Slicks and traction......

[Fast231]

Finally went to the track and bolted on my slicks (ET drags 28x10.5 with a 8.5 inch rim) I was launching lightly with about 5-6 pounds of boost, I was getting 1.7-1.8 60 foot times. With the slicks at 12psi i was happy with the 60's, but i did have a couple people say that it looked like i started to spin about 400 feet out...

I didnt have the time to play more with the pressure but i think this friday i will start with 12 and drop a pound or two and see how the car likes it, I would have thought that if the slicks are launching well then they shouldnt be spinning at any point in second gear.. I added some billet LCA's over the winter to help it bite, but other than that the best my car has gone in the 1320 is 114mph. It was to dam hot last week and all i could get running pic rich was 109....What pressure do you guys run in your slicks? If a slick bites well off the line it shouldnt spin down the track should it?

 

[azgn]

not unless the track is ka-ka........I run 13-15 lbs in mine

 

[Fast231]

Thanks Woody, Thats what i thought.......Then i will start at about 14 and work down from there and try some bonzi launches and see if i can get a better 60 foot time

 

[Chris McDade]

On a 8" rim I run 10.5-11.5. with good luck. It depends on the track. They all can very....

Good Luck

 

[Chuck Leeper]

Launch then spin??

Sounds like the suspension is unloading after the launch and the boost has risen enuf to raise torque levels.
Could be you need to look at the shocks. Some times the shocks will allow the rear tires to plant, then as the tires attempt to rebound back up into the chassis, they are unloaded and start to spin. The shock's job is to control this unloading.
I doubt it was 400 ft out. Most likely sooner. Put a white stripe on the tire and have someone video it.
The rear suspension could have some help w/ adj uppers and a pinion angle of 3-4*. That's not a major player in tuning the suspension, but helps get things headed in the right direction.
The car does not have a snubber on it, does it???
How many miles on the springs, shocks, etc?
Ft sway bar off?
The 12-14psi is a good starting point in pressure.
What are the air bag set at??
Rear swaybar on?
Have a scan tool that's fast enuf to see the shift points and rpm ?
Look and see if there are spikes in the rpm at places other than the shift.

 

[Fast231]

Re: Launch then spin??

Originally posted by Chuck Leeper
Sounds like the suspension is unloading after the launch and the boost has risen enuf to raise torque levels.
Could be you need to look at the shocks. Some times the shocks will allow the rear tires to plant, then as the tires attempt to rebound back up into the chassis, they are unloaded and start to spin. The shock's job is to control this unloading.
I doubt it was 400 ft out. Most likely sooner. Put a white stripe on the tire and have someone video it.
The rear suspension could have some help w/ adj uppers and a pinion angle of 3-4*. That's not a major player in tuning the suspension, but helps get things headed in the right direction.
The car does not have a snubber on it, does it???
How many miles on the springs, shocks, etc?
Ft sway bar off?
The 12-14psi is a good starting point in pressure.
What are the air bag set at??
Rear swaybar on?
Have a scan tool that's fast enuf to see the shift points and rpm ?
Look and see if there are spikes in the rpm at places other than the shift.

Some good points to look at Chuck, I have no snubber other than what GM put on,also the shocks and springs were new last year (less than a couple thou KM's)and i have not unbolted the sway bars. I havnt gone through the runs yet on DS but looking for rpm spike's is a heck of a good idea. Same goes for painting the tires with a stripe to verify. Also i am still waiting for my air bags to arrive.......

I thought that the front sway bar undone was typically for the weight transfer when you launch????

 

[Chuck Leeper]

Sway bar?

Correct on the sway bar unhooked.. Preferably off, due to the wt..
As for the spin.. Could be without a method to balance the rear tire loading,[no airbags] your friends could be seeing 1 tire spinning ??

 

[Fast231]

I'll unhook the frt sway bar and see if it helps my 60 foot times. I dont usually take my slicks to race (pain in da azz) but after the last time with my street tires on and sliding back and fourth all the way down the track and running my first 15 against a slugstang ( ) and still almost losing to em there always coming.

Thanks for the feedback boys....

 

[strikeeagle]

Yup, IF you spun, it could be your track had a slick spot X feet out. Did you switch lanes with the same results?

Some cars bounce on the air bags just after launch, throwing the weight forward and unloading the tires. One solution is air bag spacers, and less pressure in the bags.