At Herbs request we are going to discuss stabilizer bars……

OK, stabilizer bars, otherwise known as sta-bars or anti-sway bars. Often times incorrectly referred to as sway-bars as well. There are 2 schools of thought on sta-bars; 1) soft springs and big sta-bar 2) stiff springs and little sta-bar. I do not agree with the first, IMO the sta-bar is to be used as a tuning aid and not a crutch for poor spring/shock selection. Some argue that you can use soft springs for a comfortable ride and compensate for the weak roll stiffness with a big sta-bar. I run 750lbs/in springs and IMO they are too soft, absolutely no harshness at all. Front spring rates do not have nearly the same impact on ride characteristics that rear springs do, I always recommend to increase the front rate and tune with the sta-bar.

Specific to “A” body sta-bar information. Contrary to popular belief the “A” body really does need much rear bar. Proof of this can be seen in the sizing of the bar selection people make. Before you start with the “but I have a 1” bar and it makes a huge improvement” perhaps we should revisit some sta-bar 101. The effectiveness of the sta-bar is dependent on the swing arm as much as the bar diameter itself. For instance, a sta-bar with a typical 6-12” swing arm and a 1 1/8” diameter will provide about 5X the roll stiffness of a 1” bar on the rear, the typical sizing of rear stabilizer bars. How can this be? Not only is the roll stiffness of the bar determined by the diameter to the power of 4 but the swing arm length is also a determining factor by the power of ˝. The rear sta-bar is attached to the rear control arms which have a length of 22”, twice the length of the front bar swing arm. Since the sta-bar is attached to the lower arms, they become the swing arm for the sta-bar. This means that rear bar is only half as effective as an equally sized bar in the front.


On my daily driver I currently run no sta-bars at all, front nor rear. With the exception of the guy who spends every waking hour waiting for the next track day, most would not have any idea there are no bars. I have set the suspension up correctly, well as correct as it can be with off the shelf the parts, it corners flat at over 50MPH with very little to no roll. I will eventually tune with bars because it can be better. The point is that running sewer pipe sized bars is unnecessary and in most cases hiding a more serious deficiency in the suspension design.

Round 1 …..Here we go.

Ok, So you're saying the 7/8 stock front bar on a '67 2 dr Coupe with a 400 small block is big enough and the springs should be ???

Obviously I'm trying to pin down the configuration I should be shooting for on my front end rebuild. (BTW - no A/C)

tx

I used Global West tubular arms and components and their recommendation was that I use a 1 1/8 inch front bar and no rear bar. Using their components generally requires this combination. If you are doing a roadrace setup, then the tires in the rear are usually much larger and then they will make a recommendation as to what size bar is needed in the rear. They did say that a totally stock A-body suspension requires a larger than stock bar in the front and the rear. "The best tip to remember about choosing sway bars is a sway bar should compliment the suspension, not be the suspension. Too big of a sway bar can create other handling problems."
I couldn't be more please with how my setup performs daily and when accelerating through corners and other fun maneuvers!

The only components GW sells that have any impact on sta-bar selection are the springs. What tubular arms you run or which spindles you have places very little if any impact on sta-bar choice.

A 1 1/8" bar is wayy too big for a car with the proper spring selection, I would piuck up a tire with a 1 1/8" bar.

Running bigger rear tires would not create the need for a rear sta-bar.

Yeah Herb, with the proper springs 7/8" should be plenty of front bar.

Lots of great info here! I'd like to share an experience with a manufacturer of sta-bars and suspension components I purchased a while ago. The most memorable was from Herb Adams. I don't quite remember the exact sizes of the bars but they were huge! I think the front was 1 9/16" and the rear was 1 1/4" (could have been larger but it was years ago). The front bar mounted to the lower A Frame with Hiem links. Anyway the bars were so stiff (and hardened) that as Denny mentioned, they would raise a wheel off the ground on uneven road surfaces! Not exactly what I would consider handeling. True the car ran like a slot car on flat road surfaces and cornered like one also....but get into some rough or unever road and hold on tight!

The diameter of a sta-bar is not the only consideration for selection. The hardness also comes into play as well - IF your bar went through any heat treat (case hardening) process.

Another consideration is that some hard core corner carvers or racer's use the lighter weight hollow sta-bars for weight savings. They still have some great strength to them but use adjustable arm length to change the mechanical advantage, thus increasing or decreasing the effective resistance to roll.

Currently I have a set of bars from Global West onthe Chevelle which I purchased at the same time I placed my order for a BEAR tracker system. Also went for a Hydroboost system (a recomendation from Troy). I opted for the lower rear control arms also from GW with the spherical bearings on the frame side and Del-a-lum bushings. For now I think I'll stick with the rear stock upper F41 rubber. I did comment in another post about the group UMI purchase for the rear upper adjustables which Denny ran.

Unfortunately the car is not on the ground yet....the only thing there in this area is about 20" of snow. Even though the car is in the garage it is way to cold to do anything on it. Can't wait to test and tune!

Keep the thread going, this topic is one of the least understood and miss-informed for most individuals trying to get their car up to todays handling.

Lunch hour is over, got to get back to work....

Great Stuff!
Sam

Sam brings up a good point I neglected initially, sta-bar construction. There are many forms avilable now; hollow, splined, solid and just as many methods of attaching them; rubber links, poly links, heim ends etc...Make sure if you are tuning sta-bar that you don't make too many changes at once. For instance if you decide you need more bar you wouldn't decide to go with a size up but in a hollow form and change the mounts from poly to rod ends. This amount of change would make in nearly impossible to determine what exactly was responsible for the change in chassis behavior.

Dennis,maybe you can give me some input on my particular combo. Right now,my car has GW a-arms and QA1 coilovers up front with their BB springs and a stock 7/8" bar.(I assume that's what size it is,,it's pretty small. My car presently has a SBC up front. I'm pretty sure the car is oversprung right now but my question is this;what difference would a change to a 1" bar make? Good or bad? Would I need to put the proper SB springs on my coilovers before going any further?

As Dennis said, stabilizer bar selection has a lot to do with your spring rate. Many of the kits were designed to run with the stock rate because that is what most people had back then. Stock spring rates vary from 275 lb/in to 450 lb/in. About half of what Dennis is running. If you are running stock, or close to stock rates, then a 1-1/4 front 1" rear bar works well. Much better than a 7/8 front and no rear like many A-bodys were equipped with at the factory. Finding the right combination can take some time and experimentation. Most people don't have the finances to test several bars so the best bet is to go with what the mfr reccomends. If you keep your car close to stock, my experience has been that the 1-1/4 trans am or 1-5/16 Hellwig front bar with a 1" rear works well.

The biggest probhlem with going too big on the sta-bar sizing is eventually you will induce understeer. Sizing is more of a personal prefernce tuning thing. One driver may feel comfortable pushing the limits of understeer, on the street I guess it is better than oversteer but I am pretty good at recovering from "too loose". I don't anybody who can recover from too tight, sucks when both your steering and primary braking tires lose traction and slide straight into whatever you were trying to avoid.

Clint, I don't have much experience with the coil over rates but the guys over at cc.com are claiming documented lap time differences with as little as 25lbs of change. They typically run in the 500/250 range. Oversprung is pretty rough to do unless you are buying frm musclemotors or something. locomoptive springs might be a little tight but anything QA1 sells as a package is probably close enough to "tweak".

Get it out for an open track event with an instructor and have listen to his advice. They usually stick to driver conditions but if he says your always going to fast then maybe you could use more rear spring or a little less front bar....or maybe you just can't drive. :D Cars can easily be overdriven and if your confident enough to drive it beyond it's limits. Critisizm from an advanced level driver often shows flaws in the vehicle setup.

OK, when I put my '67 together, I put stock replacement rears springs in with HP Motorsport control arms and added a stock replacement rear sway bar (looks like 3/4", it's little). I also put stock replacement small block springs in the front which jacked it way up and installed a 2nd gen F-body 1 1/4" sway bar (which was conveniently cheap at the junk yard). All areas got new poly bushings. I don't think the car handles any better. I got an alignment that added some camber and whatnot according to what I was instructed to use somewhere else on here. What do you guys think? The wheels have appropriate back spacing. I wasn't expecting the to be an instant corner carver, I just expected a little more.

TJ

With a 1-1/4 front bar a 1" rear bar works well. I have a Hellwig 1" rear which fit really well. My 68 has stock components w/ new moog bushings all the way around. Only change is I added new moog HD coils, 5380 front / 5409 rear and Hellwig 1-5/16 front/ 1" rear bars. I had a 7/8" rear bar but the 1" bar was a noticable change. Like I said before, with mostly stock components, the Hellwig stuff works good.

from my experience on my old truck I added a 1.25 and 1" rear bar on my s-10 and it was a huge improvment front the 1" front bar. BUT what helped it handle so much better was the sticky low profile tires.(TTII of coares smile.gif )

I haven't driven my chevelle yet, but I bought a 1 1/8 and a 1" for it with a small block? will I have over steer? since they are similar in size? I want to buy differentfront springs but the replacement ones aren't tapered... and could wear a hole in the control arm....

Brian