Tuning questions - suspension settings
#1
Thu, 04/18/2013 - 14:12
Tuning questions - suspension settings
Hello folks. In my effort to understand my tunes that fit my driving styles, I've come across some confusion. I have 2 A600 cars that both handle well for me on the same track and when I looked at the settings, they are very different. In short my 2010 Camaro has a stiffer all around setting with a lower accel diff setting and a 97 m3 with a softer setting and higher accel diff setting. The Camero is around 800 lbs heavier. My thinking is that the heavier the car, the stiffer it needs to be and to counteract the stiffer setting I have lowered the accel diff. Is this assumption accurate? Also, both cars have a full roll cage, front engine RWD.
Also, both cars have very drastic changes in decel diff settings and I can't tell a difference in either of the settings. Is it safe to assume that based on my driving style, this is just one of those settings that has little impact. Do others have similar experiences?
Again thanks
I'm starting to think there is no rhyme or reason. Most of my tuning if starting out with a decent base car (no the FRS) is set up similar to how I would setup a car in real life. With that said I have found recently that the anti-roll bar settings I use are a little high. Some of my tunes, including ones I sent you are better with softer anti-roll bars. Mostly it's a feel thing though because for ME reducing the anti-roll bar size doesn't always mean the car will be faster.
And yes I've noticed that a car can accomplish the same thing with very different tuning settings. Pap the other night was showing me some things and he sets his cars up WAY different from me, and I suspect different from others as well. Other times you will find a tune that others think works well and is absolute garbage. I'm not sure why that is other than each person wants the car to do something different.
FWIW I updated the E36 M3 that I sent you and it is MUCH, MUCH better. The exact tune is on my S/F if you want to try it before I'm able to send it over to you. 1:29's at RA was unheard of in that car till now. And it's pretty good at Nurb GP too
Because everyone is at a different stage in their sensitivity of the controls. The smoother you are with power application the looser your car can (needs) to be in order to always be driving on the limit. If a driver still applies power to hard and fast then they require a car that is a little more forgiving to that trait (tighter).
If you build a car that is absolutely perfect for you today the same car will need to be rebuilt in a couple months.
Trust me I know what I'm talking about.
I'm a competent driver now, but when I started I was worse than anyone around here. I've experienced a world of change in my driving, and the way I tune my cars has had to evolve to match. Of course it's only taken almost 4 years, but hey who's counting!
The most common observation made by newer drivers that drive more experienced drivers cars is that the car is way too loose. How do you drive this? They are more sensitive to the feedback in the wheel/controller, sounds of the tires, and sight map on the screen to know that they are at the limit. Adding a 1-2% increase/decrease in throttle will get the car to behave the way you want, but a 4% increase will get you spinning. This is the level of control you only get through experience. There is no book that can teach you this skill; only explain what the skill you need to work on is.
My ideas.....Softer=more grip. So softer springs, and now also softer anti-roll bars.
Turn in is effected by the diff decell and toe out in front. Accell is effected by the diff accell, rear toe IN, rear bump stiffness.......
Everything else is just the mixer in your drink.
If you want to see the differences in diff decel you only need to set it to 0 and drive around a track the car will rotate a lot and may seem too twitchy to corner accurately. As you increase the decel settings the turn in of the car will decrease. Cornering will become very stable. The trick is to find the balance between stability and turn in that you are comfortable with, and can be a very track specific bit of tuning.
This is also where the voodoo happens.
You like the stability of the high decel, but the car just doesn't turn in for you. What he hell am I going to do???
Well there are different settings that will help you here. Toe out on the front will definately get the car pointing in a little more at turn in so you can crank it a point or two. Don't go too far with this though as it will start to create drag on the straights and add heat to those tires.
This is better but it's still not cutting it.
Ok now you can go against the common settings on the dampers and set them up to give the car more grip in the front instead of the rear. A lot of tuners out there will say that they tune dampers for tire compliance over bumps and not for handling. I say nuts to you! My starting settings for dampers is usually to leave the front rebound where it is, and crank the rear rebound up 2.0 points above the fronts. For bump I do the opposite, and leave the rears where they are while dropping the fronts 2.0 points below the rear.
Now my car is stable under braking into a corner, I get good turn in, and good rotation exiting the corner.
I usually start with my lowest spring setting about 1/3 down the scale. I adjust the other spring in accordance to the weight distribution and aero on the car. With spring settings set I now adjust the ride height to avoid bottoming out. I don't add more spring.
ARB's are set on fast sweepers. At neutral acceleration (just enough throttle to maintain cornering speed) I want a neutral car. Now when I start applying more throttle to exit the corner those damper settings are getting my car to rotate in rather than drift wide of track out. The amount of ARB depends on the inherent stiffness of the car. I start at 25 for no reinforcement and 20 for street, 15 for sport, 10 for race cage.
Camber I usually start at -1 and -1 but they rarely stay there. I'm looking for even heat on the tires after exiting a fast sweeper. The rest of the track the tires will always show more heat in the inside. Why? Because this indicates that when the weight has shifted during cornering, the tire is standing up straight and you have the largest contact patch available.
Castor I just set at 6.4 to 7 because it creates stability cornering, and the game doesn't actually make it any more difficult to turn the wheel. So go for it.
I cannot tell you how many times I have retuned my cars. With each retune my times drop not by much anymore but they are dropping. Tuning is a work in progress.
I Just tuned my second, what I would call successful, car this week. I say " I would call" as the jury (a friend or two) is looking it over.
I can honestly say some of what Pap said, I did, and some of it I didn't, as I didn't do everything...
I adjusted the stock rear toe in a touch, relaxed the ARB's alot, probably more than Pap's starting settings, Widened the tire a bit, because I could and there wasn't really any other PI that could be spent. Pretty much left the springs alone at first, and then softened the front ARB a touch, and then softened the rear springs a little. My default diff settings of 65/28 seemed pretty good at the get go before I adjusted the ARB and springs.
After all that I think I raised the car 2 tenths of an inch front and rear just because I wanted to, probably good for accomodating the softer suspension. But this was a race car to begin with, and I was tweaking as I test drove it around the track, which is a good way to feel what a change does, IF you change one thing at a time.