the mystery wire?

[riffman]

ok....i just did a custom soa conversion on my truck, and there are some wires that seem like they go right to the pumpkin. what are those? they actually broke when my axle turned....(long story)....so what are they for? does that have anything to do with why my anti lock brake light is on? do i really need to hook them back up? thanx for any help!!

 

[rpenner54]

Well I would say if your ABS light is on and you broke some wires going to the rear axle that yes the two are related. More the likly its the ABS sensor wire that has been busted and no you don't have to have it, just be prepared to stop your truck the way a truck should be stopped by pumping the brakes.

 

[Ray Hutchinson]

Pumping Brakes

Ryan,

Sorry guy, but I've just got to call you on that last statement. Test after test by professional drivers and truck safety experts have proven, without a doubt, that Pumping the brakes is NOT the safest or most efficient way to stop any vehicle, specially a truck. Neither is locking the brakes up! The best way, according to the somewhat extensive truck driver training programs I'm required to go through annually by my employer, is smooth, even, pressure just short of locking the wheels. This way you get the maximum braking action, while maintaining rolling friction between the tires and the road. When you "pump" the brakes, basicly you oscillate between the worst two conditions: not enough braking action and lock up. The steady even pressure just short of lock-up takes some practice with the vehicle you drive, but is well worth the time spent!

No hard feelings I hope! Lot's of people believe the same thing, and it used to seem logical to me, but i've watched and done the tests!

And Oh, yeah, Riffman: hook up the wires! Ford doesn't put anything extra on these vehicles thast isn't for a purpose!

[Edited by Ray Hutchinson on 10-19-2000 at 09:09 PM]

 

[gijoecam]

Hey, Ray...

There actually are two distinct (and more often than not, rare) occasions where complete lockup is more desireable than the "threshold braking" you described above... On loose gravel and in fresh snow, a full lockup builds up a mound in front of the tires which halts the vehicle in a shorter distance. However, with a full lockup you do lose all steering control, so the ability to steer around the object is certainly better than the ability to stop a mere few feet shorter. The stopping distances are shorter in only these two cases for Non-ABS equipped vehicles, but ONLY in those two instances.

Not to split hairs, but the term you call roling friction is actually called static friction, and you are right, the coefficient of static friction is higher than the coefficient of dynamic friction, which is why ABS equipped vehicles will stop shorter than the same vehicle that locks up all four wheels. That does not mean that a properly modulated non-ABS equipped vehicle cannot stop in the exact same distance as an ABS-equipped vehicle, but in a panic stop given the other variables, like loose gravel on the road, moisture, wiight transfer... I'm babbling... Point being ABS is generaly more likely to maintain that static friction between the tire and the road.

Now, back to the original question... they go to something, I'm sure. That's about the best I can do. Sorry...
-Joe-

 

[Ray Hutchinson]

Rolling Friction/ Static friction

gijoecam,

Your're most likely right: Rolling friction probably isn't the most scientific term, It's just the term our Training Officers and Videos use.... probably to drive the point home to dumb firefighters like me, that its best to keep the wheels turning (rolling) not locked up. I can agree that lockup could be better, except for steering control, in the conditions you describe. Our tests/training are for pavement, although not always be clean and dry. Also, a very ,very slight "fanning" or light modulating is often helpful. but not the classic "Pumping" technique that lots of folks were told was best.

Our test demonstrations are done with Fire Engines, and they equip the training vehicle with a device that fires a small explosive squib that produces a bang like a small firecracker, and simultaneously shoots a puff of powdered chalk down from the front bumper onto the roadway/ test pad. The driver starts his braking sequence as soon as he hears the squib fire, and the chalk mark provides a point from which to accurately measure stopping distance. Then the various stopping techniques are employed by each driver, both trainee and professional trainer. The results are quite amazing. As I said before though, you must practice this with your vehicle so you will instinctively employ the technique in tough situations.

[Edited by Ray Hutchinson on 10-21-2000 at 08:50 PM]