Drag car front lifting at high speed rear losing traction

[Quarter Flash]

Need a little advice on front and rear air foils. I have a 1980 Monza Drag car. The car weighs 2300 lbs with driver, full tank of fuel (5gal) and all equipment. The tranny is race glide with a 4500 stall, the rear is spool with 4.1, slicks are 11 X 30 Goodyear, fronts are 25" Goodyear drag tires, rear suspension is 4 link, the front tires weigh 1176 with the left being 7 lbs heaver, the rear weighs 1173 with the right weighting 9 lbs heaver with driver and equip in car. The car has a 4 degree rake and is level side to side. The bottoms of the rockers sit 6.5” off the ground. Adjustable QA1 coil over shocks at all four corners. The engine is 703 lbs ft of torque with 100 shot @ 5200. Here is the problem! The car goes dead strait until about the 660 then the front of the car starts to lift and if you stay in it at about 130 – 140 mph or about the 880 it starts to wander and loose traction. I feel the car will run 160 + and low 9s if I can solve the windage problems. How do I figure the length and angle? Is there someone that makes custom spoilers? Is it all trial and error? Is there a web site that might educate me on how to get the best results?
See other pics

[Wizeguyrc]

I would definitely add a rear wing to the car. Like a Pro Stock style, with adjustable struts. What spring rates do you have on all corners. Even though your front and rear weight numbers look to be balanced, you have to remember that the suspension, rear end, wheels and tires are unsprung weight. This goes for the front suspension and wheels and tires also. So your car doesn't have a 50/50 split as indicated by the numbers. Did you ever run the car with a "less powerful" engine in the past? If so, did you have these same problems? Also, what is your instant center four link adjustment? What did you end up with on front end alignment? Tow, etc.


Tracy

[NVEGAR8D]

Hi,
just looking at the front of your car i would say you are getting too much air under it and lifting at speed. you need a deflecter dam to push the nose down. a spitter or spoiler down front.then a rear wing or spoiler to add some down force to the back aswell.
nick75vega

[bill1978v8]

look at the Monza in this link. He seems to have it figured out

viewtopic.php?f=1&t=33845

[Quarter Flash]

My front springs are QA1 MS 365 S
Rear QA1 12 - 130/250

We did roll the car back with a MSD 7531. As long as we kept the car under 130 mph it is strait as can be. As long as the 7531 controls the rpm rate and limits the max rpm to 130 mph in second it seems to do fine. With out the 7531 it haises the tires on top end and wanders at speeds over 130
http://www.hotrodders.com/forum/journal ... ction=view

[Wizeguyrc]

My front springs are QA1 MS 365 S
Rear QA1 12 - 130/250

Any other info?

[Kenova]

Try to lower it a couple of inches and put an air dam or spoiler on the front. Drop the front suspension onto it's bump stops and that will give you a good idea as to how low you can go with the dam/spoiler.
It might sound like a lot of work but I'm sure you don't want your car doing the funky chicken at the top end.

Ken

[Fasterthansome]

Different body style but this works well for me.



Should be able to fab up something similar to this out of aluminum.

[Dreamweaver vega]

First of all You are getting too much air under the car, but look at the rear of the car. The way you have the bottom tin ed off, you have create a airplane wing. You could ad a rear wing to the car, but until you fix the bottom side of the car it will just be two forces working against it other. It will work dont get me wrong. Look at ways to open up the back of the car to release the air from the car and actually create a vaccum or suck the car down then add a wing to it with alot less down force

3-19-11%20TXDRL%20120.jpg

I removed my lower valance and sucked the bumper up and as close to the body as I could If you don't believe me look at funny cars, pro mods etc all thier butts are open I was able to lower my rear wing angle creating less drag and still the same down force to keep the car planted on the top end

[opeltwinturbo]

I agree with the front end height being too high. NHRA wants 3" minimum ground clearance. At you potential speeds you need to be there. Ed Quay makes the rear wing. That will also help plant the car at high speeds.