8% grade descent

[PatsRock]

Newbie Here. F350 and 37' fifth wheel.

Yesterday I went down an 8 degree slope and left it in Tow Haul while using the breaks on trailer and truck to slow me down. I was thinking I might have been better off starting in 2nd gear at the top of the hill.

What is the correct strategy for braking on a big descent?

[BurbMan]

I would slow enough to drop into 2nd at the top of the hill, possible 1st depending on how twisty/turny. Leave it in tow/haul, that provides additional engine braking. I know on the burb 2nd gear limits speed to 45, 1st gear to about 30 on these steep grades. As long as no sharp curves I am OK at 45.

[marcsbigfoot20b]

Tow haul mode is a seperate map in the computer. This alternate map will have things like more line pressure, TCC lock up stays on with more load or throttle, stays in gear longer before upshifting and not downshifting with light throttle......in a nutshell.

With tuning software like EFI Live you can modify these settings like I have done on my truck, like adding TCC to second gear which was not available on the OEM mapping.

[dave17352]

Dwight45 wrote:
This is how it was explained to me. Decide at the top of the pass what speed you want to descend at, say 30mph. Pick a gear that will allow that speed. When you are about 10mph over that speed brake hard enough to return to 30mph, but do not brake for more than 5 - 7 seconds. Braking hard for a short period of time and then not using the brakes until the need to brake again results in cooler brakes. As someone said constant braking does not allow the brakes to cool. Emercency option, I lost my trailer brakes at the top of Monarch Pass in CO heading west. Couldn't get them fixed so I engaged 4L (4 wheel drive truck) and went down about 20mph. Only touched the brakes a couple of times but this is not something you want to do on dry pavement. I didn't have much choice.

Dwight

Then you are saying 1st gear in two wheel drive would not have held your speed down. I found in my Jamboree that first gear would hold that motor home back on very steep grades.

[Dwight45]

This is how it was explained to me. Decide at the top of the pass what speed you want to descend at, say 30mph. Pick a gear that will allow that speed. When you are about 10mph over that speed brake hard enough to return to 30mph, but do not brake for more than 5 - 7 seconds. Braking hard for a short period of time and then not using the brakes until the need to brake again results in cooler brakes. As someone said constant braking does not allow the brakes to cool. Emercency option, I lost my trailer brakes at the top of Monarch Pass in CO heading west. Couldn't get them fixed so I engaged 4L (4 wheel drive truck) and went down about 20mph. Only touched the brakes a couple of times but this is not something you want to do on dry pavement. I didn't have much choice.

Dwight

[dave17352]

mkirsch wrote:

PatsRock wrote:
Thanks so much for the help!

If I want to start out in 2nd gear at the top of a hill do I have to put it in Neutral, disengage the tow/haul, then put it in second gear? Just wondering what the correct sequence is?

No, and why would you ever think that it worked in such a cockamaime fashion?

gosh, that wasn't very nice!:E

[mkirsch]

PatsRock wrote:
Thanks so much for the help!

If I want to start out in 2nd gear at the top of a hill do I have to put it in Neutral, disengage the tow/haul, then put it in second gear? Just wondering what the correct sequence is?

No, and why would you ever think that it worked in such a cockamaime fashion?

You slow down to where the engine won't over-rev when you drop it into 2nd, and drop it into 2nd. Tow-haul is neither here nor there in this situation because you've overridden the shifting system by dropping the truck into 2nd.

[noteven]

Edited - OP suggest you ask an experienced driver to go with you on some practice runs to show you how to control a vehicle on downgrades.

[enblethen]

There is normally truck warning signs for steep down grades. Follow those instructions.
Been over many high passes and there is signs warning of down grades, usually a pull off at the top with shoulders and some have areas to check your brakes. this is the point where you would shift transmission down.

[RoyF]

Gdetrailer wrote:

enblethen wrote:
You should come to a near stop before descending. Then put the transmission in a lower gear. You may even need to be in low.
Rule of thumb in previous post is a good place to start.
Do not use the brakes them selves. You may not have any left at the bottom.

I have been on a lot of highways with 65mph-70mph speeds where "nearly stopping" will result in someone rearending you.. Not sure if you could really apply this to all roads, perhaps a very remote mountain road with no traffic..

A near stop is not needed for an 8% descent. Don't slam on the brakes, but gradually slow to 50 mph before the descent and put your flashers on. If you can't hold that speed with engine braking then brake until the transmission downshifts to a gear that will hold the speed. The thing is to never let the speed start to get away from you.

[time2roll]

PatsRock wrote:
Thanks so much for the help!

If I want to start out in 2nd gear at the top of a hill do I have to put it in Neutral, disengage the tow/haul, then put it in second gear? Just wondering what the correct sequence is?

Just pull the lever while rolling.

[dave17352]

trail-explorer wrote:
Often times I will manually activate the trailer brakes rather than continually using (and having the fear of overheating) the truck brakes.
I will use the truck brake pedal, but only occasionally and will alternate with manual activation of the trailer brakes.

THere's times where no matter how slow you start at the top, you will have to use the brakes some. I had this experience coming out of Beatty, NV in to Death valley, and the same thing leaving Death Vally going in to Panamint Valley.

This I disagree with. If you start out in first gear I don't believe you would have to use the brakes. But that is JMHO

[Thom02099]

PatsRock wrote:
Thanks so much for the help!

If I want to start out in 2nd gear at the top of a hill do I have to put it in Neutral, disengage the tow/haul, then put it in second gear? Just wondering what the correct sequence is?

In my Tahoe, I always use the tow/haul button. I also use 3rd gear rather than OD. When descending, I simply downshift to 2nd gear. No need to go into neutral. Have never had any problems. Only time I have to use the brakes is descending in canyons and coming up on severe curves. Lightly braking, and letting the engine/tranny do what they do best.

[ReneeG]

smkettner wrote:
Did you use the brakes firmly to get speed 10 to 20 mph under the limit then coast back up to speed?
Riding the brakes gently to maintain constant speed can lead to overheating.

X2. 2011 F350 DRW Diesel here with Tow/Haul mode. The best thing we've ever had for those steep descents.

[PatsRock]

Thanks so much for the help!

If I want to start out in 2nd gear at the top of a hill do I have to put it in Neutral, disengage the tow/haul, then put it in second gear? Just wondering what the correct sequence is?

[trail-explorer]

Often times I will manually activate the trailer brakes rather than continually using (and having the fear of overheating) the truck brakes.
I will use the truck brake pedal, but only occasionally and will alternate with manual activation of the trailer brakes.

THere's times where no matter how slow you start at the top, you will have to use the brakes some. I had this experience coming out of Beatty, NV in to Death valley, and the same thing leaving Death Vally going in to Panamint Valley.