10% for 5 miles up and down. My GCW was ~21,000#, BIL was 19,000#.
Outside temp was about 90*f.
If you haven't been over it before, the grade is steep and twisty. Max posted speed is 35-45mph. It was the slow speeds and turns that were the killers. I had to slow to 25 mph to make some of the turns, and my BIL pulled over about 3/4 of the way up to let other traffic pass him. Getting going again pegged his engine temp gauge by the time he reached the top. Going up for me was ok, my engine temp gauge was way over to the right (3/4), but I made it no problem. BIL had even higher temps (see pic), pretty much pegged it. The auto fast idle engaged when we stopped at the top, 1000 RPM and cooling fan clutch electronically engaged.
The way down was another story. Smoke rolling out of the front and rear wheel wells on both trucks. We had to stop to let the brakes cool twice. First for 15 min (smell of hot brakes) and a couple more miles down the grade for 35 min when the smoke was very visible from both trucks brakes. My pedal was sinking and I was two foot braking to get stopped on the pull out from ~20 mph.
BIL has a stock 04 RAM 2500 and a 32' TT. We had to wait until there was a pull out big enough to accommodate both trucks and trailers as there is only one lane each way. There is also a runaway truck ramp on the grade. On mine, the Hypertech was on stage 1.
Checked the brakes afterwards, no cracking visible on the rotors, no damage to the pads.
That's the steepest I've ever done. Probably would avoid that grade next time, unless I invest in an exhaust brake. I might just upgrade the truck first. Exhaust brake is about $1700 installed in Canada. I think I'd be better off putting that money in a newer truck at some point.
On the other 6-7% grades we did, 2nd gear, and tow/haul mode was good enough with the addition of a few jabs of the brakes every now and then.
2010 Cougar 322QBS 5er
2007 Dodge 3500 SRW Megacab, 4x4, 5.9L Cummins, 3.73, 48RE auto HYPERTECH MAX ENERGY or DIABLO PREDATOR tuning MBRP 4" Turbo back Scangauge2 for Boost, Coolant temp, Rail press & Trans Temp
Torklift Stable Loads
We were just out there 2 weeks ago. The rental car we had only had 1300 miles on it when we got it. Turned it in with 2500 on it, and the rotors were SHOT. We went over the pass 5 times over the course of 7 days.
I know I-80 is about the same elevation, but it wasn't as steep. My gross combined weight always seems to be just over 19K lbs when I cross the Rockies and so far it's been pleasurable with no failures or white knuckle moments.
Descending down 10% grades, I can usually keep the motor spinning at 3K RPM and only tap my brakes occasionally. My Ford PSD doesn't have a real exhaust brake, but the turbo's variable vane angle functions well enough that I have not needed to add one. I think keeping the speeds down during ascent and descent have been beneficial for me. When climbing I try to keep the RPM between the peak torque and horsepower curves which will dictate my speed.
The guys that say an EB isn't needed are usually the same guys that have never used one.
I'd be willing to bet about the time the OP had both feet on the pedal trying to slow his rig,that $1700 price tag didn't seem quite so much.
It's not that I would not like to have an exhaust brake or feel they are useless, but with my current setup I have not felt a need for one. I have the same feelings about a diesel tuner or any other add-on. I'm sure if I was dragging a 15K+ lb fifth wheel on mountain passes my needs would be different.
Until I bought a TC, I had no need for air bags, over sized bump stops or 19.5" wheels since the stock configuration handled my TH weight fine. Now that I have shifted more weight to the TV with less in tow, these additions made considerable improvement in handling. When the TV is unloaded and towing heavy, I see little difference in handling with these additions from stock.