My wife and I have just planned a camping trip to Asheville NC. We'll be pulling our Toy Hauler loaded for a weekend camping trip. The TH unloaded weight is 5,900lbs. Our actual weight during this trip will be by best guess about 8,000lbs. My question is going down Black Mountain is it best to use the Tow Haul switch or manually select a lower gear? For those who don't know, Black Mountain is a serious grade with multiple run away truck ramps. I'm not worried about pulling the grade, I would like some advice about descending several miles of severe grade safely with a camper in tow. Thanks in advance to people who've done the deed.

SBB

Tow/Haul you will be more than fine...I dragged more than that down Floyd Hill on I70 outside Denver and really did not even need T/H...

Now the 16,700 lb I was pushed down by on Floyd Hill was another story entirely.

Make sure your brakes are adjusted correctly and everything will be fine.

be prepared for the first time you're heading down a big hill when your truck downshifts and revs to like 3K rpms. kinda scares you the first time, but once you realize its supposed to do that, sit back and enjoy the ride.

yep ...love tow/haul mode...you will be fine and do not need anything else

x2

be prepared for the first time you're heading down a big hill when your truck downshifts and revs to like 3K rpms. kinda scares you the first time, but once you realize its supposed to do that, sit back and enjoy the ride.
For the steep hills around here i just set the cruise at the speed i want with the T/H on and just sit back, it will rev quite high but maintain the speed setting so long as you dont tap the brake. Once you tap the brake then it will up shift and speed up.

As Woodchuck described, You will be a bit surprised the first time your trucs downshifts. I know I was pretty wide eyed when it happened the first time. Do not ride your brakes on the way down either. If you have to use your brakes (and you shouldn't) use enough braking power to slow yourself down 5-10 mph and let completely off the braks so they cool. If you ride them the brakes will overheat and you will experience brake fade which could lead to a dangerous situation. Trust your truck and you'll be fine.

I was on that hill a month ago and you will be fine with that weight. just leave it in tow/haul mode and enjoy the nice ride down the mountain.

I myself do not use cruise with any trailer loaded or empty. I know I don't have the reflexes needed should something happen & trailer brakes were necessary before truck brakes. The min. you tap the brakes in cruise your rpms change. I don't know about you, but I cannot hit the emergency button on the brake package faster than the rpms drop in order to keep the truck & trailer straight if needed. By the way my emergency button is remote & by the shifter. Just my .02. Have a good trip.

Thanks guys. I had no idea the T/H switch would hold the truck and trailer down that hill. I think it would be a good idea to set the cruise about 45-50 and just bring it down smooth and steady. However, I do wonder what would happen if I had to tap the brakes? Some describe the truck up-shifting and speeding up. Wouldn't the T/H switch hold it? Would it get out of control?

SBB

All it's doing is downshifting automatically instead of you manually picking a lower gear. There's nothing magical about it holding a speed, you can still speed up too fast if the load is heavy enough and hill steep enough.

It's still a nice feature but just be aware it's not doing anything "special". Before you crest over the top of the hill slow down some do you're not starting the adventure at a high rate of speed. Don't ride brakes, use them hard for a few seconds and really slow your speed down and then let off to keep them cool

tow haul and forget it

a lot of the big hills the tow haul will almost stop you...kinda cool:cool:

I have been off that same mountain a few times but only weighing about 12,500 LBS. gross. The first time off there I just left it in drive and as I braked from time to time the allison downshifted, holding back like a dream. Last fall I went off there with the about the same weight and decided I would put the tranny in manual mode and down shift it into 4th or 5 th gear (I can't remember) and it held back just fine. The only thing you have to watch is the sharp curves and watch out for run away trucks coming off the mountain behind you. That is a mountain that deserves respect.
Let me know how good the truck climbs the mountain on the way to Asheville.

A good rule of thumb is go down at or slower than the speed you would pull it at. Use tow/haul.

Thanks to everyone for the replies. Sounds like T/H is the winner. Since I use it every time I tow my camper, I won't have to worry about doing something different. I'm looking forward to the trip. This is the reason I traded my '97 Z71 for the Duramax. BigR, I can't wait to start that grade! My buddy has a 2003 F-350 Dually that will be going up with me. He's pulling a 23ft Nitrous camper. His camper is just a bit lighter than mine and he's got 4:10 gears. He no gotta Duramax and Allison though. There is gonna be some trash talking!!!

SBB

Tow/Haul is the answer. I would assume your toy hauler has electric breaks on it's axels so if you have to use your truck breaks you shouldn't have a problem. I learned the hard way with my 89 gasser on the down hill side of Monarch pass with my camper on and pulling my 8000# boat to Blue Mesa. The trailer has surge breaks and I was breaking very lightly on the pickup and never surged the trailer breaks. About half way down I knew something was wrong and found a pull off and checked. Right front break was totally burned up. Needless to say it made for a rather tense rest of the trip. I did learn from then on to hit the breaks fairly hard to set the trailer and had no problems thereafter.

Definiely the T/H mode. Your get grade braking that way with the Allision to assist you. I have the Cajon pass where I live and the grade braking works great. You dont have too much weight to worry about anyway. The Duramax is rated around 16000 lbs towing.

Pulled TT from TX to Yellowstone and back. Use tow/haul mode and set cruise at desired speed and you'll go all the way down the mountain without having to touch the brakes.

If you were in tow/haul mode and didn't set the cruise, would it still slow you down without touching the brakes?

Thanks to everyone for the replies. Sounds like T/H is the winner. Since I use it every time I tow my camper, I won't have to worry about doing something different. I'm looking forward to the trip. This is the reason I traded my '97 Z71 for the Duramax. BigR, I can't wait to start that grade! My buddy has a 2003 F-350 Dually that will be going up with me. He's pulling a 23ft Nitrous camper. His camper is just a bit lighter than mine and he's got 4:10 gears. He no gotta Duramax and Allison though. There is gonna be some trash talking!!!

SBBI run this route from Mooresville to Baja California 3 times a year. Loaded toyhauler @ 12,000 wet. T/H mode, center lane, watch the curves, they crown opposite of what you'd expect. Like mentioned above, the downshifting will definitely get your attention. You'll be awake for this ride, be patient, have a good trip.

I have come down the cajon pass with a combined weight of 26 k pulling doubles. I alway run t/h when towing. I set the cruise control at 50 mph and let it work, it will rev to 4000 rpm if it needs to. I don't let it go past that. If it starts to get to fast I manually give it some trailer brake(doesn't disengage cruise) to scrub some speed. She has never given me anything to worry about. I was only worried the first time. But I have never had a truck trailer combo come off the big hills so nice and easy. Ain't nothin' but a thing!

I have come down the cajon pass with a combined weight of 26 k pulling doubles. I alway run t/h when towing. I set the cruise control at 50 mph and let it work, it will rev to 4000 rpm if it needs to. I don't let it go past that. If it starts to get to fast I manually give it some trailer brake(doesn't disengage cruise) to scrub some speed. She has never given me anything to worry about. I was only worried the first time. But I have never had a truck trailer combo come off the big hills so nice and easy. Ain't nothin' but a thing!The 15 doesn't compare to this pass, nor does the grapevine ;-) The 40 is wicked on this one.

All it's doing is downshifting automatically instead of you manually picking a lower gear. There's nothing magical about it holding a speed, you can still speed up too fast if the load is heavy enough and hill steep enough.

It's still a nice feature but just be aware it's not doing anything "special". Before you crest over the top of the hill slow down some do you're not starting the adventure at a high rate of speed. Don't ride brakes, use them hard for a few seconds and really slow your speed down and then let off to keep them cool

Tow/ haul drops gears and Read on. Refinements in 2005 included an overall reduction in exhaust emissions and an increase in torque output, which was enabled by significant hardware changes in 2004. Those changes included a new variable-geometry turbocharger. Self-adjusting turbine vanes and sophisticated electronic controls automatically adjust boost pressure and exhaust backpressure. The vanes direct exhaust gas at the turbocharger’s turbine blades. These vanes can be opened and or closed to vary the amount of boost pressure. An electro-hydraulic device operated with engine oil, similar in concept to a camshaft phaser, adjusts the turbine vane angle. The variable-geometry turbo has its own sensors managed by the engine control module (ECM). A solenoid controls oil pressure against a piston that operates a small cam, which works on a unison ring that moves the turbine vanes simultaneously. As the cam turns, it varies the angle of the blades relative to the turbine wheel. The crucial advantage: With the moveable blades, boost pressure can be controlled independent of engine speed.

The variable-geometry turbo presents a number of benefits over the conventional fixed-geometry type. Boost can be controlled more precisely, with a greater range of modulation, than with a fixed-blade turbine. The Duramax Diesel 6.6L V8’s turbo eliminates the need for a wastegate, which is often the first turbocharger component to fail as mileage accumulates. Because the variable-geometry turbo can essentially change resistance and adjust the amount of exhaust backpressure, it also eliminates a separate exhaust pressure regulator, which was previously used to manage engine or compression braking.

The 15 doesn't compare to this pass, nor does the grapevine ;-) The 40 is wicked on this one.

Do you know the grade percent on this hill? I've been down it a couple of times in my Isuzu and manually downshifting doesn't come close to slowing you down. I'll let it get to about 50mph hard on brakes to about 35, then let it speed back up

Do you know the grade percent on this hill? I've been down it a couple of times in my Isuzu and manually downshifting doesn't come close to slowing you down. I'll let it get to about 50mph hard on brakes to about 35, then let it speed back upI'm not certain what the percentile is on the 40 drop through the hills. It's a forever roll down though. The turns are crowned outward. In CA they do the opposite, crowns mostly inward. Braking throws you outward and really leans the load.

you bought the nicest towing setup there is... enjoy it. isn't T/H for Toy Hauler?.... he he. I have a 7500lb Tahoe Transport, the Duramax with the Allison =no worries.

My question is going down Black Mountain is it best to use the Tow Haul switch or manually select a lower gear? For those who don't know, Black Mountain is a serious grade with multiple run away truck ramps.
SBB

Is that along I-77 just north of the VA, NC border??

I have come down the cajon pass with a combined weight of 26 k pulling doubles. I alway run t/h when towing. I set the cruise control at 50 mph and let it work, it will rev to 4000 rpm if it needs to. I don't let it go past that. If it starts to get to fast I manually give it some trailer brake(doesn't disengage cruise) to scrub some speed. She has never given me anything to worry about. I was only worried the first time. But I have never had a truck trailer combo come off the big hills so nice and easy. Ain't nothin' but a thing!

This sounds like a VERY good plan...think I'll try that next time I get my RV on a steep road...:D

I'll be traveling up to Ashville in May, and this topic helps a lot. So, basically, if going down hill in T/H I should set the cruise control at the desire speed and leave it alone, correct? Does this apply also when going up hill, or do you approach that a little different? I'll probably be pulling close to 9,000 lbs plus an 800 lbs golf cart on the bed.

Soggybottom, how did you compare to the F350? Much trash talking going on?
Let us know.

Do you know the grade percent on this hill? I've been down it a couple of times in my Isuzu and manually downshifting doesn't come close to slowing you down. I'll let it get to about 50mph hard on brakes to about 35, then let it speed back up



If I am not mistaken it is a 7 percent grade that last 6 miles or so.

If I am not mistaken it is a 7 percent grade that last 6 miles or so.

I know Monteagle is 6% most of the way and my Isuzu won't go past 40 loaded on it. There is Highway 111 between Chattanooga and Cookeville, tn that has 8% grades and sharp curves on the downhill side and my poor Isuzu was down to 25 at the top going up. the Dually on the other hand I had to back it off because it doesn't know when to stop pulling. :D

Is that along I-77 just north of the VA, NC border??

That is Fancy Gap you're thinking of. That is one heck of a hill, and about 6-7 miles long at that. Might be among the strongest hills in the eastern US, along the interstate system.

I've been through Black Mountain, NC before, I have hauled several Saleen and SVT Mustangs for Black Mountain Ford. Use your Tow/Haul, and just be careful. You can use your manual gear selection too, that will help. You'll be fine.

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