Consensus on big bar/soft spring?

[BMR Sales]

Originally Posted by Rod P

that choice is mostly decide from training and driving style...I have driven and raced both in other cars for testing

I agree. I like a RaceCar stiff, but that is not for everybody!

[bergers59]

So one isn't faster than the other? Why are more people switching to a BBSS setup recently?

[SSLance]

There is a big long explanation as to why that Ron Sutton I'm sure could explain better than I, but in a simple form...having a high travel setup lets one configure the geometry to work best in all areas of a turn and the straights as well.

With a super stiff spring setup, the static geometry is what it is pretty much all of the time. You dial in camber to help the outside front tire contact patch, but completely give up the contact patch on the inside front tire.

With a front suspension that travels, you can maximise the contact patch on both front tires in a turn. Aren't two tires gripping better than one?

Watch this video to see how well a soft spring\big bar setup helps make a G-Body turn.

[bergers59]

point definitely taken, but could you not compensate for the stiffer spring rate car by making the dynamic camber change larger for a smaller distance of travel?
Another thing I just thought of, since I intend to run c prepared and I intend to get the car as low as I can, would running a softer spring rate and higher travel limit my static ride height setting?

[Ron Sutton]

Originally Posted by bergers59

point definitely taken, but could you not compensate for the stiffer spring rate car by making the dynamic camber change larger for a smaller distance of travel?
Another thing I just thought of, since I intend to run c prepared and I intend to get the car as low as I can, would running a softer spring rate and higher travel limit my static ride height setting?

I'd like to suggest you look at it a different way. We don't care where the CG is when the car is sitting in the pits. We care where the CG is out there in turn 6 ... just before turn in.

[bergers59]

ohhhhhhhhhhh

[Ron Sutton]

Originally Posted by bergers59

ohhhhhhhhhhh

It is/was pretty common to set-up a car low, with the crank centerline (at the balancer) at 12" above ground "to get the mass low". Then with a stiff front spring set-up, the car may travel (compress) 1" ... so this mass is 1" lower with the crank centerline at 11". Modern, high travel set-ups, may place the crank centerline at 13". Then travel the front end 3" to 4.5" under braking, before turn in. That puts the crank centerline at 8.5" to 10" depending upon the travel strategy.

If we put that mass at 8.5" ... the cornering speed capability compared to it being at 11" ... is a significant difference. All things being equal ... contact patch, car weight, track width, optimized spring & bar rates ... the car with the lower CG can carry significantly more speed. The other bonus is, the front end is loaded more from static load transfer of the front end being 3"-4.5" lower. This is in addition to the dynamic load transfer from braking g-forces.

Lastly, combined with the strategy of running the car flatter (less roll angle) increases the loading on the inside front tire ... increasing it's grip ... adding to the total grip the front end has. We can't go faster through a corner than the front end has grip. That needs to be our focus. Running a low roll strategy ... say 1° ... keeps the inside tires loaded more than a high roll strategy around 3°.

Make sense?