Snap oversteer
06-05-2005, 07:13 AM
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Snap oversteer
So I was on the freeway last night when I had to change lanes really quickly to avoid another car at about 60mph. so then the rear swings around, countersteering then fishtailing a few times before spinning 180 - luckily not into any trees or anything around so the car is fine.
Car is on stock sport suspension and tyres with 38F and 40R psi.
Yes i know if i applied some throttle i might've straightened her out...but in those split seconds my mind just went blank..
So apart from driver error.... will anything else help prevent this in the future? is the tire pressure too high? will suspension help make the car feel more planted?
TIA - help the newbie out
Car is on stock sport suspension and tyres with 38F and 40R psi.
Yes i know if i applied some throttle i might've straightened her out...but in those split seconds my mind just went blank..
So apart from driver error.... will anything else help prevent this in the future? is the tire pressure too high? will suspension help make the car feel more planted?
TIA - help the newbie out
06-05-2005, 07:16 AM
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what might help prevent this in the future would be a audi Driving school..
not only do you learn about how your car handles in extreem situations but its also a total blast!!!!! that would be the biggest help so you dont "freeze" so to say..
06-05-2005, 07:29 AM
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even if your tires are junk it's still driver error. get some edumucation.
it's not that expensive and it could save your life someday. and yes, it is a hell of a lot of fun.
06-05-2005, 08:05 AM
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suspension would help. There is enough room...
in the wheel wells at stock height..you could probably sleep in there! lol Really, I noticed a big difference when I changed out the suspension. True, probably a little drivers error also. I would put some sport suspension on there and get the baloon tires off..it would be better.
J
J
06-05-2005, 08:16 AM
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a couple things
1. That sounds like a lot of tire pressure for the street. Is that what audi really recommends? You should be able to find it inside the fuel door.
2: as previous people have mentioned, this is still easily preventable with a bit more skill. When you swerve quickly like that to change lanes, you should really be making two inputs: turning the steering wheel to avoid the intial obstacle, and then returning it to the straight ahead position. It sounds counter-intuitive, but you really don't have to steer back the other way to get the car going straight in the new lane. And as you experienced, steering the other way can cause a pretty violent snap oversteer. Here's why:
When you first steer to avoid the obstacle, you're compressing the springs on the side of the car opposite the direction you're turning (the way your car is leaning). When you've avoided the obstacle and start to steer the other way, the weight of the car shifts, and the springs release all that pent-up energy and make the car snap back the other way. If you add a far amount of steering input at the same time, you're going to get snap oversteer every time.
The key is to anticipate that weight shift, and not to steer too much.
I teach at my local BMWCCA chapter's advanced skills schools, and this is one of the exact drills we do. They're incredibly helpful, and lots of fun. You should see if your local Audi or BMW club offers the classes... it's usually a day, $60 and a thousand miles of wear on your tires :-) but well worth it.
Finally: I don't view a stiffer/better suspension, OR better tires as the right fix for this. Your car already has the stock sport suspension, which should be more than enough for all street driving, and you spun because you didn't manage the weight transfer, not because of a lack of ultimate grip. Spend your money on building your skills first.
2: as previous people have mentioned, this is still easily preventable with a bit more skill. When you swerve quickly like that to change lanes, you should really be making two inputs: turning the steering wheel to avoid the intial obstacle, and then returning it to the straight ahead position. It sounds counter-intuitive, but you really don't have to steer back the other way to get the car going straight in the new lane. And as you experienced, steering the other way can cause a pretty violent snap oversteer. Here's why:
When you first steer to avoid the obstacle, you're compressing the springs on the side of the car opposite the direction you're turning (the way your car is leaning). When you've avoided the obstacle and start to steer the other way, the weight of the car shifts, and the springs release all that pent-up energy and make the car snap back the other way. If you add a far amount of steering input at the same time, you're going to get snap oversteer every time.
The key is to anticipate that weight shift, and not to steer too much.
I teach at my local BMWCCA chapter's advanced skills schools, and this is one of the exact drills we do. They're incredibly helpful, and lots of fun. You should see if your local Audi or BMW club offers the classes... it's usually a day, $60 and a thousand miles of wear on your tires :-) but well worth it.
Finally: I don't view a stiffer/better suspension, OR better tires as the right fix for this. Your car already has the stock sport suspension, which should be more than enough for all street driving, and you spun because you didn't manage the weight transfer, not because of a lack of ultimate grip. Spend your money on building your skills first.
06-05-2005, 08:20 AM
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$10 says it's the tires and the driver.
Soft suspension = greater weight transitions from side to side and front to back. So assuming you lifted throttle and steered at the same time, you basically unloaded the rear tires, and gave them a reason to come around when you steered. A stiffer suspension minimizes some of those drastic weight transitions, but in most cases it tends to compensate for a bad driver (the fundamental problem).
The second issue is a little more difficult to assess. The tires. While there might be good tread left on them, tires will harden as they age and heat cycle. As they harden, they trade off some of those grippy qualities they had when they were new. And if the rear tires are more worn (or older) than the front tires, that's a contributing factor as well. It's also possible you had a set of cheap tires optimized for 100K treadlife. The 2 psi increase in the rear is okay. It does exaggerate oversteering tendencies. But these cars don't oversteer very easily unless you do something drastic to force them to do it (like you did). Generally, I wouldn't be alarmed by +2 psi in the rear. I would focus on the tires and the driver.
The second issue is a little more difficult to assess. The tires. While there might be good tread left on them, tires will harden as they age and heat cycle. As they harden, they trade off some of those grippy qualities they had when they were new. And if the rear tires are more worn (or older) than the front tires, that's a contributing factor as well. It's also possible you had a set of cheap tires optimized for 100K treadlife. The 2 psi increase in the rear is okay. It does exaggerate oversteering tendencies. But these cars don't oversteer very easily unless you do something drastic to force them to do it (like you did). Generally, I wouldn't be alarmed by +2 psi in the rear. I would focus on the tires and the driver.
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06-05-2005, 08:27 AM
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Possibly we should review the three important laws..
Newton's Laws of Motion:
1.Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
2.an object with a certain velocity maintains that velocity unless a force acts on it to cause an acceleration (that is, a change in the velocity). force=mass x acceleration
3.For every action there is an equal and opposite reaction.
*the third one is most important for your situation. If you are gonna get jerky on the wheel, your car is gonna react in that way.
1.Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
2.an object with a certain velocity maintains that velocity unless a force acts on it to cause an acceleration (that is, a change in the velocity). force=mass x acceleration
3.For every action there is an equal and opposite reaction.
*the third one is most important for your situation. If you are gonna get jerky on the wheel, your car is gonna react in that way.
06-05-2005, 08:42 AM
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depends on how you look at it. A pro driver will run circles around you in a bone stock A4 compared
to a mildly modded one. I'd still put the money into driver ed before modifying the suspension. I drive a 7,000 lb. truck and my driver education has helped me safely maneuver out of some pretty harry situations.