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+--- Thread: Little Video From Gigi . . . (/showthread.php?tid=2042)
- George3 - 01-07-2010
<< Is that the best way to have a car set up? >>
Car setup is car dependent. The loading of the rear tires on a 911 is different (b/c of the engine weight) than the front mounted engine of the Evo.
On the Gigi Evo video... I'm not certain, but to me it looks like the rear spring rates of the shocks are softer, judging by the way the rear end bounces around on bumps and corners. This may give it a tendency to understeer.
Conversely, if the rear shock spring rates are stiffer, then the car would lean more towards oversteer... depending on how stiff the rear springs are.
Somewhere in-between is nirvana .
- bobt993 - 01-07-2010
Jim, It comes down to the driver, but I prefer the car to have slight bit over steer on entry and somewhat neutral on exit. This makes the mid corner transition fast and you must stay on top of the car with neutral or lift throttle applications. The problem with understeer on a 911 is the transition to oversteer can be induced quickly with TTO. Think of slightly loss entry as driving with a little bit of room at the edge of the cliff to catch it as opposed to driving to the edge and maintaining it with little room for error. When you are exiting a turn, understeer with no room to track out is very unnerving and you end up being slow to avoid going off the track.
- Racingswh - 01-11-2010
JimWirt wrote:
Quote:Racingswh The video of the evo. Is that car set up to under steer when entering corners? It looks like he enters corner,car initially understeers. Lifts a Little then rotates car. Then gets back on the power. Is that the best way to have a car set up? Hopefully this isn't high jacking the thread. I'm interested because this what my 911 sc does when I enter a corner. Is that good?
Hi Jim,
A little busy at work so I didn't have a chance to respond sooner and I am sorry. About the EVO many times that's just how they are unless someone has gone to lengths to dial out the inherent understeer. They are much different than your 911. When I am driving the GTR or a 911 Turbo or anything all wheel drive they all have responded well to the "lift to rotate" technique. The reason this works well is that it plants the front tires a bit and gets them to bite giving you a bit more grip to turn with instead of asking them to pull the car forward and steer at the same time while you're on power. That's one of the reasons they understeer. They don't have enough lateral grip to put down power and steer the car so they start to slide and the car goes straight instead of turning. I hope this makes sense. I generally carry the car way, way into the slower corners on the brakes in order to keep the front tires planted so I can turn. Slowing the car just enough so it stays on the track and controlling the slide with the throttle. Faster corners like one at Pocono North I am back on the gas to balance the car and flat to the floor before the apex.
Your 911 is a different animal. 60 percent of the weight sits over the rear axle and 40 percent over the front. That's a beautiful thing when you're braking in a straight line and the rear tires are doing their share of the work hauling the car down from speed. Many times though a driver will over slow the car at entry and go back to power to harshly to make up for the loss of speed. Once back to power you've now planted the rear tires and unweighted the fronts. Now you're asking them to turn the car and all the car really wants to do is go straight. This is a very typical mistake. Many drivers do it actually. Now you're into the corner with the car understeering and you breathe out of it which plants the front tires and the car turns. The problem with that is now you're unweighting the rear tires and if you do it too much you get the classic trailing throttle over steer spin the older backside heavy 911's became so famous for. They worked for years to engineer out that effect and have done so with quite a bit of success from the 993 on up through the current models. What you need to work on is keeping the front tires planted when you're turning by being extremely smooth when you're going to power after being on the brakes. Don't go back to power too abruptly. That will cause your car to understeer and you will have to lift to stay on the track which makes you slow at the least and spin at the worst. If anyone disagrees or can explain the 911 phenomenon more clearly definitely chime in.
There are many guys in the club that drive their 911's quite brilliantly and I highly suggest you pick their brains next season. I am certain they can help you drive your 911 more efficiently helping you to enjoy it even more and continue being safe while doing it.
Have Fun!
Steve W. Hoagland
- betegh9 - 01-11-2010
Nice explanation, Steve. Jim has been out with me at thunderbolt last year, and was able to show the transitions in my early 911, going from understeer to oversteer. I use front and rear adjustable sways (and I actually adjust them based on conditions). Rather than setting the car to run neutral or some understeer, I found that with a bit of oversteer I can achieve the slip angle I want and thus be able to get the tun-in I want toward the apex. As long as my turn-in point and the apex are nailed, I can track out with my eyes closed. After braking, I go into the turn with partial throttle, and once I know that I will reach the apex, I squeeze the throttle. As you said, the transition from oversteer to understeer and back to oversteer can be abrupt if one is not gentle with imputs. This year I will work on increasing corner entry speed to the OH s**t! factor with a higher corner speed, thus needing less weight transfer to the rear wheels (acceleration) at corner exit. In this case, I may be able to soften the rear sway bars.
Am I thinking this right?
hock::?