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Towing through mountains

schl44
Explorer
Explorer
I need some advice. I have a F350 with a 6.7 deisel automatic transmission. I tow a 37 ft toy hauler. So when approaching a steep long grade how do you proceed. Do you just use the tow/haul or do you select the manual shift and start down in 2nd or 3rd gear? Thanks for any pointers!
19 REPLIES 19

jnharley
Explorer
Explorer
We have a 15 Ram dually with Aisan transmission and use tow/haul and the exhaust brake. We installed and Edge monitor so we can look at transmission temp/EGTs and a bunch of different things. Rarely do we have to use the brakes when going down a grade. With the "manual" shifting and exhaust brake, we feel well in control.
2015 Dodge Dually
2012 NuWa Discover America 355CK

lightning_drive
Explorer
Explorer
I'm surprised nobody mentioned keeping an eye on EGT's and trans temp and Tach. Of course I have an OLD 1999 7.3 F550. I choose to keep it in the 7.3 sweet spot of 2200 to 2500 rpms. EGT around 1300 degrees or so. Only a 4 speed auto. on a 6 or 7% grade this = a speed of 35 to 45MPH.
Pulling a 20K# loaded toy hauler.
Not sure any of this applies to the new 6.7 which has way way more torque then my 7.3. I would still recommend keeping an eye on temps.

Planning
Explorer
Explorer
If you have a new model F350, you should have both Tow/Haul function and Engine Braking. I pull a 16k lb 5ver with a 2016 F350 DRW. I will pull most grades at 65mph unless I (unintentionally) get behind a slow moving vehicle.

I will usually start any significant grade selecting 5th (but still in cruise), to attempt quicker converter lockup. (At this point I am unsure if the converter locks in 5th or 4th on the 2016 transmission). It is rare that I will see an automatic downshift into 4th.

For descent, I will set my cruise at 55mph, and the combination of tow/haul and exhaust brake always holds me to within 5 mph (sometimes climbing to 60 prior to applying increased hold back) of 55mph.
2016 AF 29-5K; 2016 F350 6.7, 4x4, CCLB DRW

GoPackGo
Explorer
Explorer
If you Google the song, you'll find a pretty good Youtube video (Gopro ?) of a drive down the pass accompanied by the song. The song lyrics are absolutely hilarious.

Grit_dog
Nomad III
Nomad III
^Lol
All the geezers on here and only one comment about CW MCCall, one of Colorados finest??
I remember listening to CW as a kid when it first came out. You got a copy on me pig pen cmon?
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ€ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

GoPackGo
Explorer
Explorer
I have a 2013 F350 diesel dually pulling a 36 ft fiver. I will assume we are talking about non-interstate highways in states west Nebraska.

I always ALWAYS use Tow/Haul mode when I am hitched up. There is no reason not to.

Going uphill, I turn off cruise control and I don't necessarily try to maintain my normal level ground cruising speed. At best you will burn diesel at an alarming rate for absolutely no gain. Do not be in a hurry when going up or down. If the trans starts shifting down to 5th and then back up, I will generally just lock out 6th. Or 5th and 6th, etc. I usually only run about 60 mph anyway so the revs can start dropping off early in 6th and that's when I lock out 6th. I don't let the revs drop below 1500 going uphill in any gear. I don't mash the pedal in 5th just to maintain higher speed either. If revs start dropping I'll just lock out 5th and motor on in 4th. I shift down early in all gears to pick up some revs if I know it's going to get steeper. I don't use Manual mode much but might start experimenting with it. I suspect it might offer a few advantages.

Going down. I go over the crest and start down in a lower gear at slower speed. The general rule is to go down in the same gear you used coming up. I lock out the top 2-3 gears at the top. If needed, I will use the brakes to knock off 5-10 mph but you do not want to use the brakes very much. That's why it's important to start over the top at a slower speed in lower gears. Notice how the truckers do it. They don't start down going at 55 mph. I would never use cruise control going down and ALWAYS make sure that Tow/Haul is on.

** I drove it this way going both up and DOWN Wolf Creek Pass and did not hit the feed store in downtown Pagosa Springs.

Grit_dog
Nomad III
Nomad III
Seriously, let the truck do what it wants/needs going up the hills. You'll find the sweet spot for speed/rpms pretty quick.
Going down, start slow until you know how much, how fast you can run down hill with your load. And as said above, when you need to use the service brakes, use them firmly and briefly to get down below your threshold speed and then get off them. Give em time to cool before hittin them again. Don't ride them.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ€ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

Grit_dog
Nomad III
Nomad III
Listen to CW McCall, "Wolf Creek Pass". Don't crash into the side of the feed store in downtown Pagosa Springs!
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ€ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

Lynnmor
Explorer
Explorer
I leave it in drive with tow/haul on. The Ford engineers have it figured out just fine. The only time I ever use manual is cruising on an interstate, with rolling hills, to prevent downhill downshifting when moderate speed gain is OK.

BB_TX
Nomad
Nomad
I have a F350 6.7 towing a 35' 5er and have never used manual shift. I just press the throttle and let the truck decide where it needs to be. Works fine going up Colorado mountain passes.

DanNJanice
Explorer
Explorer
Also, do not worry too much about holding speed. Every time a see someone with a 15000lb 5vr going over a pass at 80mph, I am thankful I decided to buy my truck new, rather than used.
Just downshift as needed, get into the right hand lane and maintain a reasonable speed, say 45-65 depending on how steep the grade is.
On the way down, let the tranny/exhaust brake do most of the work.
2015 Jayco 27RLS
2015 F250 PSD

ChuckV1
Explorer
Explorer
I use the tow/haul going up and down long grades, I do not leave it in cruise control, I have heard bad things about vehicles jumping out of cruise because of to much pressure on the transmission... Also If the pedometer start to sound I back off till it quits, your only hurting your engine if you keep pushing it past that point of no return ...

I going down the hill useing a lower gear than I went up the hill, not applying the brakes hard (never ever hold down on your brakes hard for length of time you will loose them going down a 6 percent grade). I Only apply my brakes enough to keep me at a slow speed an not over rev my engine or picking up any great ampunt of speed ...

Some of the grades out here in the western United States are 6 percent at 10, 15 and at times miles longer... If you keep hitting your brakes every few seconds or really hard you will loose them, trust me, I've seen it...

Do not be sacred of any of the mountain passes out here, if you use you head, think about what your doing you will be fine ...

Safe travels

Redwoodcamper
Explorer
Explorer
Tow haul is a good start. If it seems to be bogging down or having a hard time keeping speed then you can experiment with downshifting. Hard to say without your trailer weight and driving it. If your Ford is stock then tow haul should do it. If you have a programmer or anything then it gets more complicated.
2011 ram 3500. Cummins 68rfe. EFI live. 276k miles and climbing.
2017 keystone bullet 204

ktmrfs
Explorer
Explorer
set cruise control go into tow haul and let the engine/transmission decide what to do on the way up. and if cruise works going down (which the allison on late models do) turn on exhaust brake and set cruise for desired downhill speed and let it do it's work to hold you on the downhill side.

sure, you could use the manual transmission mode, turn off cruise, but I've never found that to be an advantage, if anything a disadvantage. I just let cruise control do it's job. It's been very very very seldom where cruise wouldn't hold the speed I wanted, or very close to it.
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!