So my car is getting quicker at the track (12:31) (1.70 60 foot) and I have an issue with tire spin. It is not off the line but just after. My friend observed my car squatting down and then it kind of unloads and the front comes down and then I spin for a second and the it squats again and goes. This happens about the 60 foot mark. Our cars are nearly identical with the same stock suspension and shocks and he is running 12:01 and not spinning. I have an airbag in the right spring that was there when I bought the car. I inflated it to 10 psi. I have KYB shocks all around. I really dont want to put drag shocks. Can the airbag have a negative effect? I have been told to loosen the front sway bar. Can this really help that much? Any ideas would be appreciated! Thanks....
If it is unloading, unhooking one side of the front sway bar could help it stay hooked. Also, how's your neutral stance? Is the front lower, level or higher than the rear? That could influence how much travel you have before you bottom/top out. I know you said you and your friend have similar builds but could there be subtle differences that you are unaware of such as front end alignment, pinion angle, weight distribution? What is your 1/4 MPH? That's an indication of HP while ET is an indication of how well your combination is working. As for the airbag, try it with on air and see what you get for a baseline.
My MPH ends up at 108. I am only running a 27 inch tire right now. My car sits pretty level, my buddy sits probably a little lower in the rear. Running 3.42's. I can try the sway bar and letting air out of the bag. It was just fine at 12.50's and now we are running faster, this issue has come up. Thanks...
What shocks are you using up front ? If the front of the car came down a little slower than your weight transfer would hold better and your tires are less inclined to break loose. Did you remove your swaybar ? That will hold the front end down and prevent some weight transfer. These two things helped me a lot when I was running numbers similar to yours. John B.
I am running KYB's all around as it is a street car. My next move is going to be removing the front sway bar for the track and let air out of the rear air bag. I hope this will help the car stay hooked....
Back when I was younger and smarter, I calculated that the airbag had its optimal benefit at 15PSI. But that will have nothing to do with your "rebound" thing... -Bob C.
Other than a little weight savings, you don't have to remove the front sway bar, just remove one end link. That effectively disconnects it from having any torsional effect on front end lift.
The only effect a sway bar has on weight transfer is the bar rotating in the frame mount bushings. If you pack them with dielectric grease it has almost 0 drag. Change your shocks.
How does that work when the driver's tire tries to leave the ground and the passenger's tire is lagging behind? That has to wind up the sway bar and stop articulation. The Jeep guys disconnect (even electronically) their sway bars so that it will articulate.
I wouldn't mess with the sway bar at all. Bags never done anything for me imo. You either need a better track or better tires i.e. something taller like some 275/60 MT pros. If your not interested in making suspension changes that will negatively affect street manners. Back when I was running a 12.40 car at 4100lb it would squat then unload typical of stock street suspension in lower powered cars that can't really work the suspension hard enough to keep a load on it. Your kinda stuck in that middle ground rite now from my experience either need more power, better track prep, or suspension work that will probably take away from its current street manners.
Do you really want your car to twist like that? Put more air in the air bag. The car should leave the line with the front end level. When the left front is higher its because your rear suspension is not set up correctly. Way would you even mention a Jeep? That has nothing in common with a drag car.
As far as sway bars are concerned. I will usually install longer end links. Still have a sway bar but has longer UP travel. No removal or dis-connecting anything.
The only difference between my car and my buddy who is running 12:01 is the air bag. So what kind of pressure needs to be in there typically?
I'd start at 15lbs need to.Just have someone watch the car from the rear and see at what psi it leaves level, or you can do a burn out at different lbs settings till you get even black marks that's a decent indicator of load splitting. Or just get a HanR bar and ditch the bags
Those are No Hop Bars. No, the HR Parts n Stuff rear sway bar. Very pricey but well made in America and it works. It also has some very nice handling benefits. http://hrpartsandstuff.com/
Because if it is trying to lift the left front, it is planting all that extra weight on the right rear. Jeeps were just an aside about disconnecting sway bars. If that helps (which it is free to disconnect the sway bar) he can concentrate on how to use that information most economically.
I don't recommend disconnecting the front sway bar for safety reasons. If for some reason you get sideways you won't recover. Your right side will end up about 1 to 1 1/2" higher in the rear at rest. Correct pressure will be when the cars leaves the line level as Hugger said. Maybe 15 or maybe 20lbs. If the front of the car rises level the only effect of the front bar on weight transfer is the drag of it rotating in the frame bushings. As I said dielectric grease helps. A sway bar has no ability to raise or lower a car, thats what the springs do. It links the two sides together to level the car when turning. In a straight line it's just along for the ride. Except on the rear. A stock rear bar links the lower control arms together stopping some articulation that twists the car. This keeps more even pressure on the rear tires. The Kayaba shocks are not made for weight transfer. Get a good set of front drag shocks for track use. They're not hard to change out. Normal shocks have almost 0 compression damping since that is the springs job. A shock is there to control the springs rebound, thats where the damping is. On a drag shock (front) it has heavy compression damping so the front end comes down slower so the rear does not unload. Always use a rear swaybar. It really makes the rear hookup better. Longer end links won't change the effect of the bar. This could also be caused by your engine tune or torque converter.
