IchBinEinMP5

I was thinking of using a Mazda switch in one of the blank spots on the dash, along with a relay...

Roddimus Prime

I still can't understand why someone would want to disable the ABS. I personaly think thats a step backwards, but my main concern isn't shaving a tenth of a second off my lap time. It's making sure my wife has a safe vehicle to drive.

MalkavianMP3

In snow, abs is the worst thing you can have. there is a reason for this. Abs works by not letting the wheel lock up, in snow this is bad if trying to perform a panic stop. A non-abs equipped vehicle will allow the brakes to lock. This in turn allows for snow to build up in front of the tires acting as a brake(kinda like the run-off ramps on the downhill side of a mountain for truck drivers). So there is a reason for most high end sports-cars to have the driver controlled abs switch.

Roddimus Prime

makes sense. I live in alabama.....what's snow?!

Myk

I tend to disagree with Malkavian on this one. Snow building up in front of your tires is not going to slow you down. Wheel lock is the thing you do not want when braking.

Your also forgeting one important factor. With ABS, you can brake AND steer at the same time, (brake and avoid.)

I think that the 'high end' cars have a disable switch for traction control, not ABS. I may be wrong as my DB7, M5, S class AMG and SR6 have all been in storage and can't go check.

IchBinEinMP5

I want to keep my wife and daughter safe as well, hence the switch instead of pulling the fuse. (non-permenant)

I still insist that in snow deep enough for the tires to be rolling on top of it, the ABS makes stopping and pendulem turns longer and more difficult. The ABS kicks in and does not allow the tires to "bite" into the snow rather it rolls over top the loose surface.

I love this quote, anyone recognize it?

"Loose is fast, but on the edge of out of control."

Myk

Isn't that Days of Thunder?

IchBinEinMP5

Yeah, it is... I like that movie. Probably one of Tom Cruise's best, before he got all weird.

master

Why would you put your SR6 in storage for the winter? It has Quattro - much better than the front drive Protege in the snow.

Myk

Uhhhhh, too much salt, yeah, thats why!

SportMP5

I believe tha main purpose of ABS is to allow maximum sterring ability in a panic brake situation.Non ABS cars will have a shorter stopping distance...but bad steering ability when the wheels are locked.

eric1234

Hi Guys,

As an engineer, I might be able to help out with the theory a bit. There are two kinds of friction out there: Static and Dynamic.

Static friction is what is generated when one object is NOT moving relative to another.

Dynamic friction is what is generated when one object IS moving relative to another.

Static friction is ALWAYS greater than Dynamic friction.

Here's a little test you can try to illustrate the difference:

Put a little cardboard box on a ruler, and lift one end of the ruler. Note that you can lift the ruler to a certain height before the box begins to move. Up until the point where the box moves, your are in the Static Friction Regime. And the angle at which the box begins to move can be measured.

Now, once the box begins to move, You are in the dynamic friction regime. You can (carefully) lower the ruler just a little bit, and the box will continue to move. That is because dynamic friction is less than static friction. (You will have to be very careful to observe this, but it WILL work).

So, the bottom line is: You can raise one end of the ruler to a higher height (steeper angle) if the box is not moving, but once it begins to move, you can actually back off on the angle, and it will keep moving.

SO WHAT DOES THIS HAVE TO DO WITH ABS?

Well, when the tires are rolling, they are actually in static friction with respect the ground. (I know, it's hard to imagine something rolling and being static, but it's true). When the tires are locked up, they are moving with respect to the ground.

So, when your wheels are locked up, they can not generate as much friction (stopping power) with the ground as when they are rolling.

Thus, the goal of ABS is to release the brakes just before a lock up, in order to maximize the amount of friction available to stop the car.

Now, having said all of this, it has always been my personal opinion that ABS makes the car stop longer, but the engineer in me dispells this personal opinion. (Just like the fact that I might have a "gut feel" that a 20 pound hammer will fall faster to the ground than a 1 pound ball).

You can't cheat physics!

Hope this helps a little bit.

Eric

master

You are not wrong to think that ABS will take longer to stop your car. This however has nothing to do with the static/kinetic friction debate. It is because when the ABS applies and releases the brakes to prevent lockup, during the release times there is no deceleration.

Best thing to do is avoid having the ABS kick in in the first place by carefully applying threshold braking.

breiland

I live in North Dakota, and I've realized that my Protege without ABS actually handles and stops better than the Dodge Stratus I had with ABS.

erikvonb

I can't explain anything from an engineer's perspective, but what I do know is this:

I was up at Tremblant snowboarding just before Christmas and the place that I was staying at had a very steep decline on a corner to get into the parking lot.

I had already disabled the ABS by pulling the fuse because the roads were terrible. Anyway, while going slowly down the hill, I applied pressure to the brakes and then began locking up, which in turn slowed me down just enough to release the brakes and then steer into the corner. (I'm running Goodyear Ultra Grip Ice on all 4)


I thought about it after, and realized that there was no way that I would have made it with the ABS enabled. Many others did not make that corner (you could see that the snow bank had already been plowed into a few times already)

I wasn't about to test my theory, but I still stand by my decision to keep that fuse pulled. (I've learned to live with the lights on the dash)

-Erik

Hey Myk, what kind of mud flaps are you using?