Downhill Towing

[MJLANS]

Had a scary experience towing my 5er down a steep grade recently. I was in t/h and dropped to M3 to start, but to much Rpm and went to M4. Using too much break, they began to fade and fortunately ran out of hill, cuz I was nearly out of break. How should I have handled it? What is the best way to come down a steep grade with a heavy load?

 

If I leave it in D, will the tranny keep the speed down in T /H?

 

I have a 2500 6.6 Dmax. Trailer weight is about 11k.

[TimmyG]

Dang sounds like a heck of a hill.

Just a crazy guess but wouldn't a jake brake help?

 

Sent from my SCH-I535 using Tapatalk 2

[Morgan1986]

Install a Jake break first they really help . Then upgrade your breaks if you need more stopping power. I dont believe leaving the truck in tow mode in high would of helped .

 

If you where not on a busy road I would of put it in low and in like 3rd and crawled down the hill and just keep tapping on the breaks. No hard breaking or you will have one or two good pumps and then its game over .

 

The Jake break I would invest in tho .

[txab]

Trailer brakes working?

[2017HD]

There is a rule of thumb in the trucking industry - never go down the hill faster than you came up it.

 

Your tranny should have had the auto grade brake which is active in tow/haul mode - taping the brake pedal will cause the transmission to try and downshift. That combined with exhaust (Jake) brakes would provide the most engine braking. Using the auto feature will prevent the engine from over revving.

 

I think that I would also be looking at my trailer brakes as it sounds like your truck was doing all of the stopping.

[doverarjim]

Need to fill out your sig so we can see more truck info, but on my '11 in T/H pulling 20,000 lbs this last week the truck did an outstanding job of keeping the speed down and everything in control for me. Cruise set at 65 started down hill got to 70 tapped brakes it downshifted to 4th engine brake kicked in engine reved to 3000 rpm slowed back to just below 65 and as I went on down the hill started gaining speed again and tapped the brakes again and the truck downshifted to 3rd and rpm went to about 3500 and speed started dropping to around 65 again, as I neared the bottom of the hill stepped on go pedal and it shifted back up in gears until it was back in 5th and pulled back up the hill, just like Mr. Allision said it should.

[music]

Definitely need info on trailer brakes and controller.

[MJLANS]

Thanks for the help. These are probably stupid questions, but haven't owned the 2500 long and the RV is much heavier than my first one.

 

How high should the RPM's get to before manually shifting to the next gear?

 

In T/H, seems like the trans would sense the breaking and downshift according, but that didn't seem to happen. Course, I was pretty busy trying to keep the beast on the road.

 

I'm going to have the trailer breaks checked before the next trip.

[TimmyG]

Thanks for the help. These are probably stupid questions, but haven't owned the 2500 long and the RV is much heavier than my first one.

How high should the RPM's get to before manually shifting to the next gear?

In T/H, seems like the trans would sense the breaking and downshift according, but that didn't seem to happen. Course, I was pretty busy trying to keep the beast on the road.

I'm going to have the trailer breaks checked before the next trip.

why not I let it do the shifting like its ment to?

 

Sent from my SCH-I535 using Tapatalk 2

[doverarjim]

Now that I see you have an 07 I don't think that the allison had the grade braking then and I think that he does not have the engine brake either. If I remember right 08 was the first year for both of those to be used as standard equitment.

So that being the case I would check on trailer brakes and then see about one of the aftermarket exhaust brakes.

[CKNSLS]

One of the posters was correct...the rule is you go down the hill in the same gear you went up the hill in. Just because the motor was reving doesn't mean it was too many RPMs.

 

You need to use the transmission and downshift to the proper gear. Also, your trailer brakes need to be adjusted properly and so does your brake controller.

 

Safe travels.

[quinngr]

2007 trucks had transmission grade braking but not the exhaust brake. My 2001 Duramax service truck (12000 lbs) had it and I used it all the time in the Rockies. It wouldn't slow the truck down on long hills but would hold speed if you tapped the brakes at the top of the hill. Tow/Haul in auto and tap the breaks at the top and the truck should downshift. Don't panic when the RPM's shoot way over the redline. They're designed to handle it and will up shift if things get dangerous.

 

I'd have the trailer brakes checked out as well.

[Morgan1986]

2007 trucks had transmission grade braking but not the exhaust brake. My 2001 Duramax service truck (12000 lbs) had it and I used it all the time in the Rockies. It wouldn't slow the truck down on long hills but would hold speed if you tapped the brakes at the top of the hill. Tow/Haul in auto and tap the breaks at the top and the truck should downshift. Don't panic when the RPM's shoot way over the redline. They're designed to handle it and will up shift if things get dangerous.

 

I'd have the trailer brakes checked out as well.

ummmm RED line i would never recommend .

[doverarjim]

Why not red line is just a suggestion. If you are afraid of it you had better not go for a ride with me! My old 6.0 would just purr up around 6500 to 7000, little motors just love it. I would run my 396 out to about 5500 rpm before shifting it and I was never able to hurt it, doing that. I did break a crankshaft in one but I caused that by jacking up the motor on the balancer to pull the oil pan off so I could change the oil pump with out pulling the motor, You can do some crazy stuff when you are broke and broke down along the side of the road!!!

Now I have not gotten real brave with the DMax yet but I am sure with all of the nannies on it the computer will not let me hurt it. (or at least I hope so)

[MikeNH]

The electronics won't let you do anything dangerous RPM-wise.