Are we talking throttle-on oversteer or lift-throttle oversteer? I have the Hotchkis bar also, set full stiff, and I know I get some decel oversteer, but only in 1st gear do I get power oversteer.

EVOlutionary

 

I would say both. Probably more lift throttle if I had to guess. He steers with the rear of the car. That is how I would describe it.

He is on the throttle more consistently than most drivers. He is good at loading one end or another with weight to get the car to turn. One of the guys in our club datalogged him. Very interesting stuff...

A guy who is a very good autoxer described his setup as very twitchy. I have not driven his car. Like they say a loose car is a fast car if you can manage it. Especially on autox courses that is frequently like running a car on a karting track (tight courses). Everything he has suggested to me is to loosen the car up (tire pressures, spring rates, etc.). He was running a staggered front to back tire setup (wide in front) but found that the ACD was negating the benefits of a staggered setup.

 

I guess I can throw in my two cents here. You are correct that I am not running the same valving as Paul(Chronohunter) Or maybe I should say that unless we happened to end up in the same place by sheer luck, we are probably a bit different in valving. Now having said that I will clarify that Paul and I are on very much the same page on chassis setup. I did a lot of experimenting with springs, bars, and tire sizes, and I think Paul and I agree on the basic setup principles. My goal in setting the car up is stable on entry, transitioning to slight rotation under trailbraking, then on throttle nuetral to light oversteer corner exit. That being said, I never actually achieved that with my car yet. I believe a large chunk of the problem was the rear differential slipping, causing inside rear wheelspin on corner exit, causing the center diff to send more power to the front wheels, causing corner exit push. I tried all different suspension setup combos, before realizing after nationals, exactly what was happening. So yes I like a loose setup, but not on corner entry. I ended up with a setup at nationals that was just to loose on entries, and mid corner, but could still go to understeer on exits. Maybe at some point, I will get a diff in the rear and see if I am right. Yes, in all my conversations with Paul, I would say he knows what he is doing.
Mark

 

Nice to hear from you Mark!!!

Better to hear it from your mind than all of our "interpretation"...

 

The setup requirements for auto-x are usually different from those for road racing. In auto-x you want a car that is prone to slight oversteer, understeer would be a disadvantage because all you want to do is rotate the car as quickly as possible and gun it to the next corner. In roadracing a car that slightly understeers at the limit will be faster but you already knew that

 

Sorry, but I disagree. Michael Schumacher, and Gilles Villenueve come to mind as two pretty decent road racers who prefer a tick of mid corner oversteer to allow them to get on the throttle a little earlier than their competition. But what really separates those guys from others is their ability get into the corner quicker, rotate, and get out quicker. It is just that it is very difficult to do, and most people just can't pull it off on a consistant basis. I am sure that most racers have felt the effects of this a time or two, it is called having the car on the ragged edge. If it were easy to be really fast, everyone would be much closer than they are. Additionally, I have been exposed to a very obvious attitude that if someone is faster than they are that it obviously is the car. That is more prevelent in road racing because it is rare to have someone else drive your car. In auto-x, just put a fast driver in your car and see what happens. Sorry for the ramble.
Mark

 

Keep on rambling Mark. We are listening.

Too bad Rubens Barrichello doesn't left foot brake more. He could have been closer to Schumacher. LOL I know that that is only part of the story.

 

Interesting, I am at this same point and drew the same conclusions. IMO the cause for you rear diff slipping is the inside rear tire lift. When I keep the body roll transition to a minimum, I can manage the tire lift and as a result, keep the power distributed evenly. Navid has given me a couple of ideas on how to change my setup and correct this problem, but I have not had time to implment any of those ideas yet. I should have some of them implemented by the Atwater NT.

 

This is all great stuff Mark, please go on. Afterall we are all here to learn how to become faster and your input is greatly appreciated. Here is my question, if a car oversteers on throttle after the apex, then aren't you losing to the person who has grip (at the limit) and is accelerating out of the apex?
I've been under the impression that the driver who can maximize the grip of the tires to the limit and follows the ideal line will win. If you have grip you shouldn't be understeering or oversteering correct?
And in all scenarios you can hit the gas after you clear the apex, how much depends on the line you take. Isn't that why most of us chose AWD because of its traction advantage over other cars (weight disadvantage )?
When I mentioned understeering at the limit in a road course, I meant a car that understeers on high speed sweepers. An understeering car at higher speeds is also safer/easier to control. I was under the impression that this inspires more confidence in the driver and allows him to push the car harder, hitting higher speeds and thus ultimately being faster.
So, thus I came to the conclusion that an ideal car would slightly oversteer at lower speed corners and understeer at higher speed corners. Is my thinking flawed?
Also wouldn't you want a car that understeers more but is able to oversteer depending on the drivers input? That way you have a scenario where it is mostly controlled oversteer depending on the drivers preference.
Trust me when I say I want to be fast but I also need to learn from the guys who are fast to learn quickly as I don't have the time or the budget in my life to constantly go racing.

 

I'm sure Mark will chime in but I think he is running fairly high spring rates (800-900 lb?). From the times I have seen him run, there is not much roll to speak of or lifting of the inside tire that we see with stock or softer spring rates. I could be wrong though.

This is good conversation. Let us keep it going. We should probably move this to the motorsports section though. Mods?

 

I agree...but the slight understeer at the limit for the track is usually recommended becuase a "tick of mid corner oversteer" can be a bit dangerous in the 120 mph sweeper that you don't see on an autox course.....

But you're right, Schumi and Gilles can do it and thats one of the many reasons why they are F1 Champs...


- Andrew

 

actually what I have learned is that the higher spring rates may contribute to the problem rather than solve it.

What we need to figure out how to do is control the transition in the body roll. Spring rates on only a small part on how to do this. Controlling the rebound and dampening of the shock seems to be more important (in the context of this thread).



FWIW, I am running similar rates (525f/650r) and plan on going no higher than a 600/700 combo. Since I run against Vic Sias, I think I have a good measure to judge my performance. On my current setup I am only 1.6 seconds off vic, and 9/10ths off Navid (who was driving my car) That's with the stock '03 turbo and a rather old alignment. The car is almost there, the driver needs more improvement for sure.

 

I'm trying to educate myself. If I have 5 choices to pick from, I want to know why I should go to them. I also want to know what the affects are when say you add one shim on the dampening of the shock, so that I understand what is going on my car and the handling characteristics. for example, there are tuners that can tune a car to 500 hp, though it drives like ***, doesn't idle, stalls and they forgot to turn knock control off when they were tuning the timing (I was AEM trained and saw this on some frinds cars).

Maybe someone can direct me to a website or person that can better explain, on the Ohlins suspension, how different modifications of the internals will affect the damening characteristics. Or would some one be able to explain this as a separate thread? I think this would be very educational to many on this board, not too many educational things around here.

Thanks

 

Mark suggested that r-compund tires warrant higher spring rates. If I remember correctly...

I agree that there is more to this whole suspension setup than just spring rates. The suspension needs to work together--springs, dampers, sway bars, tires, tire pressure, type of driving/racing, and most importantly the nut behind the wheel....

Personally I am having a hard time deciding on my setup. I go back and forth between dedicated autox, autox/daily driver, the costs, etc.

I was drawn to this thread originally because of the postitive comments about the racing and non-racing characteristics.

Some people claim that it is impossible to combine true race setup with daily driving. Makes sense, but I and many of us live in this context.

 

I know what you mean about this black art of suspension tuning. I saw a shock dyno on SpeedTV today. Looks pretty cool.

Found this link, perhaps too general but not bad:

http://auto.howstuffworks.com/car-suspension.htm

I bet you could call chronohunter, Mueller and others and get some info on a suspension that would fit your needs.