Hi yall! I'm gonna be purchasing some new sway bars soon and I need advice. First off, I've heard that having a nice thick sway bar in the front and leaving the sway bar off in the rear is the best for handling. I would think that this would minimize oversteer, but to what degree? I don't know. Is this true should I only get a front sway bar? Next I know that there are multiple size selections for sway bars, the two biggest are 1 1/4 and 1 1/8. Unless someone tells me otherwise, I'm going for the 1 1/4, unless someone out there knows of a bigger one??? Now brand names... I know that PST or G-max makes a 1 1/4 that is about $170; ADDCO makes a 1 1/4 that is about $150 and finally there are the sway bars sold by Mid America and Ecklers, I don't think that they offer the 1 1/4 inch bars. So what do I do? Front and rear bars or just front? And who do I buy them from? FYI right now my car has the 550 springs up front and the 7 leaf HD spring in the back with Bilsteins all around. Any advice is appreciated. Thanks -Adam

I could probably answer your first question in the next few weeks. I've got a '72 Sm. Block, no ac, in other words, fairly light in the front. A previous owner installed 550lbs coil springs/ 1 1/4" front swaybars and 3/4" rear bars. I've got a horrible oversteer condition, to the point I'm about to remove all P. steering components to possibly alleviate it. A post several days ago mentioned having no rear bar as the ideal set-up. I'll be putting this theory to the test and posting the results.

JR


By the way, beautiful stance.

|UPDATED|7/19/2004 6:59:34 PM (AZT)|/UPDATED|

I have the Performance Suspension Components G-machine suspension kit on my 72 small block. I did the front end first and the handling improved greatly. I did find however, the front end stayed glued to the road on hard cornering and you could feel the rear want to come up. After installing the rear sway bar and shocks, that went away and the car stayed much flatter on cornering. I say go with front and rear sway bars. The G machine kit is quite reasonably priced as well.
Reid 72 T-top

my last 69 was a SB and didnt have a rear sway it felt very iffy in curves..

after putting in a larger sway bar and stiffer springs it improved but still wasnt right..

I had planned on adding a rear bar but it was stolen before i could do so..

my BB vette handles much better and I have to attribute it to the rear end staying put in curves..

I know some peole say its better without a rear bar, but it hasnt been my experience

A lot depends on the tires and shock rates, as well as the sway bars and suspension/alignment adjustments.

Typically, a stiffer front bar will cause understeer, and a stiffer rear bar will cause oversteer. This sound backwards. Depending on the car set up, it sometimes is backwards.

The sway bar connects to the suspension on each side of the car, and to the frame.

They have NO affect on bumps, if the bump is equal on both sides of the car. When one tire lifts or drops, the bar twists and tries to raise or lower the wheel on the other side to keep them at the same height. This keeps the car flatter to the road, instead of leaning.
By keeping the car flatter, the tires stay flat as well, allowing the full width of the tread to stay on the road. If the car leans, the edge of the tread lifts, reducing contact, and traction.
But if the bar is too stiff, the suspension is not as active and does not absorb irregular surfaces as well. It can also make the tire interact with the surface of the road differently, changing the slip angle. You will find that a sway bar makes a big difference in how the car handles on pavement cracks and crosswinds.
That's the basics.

But by adjusting steering and alignment angles you can create some of this without sway bars. Then the bars still make a difference, but have a different effect. Typically, if adjustment is use, the tires wear faster. Again this depends on suspension design. The Acura NSX is a great example. To make it handle it's best, it eats a set of rear tires every 8 to 10 thousand miles. Get rid of the wear, and the handling drops way off.

Suspension geometry plays an equally big part. This is something most folks can not, and should not, change. It involves relocating suspension mounting points and making major changes to components.

Geometry can be and is changed by changing ride height. Raise or lower the car and the angles of the suspension move, and change. This can have a drastic affect on the car. A change in ride height of only one inch will change the geometry enough to require an alignment. Some times an alignment will bring the car back to specs, but it does not completely fix the geometry.

Ride height also changes the center of gravity. This is not only due to the acutal weight being raised or lowered, but the change in suspension geometry as well. It changes the roll center of the car, and points where the car piviots on a line through the car front to rear, and side to side. Where these meet is the center of gravity. So where the weight is located, and how it piviots both have a large affect.

Slip angle is the difference between where the tire is pointing and the angle it is traveling. All tires slip. They must slip to develop traction. A free rolling tire has no friction to the surface it's on, and therfore little or no traction. When the tire is flexed, it creates friction and traction.
If the tire is turning more than the angle it's pointed in, thats oversteer. If it's turning less than pointed angle, thats understeer. This is not limited to the front tires. The rear also creates the same forces. The combination of front and rear slip angles create the overall over or under steer of the car as a whole.

Acelleration and decelleration also create slip angles. When you slip you create traction. When you exceed traction limits, the tire spins or slides. This is 100% slip angle.
And when you acellerate or brake you create slip, then add slip from cornering, and it's easy to exceed total traction. But even not exceeded, it changes the operation of the tire.
Any one who has made a car change it's line in a corner by pushing or lifting the throttle has felt this. I'm guessing all of us have done that. A low speed example is driving on ice.

The point is that there are many things that affect the slip angle, including alignment, suspension geometry, shock action, sway bars, spring stiffness, and the tire itself. Thats why some of our cars respond differently than others to the "same" changes.

I never make these easy, do I?

Call up Vette Brake Products and ask for a catolog, it shows their suspension products and explains how they work, when you change one part it effects the rest,too stiff in front car gets tight, too stiff in rear car get loose, its a balancing act if you want your car to handle it's best to put a "package" together,lower the roll centers, ride height,check bump steer with a good set of performance tires, your suspension pieces have to be in good condition with a proper alignment for the way you are going to drive the car.

|UPDATED|7/21/2004 9:56:21 PM (AZT)|/UPDATED|

I'll make mine simple. I've always been told that its best to have front and rear sway bars.

Mark

Hey Ken, how in the hell did you get all that typing done before I finished my piece, last time I looked Ben had the last post.

I saw them putting an 11/4 inch sway bar on a pickup on TRUCKS yesterday,the thing looked huge,thats a lot of steel to hang under a Vette

My LT-1 AC coupe came with factory HD F-41 suspension, 550lb coils, 1-1/4" front bar,7/16" rear bar,when I rebuilt the susp. I went with poly bushings through out,360lb TRW composite rear spring, 8" spring bolts, rear cross member reinforcing kit, VB products Smart Strut Kit,KYB's handles great, still have to rebuild the steering box