Tommy Campbell

I need some advice. I am installing the QA-1 double adjustable rear coil over shock kit with the soft springs on my 1987 Camaro. It is a track car only never on street. It has a 454 bbc bored .70 over with Brodix Race Rite aluminum heads. It made 750 hp on the Dyno. It has 28x10.5x15 sticky mickeys on back and 90-10 Lakewood drag shocks on front. Has relocated lca bracket as well as subframe connectors and adjustable torque arm. It has a 9" rear end and 456 gears. The car weigh 3375 with me in it. I was hoping to get some sort of advice on how to set up the compression and rebound settings on the rear coil overs.

SlickTrackGod

Any video's pf the car launching would be helpful. If not then you will have to take some of the rear tirewell and tire sidewalls as the car launches to see just how much force/load is applied to both the suspension and the tire.

I did a quick check on QA1's site (I am very familiar with circle track and roadrace dampers from them 1-12 valve settings) to see what the double adjustable settings are- there are 18 clicks each, not 12.

I was going to recommend to use aprox 5/7 setting Comp/Rebound for starter but since you have 18range not 12 I would say start with 8/12.

What you are looking for in the video is the car not to "shockload" the tires and make them bounce on recoil. You of course want plant and go with the front end coming up for weight transfer. The rear should squat enough to absorb torque... but not too much to invert and cause wheelhop or invert the LCA.s past parallel thrust angle for forward push of the chassis. If the tire comes down fine but then comes off the ground in recoil then the rebound is too high. On the other hand if the rear chassis bounces up and down allowing suspension motion after launch then the rebound is too low. I would work on the comp side forst to get the car to sit hieght wise under initial torque for launch and grip. Too much comp can cause wheelspin since it would load too stiffly like too much spring rate (the rear suspension starts to fail to move/work if too stiff.

SlickTrackGod

I will also add that if you have to eventually turn the compression up higher then lets say aprox 12-14 range to keep the chassis from too much rear squat then you will want to then consider upping the rear spring rate and lowering the comp valving back down to about 8 again and start over.

Tommy Campbell

Got the car to the track I tried to upload a video but it would not upload. But here is explanation the best I can on a slow mo video the tires hook for one or two revolutions then just break loose and spin. The weight looks to be transferring to back tires and rear seems to stay planted but the car spins from about 10'-200'. Settings on best run which was still 4 tenths slower than car was with original suspension were 4 on comp and 14 on rebound.

SlickTrackGod

Tommy, Do you have a picture of the car at stagnant height?

I notice the wrinkles are almost gone in the second pic. The bumper level looks the same first and second pics, as do the fender height to the wheel lip does not appear to change.

I am wondering if the tire is loading abruptly and then the tire and entire car are coming off the ground (in essence) which is lighting up the load of traction tot he ground thus making the wheels spin. Best if I can see where the car sits before power is applied (wheel to fender height - in order to observe chassis squat under initial thrust.)

Dean

Also- what are your measurements of the LCA bolts from ground both front and rear bolt centers. I see you installed LCA relocation brackets, I want to make sure you are not angling them downward too much and causing chassis lift (this will load the tires and bounce them.)

UMI Sales

Did you try turning the rear rebound up?

Craig

SlickTrackGod

Rebound is already too high if the tire is coming off the ground (ie- the wrinkle is gone)

UMI Sales

Sorry if I misunderstood. I though the car hooked at launch then the rear was unloading causing the tires to break.

Craig

articwhiteZ

iTrader: (56)

You would /should start off will the rear shock rate of 50/50.. as you transfer weight to the rear. You want the shock To help put that weight on the rear tires.. and keep it there through the 60-foot only leveling off as the powerband smooth out.. Call the manufacturer and find out what the setting is for a 50/50 rate setting... tuning will be easier from that point on..

SlickTrackGod

Perfect example of the biggest mistake people make in car setups.

You do not throw out data you already acquired to start at a completely new blind setup. Tune off of what data you have. This is why I am still waiting on the info I requested from him about what some of his other settings are. Shocks do not sound like his priority problem right now so why make things worse?

sofakingdom

iTrader: (1)

Video would REALLY help. Preferably slo-mo.