D/A Grade Braking/Exhaust Break

[RKassl]

Going to be taking the Monty out in a couple of months to Western South Dakota. I will probably see some steep grades and was wondering what I will see with the D/A grade braking? Is this equal to an exhaust brake? If not has anyone put exhaust brakes on a D/A?
In about 24 months we are thinking about our Alaska trip. My D/A has plenty of power for towing, but I want to understand the braking and how to do it safer and smarter.

Any experiences will be appreciated.

Happy Camping!

[ols1932]

Bob,
I don't have the same truck you do but from what I understand, you have just about everything you need. I'm sure there will be someone who has the same setup who can advise you. But I wouldn't worry about it. You have plenty of power and the theory is that you go down the hills in the same gear that you climbed it.

Orv

[2007dura]

I have pretty much the same set-up as you, and have not seen a need for the exhaust brake. Have been through the Smokies, Sam's Gap at the NC/TN line, and various other mountains in the southeast, and the Allison does fine for me.

[Montana Sky]

Bob,
I have not had any trouble towing my 3400RL through the Black Hills or any part of I-90 from S. Dakota through Wyoming or Montana. Your truck is going to do a fine job of towing your coach. You are going to be so happy with how it handles the grades and the open roads. If you are coming from the East, there really is not going to be any "hard" pulls for you. Depending on where you stay in the Hills will determine the grades you will encounter. If you come farther West, that is going to be where you will start seeing the bigger grades. As far as any tricks I have found when using the grade braking, the biggest thing is to start the top of the grade slow. It is always easier to speed up than it is to slow down. I usually use 3rd gear when coming down and try to keep my speeds around 35mph on the longer ones. I have only crossed 2 grades that required 2nd gear on the downward side. I am not sure how heavy your coach is, but I do not think you will need an exhaust brake or any other aftermarket brake. The truck will do all the work for you. Just sit back and enjoy the drive!!!

[RKassl]

Thanks, it nice to draw from your experience. Better to ask now that when going down a step grade. But I am still not clear, is grade braking on the D/A combo nothing more than automatic down shifting?

Happy Camping

[Dave e Victoria]

Bob,
Automatic downshifting is exactly what it is. The braking action occurs due to the parasitic restrictions in the exhaust path of the engine. These restrictions come from the turbo impeller, the catalitic convertor, and the muffler/exhaust pipe. It works suprisingly well. We are homebased in AZ so encounter a lot of mountain driving. As Sky said, the secret is in starting off at a reasonable speed. Also, be careful until you are sure you are at the bottom; many hills will have a relatively flat period before going down again.

[Devildog]

I traveled the areas of Western South Dakota last summer all the way through into West Yellowstone, Montana and south through Idaho with my 10,000lb travel trailer and my 2001 GMC with Duarmax and Allison. Grade braking handled it all very well, as long as I was in the Tow/Haul mode. No warped rotors, no hot brakes, no white knuckle adventures. Dmax pulled all hills well and stopped well. Just follow aforementioned common sense about topping at a speed you want to descend at on the long grades, and watching your EGT for the climbs. All will go well.

[rickety]

I don't know if your truck has the variable vane technology on the turbo. If it does, then you won't need or want an exhaust brake. I have a 2004 Dura and my diesel guy said that the only thing I would ever need would be the exhaust brake, for nothing more that keeping the engine revs down on steep downgrades. Plenty of power, etc. I had it put in and it works great! the BD unit interacts with the tranny to keep it locked up down to 15mph and thenit cuts off. great unit!

[mobilrvn]

We are the new owners of a '06 2500HD D/A. Had a boost and EGT gage installed. Our prior TV was a F-350 powerstroke. Rarely did the EGT go over 950 (monster exhaust) unless it was a long steep grade and then it might hit 1050. The Chevy goes over 1200 very easily. What should the upper limit be---temp and time?

[Montana Sky]

mobilrvn,
Is your pyro installed "pre" or "post" turbo? Mine is post turbo and while I can get into the 1200 degree range it is not very often or easy. Most of my hard grade pulls are in the 1100 degree range. I would try to keep your temps at 1200 or less, that is what the shop told me who installed my pyro and boost gauge.

[sreigle]

Bob, I didn't see any real serious grades in western South Dakota although we did not cover every road.

If you have the new Duramax with the variable geometry vanes in the turbo then you have a similar setup to my 2003 and 2005 Ford 6.0 diesels. In that case I do not feel an exhaust brake is necessary. In this past month we did a 100+ mile stretch on Utah highway 12 where we went both up and down several serious grades, exceeding two miles in length each. Several were marked 8%, two marked 10%, plus a 12% and a 14%. I have to admit being nervous at the outset of those 12 and 14 percent grades, both up and down. But we handled them all rather easily. On the downhill side of the 12 and 14 percenters I did use the service brakes for 3 or 4 seconds about every half mile or so but that's it. On the 10 percenter I think I used the brakes once for a few seconds. On the 8 percenters I didn't use brakes at all. On 6 percenters and sometimes the 8 percenters if I manage to get it shifted down lower than I'd like I find the rig decelerating and I have to give it some throttle to keep from going too slow. Our total rig, full of diesel, 2/3 water, and us onboard scales at 22,920, to give you the idea of our load.