Downhill RPMs and downshifting

[jebjam]

Looking for advice and experience. I drive through the mountains every week or two with a 10% grade for miles, mostly without a load but will occasionally tow in the months to come. I have used manual shift to assist braking. I've read in the general forum some find setting cruise going downhill the vehicle will downshift automatically to maintain speed, but these conversations all center around the hemi. I haven't tried that yet, but will.

My question relates to RPMs - when you're manually downshifting to assist braking, how high do you allow the engine to rev, what RPM do you allow your engine to reach before applying brakes rather than downshifting further? Any experience using cruise downhill, with or without a load with the ecodiesel?

 

[Rebelguy2020]

Looking for advice and experience. I drive through the mountains every week or two with a 10% grade for miles, mostly without a load but will occasionally tow in the months to come. I have used manual shift to assist braking. I've read in the general forum some find setting cruise going downhill the vehicle will downshift automatically to maintain speed, but these conversations all center around the hemi. I haven't tried that yet, but will.

My question relates to RPMs - when you're manually downshifting to assist braking, how high do you allow the engine to rev, what RPM do you allow your engine to reach before applying brakes rather than downshifting further? Any experience using cruise downhill, with or without a load with the ecodiesel?

I use the adaptive cruise control almost all the time, on my Rebel diesel, it functions the same way with or without a trailer, the hills are not that steep and are not that long where I travel most of the time, the first thing the truck does while on cruise and going downhill is that it will downshift, and if it keeps accelerating the brakes will apply automatically, the adaptive cruise will not allow the truck to go more than approximately 5 mph over your set speed, in my case because the hills are not extreme I usually cancel the cruise to avoid the downshifting and avoid the braking application, I don’t care if I go a bit faster than the posted speed limit, saves on fuel and saves the brake lining.
If you want to see the ecodiesel on the world toughest Gauntlet hill in Colorado, search TFL.com on YouTube, It did quite well.

 

[Dragonmaster13]

Alex on Autos did an extensive test on the ED on YT as well. According to him and TFL the Hemi downshifts and reduces speed much more than the ED.


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[jebjam]

If you want to see the ecodiesel on the world toughest Gauntlet hill in Colorado, search TFL.com on YouTube, It did quite well. View attachment 86474

Yes, I watched these before I bought. This is actually the mountain pass I travel...!

Thanks for the advice on using cruise I'll do that. Still the same question though, how high to allow the RPMs when doing this manually (or with cruise, though I suppose that's already sorted out by RAM).

 

[Rebelguy2020]

Yes, I watched these before I bought. This is actually the mountain pass I travel...!

Thanks for the advice on using cruise I'll do that. Still the same question though, how high to allow the RPMs when doing this manually (or with cruise, though I suppose that's already sorted out by RAM).

Sorry, I didn’t try to answer your question, I don’t think the truck computer will allow you to downshift excessively, but I haven’t tried it myself.
My suggestion is to make sure you stay out of the redline.
Let us know when you try it.

 

[LeeVanCleef]

I drive that stretch of i70 relatively often and 6th gear will usually hold it where I want it on the steep downhills while unloaded. 5th gear with my small trailer and going slower. Like someone else mentioned, the computer likely won't let you downshift too much.

I have noticed it downshift in cruise control to maintain speed.

edit - 2nd gen 2016, but same should apply

 

[Dragonmaster13]

The computer will not allow over rev of the engine and if over limited with manual gear selection it will not down shift.


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[WXman]

You can't manually shift the EcoD in the Ram. You can in the Jeep. I have no idea why. I would LOVE to be able to manually shift this thing.

In the Ram all you can do is lock out gears from the top down, which is a rarely useful feature.

 

[Rebelguy2020]

You can't manually shift the EcoD in the Ram. You can in the Jeep. I have no idea why. I would LOVE to be able to manually shift this thing.

In the Ram all you can do is lock out gears from the top down, which is a rarely useful feature.

It is called gear limit, but on my Rebel diesel, if I want to, I can manually shift and pause between 1st to 8th allowing the engine to keep higher revs and I can also downshift and pause from 8th to 1st, I can feel the engine slowing the truck, however the truck computer will not allow the truck to over rev while going up gears or down gears.
The manual mentions a WARNING not to downshift for additional engine braking on slippery surfaces....

 

[WXman]

It is called gear limit, but on my Rebel diesel, if I want to, I can manually shift and pause between 1st to 8th allowing the engine to keep higher revs and I can also downshift and pause from 8th to 1st, I can feel the engine slowing the truck, however the truck computer will not allow the truck to over rev while going up gears or down gears.
The manual mentions a WARNING not to downshift for additional engine braking on slippery surfaces.... View attachment 86694

How do you activate the manual shift feature? Because on my Bighorn Level II, it works only as I described in my last post, which mirrors what the owners manual says on that page you posted. No manual shifting, only locking out gears from the top down.

On the Jeep pickup, you can actually manually shift it. You have full control.

 

[Rebelguy2020]

How do you activate the manual shift feature? Because on my Bighorn Level II, it works only as I described in my last post, which mirrors what the owners manual says on that page you posted. No manual shifting, only locking out gears from the top down.

On the Jeep pickup, you can actually manually shift it. You have full control.

The manual shifting is not something I usually use but I specifically tried it again when I went to work at 5:30 this morning, I was coasting at about 50 mph and all I did is press the -button a few times, I didn’t even pay attention which gear I had selected, but it sure slowed me down and the rpm’s went higher, I then pressed +button to shift gears and lower the rpm’s because I didn’t want to scare the people when I got to the mine parking lot.
Maybe the Rebel has different functions then your truck.