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Understanding and Driving Mountain Grades
If you’ve driven for long, at some time or another you’ve come to a sign that said something like, “7% Grade next 5 miles, Trucks Use Low Gears” You probably know that means there is a hill coming up, but you didn’t really understand exactly what it meant, how it will affect you or how it compares to other grades. In this post, I want to explain all that.
What is a “Grade,” and what do the percentages mean?
Grades are measured in units of 100 feet. If you drive 100 feet and you climb or descend 6 feet in that distance, then that grade is 6%. If you travel 100 feet, and you climb or descend 10 feet, that’s a grade of 10%. Because very few of us think in terms of 100 feet at a time, a more practical way for Americans to think is in miles. A mile is 5,280 feet, so if you drive 1 mile, and climb or descend 528 feet in that mile, it’s a 10% grade. If you climb or descend 370 feet, that’s a 7% grade, or if you climb or descend 264 feet that’s a 5% grade. Carried to it’s extreme, a 30% grade means you go up or down almost 1600 feet in a mile.
How do the number of curves and sharpness of the curves affect me?
On a long straight stretch of hill, you can just put it in a lower gear and let the engine do much of the work of getting you up or down the hill. But if the hill is full of sharp curves, then you have to slow down to go around the curves. By doing that, you lose much of the momentum you had going into an uphill climb, or it forces you to slow down much more than the engine wants to in a steep downhill. For example, my van can climb 6% grade comfortably at 40-50 mph. But if I slow down to 25 mph for a curve, I can’t accelerate much beyond that unless I come to a level spot where I can accelerate, that means I’m going to climb the rest of the hill at 25 mph. Going downhill on a straight 7% grade, if I put it in third gear I can maintain 45-55 mph with a little use of the brakes. But if that same hill has 25 mph curves, I’m going to be using my brakes very hard to go that slow even in second gear.
How do I apply that to my life? By taking notes.
It’s nice to understand what the numbers mean and the math behind them, but what’s important is that we apply that knowledge to our lives and make it useful. Because all of our vehicles are different, they’re going to mean something different to each of us. For example, if you have a high-powered sports car, none of the grades will mean anything to you because you have so much power you can just fly up and down all those hills. On the other hand, you might have a 1973 Dodge Class C with a 318 V8 towing a Jeep and you will just barely be able to make it to the top of some of the bad hills. And if you do, it will be at 15 or 20 mph and your engine will be screaming the whole time. In fact, on the steepest of them, you may simply not be able to drive up them at all, you’ll need to find a different route.
Most of us fall between those two extremes, we are either living in a van or RV and while they can climb and descend most of hills we come to, the question is how difficult, or even dangerous, will that be? To find out, you need to start studying the hills you climb and even taking notes. I suggest getting a notebook or using your phone and have a page called “Hills”. For each hill you drive, write down the location and description of the hill including its grade and its curviness. After you’ve gone up or down it, take notes on how difficult it was:
- Did the engine temperature rise, did it start to get hot? Even worse, did it steam?
- What gear did you use going up and down?
- What speed were you able to maintain?
- On a scale of 1-10 how much did the engine seem to be struggling?
- Did the brakes start to fade or need extra pressure? Did they get hot or did you smell them burning?
Over a period of time you’ll start to see a pattern and you’ll know how capable your vehicle is for each grade of hill and also learn what speed and gear works best for your vehicle. You can use that to decide which hills you are willing to climb or descend and which you need to find an alternate route.
It should gain you more confidence and extend the life of your vehicle.
Tips for Driving Uphill:
- Hit the bottom of the hill with as much speed as you can and let momentum carry you as far as it can. Sometimes this just isn’t an option but sometimes it is. Take advantage whenever you can.
- Keep your vehicle as light as possible–extra weight just makes the engine work harder going up and the brakes work harder on the way down. Since we are living in our vehicles, everything we own in the world is in them and they are going to be much heavier than the average vehicle. This alone is a very good reason to adopt a minimalist attitude toward your possessions.
- Carry as little gas and water as possible. Sometimes you have no choice but have full tanks, but as much as possible have all your tanks as low as you can. 50 gallons of water and 20 extra gallons of gas in the tank is an unnecessary 560 pounds. Give serious thought if you can climb the hill without it.
- Turn off the air conditioner. The air conditioner in your car draws power away from the wheels and creates extra heat under the hood. Roll down your windows and be hot if you must.
- Plan your schedule around the hills. With some really bad hills that you can’t avoid, you might give thought to climbing them earlier or later in the day when there’s less traffic and its cooler. That way the engine will have an easier time and here will be less traffic to back up behind you. On a really bad hill, you might even give thought do driving it at night.
- Add a transmission oil cooler to your vehicle. Heat is what kills automatic transmissions and the cost of the oil cooler will pay for itself many times over with longer life for your transmission. This is especially true if you are towing a trailer! I recommend U-Haul service centers. They put one on my van and did an exceptional job at a great price.
- Take the transmission out of overdrive and downshift as needed. You want to use the lowest gears possible that will let you maintain the most speed you can. You’ll need to study your vehicle to learn what works best for it, but my van will climb a 5-6% grade in third gear at about 50 mph, and a 7% grade at 35-40 mph in second. It will barely climb a 10% grade in second gear and anything steeper I’ll be in first gear. I never climb any hill in overdrive.
- Pull over and let the engine cool down and give yourself a break. However, some hills are so steep you won’t be able to accelerate up the hill from a dead stop. In those cases just crawl up them as fast as you can without stopping.
- What do you do if your engine starts to overheat or if it starts to give off steam, I’ve got to be honest with you and say I found a lot of webpages that gave opposite advice of each other. Many said find a safe place to pull off the road, park it and turn the engine off. Others said not to shut off the engine, but to step on the gas instead and bring it up to a high idle. Since the experts can’t agree, I don’t know what to tell you.
- However, all the experts agreed that you should never remove a hot radiator cap! Steam and very hot water will come shooting out and you could be severely burned.
- A faster way to cool an engine is to turn on the heater. If it’s a hot day you’ll just have to endure it, or pull over, get out and leave the doors open while the heater is on.
- If you have extra water, you can pour some cool water over the radiator to cool it faster.
Tips for Driving Downhill:
- Use a lower gear. People behind you may be pissed off, but you have to stay safe!! Big, heavy vehicles must be careful with their brakes on extended down-grades or you can burn them to the point of total failure and you’ll become a missile flying wildly down the hill endangering you and everyone around you. Newer vehicles have much better brakes than older ones, but the majority of us have older brakes so you’re just going to have to make some people angry. Near Steamboat Springs, CO is a 7% downgrade that lasts for 7 miles. I went down it in third gear at 35-45 mph. I had a line of cars behind me but my brakes were in great shape at the bottom
- Don’t ride the brakes! By riding the brakes I mean having your foot on it the whole way down the hill applying a small amount of pressure constantly. Instead, you want to let the van start to speed up and when it’s going as fast as you can allow because of the speed limit or curves, step on the brake hard to slow down slower than you would ideally like. Then get off the brake entirely and let it accelerate. It may seem like you are not off the brakes enough for them to cool down significantly, but you are. I’ve counted the seconds (one thousand one, one thousand two, etc…) for the amount of time I’m off the brake and the amount of time I’m on, and it’s usually a 3 to 1 ratio. If I’m on the brake for 5 second, to slow it down from 50 to 35 mph, it’ll take 15 seconds for it to accelerate back up to 50 mph where I’ll get on the brake again. That’s enough time for your brakes to cool off and it will get you down the hill safely.
- If your brakes appear to be getting hot or fading, pull over and let them cool off. Our lives and the lives of those on the road around us are worth much, much more than those few minutes it costs out of our busy lives. Just as importantly, it’ll be a great opportunity of practicing Zen and training yourself to actually enjoy your life instead of rushing through it as quickly as you can without thought of enjoying it.
So there you have it, some common sense ideas about climbing and descending steep hills. Now go out there and enjoy the beautiful mountain views to their fullest!