are actually doing.
i know one requirement is some empty, flat pavement. but what are the specific attributes required for this? radius? co-effiecient of friction?
i was trying to figure it out using math, and it seems like a fairly easy Physics problem...but i'm just lazy to go through my University Physics text book...

 

hmmm...i think i figured it out. all you need is a circle of known radius. after that, you just see how fast you can go without losing traction. knowing the radius of the circle and the max speed at which your car can travel on it, you should be able to calculate lateral acceleration...
but maybe this is known to all of you already. if not, there must be an exact way to determine this using the physics method...

 

You have the right idea. Measuring the time you can complete a circle in a given radius should tell you what your lateral g's are.

http://www.iroczone.com/calcs/chassis.htm

Example: A 100 ft radius circle, completed in 11 seconds would give lateral g's of 1.0124

 

cool. thanks for the info.

...wow, i just realized that doing anything more than 1.x G is pretty hard...puts into prespective the little fact i know about Formula 1 cars being able to pull off 3.5g of lateral acceleration

 

A well set up FD shold have no problem pulling 1+ lateral Gs

 

yes, but that would have to be a very well setup FD...but anything more than that would be really hard to get, no matter how much money you spent.

i think it would be cool to get those who have done a lateral accel test to post their figures. i'm sure some have done it on an actual skidpad, some with an electronic device (i.e g-tech), and some doing it the ghetto way, going to a Wal-Mart parking lot (which i will prob be doing in the near future), and using a calculator like that posted above...
we could see who has the highest #s, i'm sure it will be an FD, but FCs weren't too far behind from the factory, so who knows...i'm also curious what the various suspension mods do to these cars...

 

I don't think the calculation method would be that accurate. You would have to drive exactly on that circle as fast as possible without loosing it. If you stray from that measured line even for a moment, your calculation is off. G-tech would probobly be the easiest way to go if you could get ahold of one.

 

Not on street tires it won't unless the car's suspension (and alignment) is nowhere near stock. It will get close but it won't pull 1g.

On 245/45/16 race tires, stock springs, Koni shocks, a (big) adjustable front bar and an alignment with nothing but stick in mind I can sustain 1.3g in long corners.

 

it's just a 'ballpark' anyway. if any one condition changes (temp, humidity, quality of surface, anything...), so does the amount of grip. also, does that g-tech measure sustained lateral g's? that's what a skidpad test is for. i remember seing a pic in a magazine of that new caddy cts-v (or whatever it is), and it has one of those guages built in. the lateral g displayed was 1.13 or something. that doesn't mean it can hold that figure for any amount of time. also when you factor in any bank in the turn, the number goes up.

just making sure we're on the same page.

 

very true about having a banked turn^

i'm sure there are different ways to test lateral accel with the g-tech. i assume a dry, flat parking lot would be best...

 

I pulled .97 on SO2's with bone stock 65,000 mile touring suspension

 

Edit- this was on a g-tech on slippery new pavement

 

like i said, that's just a peak figure.

 

so magazines such as C&D use the max AVERAGE lateral accel for the entire circle?
if so, that method can be done using calculations or a calculator, as mentioned before.

as for staying on the line of the circle, i think that it wouldn't be that hard. also, you will not get faster number by straying OUT of the circle, since you will then be having to cover more distance. similarly, if you go into the circle more you will probably lose traction, since it requires more of it to pull a tighter radius turn...

 

yes, the magazines use an average aroung the skidpad circle and that means you can do it with a calculator and stop watch like you said.

 

Yes. That is the most accurate way to get a true cornering capability. You know the diameter of the circle on the flat pavement and you then measure "lap" time around it. Lap time gives you average speed and that with the cricle diameter gives you lateral acceleration.

Beware of "max" numbers. Using Geez! I have seen spikes in my car up to 1.4g but those were only for a tenth of a second or less. I smooth the cornering g's by having the system only display anything sustained for .5 seconds or more.

 

okay, cool. thanks for the info.
and some of the #s you guys are posting are pretty impressive, especially 1.3g sustained Damon...
i'll be lucky to get even 0.9g

 

Again keep in mind that is on race tires and with a suspension setup designed for max grip (as in all the camber eats tires twice as fast).

Here's some cornering numbers from six runs this weekend. The "sustain" is over .5 seconds and the "absolute" is over .1 seconds. The tires are just a little past their prime.


Here's a track map of the course. I haven't corrected it yet but it's 80% right:

 

My FD on R compound tires in the stock size pulled steady .98 to .99 and peaked out at 1.01 and 1.04 gs in a parking lot according to a G Tech... that was both directions. This was a tight circle with some pebbles on it... on a real track I'm sure it could have done more.