Downshifting down hill and uphill!?

I'm no expert on this stuff, I just do what works for me. When I'm with a new driver and they struggle with this it is usually because they were told they have to rush that gear change or they'll be stalled out on a hill, or worse, they'll be out of gear and racing out of control down a hill. I understand what trainers are trying to tell them but it instills this panic in them that really messes up their shifting. Took me a long time to break out of that myself and stop rushing my gear changes on the hills.

I drive an 18 and split my gears so I can't tell you exactly where to shift your 10 speed. I've driven them, but it has been a while and I shift a lot based on sounds of the motor. But what I remember tells me this...

Downshifting while climbing a hill I'd run the tach down to say 1300. By then the motor was about powered out and if I ran the RPM's any lower it would make it hard to get it out of gear. So 1300, I'd pull gently on the stick and let off the power and it would slip out into neutral. Now gently run the RPM's back up to 1700 and float it back into gear. When it nestled in nice I'd get fully back on the throttle. That is a 400 RPM spread and that is enough to offset the speed I would lose on the hill during the shift, without rushing the shift but not wasting time either. No where near the hectic rush they told me I'd need to grab gears back in trucking school.

FYI, I'm talking about floating gears here. You ask me to clutch my gear changes and I'll probably grind them worse than you are.

To pick up a gear coming off the hill isn't much different than on the flats except that if you don't make the gear change on the first try (too much grinding) you need to remember that you are picking up speed, not losing it and either rev higher on the second attempt or use your brakes and slow back down. If you want to drop gears going off a hill brake all the way down to 1000 RPM's and rev up to 1600 (or 1700 if you feel yourself picking up speed).

None of this helps much because it all sounds so simple to say it but quite different when you are actually in the truck. Easier if you float your gears because you will feel what the transmission is telling you about how close you are to matching things up for a smooth shift, but if you aren't comfortable floating then no worries. I would advise you that when possible you don't just grind it in. If you fail to make the gear change and need to hit your brakes and slow back down and try again then do that. Better to use some brakes and learn where the sweet spot is than to just force it in, ruin a transmission, and still not learn how to shift in the process. If you are climbing the hill and have to try again, you just go for the next gear down. You missed 9th so you go for 8th instead, you rev and try and if it grinds, you rev and try again. No forcing, just looking for that sweet spot to open up. Two gears down is a lot of road speed so you have plenty of time to keep trying as the truck slows and eventually it will match up. Even old hands sometimes miss a gear pulling a hill and have to drop to a lower one, it isn't the end of the world.

This next part isn't ideal shifting, and I'll probably regret saying it, but if it really, really goes wrong for you and you get stuck in that cycle where you keep chasing down gears and can't catch one and you are worried you will stall out in traffic climbing a hill you can go to a gear you know is lower than you need, give it a little RPM and let it bump until your road speed drops enough it lets you in. You'll save yourself stalling to a stop but if you are overly aggressive you will grind up a transmission and then slam into gear and maybe break it or your drive train. I'm telling you to let the stick bump and then slide in if it will, not to forcefully grind it in. You can only get away with that for so long before something breaks. By bumping I mean you put the stick against the gear only enough to get feedback to your hand what is happening.

And I don't know what you mean exactly about stalling out in 2nd gear, but loaded you want to take off in whatever gear the truck will pull to a start without needing throttle or the clutch slipped. If you take off in 2nd and the truck stalls it is too heavy, or on too much of an incline, for that gear and that load. Just take off in 1st if that is happening to you.

 

Was his response the cause?

 

Eaton automatic: for fun the other day I manually shifted this dog out of 10 at 1050 rpm to 9 at 1350 going up a hill yo try and go faster. The thing actually slowed down more. This is the strangest truck I have ever driven. Nothing makes sense. Going down a hill with engine brake off the tach is at 1450. When I hit the bottem, then it goes to idle, I lose 5 mph then it catches. It's a doing going up even the slightest hill, Losing 5-7 mph. But going up big hills, it gets to a point at 53 or so and grunts down and I pass most everyone. Crazy truck.

 

To state the obvious, you aren't getting the engine speed matched with the transmission input shaft speed, when you're trying to go in gear. Either you're over revving on the uphill, or you aren't bumping it up high enough. Downhill, you're either moving the shifter too slow, or you're moving it too fast. You have to figure that out. Watch the tach. If you're at 1100 going up hill, go to neutral, bump it. If it goes to seventeen, wait till comes back down to 1400 before you in gear. Did it even make it to 14? Some engines have good throttle response, some are lazy. If you're in a truck that hasn't had good drivers in it, the gears may be chewed up from other people forcing and grinding. That makes your RPM window even tighter. Focus on what's happening with the truck's speed, and what the engine does, and make those mental calculations to compensate for what you need to do. Do you know what engine you're running?

 

Its not really a good idea to shift going downhill, especially if you are trying to downshift. Its best to get in the gear you want to go down the hill in Before you drop off the hill, especially if youre dropping off a mountain. If you miss a gear, the only thing that will stop you is your brakes, if they dont get hot, then nothing will stop you. Jamming the tranny in gear could break the teeth off the gears in the tranny, then you would be in a fix.

 

You're trying to shift at too high an RPM.

Your gear needs to match your road speed on the 5s. 45mph? Add the 4 and 5 together, and you'll see you'll need to be in 9th gear. 35mph? Add 3 and 5 together, and you'll see you need to be in 8th gear. 25mph? 7th gear. 15mph? 6th gear.

Low range: In 5th gear, the RPM will match the road speed multiplied by 100. At 10mph, you'll need 1000RPM to get 5th gear to drop without grinding. 12MPH, 5th needs 1200RPM. Don't try to downshift below 5th until you get a few years under your belt. If you're slowing below 9mph, plan to come to a complete stop and then shift to your starting gear.

Hope that helps.

 

Take it to a shop and get it programmed to match your driving style. Sounds like it's not set up the way you'd like to see it.

If you own the truck, that is...

 

As someone else said, downshift at a higher speed, which puts it at a higher rpm, to give more time to catch the gear. Sounds like you are lugging the engine down too much.

Dont forget to pop the throttle a little so you dont miss the gear at the higher speed and rpm.

Does your temp gauge get hot lugging the engine that much?

Practice more downshifting on flat ground to improve your skill at downshifting. Use the interstate off ramps to practice downshifting.

Expect 20,000 or more miles to get better at downshifting.