[TCracingCA]

I was tired from a 1300+ mile road trip I just took this last weekend. So had to edit fix what I typed.

In this thread, we keep having guys come in here from the race track lapping world, or they street drive their performance cars.

I know this is a Porsche forum, but I have suspension setups that differ for all three disciples for a couple of our Corvettes.

Canyon racing, point and quirt, point to point speed run, is a far different specialty. This whole thread kind of wanders off path from the disciple of the venue discussed. Sure back in the day, the science was quickly changing, as tire size grew. We were the first C3 in the entire Country on 17 diameter 315s in the SCCA autocross world 80s. We were solid bushed, heims, HD most everything, since the early 70s. The kids were big sway bars, HD performance shocks (single adjusts mostly, the better off financially, had maybe some Webers, hot ignition, and sometimes a set of headers, of header. I dont remember true hardcore race car mods yet.

Sure a 2.1 mile balls to the walls run, fatigue is N/A. Naturally hope guys have biceps, combined with adrenaline. Also if you truly know the nuisances of the road, there would be a predictability to where your suspension will take you. I am a notorious late Apex guy, especially on an unknown road. I wait further to the outside to see further around the bend going in, and I want to be back on the fast pedal as quick as possible, seeing the apex for the best exit window. Now If it goes into another tight turn, then I will ride the gearbox and brake hard to set up.

So is the car wandering, under controllably so! If it is faster, I will allow a not so perfect looking maneuver.

I rented a car this weekend and put near1400 miles on it in 2 days. I dropped down 89A south of Prescott and that is now my favorite road. Wow! As I left the City, it said 42 miles to SR-71, to diagonally cut Arizona. I slow down for the small towns, to be polite. Damn speed limiters. But there was two stretches of twisties, the first was taxing, even with power steering, abs brakes, and manhandling the automatic manually. First section longer, a little looser. Had about three major off camber turns (my nemesis), that totally were sending me toward the mountain. I assume I was traveling thru mountains, ir was real dark. Elevation drop helped the rental car's momentum. The second section was tight and really road fun. I hate when the front wheel drive crabs sideways (clawing), and you have no rear wheel drive power, to throttle steer. Wandering in that stock, I think it was a 2020 Sentra was interesting. The tires didn't last long, the brakes got soft, but it seemed like mile after mile after mile of great road; Mentally fatiguing, not knowing the road, but enjoyed it, and I lived. Hi-beams were essential, and I was out running those alot. It was necessary to re-aim the car into the dark, on the memory of what the sign said, that warns of the approaching turn direction and speed recommendation. Sometimes the lights weren't in the direction to light the signs, so kind of messed up my rhythm, but it was a virgin run. Could have used a navigator. But this is a different venue. You need a more overall friendly suspension set up for handling whatever comes at you out of the dark.

I think my Dad's old Canyon racer is a little more forgiving than my race car, due to some toe and stretched castor, lesser spring rates, more suspension travel. Is that quicker, it can be under certain circumstances. It definitely is less fatiguing, so you feel like you are doing a better job. So now analyze the times, and the solid bushed, heavy spring car, shorter caster, zero toe I have compared that to the race car, and heavy planted footprint from coilovers and racing spring rates, it can get scary jumpy, snap out at the limit, but generally is faster on my known, memorized road, but I can take Dad's Corvette down an unknown road faster.

I think built in engineered Ackermann is most affected by Castor change, and turn in/ self centering is toe, but can be caster too, depending on tire contact patch in the dynamic. Opinions!

I don't think more castor, stretching the wheelbase gets you more self centering, straight line stability, YES!. It basically let's it go straight, harder to turn it. Going to the extreme--- a dragster is long, as it is designed to go straight. To u-turn and bring it back down pit road, there is crazy Ackermann there. But the lengthened wheelbase doesn't necessarily help it seek straight like toe. If that dragster gets pointed at the wall, it is very hard to turn it. Camber gain is the tricky explanation. So let's talk about why you even dial it in. As you put forces that change camber, at the limit you pray for a flat or maximum footprint, contact patch. Thus prior to the limit or going straight, camber can cause issues with stability, especially on an uneven, varying condition road. They attempt to crown most roads, wheras race tracks are generally flat, so a lot of camber is not a good suspension for street driving. If you drive mostly freeways, then stand those tires up to get maximum tire life. If your commute is thru the twisties, you want the tire to lean over to a flat footprint turn to turn, side to side. How the inner or outer or the reverse into the next turn grabs flat or on edge, that can have a centering effect or a crash effect.

Ackermann in case anyone is lost, is basically inner or outer tire steering geometry, built in by design so the car can get a turn assist inner tire turns less revolutions than the outer tire in the turn, so there is a changing tire singularity upon turning. Ackermann I feel is extremely important for going into a turn, and coming back out. The back tires follow. To make my cars fast, I have a lot of spherical joints to track any radius, that the front end is forcing, and we have the rear differential action too! Not sure I nailed that. Ackermann not easy to explain. Some cars,scrub worse than others.

PS since I have fancy multi-link C2/C3 rear suspensions,I have set rear toe out, and zero toe at the front. Give that one some thought.