Chevelle suspension help!

[Ovrnightr]

I have a suspension problem with my 69 Chevelle I was hoping you could help me with. The car twists quite a bit off the line which causes the 60’ times to be slow and inconsistent. On a good track it lifts the driver side front wheel about 2’, the passenger side 1’. The passenger rear dips about 5” – 7”. The best 60’ is 1.635. The average 60’ is 1.675 – 1.725 :eek: . On a marginal track the 60’ averages high 1.70’ to low 1.8’s with some tire spin.

Car details:

-Competition engineering 3 way adjustable shocks. Front set : 90 – 10 Back set: 50 – 50
-Moroso Drag springs. Front 47160 Back 47500
-Hotchkis upper (adjustable) and lower control arms.
-Moser 12 bolt rear end (with the raised upper control arm mounting location) 4:56 gears. Pinion angle set 2 – 2.5 negative degrees.
-29” x 11.5” Hoosier Quick time pro tires @ 9 psi.
-Turbo 400 transmission with a trans-brake. Launch RPM 4800 on the rev limiter. The converter will stall to 5200.
-Car weighs 3300 LB with driver.
-Engine has ~600 HP at the fly wheel, ~470 at the wheels. (Dyno tested)


What can be done to increase the 60’ times and straighten out the launch? :confused:

Ovrnightr@cox.net

[Jeff Chandler]

A very inexpensive thing is to add an air bag to the RR coil spring, you have to expirement with bag psi to see what works but to really fix the problem properly is to install anti-roll sway bar like you see with the Mustangs.

[Jeff Chandler]

Like this:

http://www.wolferacecraft.com/detail.aspx?ID=320

Spherical Upper Control Arm Bushings are a must for this application in my opinion.

Good luck

[Mike Lough]

Go to HRpartsnstuff.com and check out their bolt on anti-sway bar. My old '83 Hurst Olds used to leave like that until I bolted on their rear suspension package. The biggest change was due to the anti-sway bar. The best part was that I did not have to cut through the trunk floor and connect it to the cage, it bolted right to the frame. Paul has some pics of a 69 Chevelle on there, before and after the sway bar was installed. My 60' times went from 1.50 on a good track to 1.38-1.40 on a hot slick track just by changing to their parts.

[chvlle383]

dick miller racing also has some nice stuff, and is pretty knowledgeable on the gm a body suspension.

[Elkyman]

Check your pm's I sent ya one.

These guys are all right with these parts they mentioned, just some input on the rear gm stuff, without having to back half these vehicles, and they (A-bodies) being basically a poor mans 4 link, built for comfort, you also need to get the chassis stiff so the suspension can work for you.

A ladder bar is violent to some and a 4 link is a tuning game, and once set up works great, but keep in mind that all work does need to be done with the vehicle at ride heigth and race ready, ie; fuel, and weight for driver, unless you can be in 2 places at once!!!:D Also, that lower rear control arms need to be as parallel to the ground as possible, than, adj. with the upper control arms and you may have to relocate the mounting point up, the front mounting point that is, draw your imag. instant center and try to get it in the 35-45 inch range if possible, this will lift and transfer your weight and this should drop your 60 ft. pretty good. I know that trying to get the LCA'S level will be a challenge, and will usually causes problems in other areas when adj. is not available, ie front shocks and spring heigths, the gm QA1 replacement kit is awesome for this, read up on it if you can, works great.

The suspension can be a fun thing to learn, if you go the right direction. From experience, going the wrong direction can also be a nightmare and be frustrating as well. I am a believer in the drag sway bar also, this will control body roll and keep the chassis more rigid in the rear to make the suspension work for you. Hope it helps!!!!:) :)

Elkyman John
O/C 9900

[Mike Lough]

Another useful tool for me was Dave Morgan's book, Door Slammers. $30 well spent IMO. Elkyman, you are right on about the IC. That is something that eluded me until I got the book (and finally started listening to some of the old school drag racers!). To adjust my uppers at the track I would have my Dad sit in the car while I adjusted the control arms. It is also easier to sit the car on 4 large wood blocks (same height of course). Cuz I'm a big boy and need my space underneath!

[Elkyman]

Mike, I believe your not a real drag racer until you have red Dave's book, indepth and very informative, he has helped me out a few times.
And I almost forget about the raise the vehicle so YOU CAN do the adjustments, but I didn't know how indepth the chevelle guy is with these parts and techniques for tuning. Dave Morgan's book will definetly fill in the blanks and make you feel like you are the engineer also!!!! but very needed to understand your chassis, if you can read and relate to reality, you will have mastered his book.

You, a big guy?, naaaaa, just not enough wood:D
Forgot about his book also, go figure, the best book I ever red. Good input!!

Elkyman John