Skids - PeachParts Mercedes-Benz Forum

jamesnj · #1 06-25-2002, 05:24 PM

What is the hardest part of a skid to control(initial lockup, middle, or the final stages)?

Generally how do you guys control or come out of a skid on snow, ice, or just plain dry road?

If a driver is skidding is it better for him to let off the brake before he impacts something or should he just hit the object with his foot on the brake maintaining the skid?

#2 06-25-2002, 06:07 PM

Personally I think the middle of the skid is the worst because you MUST decide what to do. I know when I had the BMW slidding through a intersection (rainy day to fast red light) I paniced and left my foot on the brake. Anyway I slid side ways through the intersection thank god there were no cars. I have learned to pump no matter how bad I think the lock up is. Matter of fact in my friends Civic we go out and pull ebrakes for fun.

MikeTangas · #3 06-26-2002, 12:45 AM

All three points mentioned have their respective difficulties. With today's ABS systems most of the thought required to handle a skid is no longer necessary as the computer takes over braking. Non ABS cars still require thought on the part of the driver.

A good idea would be to locate an instructional driving track with a dedicated skid pan. A really good skid pan track will have several skid pan courses - from straight line all wheel locked tracks to circular tracks and my personal favorite was the Le Mans style skid track. Got to spend a lot of time getting the car perpendicular to the track and holding it there through left and right turns.

Simplest things to remember: get off the brake, steer into the skid and remember that sometimes a little power will get you out of trouble (even though it's what likely got you in trouble in the first place). Also remember that if you are in a skid, you have no traction and therefore no control.

akry · #4 06-26-2002, 01:02 AM

MikeTangas has very good points, and so are many of you.... understeer can be overcome by pulling the hand brake OR, believe it or not, nail the gas pedal(especially on AWD cars)....when you are sliding in snow, the very last thing you want is step on brake.. it would just make the situation worse... especially when going down hills...

Andy Kuo

jsmith · #5 06-26-2002, 10:03 AM

i'll have to try out all these theories next time on the track...

...on Gran Turismo on the Playstation:p . i just picked up a mad catz steering wheel for the kids

well, i'm having a blast too. one of these days i will definitely go out to lime rock...

#6 06-26-2002, 10:46 AM

When I get the BMW running right and do some work with the suspension I'g going out to a BMWCCA driving school and then hitting the track to see how I can do.

bobbyv · #7 06-27-2002, 12:05 AM

when ABS was not yet widely available, the popular advice we got was to "threshold-brake", i.e., brake up to, but not exceeding the lockup point.

However, threshold-braking took too much skill for most people to be done properly in an emergency situation. Moreover, because of the car's dynamics & weight distribution (especially if there is only the driver on board), it was easy to lockup one rear wheel and make the car spin.

As such, there was another school of thought that told drivers to lock up all 4 tires as quickly as possible, making the car skid in a straight line (if the car is a manual, disengage the clutch as well). While this was happening, the driver was taught to steer the wheel towards a safe area/target, noting that it was easier to steer, with the tires skidding. After this, the driver reduced brake pressure just enough to let all 4 tires regain traction, with the fronts now providing steering action. Trail-braking (braking while steering) enhanced the front tire's cornering traction as well.

Needless to say, this school of thought became obsolete with the wide availability of ABS, Brake Assist and Stability Control systems. But nice to know if you have a non-ABS car.

In an emergency, most people will use the brakes to the max then give up. Accident-avoidance schools teach them to realize that they still have control of the car, via the steering wheel. And that your front tires' total traction is apportioned into braking and steering traction - use either to the max and you give up the other (some call this the "friction circle").

Race car drivers (e.g. F1) on the other hand, let go of the brakes (and the gas) just before impact - to protect their feet. If you think about this, it is quite un-instinctive.

For everyday driving, I believe that one must get familiarized with the skid and recovery characteristics of one's car - each car is different. In particular, one must get familiar with the "swing-back" that BlackMercedes refers to, so one can prepare for it. If the car has ABS, then all the more must the driver get familiar with the behavior of the car when it is invoked. A vacant parking lot in winter provides an excellent environment for testing this.

For understeer, the general remedy is to reduce power. But on oversteer, it depends if you have RWD or FWD.
- on a RWD car, countersteer and reduce power (unless it is one of those older Porsche 911s, where one must keep one's foot down on the gas, steer and hang on !!!).
- if you have a FWD or AWD car, countersteer and apply power.

David C Klasse · #8 06-27-2002, 03:17 AM

I agree with John... I think that one of the hardest part of a skid is RE-gaining control again...

About a year ago, I was on a freeway on ramp that sloped down and curved to the left. There were 2 lanes that merged into one before the ramp actually hit the freeway. I was going about 75 mph (I take this ramp daily, and know that 80 is the max speed to safely go around the corner my C280.), and decided to pass a Ford Exploder before the 2 lanes merged to one. I was rounding the ramp on the outside lane just before the merge. Well, at the last moment, I decided that I would have to pull a rude (CUT-OFF) manuever to get around him, so I decided to slow down and let him go ahead. My decision was made quickly, and it was just before the merge... I hit the brakes, TOO HARD. I could feel the car sway from the suspension... next I realized that my car was on the path of a spin out (due to hard braking on a curve going 75 mph). So I swung the wheel back the other way to regarin control. LUCKILY, I regained control safely. But I was on the brink of nailing that guard-rail due to my slightly TOO quick/much of a correction.

So, there's my story... all parts of a skid are scary and I try and avoid them, but regaining control is definitly one of the more difficult aspects of it.

omegabenz · #9 06-27-2002, 05:45 AM

Right after the initial is the hardest part because you cant think about what to do, you have to know what to do.

As told about the Civics, those are good cars to learn in because you can put trays under the tires, or skateboard decks and slide around. Its best to learn how to react to the skid so when it comes time for it in an emergency, you dont have to think about it, you just do it. Practice in snow if you dont have a civic to expend.

Austin

pentoman · #10 06-27-2002, 07:28 AM

Most of us have the benefit of automatics, making it very easy to left foot brake (i.e. to juggle both throttle and brake together), which can really help stability, as you can throw the weight of the car either forwards or backwards as necessary, while still accelerating, braking, or turning.

Kuan · #11 06-27-2002, 07:46 AM

It's different if you know bring the tail around on purpose, but if it comes around unexpectedly, then you'll probably find it quite difficult to regain control unless you're intimately connected with your vehicle. If you can get up in time, watch F1 racing on Speedchannel one morning and even the best of them with traction control and all spin out. Michael Shumacher did last weekend at the new Nurburgring.

For emergency straight line braking on slippery surfaces, I was taught to brake UNTIL the brakes lockup, release, brake, release.

Oversteer is the lack of traction in the rear, so to put the traction back over the rear wheels, you have to shift the weight to the back. This means you accelerate! Point your front wheels in the direction you want to go and gun it.

Understeer is the opposite, where no traction is available on the front so it'll go in the direction you were going before no matter where you point your front tires. If you can slow down the car, the do so. If not, I think you're basically SOL when understeering.

Kuan

Kuan · #12 06-27-2002, 07:49 AM

Quote:

Originally posted by omegabenz
As told about the Civics, those are good cars to learn in because you can put trays under the tires, or skateboard decks and slide around

I need to see this, really... you've got to be kidding! Rears only right?

Kuan

#13 06-27-2002, 08:09 AM

HUUMM I wanna see the civic thing to I might still get my friend to do it after he gets his new rims that way.

Kuan · #14 06-27-2002, 09:09 PM

Quote:

Originally posted by Benzman500
HUUMM I wanna see the civic thing to I might still get my friend to do it after he gets his new rims that way.

I want pictures

Kuan

jsmith · #15 06-27-2002, 09:26 PM

i think it's saab that has these programs where they mount outriggers with wheels on the cars that make it really easy to skid. this is probably the next best thing to practicing in a parking lot in the snow. as to rolling trays under a honda's rear wheels - i don't know about that, i think that would make it swing its tail wildly don't you think?