HI, I have been tying to get my car tuned and wondering why it lifts at the line so much.
When my car launch's The whole car rises then takes off. it pretty much limits out front suspesion and raises the back up big time to there is on squat. which gives me horble reaction times and it looks funny. Im pulling off 1.7 60 ft times and running around 12's at 110-115mph.

I have 90/10's in the front with no sway bar
The rear I have gta springs summit shocks at 60/40 1" sway bar and tubular control arms and panhard. the torq arm is stock.
I am running some sticky 29 x 9" wide slicks
when the car is sitting the rear of the control arm is higher than the front of the arm in the car.

If you guys could help me get this thing to bring the wheels up and squat alittle in the rear it would help alot!
Thanks

 

Sepperation in the rear is generaly a good thing, it's just a matter of tuning it to what the car and tires like.

When the rear rises at launch (sepperation) you are seeing the effect of the engine torque driving the body up and conversely driving the axle and tires down. Squat is the exact opposite, the body is dropping and the axle/tires are lifting.

I am supprised you are getting dramatic sepperation with the LCA angle so bad. A set of lca lowering brackets are proabably a good idea.

Lets look at the rest of your combo... You seem to be running a lot of tire and getting good suspension action and despite what you say your 1.7 sec 60ft is pretty good. But your 12 sec ET is a bit off.

What are you making as far as HP? What are the overall specs on your motor and drivetrain?

I suspect that your tires and suspension setup are giving you too much bite off the line and that you lack the power to use all that traction.

Softening the innitial bite may give you the off the line response you are looking for but I wouldnt go about it by trying to induce squat, just look at ways to reduce front end lift a bit like using your old stock struts.

 

Pushing the rear down (giving you body lift rear rise) is what you want. That is the effect of the suspension pushing the rear tires down into the ground.

None of what the suspension does has any affect on your reaction time.

Look at limiting your front end lift, like limiting straps. Sounds like your rear suspension is already doing exactly what is should be doing. Now you just need to direct the power into pushing the car forward, not lifting the front end.

 

iirc once the front has lifted to the point of the car being level or the front tires have cleared the pavement (what ever comes first) any further lifting of the front end is simply wasted energy and potentialy aditional drag if the car remains nose up at speed.

Lifting the front to a point will obviously transfer weight to the rear but like all things there is such a thing as too much.

 

My combo is off I was running 3.73 gears with huge cam and dual plain now im going to 4.56 gears and a single plain so I can get it revved out better. Im pretty sure thats what was throwing my mph off.
It does hurt my reaction time becase the car pretty much jumps strait up in the air befour it goes forward.
Im thinking of going with a jegster type shorter torque arm. I read in a car craft that the further forward you have the instant center the more the rear of the car is going to lift. So with a shorter torqe arm it was move the ic back. Then put the limiters in the front. I am not sure now much to limit the front. maby 3" more than its regular stance.
Im still wondering if the relocation brakets would help me I see alot of 3rd gens at the track with them.

 

As everyone has already mentioned, body separation is what you want but doesn't necessarily work for everyone. You want that separation to drive the tires into the ground. Rear shocks need to keep it there for as long as possible before it goes into tire shake. Cars that squat when they launch probably go into tire shake if the suspension is adjusted to separate on launch.

One suggestion is to increase the compression of the rear shocks. If you get too much traction and get tire shake, soften the compression.

If you want to play with suspension to lessen the amount of separation, you can try and lower the front mount of the torque arm but don't change the pinion angle at the diff. The lower control arms should be parallel to the ground or down slightly in the rear. With a lowered suspension, the LCA is usually lower in the front and relocation brackets are required to correct the geometry. Using an aftermarket adjustable torque arm will help correct some geometry and will also allow you to adjust the pinion angle. You're in the 12's now with a stock torque arm. You're about to the point where stock components, although they work, just don't cut it any more.

Pulling the front wheels like I do looks impressive but it doesn't make you any faster. It's wasted energy moving the car upward instead of forward. I also have a lot more torque with a high rpm transbrake launch to help get me moving. Now that I have the car launching faster than it ever has, I need to keep the front end down by stiffening up the front shock extension or by using travel limiters. Front suspension that's too soft causes bouncing when it comes back down which unloads the rear tires.

 

How in the world does he manage to get antisquat with the stock suspension, I thought that was next to impossible?

 

I think its because of the gta spings and my car being stripped so its light in the rear and the 29" slicks. But its weird that when it sits the front of the control arms are lower than the rear of the them. But now that I think of it I have the front lowered and 25" tall tires.

 

I don't know a lot about drag suspension but it seems like putting limiting straps on the front would hike rear springs rate drastically when you hit the straps. maybe I'm wrong but just throwing out an idea.

 

Odd. Usually, fronts lower than the rear, will introduce wheel hop, which leads to breakage of parts.

 

I did twist up the stock drive shaft pretty good though.
Im doing a ford 9 swap to the the car now and Im planning on building a custom torqe arm out of some 1.25" .120 tube. Im going to make it about 6" shorter than the stock arm and lower the top mount point about and Inch. also Im going to try a set of v6 springs in the rear. Planning on going to the track in April so Ill probly find out the difference then.