Sway Bars

[Tom73]

I have seen alot of discussion on what is the proper size sway bar and if a rear bar should be used. I just saw this posted over on the NCRS site by Duke Williams and thought it would be good to share here. The link is:http://www.ncrs.org/forum/tech.cgi/noframes/read/100421 It was originaly about a C2 but most of the info also applies to the C3.

Base SB C2s have a 3/4" front bar. Base C2 BBs have a 7/8" front and 9/16" rear bar. Z06/F40 SBs have a 15/16" front bar, and F-41 BBs substitute the 15/16" front bar and have the same 9/16" rear bar as base BBs. Of course Z06/F-40/F-41 also have stiffer springs - about double the wheel rate - as base suspensions, so these stiff springs add considerably to roll stiffness.

Increasing/decreasing front bar size increases/decreases understeer.

Increasing/decreasing rear bar size increases/decreases oversteer.

If a car is set up close to neutral as C2s are then decreasing understeer is the same as increasing oversteer.

Even if you install the 15/16" front bar the car will probably oversteer. You either need to further increase the front bar size or reduce the rear bar size.

Note that the FE7 Gymkana suspension available beginning in '75 included a 1 1/8" front bar and 7/16" rear bar. Of course, only a SB engine was available in '75.

If you want to keep the 9/16" rear bar you are going to need about a 1 1/4" front bar.

Also keep in mind that C2s have a higher rear roll center than C3, so C2s have more inherent rear roll stiffness due to the springs alone. My recommendation is to install the 15/16" front bar, remove the rear bar and run about -1 degrees camber on both ends. If this causes too much understeed you can either increase front negative camber or install the 7/8" front bar.

Before one embarks on re-engineering their suspension, I would recommend the purchase and study of Fred Puhn's "How to Make Your Car Handle". It is old, but the basics haven't changed. I think it's still available from Classic Motorbooks.

tom...

 

[Bob Chadwick]

Increasing/decreasing front bar size increases/decreases understeer.

Increasing/decreasing rear bar size increases/decreases oversteer.

Tom,

I think we are saying the same thing here but correct me if I'm wrong. I need to talk it through. I was was always taught in terms of increasing sway bar size, never reducing one and I think that is what is confusing me. Hey, who ever brags about having a smaller sway bar, or smaller anything for that matter.

The way it was explained to me is if you oversteer, you need more front sway bar to neutralize the effect. As you explain it this is increasing the understeer and balancing the car. This would be the same as decreasing the rear bar which would decrease oversteer. (Assuming you have a sway bar in the car to begin with)

If you have too much understeer, you increase the size of the rear bar. In your terms this is increasing oversteer balancing the car again. This would be the same as decreasing the front bar which would decrease the understeer.

Do I have it?

Bob