Suspesion setup with radial slicks "help"

[DCVING]

Hello everyone, My name is Jon and I am new to this forum. Im reaching out looking for some advise from fellow racers. Although my car ( 1965 GTO ) is not a legal Stocker, Ive built it very similar in terms of suspension, looks, tire size and such.

So since I finished this new build last year I have had some struggles with getting the car to hook consistently. When it hooks up it will 60 in the 1.37 rang, 2500 rpm footbrake. The car previously was setup to run a DOT drag radial and I had success with it, 1.40 with 100hp less. I was running no-hop bars and soft rebound to really hit the tires ( M/T PBR ) hard and 90/10 shocks up front.Fast forward to now, In the rear now I am running all tubular arms with spherical joints in stock locations, Viking DA shocks, BRM antiroll bar, UMI lower relocation brackets. Front has Viking coilovers with double adjustable shocks as well and stock control arms.
Tires are Goodyear 5202 30x9 Radial Slicks which have a much much softer sidewall than the M/T PBR.

So im really struggling with how to setup the suspesion with these tires. Do I setup as if they were a bias slick, or do I setup as if they are a Drag Radial? I have about 165% antisquat currently. When the car hooks all is well, when it dont hook though my sympoms are it hooks then comes unglued a couple feet out then it rattles the tires. Ive tried up and down on tire pressure and played with shock settings a little bit too. Is it possible im hitting this radial slick too hard and causing it to bounce? Should I keep hitting it hard and tighten compression more? Please help...

[Hacksaw]

Sounds like yor hitting the tires too hard. I would loosen the rebound up front and tighten the compression in the rear. Probably about 18 lbs or more in the slicks. Because you changed a bunch in the rear, doube check that there is no suspension bind when it travels. Hope this helps.

[1320racer]

before we talk about shock settings, what do you have for pinion angle and preload? I will also tell you that coilovers with the stock arms is a mistake.

3880 lbs. 59%F/41%R weight bias launched off the footbrake on Hoosier 30x10.5 radial slicks. .Stock A arms, coil springs and Koni shocks up front.

[DCVING]

Originally Posted by 1320racer

before we talk about shock settings, what do you have for pinion angle and preload? I will also tell you that coilovers with the stock arms is a mistake.

3880 lbs. 59%F/41%R weight bias launched off the footbrake on Hoosier 30x10.5 radial slicks. .Stock A arms, coil springs and Koni shocks up front.

Pinion angle is 1.5*
Zero preload wiwth me in car.

3500lbs with 53F 47R bias, why is the stock arms a issue with coilovers?

[DCVING]

Originally Posted by Hacksaw

Sounds like yor hitting the tires too hard. I would loosen the rebound up front and tighten the compression in the rear. Probably about 18 lbs or more in the slicks. Because you changed a bunch in the rear, doube check that there is no suspension bind when it travels. Hope this helps.

No binding as Ive checked that, thanks for the advise.

[1320racer]

Originally Posted by DCVING

Pinion angle is 1.5*
Zero preload wiwth me in car.

3500lbs with 53F 47R bias, why is the stock arms a issue with coilovers?

Typically limits front end travel which these cars need all they can get. The car needs to be put on 4 corner scales to dial in the preload.

[DCVING]

Originally Posted by 1320racer

Typically limits front end travel which these cars need all they can get. The car needs to be put on 4 corner scales to dial in the preload.

Got it! I have stock limiters removed and it does have decent travel.

[DCVING]

video

[1320racer]

not nearly enough, I had the stock limiters installed.

[Terry Cain]

Originally Posted by DCVING

video

Looks to me like the front is not loose enough. the front settles back too soon.