So I guess I probably shouldn't take that curve @ 70 mph again...

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This is the story of how my foolishness nearly got me into an accident.

The curve I'm talking about is the merging area from one major highway in my city to the next. This curve is really quite sharp, but I usually have to slow down because there's always someone in front of me.

Well, today, both lanes merging into the highway were all clear so I was cruising @ 70 mph. At the last minute, I decided maybe it'd be a good idea to slow down just a little. I don't exactly recall stomping on the brakes, but the result was the car swerving uncontrollably to one side. I turned the steering wheel which in turn overcompensated and swerved it hard to the other side.

No big deal, right? WRONG!!! This happened FOUR times before the car finally stabilized! While it was doing this, I decided not to hit the brakes again 'cos that's what got me into trouble to begin with... uh... that and speeding on a sharp curve.

Luckily, like I said, there was no one on either lane, so the only people hurt would have been the ones in their cars wondering what the hell just happened and how lucky I was. For a moment there, I considered pulling over to check the tires or something, but I figured it was a one time freak thing. The tires were probably almost @ a 90 degree angle to the vehicle when I hit the brakes so the break pads probably couldn't grab on right.

At this time, I'm really quite interested in a technical explanation for what happened to the car, and also if there's anything in particular I might want to check out. eh... I guess I posted this in the OT section 'cos it's much more about the story about how I almost got into an accident than it is asking for car advice of any sort. Let me know what you think, though. :thumbs:

posted by  JaneiR36

I'm not sure what you want a technical explanation for so I'll brifly hit both.

What you experienced today is known as oversteer. Your front drive car (Camry, right) will generally understeer and keep you safe but by hitting the brakes when you were already no doubt near the limit of adhesion you caused a severe change in the vehicle's dynamics. If this is the explanation you want just say so but I'll let it go there for now.

If you want to know about your car, then the answer is very simple. As long as you didn't hit anything, the only possible problem you may have is flat spotting or increased wear on your tires. If you don't feel anything unusual when driving it's basically a non issue.

posted by  vwhobo

Those were exactly my two questions, thanks :thumbs:

That's pretty amazing that the car could get whipped around like that and pretty much end up just fine!

Yes, it's the Camry.

Oh, by the way, is there any formula or listing where one can find the speed at which you'd hit this adhesion limit you mentioned? For different kinds of vehicles, I guess...

posted by  JaneiR36

You're most certainly welcome. Cars are amazing things, almost as amazing as me. :roll: :puke:

posted by  vwhobo

sorry....... I editted my post after you posted. Can you answer the other question, pretty please? :laughing:

posted by  JaneiR36

well, there are a bunch of Physics formulas you could use to calculate how fast you can go around a corner...

you'd need to calculate a force of friction, and see what the centripetal force is going around a certain corner at a certtain speed...the centripetal force would have to be less than or equal to the force of friction to stay on the road.

it can get pretty complicated...

posted by  SuperJew

You mean Centrifugal Right?

posted by  Zalight

ok, what happened was that when you decided to abruptly slow down, you unloaded teh rear suspension (rapid weight transfer to the front of the car) and overloaded teh front suspension. This is typical of FWD cars, but ANY car can end up with bad trailing throttle oversteer.

The problem was compounded by overcorrecting on your part because you dont' have a feel for what the car is doing in that situation.

It isn't a case of going too fast into the corner, but in trying to slow too rapidly, too late. Had you slowed a tiny bit earlier and a tiny bit gentler, you could have gone through teh corner just fin (in fact, teh unloading of the rear suspension in teh FWD car can be a benefit to going faster). As you started to slow and the car FIRST started to come around, slightly letting off the brakes and getting back on the gas would have pulled you smoothly through the corner. Instead, you stayed off both the brake and gas and overcorrected back and forth until it slowed WAY down. In a FWD car especially, get back on the gas as the rear starts to come around and it will straighten out. This is most important. Most modern FWD single car accidents happen becaeu people forget that adding throttle will save them: point the front wheels where you want to go and let them pull you out of trouble.

I've taught my wife how to take advantage of this phenomeneon (trailing throttle oversteer) in a FWD vehicle to corner faster: left foot braking. When entering a corner start to squeeze on teh brake with your left foot while remaining on teh throttle lightly with your right. Balance teh rear losing traction with the front gaining power and teh car will turn tighter (not understeer) If the rear comes around too much, let off the brake slightly (you're only on it lightly to start with) and give a little gas. If the front is starting to push ******d, squeeze a bit more on the brake to make the nose tuck back in.

posted by  ChrisV

No. He means Centripetal Force.

posted by  DodgeRida67

hey what's up, SJ.

I think I was actually going around the corner just fine till I decided to brake at the last minute. I think those formulas are basically for the test tube example commonly used to illustrate centripetal forces. The tube is either staying attached to the center or flying off at a tangent. While that is exactly what the maximum speed for rounding a corner will tell you, I'm looking for the speed at which hitting the brakes when you're rounding said corner would cause your car to flip around so uncontrollably (or "oversteer," as I now understand it :smoke: ).

ChrisV, press the gas to get out of situation like that? Wow. I never woulda guessed. I certainly would have been too scared to do anything of the sort. While there were no cars around me (in front of me, anyway), there was the concrete supporting the overpass to my right and then traffic I couldn't really see possibly coming from the left (the other direction of the highway I was coming from; also merging into this new highway). All I could think of was getting the car under control without hitting the brakes again.

Whew! Glad that's over :laughing: I went by that same area again today. 55 mph was just fine for me :laughing:

posted by  JaneiR36

55 is fine for me on most highways. Freeways I'll hit 60-65. 70??! Maybe I missed it, but what is the speed limit at that location?

posted by  DodgeRida67

Who cares about the speed limit, Mr. Goody Two Shoes :laughing: Personally I feel a little unsafe doing the speed limit on the highways. The car feels more stable at higher speeds (especially when those big-ass trucks pass you; it's like the air current is as strong as an ocean wave that could capsize you in a split second :hi: ).

eh... just ignore me. Do the speed limit and always eat your fruits and veggies :laughing: :thumbs:

posted by  JaneiR36

You think you little car is bad? Try driving one of the older VW buses on the interstate. You will think your butt is going to be sucked under their wheels. Who wants to ignore you little girl?

posted by  lectroid

Theres is a fine line between fun and retarded.

posted by  shev

Bite me, please. :hi:

posted by  JaneiR36

There is NO fine-line or line period between fun and retarded! Might be for you, I can't think of anyone I deal with, where I have to worry about retardation,except on this forum. :sleep:

posted by  lectroid

lol ok

posted by  shev

That's because driver's ed teaches people the difference between the steering wheel and brake pedal, then send you out on teh road as though you're ready. And the safety nazis tell everyone that the only safe way to drive is to slow down.

If driver's ed taught true vehicular dynamics, there would be far fewer problems on the roads...

posted by  ChrisV

that is SO true...I just finished Driver's ed, and it is the most worthless course i've ever taken. they teach nothing about the dynamics and physics of the vehicle. only "this will get you drunk. don't drink. drive defensively." only reason i took it is because now i can get my senior license at age 17 instead of 18. that's in...one month and 3 days. :smoke:

posted by  SuperJew

Centripital forces or the forces pulling on an object in an orbit that keeps that object in a circular motion. Centrifigul forces are the forces of inertia trying to pull a moving body in a stright line, so if an object is moving in a circle the centrifigul forces sre trying to pull that object away from the circle.

I figured that because the car lost grip around the turn because of the weight transfer, that this would mean the iinertia of the car was pulling her in a stright line away from the center of the circle her turn was a part of and this would count as a centrifigul force, but Im not a physics teacher so don't mind me iof i am wrong.

posted by  Zalight

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