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-   -   Driving downhill (http://www.irv2.com/forums/f44/driving-downhill-215772.html)

gator67 08-15-2014 04:52 PM

Driving downhill
 
We recently traded our motor home for a fifth wheel. When going down a long 6% grade (for example), I geared down and engaged the exhaust brake. When a 30,000 lb. motor home has the engine brake on and it's being pushed by a 4000 lb. car... no problem.

My concern is that now I have an 8000 lb. vehicle with an engine brake being pushed by a 19,000 lb. trailer. What is the best way to handle going down a mountain yet remain in control?

Snappy2265 08-15-2014 05:05 PM

You didn't say what type of truck you had with a exhaust brake, but you should be able to handle it the same way w/ the possibility of using a lower gear to help hold the speed down which also creates more back pressure.

Ranger Smith 08-15-2014 05:32 PM

Quote:

Originally Posted by Snappy2265 (Post 2184097)
You didn't say what type of truck you had with a exhaust brake, but you should be able to handle it the same way w/ the possibility of using a lower gear to help hold the speed down which also creates more back pressure.

I think if you look at his sig it is there. I handle it the same way as when we had the MH. My exhaust brake does most of the work with some gear shifting.

MCJones 08-15-2014 05:55 PM

I have had 2500 and 3500 Silverado's when I was pulling 5th wheels. They were both diesel. The tow/haul mode is what I used to reduce speed on downhills. I found that making sure it was in tow/haul and "setting" the brake a little would put it in exhaust brake mode and I wouldn't have to touch the brakes. I didn't hesitate to put it in and out of tow/haul mode to feather speed when the grade got less intense. My goal was to get down the mountain without touch the brakes. Wasn't always successful but with experience you can get pretty good. I do the same thing with "high/low" engine brake on the class A that I now own. Good luck and have fun - enjoyed my 5ths.

wingnut60 08-15-2014 05:58 PM

I have a Ford with no exhaust brake and tow 17400--I have been up and down some 14% grades with no problem and have crossed Slumgullion Pass in both directions several times. All one has to do is keep the speed down, never letting it rise above possibly 30. Your engine brake has had good reports, so I would get used to it and enjoy. If you gain speed, it is time for a lower gear. There is nothing wrong with applying the trailer brakes manually from time to time to apply some drag while the truck brakes are resting.
Joe

MCJones 08-15-2014 05:59 PM

Forgot to mention one thing about the tow/haul mode on my Silverados. I wouldn't have to "downshift" if I used the tow/haul aggressively enough - the computers took care of that. Now going uphill, was different - Sometimes I would lock in the transmission to a lower gear so the tansmission wouldn't "hunt" if the grade lessened for a moment - I didn't like all that "gear hunting" on the way up sometimes.

jimcumminsw 08-16-2014 09:00 AM

This information was passed on to me from Turbo Diesel Register. Com towing site. Most of the users state that whatever gear you go up the hill in than that is the gear you go down in. IE if you need 4th gear to go up than 4th gear is what you go down in this way you do not have to worry about shifting the transmission.

I have followed this advice ever since I bought my 08 Ram truck new and have had no issue with drivability and towing out west in the mountains. The exhaust brake is on continuously, tow/haul engaged and the toggle switch is used to lock-out whatever gear is necessary as I climb a 6 to 7 % grade. When I peak the crest whatever gear I am in is the gear that I will descend with, usually 5th gear which is a single overdrive gear.I am also in the trucker lane with the 4-way flashers on. I also watch my EGT’s, Boost pressure, transmission and water temperatures as I climb that is why I am usually in 5th gear to push more air thru the intercooler.

Jim W.

road dogs 08-16-2014 10:24 AM

I've towed coast to coast, through some pretty steep local terrain, and we like to spend time in Colorado's San Juan Skyway area where there are some fairly steep passes. As Jim stated, start your descent in a lower gear-and lower speed. I generally lock out OD on my Allison 5 speed and almost always keep my truck in T/H mode. I also have my turbo programmed to work like an exhaust brake when towing. Occasionally I'll have to apply brakes to maintain a lower speed and sometimes RPMs will exceed redline-not a problem on deceleration though....

jacknife 08-17-2014 12:09 AM

lf you don't have an exhaust brake use all your brakes when decending. Use a stab brake method and they will stay cooler longer. Never use just half your brakes on a long descent. If you have an exhaust brake the higher the rpm the more braking power the engine has. This is 35 yrs of trucking
experience going down mtns all over America grossing 80,000 lbs. Remember you can go down a mtn too slow many times you can also go down too fast just once.

wrp75 08-17-2014 07:47 AM

Thanks for the post. We will be doing CO mtns in a 5r soon (I hope) and all the advice is appreciated.

Chalkie 08-17-2014 09:03 AM

Quote:

Originally Posted by jacknife (Post 2185732)
Remember you can go down a mtn too slow many times you can also go down too fast just once.

As someone who lives in and drives in the mountains all the time, that is some of the best, most simply worded advice I have seen.

CCFROMFL 08-18-2014 06:23 PM

I have a 2013 Ford F250 with the 6.7L diesel option, I also have the tow haul and manual option.

Rule of thumb is what ever gear it takes to get up the hill, use that gear going down the back side.

WaterFolk 08-25-2014 10:18 PM

Jackknife...I recently read in a trucker's magazine an article on downhill braking. They didn't mention the exhaust on rake but focused only on the wheels. Their rule of thumb was to brake hard for three seconds...allow brakes to cool 8-10 seconds. What say you to that?

WaterFolk 08-25-2014 10:19 PM

Damn spell check! Exhaust brake.


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