New springs cause oversteer for a few. Why?

#21

Well… I actually don’t know what Neil runs. You still have Ed and I to guess.

#22

You are the white car? And good job beating up on Steve :grin:

I can’t tell, is that Star Mazda???

#23

Yup white car!

T18.

Thanks, but it was his own fault.

#24

@Ranger send me an email offline after the weekend.

#25

I’d be interested in whether the cars having oversteer problems are early or late models. I must have gotten the setup wrong with the new springs and my car was undriveable due to oversteer even with the rear bar disconnected. I have an early model.

#26

Late model

#27

I was expecting all the cars to see a decrease in understeer (transition to oversteer), based on the new springs adding a lot more roll stiffness in the rear than the front. The fact that it’s only affecting SOME, and in apparently dramatic fashion, is interesting, and could point to something else.
Has anyone MEASURED the spring rates of the cars that now have oversteer vs ones that didn’t find a change in handling balance?
For anyone discussing coil-bind, I would expect to find snap-oversteer when suddenly bottoming out.
The consideration of the front having previously been utilizing the bump-stops is interesting, I would expect those cars to have had severe understeer, though, especially when hitting mid-corner bumps. In any case, if the car is now NOT using those bump stops, then the increase in the rear spring rate vs the front may be even more dramatic than the spring rate changes alone had indicated.
I would suggest looking at ride heights as a potential common theme. If the rear roll center is too high, or had too much rake, it could create oversteer. If too low, it could be getting into the bump stops, possibly.

#28

Anthony or others,
What are the best measurement points to determine rake?

#29

New springs added a lot more roll stiffness in front then rear. 40-47% more stiff in the front, depending on who’s #'s one uses for H&R Race. 14% more stiff in the rear.

#30

When I switched to these springs I had oversteer, I reset my camber, ride height and sway bar settings to essentially “zero them out” and soften my rear bar settings. It’s pointless chasing this until people with issues have done this.

#31

I still think the mindset of lower is better is wrong. I think you need to raise the car in order to let our suspension do what it was designed to do. But I really have no other basis for that other than looking at how things work back there and applying some simple logic…which probably means I am wrong.

#32

That synchs with what the Aussies have been telling us. They said “don’t go low”.

#33

My understeer problem was solved by using a 16mm rear bar on its softest setting. I was running with no rear bar and got push. The OEM rear bar is to thin and the typical Suspension Techniques 19mm rear bar it to much for these cars.