For those of you who are into huge sway bars on C3s, take a look at the Addco web site and focus on the table under "Some Important Notes on Sway Bar Diameters". It illustrates the dramatic increase in stiffness due to a small increase in bar diameter. This shows why bigger is not always better in suspensions.
In my case, reducing the rear bar from 3/4 to 5/8 took my 71 from squirrelly oversteer to neutral with no other changes.
IMHO, this table should be in the Archives under suspensions.

 

flynhi,
Good point with regards to that sight. The site shows that as I get ready to adjust my setup I should do it 1/8" at a time.

I'm experiencing slight understeer with my current set up (1 1/8" front sway with 3/4" rear) when I am pushing my front tires during hard cornering at the track. Its actually quite neutral until I really push it and provide moderate power. I would like to dial in just a bit more oversteer because I am used to driving by focusing on the rear axle sweep and not thinking about plowing the front end. According to your statement, I should be increasing the size of my rear sway bar?

I am usually pretty good at the physics but I get confused easily too so set me straight, but it seems that I would want to decrease the effect of the rear sway bar- thus increasing the amount of energy shifted at the back axle during a corner- resulting in an increase of oversteer. Where is my reasoning flawed?

 

Hi David,
Well, I'm not sure I'm the best one to answer your question, but I'll pass on my experience.
1. Get a copy of Guldstrand's catalog. the first few pages has an excellent layman's description of vehicle suspension dynamics.
2. As I increased the size of my rear stabar, I experienced more oversteer. I think what happens is that the stiff bar reduces the effect of the independent rear suspension and you loose traction and begin to spin.
3. Increasing tire pressure in the rear will have much the same effect as you reduce contact patch.
4. Decreasing contact patch with narrower tires should have the same effect.
5. You may be able to have the same effect by reducing the size of the front bar.

Redvetteracer is probably a better source since he is an experienced racer.

Looking forward to seeing you Saturday at the Dell Diamond.

Will

 

ttt

 

dshrack, I think your reasoning is sound based on my experience (which is limited). I got a good deal on a rear 3/4 swaybar for my car and put it on with the stock front big block bar. It plowed through the corners terrible, very bad understeer. I put on the 1 1/4 front bar ( I went heavy considering all the weight on my nose with the BB) and all was happy again with a little more of an oversteer situation but not bad at all, later switched the rubber center links on the rear bar to poly and it's pretty neutral with still at tad of wanting to oversteer but that's kinda the way I prefer it besides being completely neutral. I bet if you switched to a 5/8 rear bar you'd be a lot happier.

:cheers:
Pat Kunz

 

Let me see if I can tackle this one with a good explanation.

You hit the limit of cornering when one of the outside tires (front, rear, or both) reach the point where they're "saturated". That is, for the amount of weight on them, they can't generate any more cornering force.

The question is, which tire saturates first? Ignoring steering effects, geometry effects (camber) and whatnot and assuming that everything is pretty much equal front to rear, the tire that gets the most load transferred to it will saturate first.

Imagine you have a big sway bar on front and none on the rear. Go a step farther and think of the rear like an axle from a tractor that just pivots freely about a single point or pin. It shoudl be easy to see that ALL of the load transferred is going to be on the front. Logically, the front should saturate first.

Now as you add a bar to the rear, you're increasing the amount of load transfer that goes to the rear. Eventually you'll hit a point where things are well balanced. Go beyond that point and you start transferring a disproportionate amount of load at the rear, it saturates first and WHEEEE!!! the tail comes around.

Now there are many other factors that play a part. The roll camber in the front and rear, the roll center heights, the roll steer in the suspension, the compliances of bushings and the effects they have on steerign the wheels, etc.... but the basics are pretty much as I described.

Hope that helps.

Dave

 

If anyone (who is serious and has the cash) is interested I have a brand new NOS/GM Corvette 7/16 rear bar $100 +UPS owns it please e-mail me direct redvetracr@msn.com

 

Anyone have a link to this Addco site? I'd like to include it in Corvettefaq.

I had the 3/4" sway bar and the car was WAY squirrely. I then went down a size and it was better, but still a bit squirrely. I now have no rear sway bar and am happy. I wonder how much stickier 17" Z-rated tires plays into the balance of things too.
-terry

 

try http://www.addco.com
W.

 

Yeah that site looks like just traffic signals and stuff. Do you have a direct link to the sway bars?
thanks!
-terry

 

Oops.
try http://www.addco.net/install.shtml#importantnotes