Downshifting down hill and uphill!?

Your going to blow that transmission apart. Downshift at 1,300 when pulling a grade. Upshift at 1,700. That is a good rule.
Do you have a 10, or 13 speed?

 

What engine? Each engine drops RPM at varying rates. Just practice your timing between shifts. You're either shifting too fast before the RPM falls to meet the road speed or you're shifting too slow. Keep an eye on the tach and use 500 RPM or so as a base guideline. It really just takes practice. Try to avoid grinding it in though. Transmissions are very expensive.

 

Cummins, or MX13?

 

I take it you’re not double clutching?

 

You do not shift what your speedometer says. That's NOT what's its for.

Your RPM Gauge tells you where and when to shift.

There are two numbers on that RPM gauge you need to learn. Torque and high horsepower.

On a 500 detriot that I had, I think I downshifted at about 1300 or so and upshifted no more than 1600

If you are going uphill and rpms fall towards 1300, your truck will begin to shake a little bit and you put the clutch in, slap the hammer to get RPM's up while in neutral and click it right into 1600 or whatever it is supposed to be for the next gear down. Eventually she will settle and stay in one gear the rest of the way up.

After you come off the top, downshift one more time, set up the jacobs braking. If she stays in that gear without HOPPING or BUCKING you are doing well You might have to take a gear up until the jacobs braking takes control asserting one speed without touching brakes at all all the way down. Without the lurching, hopping or bucking. You will find the RPMs pretty high, but as long you are not over redline which I think is around 1950 or so you hold what you got.

The theory is that you come down the same gear you come up. If it is a major mountain with a PULL OFF at the TOP you pull off a minute and do a pretrip looking for trouble areas, flats and so on. (Hot bearings, hot hubs, hot brakes etc) And espeically get your hand close to but never touching the main line feeding your primary air tanks from your engine air compressor on the left side. If that line is cold and you feel no ticking inside that compressor you should consider that you have no air and cannot make it down the mountain safely.

Make sure your coolant is normal and not overheated. Same thing with your engine oil and pressure along with your transmission, drive axles and especially that Pyro. RUn your hands along the clamps holding the big intercooler air supply towards your turbo to make sure you aint leaking there. If you are leaking you not only are going to smoke way too much but you will not be able to generate real power.

If that downshift scratches, immediately try to get the next gear down. Or return to the gear you left. If you missed all of that then take the next gear above where you are. If you missed everything STOP on the side instantly and start over. If you don't you have a runaway.

Drive downhill the slowest truck on the mountain. Don't be so slow to cause a crash. Pay attention to your escape ramps. If you are above a certain speed and cannot get air back or already smoking badly etc take the ramp. (it's going to cost you financially, but way better than being killed or killing a family past it)

If you do these things safely and slowly taking your time in any mountain you will get down everytime regardless of the weather. With one exception. If you have chain and are told to chain up YOU MUST CHAIN UP PROPERLY WITHOUT FAIL. If you don't have CHAIN, then DO NOT go that way. Learn how to use them properly at home shop LONG BEFORE you do get there and have to use it. The mountain is not the place to learn how to chain.

I spent my life time doing nothing but mountain. It will absolutely kill you or try to hurt you if you make mistakes, and it will be all your fault. What a waste. So don't make mistakes up there.

 

Once again, my head just exploded like in scanners.

 

You can shift gears on the level and getting up to speed. That's a good thing.

Uphill and downhill something different is happening and you need to understand it better.

When you are going uphill and you need to downshift that condition is different than being on the level because as soon as you take the truck out of gear to shift the truck itself is going to slow down. So in order to compensate for the truck slowing down when you shift you have to begin your down shift at a much higher RPM. In fact, the idea is to downshift at an RPM that when you get into the next gear you are just about at Full Throttle. Ideally after you downshift you really want to be at Full Throttle. That way you get the most out of the engine pulling the hill.

I don't know how the newer trucks are set up or how that engine is. I know some of the trucks are governed at 1800 RPMs or 1900 or whatever it is. You're going to have to experiment with downshifting from say 1300 to 1500 RPMs or something like that. 500 RPMs between shifts is about right as the guys have said. So if you're governed at 1900, you could downshift at 1400 or maybe even 1500. If you are governed at 1800 try downshifting at 1300 or so.

When you are shifting going downhill, the opposite applies. When you begin your shift and the truck comes out of gear the truck is going to want to pick up speed. So in that case you need to shift earlier.

So let's say on the level you shift at 1600 RPMs. Depending on how steep the hill is and how heavily you are loaded you may have to upshift at 1200 to 1400 RPMs.

Try not to get caught up in the actual numbers, but understand the concept. As you climb a hill loaded the truck will slow down as you begin to shift so you need to downshift at a higher RPM. As you go down a hill loaded you have to upshift at a lower RPM. The same applies to uphill and downhill empty, but the truck won't slow down or pick up speed as quickly between shifts.

Practice, and it will all work out for you.