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Re: Setup for sweeper and hairpin turns
Posted: December 5th, 2010, 1:11 pm
by Mystique Racing
John,
That is the article that I was referring to.
Re: Setup for sweeper and hairpin turns
Posted: December 5th, 2010, 4:28 pm
by brian
Great article. I had a deja vu moment when the author was talking about the old days. I crewed on sprint cars in the early 70's. I noticed he mentioned that they run toe out to provide stability on dirt, certainly not something we want to do on a road racing car, but running toe out will provide some of the lead I mentioned before.
John, regarding this thread, are you talking about tire scrub or the other factors regarding tight vs sweepers?
Re: Setup for sweeper and hairpin turns
Posted: December 5th, 2010, 9:59 pm
by jpetillo
brian wrote:Great article. I had a deja vu moment when the author was talking about the old days. I crewed on sprint cars in the early 70's. I noticed he mentioned that they run toe out to provide stability on dirt, certainly not something we want to do on a road racing car, but running toe out will provide some of the lead I mentioned before.
John, regarding this thread, are you talking about tire scrub or the other factors regarding tight vs sweepers?
Yes, the article in Circle Track was good. What I took away from it is that you should know what Ackermann you're running and correct it if it's off, and not necessarily that it was a bad thing.
About tire scrub or the other factors regarding tight vs sweepers, they seem too related to talk about separately. I suppose if we go back to discussing factors regarding tight vs. sweepers, then it will pull back in everything else. There was a post in a different thread that I need to go back and read.
Re: Setup for sweeper and hairpin turns
Posted: December 6th, 2010, 3:05 pm
by brian
My understanding of the two different turns comes from Joe Stimola's mantra regarding shocks and turns that was, " high speed valving for slow speed turns and low speed valving for high speed turns." While confusing in language, it makes sense when one realizes that the car is in a steady state longer for sweeper and the chassis must be held still to avoid movement once the car has taken a set. I know in our vees, with "constant camber change" in the rear, any vertical movement changes the tire patch. When the car is oscillating up and down on high speed turns, usually due to insufficient dampening, it can be a real handful.
Re: Setup for sweeper and hairpin turns
Posted: December 6th, 2010, 4:24 pm
by hardingfv32-1
"high speed valving for slow speed turns and low speed valving for high speed turns" Now that is wonderfully ambiguous statement from an expert. If we are going to learn anything from this tread we are going to have to agree on the meaning or significance of a shock's low speed and high speed range of operation.
1) I start with a simple statement that low speed valving is concerned only with chassis roll: acceleration, braking and cornering forms of weight transfer. High speed valving with tire contact patch compliance.
2) Since low speed shock activity only takes place for about half the turn, I propose that we first discuss the dynamics of the center 50% of the turn when the shock is traditionally considered not to play a role.
Brian