V-10 Killer

iTrader: (22)

I just picked up a set of 26.0x10.0x15 ET Drags and Bogart 15x9.75" Drag-On Star 2's for the track. I've never run anything but street tires at the track, and was wondering if you guys could give me some pointers as to what to expect (handling/braking...) and the proper way to dial the car in (burnout/tire pressure...)with them. I'll give a quick rundown of my setup if it'll help:

'98 Trans Am.
~3700 raceweight.
Strange 12 bolt w/3.73's.
Spohn Torque Arm set at -2deg.
Adj. Panhard rod.
BMR LCA's and relocating brackets.
QA1 front and rear 12 position shocks
QA1 front drag springs.
Whole car lowered almost 2" (I know, bad for drag racing).
FLP Level 5 4L65E tranny.
TCI Competition 3800 Torque Converter.
Car makes ~425 rwhp N/A, with dual stage NX kit yet to be dialed in.
Peak horsepower is at 6500 rpms N/A.

McRat

When buying, most slicks are marked by their actual circumference. If not, measure them around the center. Try to get a set that is within 1/4". Also avoid "stale" slicks. If they've been on the shelf for over a year, see if you can find newer ones.

Before going to the track, check how much weight they are balanced with. If they threw a buttload of weight on to get them to balance, complain to the tire shop, and have them remounted. The less balance weight the better. Mark on the tire sidewall with a window marker where the valve stem is. This will tell you if the tire moves on the rim. Get a high quality tire gauge that fits in your pocket without stabing you. You'll use it a lot. Fill tires with nitrogen (Costco will do it) if you can. This will keep the pressure more stable when the tire changes temp.

The first time you take them to the track, you'll need to break the glaze off. Get them really wet, and do a nice long low mph burnout. Never burnout on asphault with them, it will chew them up. Start with 20PSI until you get familiar with the handling. Take your time. Slicks can be spooking feeling. I feel you should always run skinnies up front for safety, but many people call me a fool. This fool has about 1000 passes without tagging a wall. Skinnies work with slicks, street tires don't.

When you are familiar with their handling, you will drop your pressure based on track prep. For a Z06 I go down 15 to start, and drop 1 psi a pass until my 60' stops improving, then air them back up a lb. Check pressure after each pass, it climbs.

Good luck and have fun.

Steve Burger

iTrader: (33)

Very good advice. Don't mix a full slick or ET Street with a full size radial in the front. This will make your pass a lot more Spooky than it needs to be. Be prepared for the car to wallow back and forth a bit on the big end. Don't panic and attempt to correct. You will meet the wall. It's just a fact of life with a wrinkle sidewall and low air pressure. You wil get used to it.

V-10 Killer

iTrader: (22)

This is interesting, and the first time I've ever hear this info. I'm not doubting you, but I don't understand why. I bought some really big ticket items this year (F.A.S.T., 12 Bolt, new trans, etc...) and only had enough for the rear two slicks and rims. So now I shouldn't run them until I can get a complete set I don't have a trailer, so that means I'm gonna have to haul a jack and four tires in the back of my car. Plus, I don't have a trans brake and I'm not sure the how well the skinnies will hold the car at the lights. Then there's the whole proportioning valve deal...

This is the info I asked for and I'm thankful, but it kinda sux now

McRat

You can drive with skinnies on the front. If you are on a budget, get the Convo Pro's and put 165-15 VW tires on them. Night and day difference.

Do what you like, but be gentile with the steering input. If the car starts to get sideways DO NOT HIT THE BRAKES unless you were going to repaint your car anyways. Push in the clutch, or gently roll out of the throttle instead. Severe moves are your enemy.

PS - If that's the first time you've heard that... Perhaps you should do a few solo passes before you line up with someone in the other lane.

V-10 Killer

iTrader: (22)

Now THAT's some wise advice. I'll remember that
I certainly wouldn't want to be responsible for taking out someone elses pride and joy.

V-10 Killer

iTrader: (22)

What factors do I use to determine whether I need to add or remove more air from the tires?

slow trap

iTrader: (22)

too much air and you spin worse.i'd say start at 20 lbs also.i run factory wheels on the front for now.my car only trapped 100 in the 1/8th but i can't tell much of a difference from skinnies up front.is the skinnies more foregiving when the slicks start wallowing to not upset the car?

McRat

At 20 psi you shouldn't have too many problems. Most tracks won't hook at 20PSI though. Don't lower the pressure anymore than necessary in any case.

I never go any lower than 13 PSI because the tires move on the rims at 12 and I did not screw them on.

I've run with 14 PSI, in a front heavy 3800lb raceweight 460 RWHP 03 Cobra at a poorly maintained track with Z-rated 275 tires on the front. So YES, it certainly can be done. But is it safe? Until you wreck, you will think it's safe. After you wreck, you will change your mind.

I AutoX, have RR'd a little, and attended several driving schools. I have run with skinnies up front, and Z-rated's up front on Bias Ply slicks and cheater slicks. Hell, I've run a 7500LB 4WD with slicks on all four corners! And ran bikes on the wheelie bars to 1/2 track.

Your choice. Learn from your own experience, or listen to others with experience. As long as your experience comes without hitting someone else at the track, it's all good.

V-10 Killer

iTrader: (22)

1.) A fool never learns from his own mistakes.
2.) A smart man does learn from his own mistakes.
3.) But a wise man learns from other peoples mistakes.

A quote I try to live by. And seeing as how I'm asking for advice from seasoned racers, I'm trying to be number 3. I thought taking this step (buying slicks and new rims) was wiser than trying to run a 10 second nitrous run on a full weight car and street tires. I guess I'm going to just have to bite the bullet and buy the other two rims and tires. Or wait until next year to don the slicks... I've already spent 5 grand more this year than I told myself I was going to

McRat

I guess I should explain the physics a bit, so I don't look like a party pooper or wuss.

Your car normally is like shopping cart being pushed forward. The rears are fairly well planted and the front is capable of turning. It's pretty stable. Now push a cart with all 4 wheels on swivels, or hell push the cart backwards. This is what running low-pressure bias ply tires on the back with stiff sidewall tires up front. Sure you can do it, but it's less stable. With stiff fronts and loose rears, the car steers with the rear tires. And side loads on the rear makes the car turn even if you are holding the wheel straight. And putting any kind of steering input into it amplifies the effect.

This was discovered in the 1970's when radial tires first came out. Unexplained loss-of-control accidents were tracked down to people running biased rears and radial fronts. If you go to the MT site (or other companies that make bias ply tires) they will warn you against running radials on the front and biased on the rear. But it is not the entirely the tire designs fault. It is more of a function of tire "give" to lateral force. You will find that running high profile narrow radials in the front has enough give to negate most of the instability the bias ply tires cause in the rear.

If you must run bias slicks with stiff radials up front, run no more than 32 PSI up front and keep the rear pressure as high as you can and still hook.

Pro Stock John

iTrader: (34)

I'd baseline the car at 18psi cold, that will be like 20psi hot.

Get at least two runs like this before you mess with tire pressure.

I would not go under 14psi cold.

Mike K.

I have run with slicks in the back and radials up front and the rear end did move side to side alot, I first thought to myself is the car spinning?? but it wasn't, just be careful and like these guys have said don't make any sudden jerks of the steering wheel cause the swaying at the big end is normal.

2001-WS6

Are you going to be making your first passes at Stanton? If so, then traction will be just fine. It's a great place for you to break the combo in.

I've ran that basic setup with an extra 150lbs and the F1s up front as a combo for over a year without any issues. So don't worry about the skinnies up front at this point until you find the need to drop below 15psi on the rears. You can worry about that when you've dialed the car in for power and gotten used to it and you need that last .1 or .2 on the ET.

You'll want to start at 18lbs to get the feel for a few passes. Then start dropping .5lbs every 2 or 3 passes until you hit your best 60' times. You've got plenty of time so don't rush things. If you're only running a 100 shot out of the hole then it will probably be in the 15.5 to 16.5psi range.

The real things you want to think about is how are you setting up the NX kit? Are you going to run a progressive contoller or run stage 1 on a WOT switch with stage 2 on button? Either way run you first passes on Stage 1 only in the 100-125 shot range to learn the car and setup the QA1s properly. The weight of the stock front tires will actaully payoff in allowing you to comfortably get used to seeing the sky.

I went with WOT for Stage 1 and the Button because it's fun to use it when you want it. If you mount it on the stearing wheel or the shifter it's easy enough to reach and launch with both stages if you need to do it.

Then the next big question is, do you care about the driving the twisties on the daily driving or do you want to be dead nuts straight on every launch? If you can handle some suspension noise and don't mind not being about to pull monster Gs when cornering, then a dragrace rear anti-roll bar like the BMR Xtreme duty or the Wolfe piece will lock in line like you were on rails.

In the end, you really won't notice the ChaCha on the big end until you drop below 16.5lbs on those tires or you cross the 128-132mph mark. When it happens the first time you might feel the need to let off and that's OK but your car is going straight so just ride it out. After the first time you just won't care about it once you see the time slips.

Rick

V-10 Killer

iTrader: (22)

Yeah, I only run at Stanton for now
That way if I break something I'm not 3+ hours from home without a trailer.
Maybe next year when I buy my truck and car hauler I'll venture further from home. I'd love to hit some of the MM events at Milan, but not until I can guarantee a ride home.

The NX setup is gonna be something to deal with indeed. It's set up in two stages for running on street tires. I currently have pills in for 50hp first stage, and 125hp second stage, so 175 total. Both thru a "master arm" and WOT switch. Also both thru a MSD window switch. But the second stage is also running thru a time delay relay, with a bypass wired in in case I want to run both stages out of the hole. But the more I think about it, I don't think I want to spray 175 out of the hole for a while, especially on a stock lower end right now.

I won't spray at all my first time to the track with these as i want to see how they behave thru the full length of the track at at least 18psi. Then I'll experiment if I feel comfortable. Baby steps...

As far as suspension, I enjoy the occasional river road, but never auto-x the car. I drive it at least 3,000 miles every year and haven't decided if I'm going to do the rear drag sway bar or not yet.

Thanks for everyones input. I'll use it wisely

ITLstallion04

I run 10-11 PSI using the new M/T. No tail wag @ the topend of the track either, even at 145+MPH.

These tires wont hook that well if u do a light burnout, u gotta smoke em, then they hook!