2007GT/CS

Can someone point me to some information on how to set up a standard straightline slalom and skidpad?

Would like to assess suspensionchanges in a repeatable fashion with something other than the handling version of the "butt dyno".

Thanks!

Norm Peterson

Find an off-road site and get written permission to use it in this fashion. Keep a copy of the agreementwith you. This is not an optional step. There may be more things like this as well.

Round up a 100 foot tape and some pylons.

Space the pylons for a slalom as you see fit. There is nothing sacred about 100' or 70' spacing as used by some of the monthly magazines beyond your being able to make more direct comparisons. Give yourself room to stop and adequate clearance sideways. Autocross standards would probably be adequate as long as you're within the speed attainablein 2nd gear.

Drive a large nail into a block of wood. Have a barbell plate handy to keep the block of wood from moving. Use that as the center of your skidpad. Again, your choice of radius, but leave yourself plenty of runoff room.

Plan on picking everything up and going home if others show up. Remember whose name is on the agreement.


Norm

Sleeper_08

Norm

Sounds like you've been through it a few times.

2007GT/CS

Thanks Norm!

I'm thinking of a 600 ft course with the pylons at 100 ftintervals. Looks like some testers (Edmunds) enter at 60 mph(!) and then have some kind of beam at the beginning and end to measure the elapsed time.

Norm Peterson

Sounds too fast to me unless you have an unusually large or deserted lot out in the boonies(or perhaps you own it yourself). 60 is getting awfully close to the top of 2nd gear, 70 is past it, and I think the better cars are70+ on true street tires at this point in time.

Have you estimated the total length required, including generous distances for acceleration and braking zones? A dragstrip might be too narrow, and if you keep crossing a paint stripe, your results will be reduced slightly. Less grip anywhere isn't a good thing for either performance or safety.

Keep in mind that 'adequate clearance' applies to more than just the edge of the pavement (trees, fences, fire hydrants, light poles, curbings, drainage grates, parked or abandoned cars - just about anything you can name that you can't easily move).

I'm kind of hoping that Sam Strano will add some input here. IIRC, he's a licensed SCCA Solo safety steward.


Norm

Sam Strano

There is nothing to doing either. A slalom is just a line of striaght cones. Spacing can be whatever you want it to be. Same with a skidpad, radius is up to you.

I'll warn you that these things are simply measures of how the car transitions and steady-state corners. It is not a measure of driveability. I never test and tune my cars with these things alone. Sometimes I'll run a slalom only test to see if the transitional stability is what I want, or the transitional response. If it's what feels balanced and predictable, then it'll be fast... so I don't worry about the speed itself. I run as hard as I can and judge and make changes from the way the car drives, not the clock.

Here's why: Ever see a slalom or skidpad on the road? Nope. Might see some slaloms, and maybe more than one on a autox course... One might be 3 cones long (not really a slalom), then next might be 7, with 60' spacing, the next might be 5 with 80' spacing. All those changes mean different speeds and duration you are transitioning. As speeds climb, cars tend to get looser (not touching the setup at all).

I rarely setup cars to pull the most G's possible on a skidpad, because it compromises stability. A fast car is a car you drive fast at the limit, not one that can pull an extra .04g in pure steady state, neutral throttle situations. How many of those do you ever see? And what's more is you can have a balanced car at neutral throttle, and it can push or oversteer terribly on or off the gas. Pulls lots 'o G's, not real driveable in the real world.

If you want to see how your car handles I'd suggest going to an autocross. At first no matter what most think the car terrible (and it often is), but that's usually due to the driver not driving very well... autox is a learned thing.

I think you need to anyway, because finding venues that are big enough, and willing to let you run these tests is next to impossible with huge insurance coverage through clubs like SCCA. Doing it along is even harder.

HunterS664

I literally just did this about 2 weeks ago
I went to an abandoned parking lot and bought little soccer cone things that look like orange paper plates... kinda lame, and some chalk from sports authority.

I had a 100' measuring tape and set each cone 70' apart and marked each distance with chalk so i didnt have to remeasure after i did my suspension changes.

I dont remember how many cones i set out but it was either 6 or 8 idk, it was a pretty short course

I had someone to time me also when i did the course (unfortunatley only after the changes)
But i did video tape before and after slalom runs and brake dive tests

I did the slalom and brake dive tests, went home, and installed :
D-Specs
Steeda Competition Springs
Steeda LCA's
Steeda adj. Panhard Bar &
Eibach Camber Bolts

Man does the course really make the changes shine. I was AMAZED at the difference. It is truley incredible. It feelsso much more controlled and confidentinsteadof likethe Dukes of Hazard.

If you replicate what i did post your time!!!!
i forget what i got it was like.. well i dont even know ill have to ask my brother who timed me.

Let me know how your before and after tests go.
and maybe i can post those videos that i took if you would like.

what mods are you doing?

HTH

Hunter

Sam Strano

70' slaloms are huge, and frankly way too fast to really see how a car reacts at the limit (you can go fast though). I recommend picking up a Car and Driver magazine. Look at the section in the back with test results, which include slalom speeds in a 70' spaced slalom. The speeds are in the mid 60's to low 70's for any kind of performance car. But look closely because you'll also find some other cars that aren't so "performance" running similar and at times even quicker speeds.

Hell, a test of a car with particularly bad shocks then replaced with good performance ones yieled almost a full5 mph increase.

Also remember the grip has a lot to do with it. Dirty surface will be different than a clean one. Concrete is different than asphalt. It's an easy test, and fun if you can do it safely and responsibly. But I still say you'll find out way more about real-world handling at an autocross.