Bad Morning

[ladyjaine]

Downshifting and brakes

Yeah, I don't think the exhaust brake would be the first thing I thought of, but letting up on the brake? I do that all the time. Neither of my current beasts has ABS and I've never had a car or truck with ABS. "Skidding straight, keep the brake, skid and spin, brake again. " If ABS allows me to keep my desired line and brake at the same time, I won't have to change my rule because I won't spin.



The downshifting is the thing that might have made a difference. Being in top gear to go down a wet hill in a truck sounds more and more like a Bad Idea to me. Kim has an automatic and I dunno if her right foot is lead weighted or not. She did gain speed while standing on the brake. If she'd been in in a lower gear, she might not have gained speed the same way. I've heard semi drivers say that you should not go down a hill in a different gear than you used to go up the hill. Gotta downshift.



I tend to use brakes around here because I need to flash the lights so the idiot tailgaiting doesn't smush me flat. I am downshifting at the same time.



Jean

 

[QRTRHRS]

Jean, one thing I learned about the ABS on my 97' is to push harder when it kicks in. When I first bought it, hitting a bump while braking would seem to render the brakes useless. One time for whatever reason, I pushed harder and the brakes "chattered" like I would have expected.



My truck has an aluminum bed so empty weight is only 7600 lbs. I have a 100 gallon off road tank for filling my tractors. I try to keep it topped off especially in the winter. Big help on wet roads.



Exhaust brakes on a slippery road especially ice will bring the back end around real quick if the pressure is set up good.

 

[Vaughn MacKenzie]

Just a thought, but maybe the power steering/brake pump failed?



Vaughn

 

[JyRO]

ABS...

QRTRHRS - One of the previous winters here in MI. I tried out the ABS purposely. I wanted to know what to expect from them. On a fresh snowy slick road I whomped down on the brake pedal on a straight road to see what it did. They reacted quickly, but sure didn't seem to want to slow down the truck much. I did it again and mashed harder (like you said in your reply) and they did actually stop the truck quicker.



Then I tried the same experiment in my Y2K 4Runner. I couldn't believe the difference. Even in snow covered roads the 4Runner WILL STOP (and in a straight line)! I'm glad my wife has fully functional ABS. Made my Ram's ABS feel like junk. Don't get me wrong, the Ram's work, but no where nearly as effectively as the 4Runner's. Of course shear mass has a hand in that too, but it shouldn't be to that degree.



Just for giggles... I was running about 45 mph on snow covered roads in my '90 Celica (as was everyone else). It took me about a 1/4 mile to get stopped, and I was fighting that sucker like a S. O. B. Some dude had stopped way ahead to be a good samaritan to help someone who'd done a 180 and backed it into a snow pile. I was lucky to not add to the incident, the first guy didn't even pull out of the drive lane, of course there was no where he could pull off. Not his fault, my winter stopping ability in the Celica just sucks.



- JyRO

 

[Pit Bull]

JyRO the reason you see the big difference is you have rear drumms on that 2000. I had a 2000 with rear drumms and I now have a 2002 with disc's all around. World of difference!!!

 

[QRTRHRS]

A coworker of mine is diehard FORD but he decided to try a Dodge for the Cummins. He leased a new 96' auto 2500 4x4. From day one all he ever did was complain about the ABS brakes and not being able to stop. He hated it so bad he traded back to FORD before his lease was up. I had not yet bought my 97' so I had not yet experianced the brakes and never drove his Ram.



I have had a couple of other vehicles with ABS and with just steady pedal pressure, the pulsation would take place. I had a Toyota Camry that would stop real good but drift sideways real bad on a road with some tilt to it.

 

[fest3er]

The drum brakes on the Ram work pretty well, *if* you keep them adujsted. And the auto-adjusters *do* work, if you use them right, which involves:

• moving backward
• applying brakes reasonably hard
• waiting for the truck to completely stop moving backward and rebound forward just a bit

It's the rebound that seems to cause the adjustment to actually take place.

Glad your friend is OK, Jean. But do train her to downshift, whether she drives a manual or auto. Also teach her to pop the trans into neutral the moment she suspects braking problems; she doesn't need the engine pushing the truck forward while she's trying to stop it. Ripping it into 4X4 might be of some help, too.

And one last thought. If it was a fresh rain and there was a fair bit of oil on the road, *nothing* was going to stop that truck. I encountered that in Frederick a while ago. I had *never* before come that close to a head-on collision. Not in winter, not driving on black ice on I-89 in VT, not driving from A-Basic to Monarch to Wolf Creek to NM skiing. I even drove from Newburgh, NY to western PA in the storm that dumped 12" on DC in '85.

Wet, oil-slicked road? Forget it. *All* you can do is try to steer for clean pavement and pray.

As to tire traction, I generally agree that skinny tires produce more contact PSI and generally work better. But the tread pattern is equally important. I used to drive my '87 Formula 350 across the Kancamagus Highway in NH to go skiing at Wildcat. I had VR M+S tires on it. I was amazed as how well that car handled in 4" of snow. The M+S tread made all the difference.

Well, enough babbling.

Fest3er

 

[Hohn]

quick correction

I know this is way back in the thread, but it is important:



Pressure= FORCE/AREA..... NOT MASS!!! That's why PSI= Pounds/square inches... .



Pounds are force, i. e. how strong does gravity pull on this mass... .



The correct unit for mass in the English system is the Slug. . (aka Pound-mass).



Jean:

You are right that there seems to be a crossover point where load eliminates thelikelihood of hydroplaning. My Stepdad is an OTR trucker and he says that you have to be going WAY too fast to get a big rig to hydroplane when loaded up to 80K+ pounds (force, hehe).



I would tend to think that the Cummins is heavy enough (almost 1K) to reduce the likelihood of hydroplaning UP FRONT. The problem is that the rear isn't nearly as heavy, and probably can't resist planing out as well.



Since about 70% of your braking force comes from the front in a normal car, it is probably much higher for a truck (so front heavy) and HIGHER STILL for a Cummins Dodge (even more front heavy).



I would feel comfortable with wide tires on the truck since the front has enough weight to get them to the ground. Beware pf the rear, though, as it is much lighter empty.



THERE IS STILL NO FIX FOR GOING TOO FAST FOR CONDITIONS. No tire combo will fix that.



Sorry to hear about your friend's truck, and I am so glad that the injuries are minor. The other's are right-- truck can be replaced; friend cannot.



Hohn

 

[JyRO]

P=M/A

Hohn,



When you say Pressure is not equal to mass divided by area, you are wrong. Mass is a measurement of force. Whether that mass is pounds, kilograms, ounces, milligrams, newtons, it doesn't matter. They are all masses, and they are all acted on by gravity. So my original post was correct. Take a look in a textbook if you don't believe me. Not to seem like a know-it-all, because I sure don't, but I have a mechanical engineering degree and work for a major automotive manufacturer as a design engineer. In summary, I understand this concept.



- JyRO

 

[Will24]

Isn't mass a measure of the matter within an object? I thought mass did not change, say, on the surface of the moon. I was under the assumption that weight was the pull of gravity on an object





-Will

 

[Pit Bull]

You guys are all wrong, I was Albert Einstein in a previous life and E=MC\2, if you had MC\2 tires they would have all the energy they needed to not hydro-plane :-{} :-laf

 

[JyRO]

kgm or kgf...

Will, matter within an object? Maybe you're thinking of volume.



You can have lbf or lbm (same for kgf, or kgm), where the lbf is pounds force & lbm is pounds mass. Like I said, I'm no expert on this, understand the concept of pressure though. My understanding is that lbf is basically what we understand as weight, where earth's gravity acts on an object's lbm. And you're right, the lbm would not change on the moon, but the gravitational constant would, therefore its lbf (weight) would be different on the moon. In the case of P=M/A, the M (mass) would be lbf (or kgf etc). I doubt that is explained very well.



Regardless, the more mass (lbf) or weight is exerted through the tire, the more capable the tire is at pushing water out of the way and taking advantage of the tread pattern and actually making contact to the ground, instead of riding on a thin layer of water.



- JyRO

 

[Hohn]

OK, JYRO, riddle me this.... (Physics 101)

Jyro, I am not an engineer by trade but I did have to take a LOT of engineering classes in college.



P= Force/Area. It's not mass. Plain and simple. It's force. Let me explain why.



Your dissertation on lbm vs lbf is only partly correct. Lbm is mass. lbf is a force. The force is F=MA, or mass times acceleration. In this case, the acceleration is caused by gravity, and is known as the gravitational constant. At sea level, it is about 32. 2 feet/sec/sec or 9. 8 meters/sec/sec. This is the sea level gravitational constant-- yes it gets less as you go higher in altitude away from the Earth's center of gravity. Then we're getting into gravitational field equations, so it's beyond the scope of this.



Actually, WILL is 100 percent correct. Mass is the amount of matter within an object. Volume is how much space it takes up. They are not the same. This is another concept called density (Greek letter rho). Density*Volume= Mass. The whole metric system is based on the constant that one milligram of water MASS takes up one milliliter of VOLUME.

When you say Pressure is not equal to mass divided by area, you are wrong. Mass is a measurement of force. Whether that mass is pounds, kilograms, ounces, milligrams, newtons, it doesn't matter. They are all masses, and they are all acted on by gravity

Check your facts again. Mass is not a measurement of force. This is proven by Newtons Second(?) Law Force= Mass*acceleration. It is the opposite: Force is a measure of mass, and acceleration acting upon that mass.



You are further wrong to say that the units don't matter! Pounds is force. Kilograms is Mass. Ounces is volume or force (if you mean weight vs. fl ounces). Milligrams is mass again. Newtons is the metric unit for force. In fact, going back to the F=MA equation-- one Newton of force is enough to accelerate 1 Kilogram mass at a rate of one meter per second per second (per sec^2).



Think of the definition of Torque. Torque is a FORCE acting at a DISTANCE. Thus, our unit is Lb (force)* Feet (distance. The metric equivalent is Newton(force) Meters(distance).



Think back to your Chemistry classes. Remember the concept of a MOLE? I. e. , one mole of this element, one mole of that, etc.



A mole is a constant number of Atoms, it's something like 6. 28x10^24 or something (I don't remember). BUT a mole of tungsten has more MASS than a mole of helium. Why? More protons, neutron, & electrons. MORE MASS! Refer to the periodic table to see the huge difference in atomic weights of tungten (W) and Helium (He).





The bottom line is this: People get confused because the only way we have to measure mass feasibly is to weigh the object and divide by the gravitational constant. F=MA, so M=F/A. Since gravity is relatively constant, it gets dropped, thus one Lbm comes to be understood as on Lbf. Same thing for Kg, though properly the metric "weight" of something should be in Newtons.



I am trying to avoid urinary olympics here, :-{} :-{} but I know that we here in the TDR all value solid, accurate facts. We are also big enough to admit when were are wrong, and if someone, anyone can demonstrate to me how I am in error, I will eagerly apologize. I value accurate facts as much as anyone, even if they come at the cost of my fragile ego



Your Geeky Servant

HOHN

 

[Hohn]

good link that explains this

Here's a good link that Explains all this in simple terms... .



Howstuffworks.com on force, torque, power and energy



HOHN

 

[Pit Bull]

You guys are making my head hurt

 

[pkennedy]

Without seeing the scene and all the particulars of the accident it is pretty hard to make all these judgements I have read here. Anyone who drives continously in ice and snow conditions will tell all the professors out there that the narrower the tire the better the bite on ice pending tire compound hardness. Lady Jane before I would give my friend any advice on the situation it would be recommended to travel with her in a vehicle like her dually and observe driving technique. Generally you will find that there are things that in her driving style that will direct you to problematic behaviours, empty duallies react with more rear swing out than a single wheel p/u when brakes are spiked even with ABS. This combined with a habit to overdrive these vehicles (they are not cars) has caused concerns with todays drivers , SUV statistics in accidents show this all too well. Keep your observations to yourself and suggest to friends or club members an events day with an organized skid school or agressive driving course and invite her even if you have to pay her entry cost. The education you get out of this for you and everybody else is worth it, confront her directly and you will be minus a friend. Most sports car clubs have these events and comparing your trucks to there cars may inspire them to invite your members/friends along and usually have one or two professionals willing to teach without intimidation. Part of my job in safety is to teach pro-drivers better driving techniques especially in adverse conditions and when some have 30 years driving and bad habits personal confrontation is bad news, make it a competition and they usually have fun and recognize their mistakes. Hope she is okay but realize she will already be second guessing herself. PK

 

[Champane Flight]

No substitute....

I think after reading this thread that everyone has way too much time on there hands.



The reason her friend piled it up was very simple. She was driving TOO fast for road conditions. Driving along, going down the same road over and over again and not paying attention to the road conditions until it is too late, then slamming on the brakes.



There is no substitute for good rubber (siped tires) and WEIGHT in slippery conditions. That and good defensive driving skills. If you know it is going to be slick, load the truck up with at least a thousand#s, tie it down, and take it easy. Have tire chains, sand, shovel, blankets, snacks, flashlight, and warm clothes in your vehicle in bad weather conditions. If there is a chain law in effect, abide by it.



Most times bad roads can be avoided by waiting a few hours for highway crews to get to it, sometimes it is better to stop for twenty four hours, than to risk your life. :{

 

[pkennedy]

If you read into my post that has all been stated in a way to maintain this ladies friendship and to analyze the problem. You are absolutely right in fact but the way we transfer this info to friends is not so easy, like I previously said set it up so that a group of people benefit from this information. When setting up events like slalem racing, skid school and agressive adverse driving each person will demonstrate to themselves their short comings. If you can get some pro drivers out to these events and volunteer some tips everybody goes home with some important info and a smile. Those that dont probably will never pick it up until a serious event with consequences push them into different thought patterns and change their ways. PK

 

[ladyjaine]

Lost Cause

I wish I could get the historical re-enactors I hang out with to pay more attention to their transportation. This is a group of history nuts with limited practical engineering experience. If the idiot light isn't on, it's fine. Some can and do take care of their vehicles and know how to manage in bad weather and how to haul a load of junk to an event safely. Most pile way too much stuff into a minivan or a 1/2 ton cheap gasser to get to events.



The most common response I got when I let people know what kind of a truck I wanted was, "Are you crazy? My (way underpowered gasser) didn't cost half that much and it can tow a (small and not at speed up hills) trailer. " Coming from people who break axles on trailers, tow trailers with siezed bearings (for hours!) and have burned up transmissions from towing overloaded trailers. I expect to be a 'rescue' truck a lot.



I'm not planning on setting up a driver training day for these folks. Nobody would show. However if the M-D TDR group is interested, I'll look into it. Summit Point?



Jean

 

[JyRO]

Scummit Point...

Ladyjaine - I've raced at "Scummit Point" on 2 wheels. And covered that track mighty quick. It earned that name because for 2 wheels, IT SUCKS! I don't know what it was like on 4 wheels, still rough I guess. Also I don't know if they've re-paved. Regardless it would still be a good place to try an event. Too bad I'm up in MI. Any type of motor event, I'm interested.



- JyRO