Right now I don't have a rear sway bar on the car and was wondering how big of a deal it is when drag racing. I have Hotchkins (spelling?) control arms with poly-eurothane (spelling?) bushings and anti-hop bars so it actually drives well. At this point the car desperately needs front springs because I installed a 454 in a small block car and it's pushing the front end down. I have to lift up on the front bumper just to get my floor jack under the cross member! Thanks.

One of the best little books on "A" body suspension for drag racing is found at www.dickmillerracing.com (http://www.dickmillerracing.com) spend a couple of bucks, it is a worthy read.

First question: have you even made one dragstrip pass with your car? If yes, then how was the launch? Not just the actual 60' time, but wheel spin,wheel hop, chassis twist, etc. If you stand back and watch cars at the dragstrip you should notice that many of them twist: lift the left front and squat the right rear. This is all just regular physics at work. Many people remove the front sway bar on purpose to help the front end rise faster and transfer more weight rearward. When a car lifts its left front tire it is simultaneously transferring weight to the right rear. A sway bar transfers some of the overloaded right side weight to the left rear - helping to even the weight distribution. You can tune the launch twist to a point by increasing the diameter of the rear sway bar. My '65 twists upon launch, so I just upgraded the rear sway bar from a 1" bar to a 1-3/8" bar. I'll be racing again on the 26th and hopefully I can better my previous best 60' of 1.57 seconds.

Thomas

Thomas, thanks for the reply. No I haven't made it to the strip yet but would like to sometime in the next 3 to 4 months. I used to have a problem with wheel hop but the anti-hop bars worked great and took care of that problem. It sounds like I would benefit more with new front springs as opposed to the rear sway bar, just basically trying figure out the best way to spend the budget on the car.

Keep this in mind:
If you use adjustable links, you can "preload" the right side more, to transfer more weight to the left side. Using a stiffer bar with adjustable links is considered a "Anti-roll" bar. It , in effect, "borrows" spring rate from the left side to help the right side.
Have someone video the rear of the car on launch. Also use a white stripe on the tire to gauge tire spin.

i have a H-O racing rear 1 3/8 swaybar and it works great

"A sway bar transfers some of the overloaded right side weight to the left rear - helping to even the weight distribution."

Actually, "physics" loads the left tire and unloads the right. The drive shaft is turning clockwise and the ring gear resists. The drivers side of the diff is pushed down, the right unloads. In the '60s, we ran with one airbag in the right rear to compensate and to prevent the premature failure of our posi units. My '65 L79 Chevelle turned a best of 12.73 on 7" wide tires. The car left the starting line dead level although it sat with the right rear slightly higher than the left.

To answer the question, an antiroll bar could be used to increase right rear spring rates if it has adjustable links, but it is not important in drag racing.

Not a racer, but the addition of a sway bar, and solid uppers pretty much negated the need for air bag. Still have it in there, but not inflated. fwiw. oh, and it corners better!

Well, as proof that not all misinformed '60's thoughts on Chevelle drag suspension setup have died out, we have Graybeard's (rear sway bar) "is not important in drag racing".

All the following pertains to a car that has had its instant center setup for drag racing (no-hop bars, lower relocation brackets, etc).

I do understand that the car tries to "resist" movement with an opposite reaction. Let me go over this slowly: upon launch the driveshaft is spinning clockwise (as you face the car), the drivers side rear axle initially resists the movement by going down. Since it is limited by the ground and suspension in its opposite resisting movement it starts to lift the driver's side of the car up. Since you are moving forward it tries to lift the forward part of the car first. This weight being lifted off the left front of the car, as an opposite reaction to the clockwise spinning driveshaft "climbing" the ring gear has to go somewhere. Since you are under acceleration, most of the weight that is lifted from the left front is transfered to the right side and rearward.

Only a rear sway bar, or the more technically sophisticated anti roll device (all the drag chassis companies have one of these ard's, requires quite a bit more work than a sway bar to install) can transfer weight from one side to the other.

Air bags have their place in drag racing, but they can only serve to limit travel rather than transfer any weight side to side.

The goal of a level launch on a "stock style" Chevelle should always employ a rear sway bar or ARD first, then employ a limiting device such as an air bag second. If the biggest rear sway bar, or ard, does not level out your launch, then limit movement ala air bag in the right rear.

What Graybeard is confusing is the difference between a car with a stock biased instant center vs a drag biased instant center. An airbag will work with either bias, the sway bar is most effective when instant center is setup for drag racing.

Don't take my word for any of this, there are several good books written on the subject, such as the one I referenced.

Thomas

Good Stuff

Anti-roll bars are nothing more than a torsion spring. It increases your roll rate ( spring rate resisting roll). Instant centers help you determine the wheel rate. ( spring rate the tire actually sees). You can also change the wheel rate by changing the springs.

The biggest reason for the anti-roll bar is to equalize the loads on both rear tires AND to maintain the instant center from side to side. This is why it is almost impossible to tune a a-body suspension without some sort of roll resistance. As the car rolls the instant center on both sides are changing opposite of each other. Therefore causing different and/ or unequal loadings on each tire.

The comments about the bag is correct. It only limits movement. The sway bar, anti roll device, and/ or torsion bar ( what ever you want to call it) is the better choice.


Todd

I use a rear sway bar but a buddy doesn't. He has a 1980 Olds "G" body (SBC 350 powered) that has a best 60' of 1.45 and usually gets 1.49-1.52. His car has 4.88 gears, SSM uppers and lowers, a right side air bag that he leaves it empty, Moroso front springs, CE 3ways front and rear, and Hoosier 28x9-15 tires. The car pretty much twist like a pretzel. I've suggested a rear bar but he isn't interested. He's happy with his 60's. It's possible to get good 60's without a bar but probably easier with one.

Pat, I know you have noticed this, but that Olds is seriously pre-loaded on the right side. When doing anything except for launching, that Cutlass is appreciably higher on the right rear than on the left rear. No one would want to drive anything like that on the street. Upon launch the car twists, but due to the pre-load it ends up leaving more level than not. At least that is the way it looked to me. Perhaps he could be even quicker(!) with a rear sway bar, but I'll bet it would take time and a learning curve for him to tune the suspension to newfound advantage. With 1.45 60's it is easy to see why he is loath to make any changes.

Thomas

It's not by design that one side is higher than the other. He want's to level it out.

After nearly 45 years in motorsports, one AHRA National record and two NHRA records, Two APBA (American Power Boating Association) World records, and contributing to a NASCAR NW Tour Championship, I don't usually respond to people who give erronious information or don't have the facts straight. It's simply no skin off my nose if someone takes what is said and responds to it.
Because there are nice people asking for straight information, I'm making an exception.

" A sway bar transfers some of the overloaded right side weight to the left rear - helping to even the weight distribution."

The ARD helps load the right tire and unloads the left. If the author of the above quote read the book, he shouldn't have been 180 degrees out.

Morroso sells rear springs for the A-body that "feature stronger right spring for balanced weight transfer and more consistant 60 ft times."
Higher right side spring rate. Kinda like changing spring rates with a right side airbag.

Competition Engineering builds an ARD that is adjustable, that "makes it possible to PRELOAD the chassis, eliminating body roll during hard launches, the car drives straighter off the starting line, helps 60 ft times. If you "preload" the chassis, you changed the static weight on the rear tires. The car will probably sit uneven with the right rear up. The same as if you'd changed to the Morroso springs with different spring rates right to left, or with airbags which also change spring rates. If you do it with an adjustable ARD, then the ARD wouldn't be neutral and would react differently around left and right corners. "No one would want to drive anything like that on the street!", to quote a responce about a car that sits uneven--and doesn't use an ARD

If you really want an answer to the question without bias, go to an NHRA points race and look under the cars in the heads-up catagories. Thats the place where thousandths, of a second count, hundredths are a goal, and finding a tenth is cause for a party. You'll find your answer.

I think I'll go out and bring the Firehydrant in.

My son has tried about everything to find more bite. The factory roll bar slowed the car's 60 ft. and removing it got it back but the drivers side lifted about a foot higher than passengers side. Moroso high energy springs in the front helped, removing the front sway helped, adding a Dick Miller anti-roll bar helped and got the car to leaving straighter. The best 60 ft. has been a 1.38 but most are around 1.43-1.45. I think rear double adjustable KONI's are the next thing to try as well as a back-braced Morrison 9" with abjustable tabs to change the car's instant center. Some debate exists over the exact physics of what the suspension does when the car leaves the line and i've read Dick Millers pamplet on the subject.

This is GREAT STUFF !!!

Not to de-tract from the post, But...

I have a stock rear set up in my 69 (Open upper and lower control arms with rubber bushings), but just added a 12 bolt posi. (Car originally had an open 10)

This is my first car with a posi and I noticed during a burn out the car "hooks" to the left.Seems like that is what this post is about more or less.

Will the sway bar help straighten that "left hook" out?
Also getting mild wheel hop and I have been trying to gatherinfo so I don't spend the money where it's not needed.
Was thinking of going with boxed lowers w/poly bushings first and see if that helps the hop. As for the straighting out the launch I will wait to read some replies to see if you all think the sway bar would help.
Not draging racing this car,just trying to straighten out the launch and wheel hop.

Thanks

ttt

Hey ya redneck, sorry, I had too,

After reading all the info posted, most of it will work for you, but, what is your final outcome of the car you would like to see? This is the where the buck stops if you are not serious about your car being a race/street car. :(

Being from the Detroit area and seeing at least 50,000 cars launch from behind, in front and on both sides of GM heavyweights, the Anti-roll drag race sway bar is the only way to go if drag racing, sorry guys, but the top teams all have the anti roll bar in them, even the blown alcohol altereds and pro mod cars, go check them out.
But, I am good proof of the power of sway.

I have 72 Elky, 3650# with me in it, a 454 with oval port heads, 830 Holley, 5000 stall conv., glide with stock gearset, 4:56 12 bolt out back, and an ANTI-ROLL DRAG RACE SWAY BAR setup and I'll swear by it.

Picture this, My car had a small block and 350 trans, I put an all steel bbc, glide and stripped the rest, added a 8 point cage and solid motor mounts, with a poly trans mount, (don't use a solid trans mount, it will crack the case eventually), no-hop bars on the uppers with adjustables as well, on the lowers, I made my own chrome moly dbl adj. control arms with heim joints. Anti-roll drag race sway bar kit and I still have the air bags in the coil springs with little to know air in them, I need them to keep the rubber off the fenders.
I'm crankin out 610 hp at the wheels and both front skinneys see daylight nearly every pass, and the rear of the truck is level as to the video from my Superchips Open comp race in New Jersey a few weeks ago. So, do what you want but you have to pay for speed & et, there is no way around it, if you want to play, you gotta pay, trust me.
My 60 ft's are from 1.668-1.655, with a bad fuel pump and still ran a 11:59 @ 117 mph. I have a new pump on now and a bigger carb to go on next after I test the fuel system first. My cam is in the low .600 in. lift range and launch rpm from 2000-4000 rpm. Don't forget to set your pinion angle @ -2 degrees for A-body cars, they really like this angle with this setup I have, and many other setups like mine as well. Tire psi from 18-12 psi unless slicks are used. Wish I could show you all video of my truck, yep, an elky showin daylight under the front skinneys, I had a slew of guys in Jersey asking & looking @ my truck all weekend, trust me, spend the cash, have a good shop or friend put it on. Also, I have the QA1 12 way shocks in the rear and the comp Eng. 3 ways up front with Moroso trick springs up front with 3/4 of a loop cut out.
I'm tellin ya, this is the hit for A-body cars with some power, in the suspension that is. Hope this helps out, I can't wait to yank the skinneys again the 4th of July weekend. graemlins/waving.gif

John G.
"The Elkymann"
O/C 9900

610rwhp and only mid 11's? I must be missing something.... my wifes car is making 425rwhp, weighs 3565 and runs 11.20's at 7000 feet. My chevelle runs 11.7's with the same rwhp but it weighs 3875 and is in full street trim.

Lee

Try a Holley blue and you'll see high 11's! I just ran out of cash before my first event and threw on the blue and found out 2 weekends ago with the fuel can test that I was way under fueled hence the slow times. 140 gph now and I'll see what happens next weekend.

Why put an airbag with no air in it? AirLift says to run one with no lower than 5 psi or you risk damage to the bag. Those guys have been around forever and probably know 10 or 2 things about this. Why spent the money and the hassle of stuffing one in there and not pump it up? Enligthen me please!!!

Greg, I have air bags in both side but really only needed the one in the right side. The left one is in there and cannot be taken out with cutting it out, so it's just along for the ride. Since I don't drive on the street, I really don't care if it gets damaged. Same situation with my buddy's Olds. He doesn't need it or use it but cutting it out is the only way to remove it.