First long haul w/ 4K lb - Engine/Trans Braking in mountains?

I have had many trucks through the years, and about 6 months ago I replaced my 2014 2500 with a 2017 REBEL (5.7L, 8 speed, 3.92 4x4, CC, Air Suspension). I have towed a lot, but all usually within 20-30 miles, and never through the mountains. I have driving Pike's Peak and Mt. Washington so I am fully aware of engine breaking and not riding the breaks, however, those trips were in my 2007 Tahoe, and my wife's 2016 Durango (paddle shifters for win!).

I will be towing a 4K trailer (flatbed with a load) from central Illinois to southern Tennessee in the coming weeks.

My truck did come from the factory with the class IV hitch (but no trailer brake installed). Should it have the tow package trans cooler?

Sorry for the long intro, but here are my questions.

1. Engine/Transmission breaking, what are "safe" RPMs? The newer RAMs don't have a red line for the tach, but obviously, 8000 RPMs is not safe. My guess is that in a lot of the steep down-hill areas, I will be running in 4th or 5th to keep it under 60-65, but I don't want to trash the trans or brakes.
   
   
2. What is a safe or normal trans temp? I have done a TON of research, and the only thing I could find was one page saying that ~195° is normal and 248° is the start of the danger zone.

Iv assume the trailer has brakes... I would install a brakes controller but otherwise your truck should be ready. Mountains in TN are not as bad as say out west. You are also well within limits for that truck esp with the 3.92. trans or engine temp approaching 240 is bad news but I highly doubt you will see that with your rig.

Fwiw I managed to tow a nearly 3k trailer (3.5k west tow rating) thru some serious grades out west with my old Town and country minivan. Only once in the worst grade did I have to pull off and stop. Your setup has tons more room in tow limits than i did and the grades you see will likely be much less.

I just talked to my dad, and the trailer loaded will be closer to 3K lbs... But it doesn't have brakes. I just replaced all brakes on my truck (ceramic) about a month ago. Now, I'm a bit more nervous. I'm thinking of just getting a uhaul 6x12 and let him pull his trailer empty.

My dad seems to think 3K lbs with my truck will be fine without brakes, just give a little more stopping room.

Thought?

I have a buddy...seriously, NOT me, that pulled his JKU out to Moab from Michigan. Descending a couple of mountain passes he put it in 4wd LO, just for the engine/trans braking. He said it was not a problem. I will keep that in mind should I ever do the same. 4wd is not good on dry pavement but I wonder how bad it would be on the freeway with no sharp turns like street intersections?
His truck was a 2015 2500.

The trailer in this case is a tandem axle wood deck utility 6x12 trailer (converted boat trailer). We have the following loaded on it. Tiller, generator, log splitter, two large tool boxes, wheel barrow, 3 extension ladders, a tote full of tools, and a wheeled garden cart. My guesstimate is about 1500 lbs of cargo, and my dad thinks the trailer is 800, though I would guess 1200 lbs. The only spot I'm nervous about is between monteagle and Chattanooga. The rest is fairly flat and I can keep a gap.

But, for $80 and the work of transferring the load, i might move everything it a uhaul.

Intense-Dakota said:

I just talked to my dad, and the trailer loaded will be closer to 3K lbs... But it doesn't have brakes. I just replaced all brakes on my truck (ceramic) about a month ago. Now, I'm a bit more nervous. I'm thinking of just getting a uhaul 6x12 and let him pull his trailer empty.

My dad seems to think 3K lbs with my truck will be fine without brakes, just give a little more stopping room.

Thought?

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Personally, I would never pull a trailer that heavy without brakes. In some states that would be illegal...that part wouldn't bother me. 3000 lbs in the bed is different that 3000 lbs of trailer weight. The bed will never try to pass you going down a hill! You cannot jack knife a bed.

Get brakes on at least one axle.

If it were my trailer, it would have brakes all both axles, but it's not mine. We are leaving in 1 day, so not enough time to add the brakes. Which leads me back to renting one with surge brakes

If possible, rent one with brakes. Why beat your truck up for $80?
3000# doesn't sound like much, but it is a good bit of weight pushing you and why in most states trailers rated at 3k and up require brakes.
How did he ever find a tandem boat trailer without brakes??? Tandem are usually fairly high capacity.

I decided to go with the uhaul with brakes just to be safe. If it was all flat roads, I wouldn't even worry about it, but with the mountain grade, I don't want to chance it or worry about it. 20+ hours driving plus unloading the trailer is enough for 2 days.

You'll definitely want to use the Tow/Haul mode when towing the trailer. Don't be afraid to use the cruise control while towing, it's not reckless as you think it is. The truck will actually downshift to maintain your speed when the cruise is set.

crash68 said:

You'll definitely want to use the Tow/Haul mode when towing the trailer. Don't be afraid to use the cruise control while towing, it's not reckless as you think it is. The truck will actually downshift to maintain your speed when the cruise is set.

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I will likely have it in tow haul the whole trip. 8 have heard the 8 speed really likes to tow. I drive all over the country and rarely use cruise. I had knee surgery about 20 yeara so I turn it on to move and stretch a bit but then go back to the gas pedal. For me it's more of a need to not feel complacent.

Right in the wheelhouse of the air suspension with plenty of engine to pull, so the only variable is the brakes which would be optimal with some trailer assistance.

Sounds like you have made your mind up. If it were me I wouldn't worry about 3-4,000lbs. without trailer brakes. If it was something you did often then yes you wouldn't want to put that much wear & tear on your truck brakes. Years ago I moved across the county a couple of times with nothing more than my 05' Dakota w/3.9L & a 6X10 cargo trailer. Weighed the load & it was nearly 3,500lbs. It struggled a bit going up the mountains but I kept it in a lower gear going down & had no issues what so ever. As your dad mentioned, you just have to give yourself some room to slow down.

So, for anyone else coming here with the same question, here is the outcome.

The 2017 REBEL w/ Air Ride is bad ass towing rig!

There were ZERO problems. With the 5.7 with 8 speed trans and 3.92 gears, there was power to spare. I ran in tow/haul the whole time, but honestly I really didn't need it at all. The trailer tipped the scale right around 3500 lbs loaded (1700 empty). I do have new ceramic pads all around, and the trailer had the surge brakes, but it was no problem slowing or stopping.

The engine/trans braking on this truck is unbelievable! Going through Tennessee, with a 6% downhill grade, the truck shifted into 5th and held 65 MPH at 3500 RPMs. Never needed to even touch the brake to slow it down.

The tongue weight was right around 400lbs (a tiny bit heavy for the load), but the air ride kept it level without any issue. That was also with 3 grown men (2 of which are over 230 lbs) and also about 200 lbs of gear in the bed.

I did tow the empty trailer back from Tennessee to Illinois, and I will say the truck felt much better when the trailer was loaded. When it was empty, I felt a lot more bumper bounce, but I guessing this is more trailer related than truck related.

Now, the important thing... MPG. Overall average was 12.84 mpg. That is for the entire 1400 mile trip. There was very little difference in MPG between 1700 lb empty trailer and 3500 lb loaded trailer. On flat Illinois roads (lol, flat when there are no potholes), I averaged around 13.7 mpg. In the mountains, I was sitting between 12.0 - 12.4 mpg average. I was filling up at each stop (other cars in the caravan), so usually never ran it below 1/2 tank. These are hand calculated numbers. The dash showed an overall average of 13.7 MPG.

I was holding an average speed of 70 MPH the entire trip except where we were required to run slower. In construction areas with speeds around 55 mpg, I was getting near 17 mpg based on the dash which from the numbers I saw at 70 mph, I would guess are pretty accurate. So, assuming the same towing situation as above, if you keep it at 60-65 mph, you should get 16+ MPG on fairly flat roads.

NOTE: I ran 89 octane most of the trip except 2 1/2 tank fill ups where I ran 92. Those were both before heading into the steeper parts of the mountains.

Glad you had a good trip Chris... I didn't realize who you were when I originally replied to your post . BTW 400lbs tongue weight on a 3500lb load is right in the 10-15% range so not too high at all.