Towing in the mountains

[Greg Watkins]

I will be towing in the Western North Carolina mountains for the first time in a couple of weeks. I am towing a TT (approx 6K) plus 4 people and the gear. I am curious as to whether or not I need to use Tow/Haul during the time I am actually in the mountains? I have towed this same set up over mostly flat land with no issues what so ever. And, the only time I have used Tow/Haul is when I am coming to a stop. So, will Tow/haul be needed or beneficial or should I not worry about it?

Thanks,

greg

2002 D/A 4x4 SB CC

[BobNelson]

While towing in your "small hills", you will probably use tow/haul, occassionally, depending on your driving habits. Really handy on long downhills, but also gives you better control over any possible shifty issues.

Have a great trip... I'm heading for JellyStone in another week. Plan to spend several nights camping at a lake near 9000'. Griz country... smile.gif

[csimo]

Yes, use the Tow/Haul mode when towing... even 6K. There is really no downside to using it except harsh shifting. The up side is that your tranny temps will be cooler if you use Tow/Haul.

You never know when you need to make a fast stop, and when you do the Tow/Haul will help you out.

[chipper]

greg,
I have about 20,000 towing miles with a 12,500 lb 5th & the only down side to using tow/haul is it costs you about 1 to 1 1/2 mpg on your fuel.All the other above info seems to be true.

[Russ Denman]

I use tow/haul anytime I tow and when I am pusher her unloaded on mountain curves.

Tow/haul give locks the torque converter in 2nd through 5th while normal only gives you TC lock up in 5th? (An article in Truck Trend said 4th and 5th get TC Lockup in normal but most of what I have read states 5th gear only.) The TC generates extra heat when not locked up. The shifting is a little harsher but I haven't really noticed because most of the time she holds 5th unless I am passing a F**d.

I have put on about 6,000 miles with a 7K TT running between Oregon and New Mexico. The engine and tranny temps never exceeded 195 even when the OAT was above 100.

[JimErickson]

In my experience Tow/haul makes no difference in tranny temps.

Tranny usually stays around 200 except for pulling hills or big head wind. Then it can climb fast. Have seen 240 before when pulling a 10% switchback grade pulling heavy load. Even had the Tranny hot temp light come on.

I'm thinking of trying the air deflector and see if it helps.

Jim

[sswilliams]

I pull from Elizabethton TN up to and on the Blue Ridge Parkway frequently. If you are on long, straight highway type of conditions, you will have difficulty getting it to go into OD. Suggest not using tow haul. BUT, when you hit the mountains, definitely use it. It helps not only going up hill, but also the Allison will not grade brake without tow haul being engaged. Getting into the mountains will really make you appreciate how great the D\A combination really is.

Have fun.

[David Utz]

We just finished a week of pulling a 7K 5th wheel Prowler up and down the Blue Ridge Parkway from Cherokee to I-77. I only used tow/haul for grade braking. Transmition temp. never went over about 210 deg. and then only in the parts that require constant speed changes due to the sharp curves. Speed up to 45 - slow to 25 for the curve - then back up to 45 - repeat for next 45 miles. These are probably the worst conditions for the transmition, but the 15K combined load wasn't enough to make it heat much over normal. I'm still learning how to best control the grade braking. The T/H button will usually drop you back to 4TH. Apply the proper braking and it will drop back to 3rd. The highest breaking RPM we hit was 3200 going down an 8%. When the grade braking is engaged, I can usually take my foot off the brake and just ride it to the bottom. At the bottom, turn off T/H and it goes back up to 5th. If the conditions were just right, I can get it to stay in 4th and grade brake down the hill without using T/H. I just wish I could have spent more time looking at the great views and less watching the road curves. Mileage ranged from 12.08 to 13.84 with an average of 12.97 for the entire trip. Next time the wife can drive-----well, maybe not. This is too much fun!

[ 08-14-2002: Message edited by: David Utz ]</p>

[Dave]

I always use tow/haul when pulling my RV. The only time whenpulling the RV I take it out of tow/haul is when I'm doing 60 and want to go up to 5th gear. I put it in normal till the up shift and then right back to tow/haul. I very frequently pull my RV through TN, and NC on I-40 and SC on I-26. Does great through the smokies. With the juice I pull All of I-40 in 5th in tow/haul. It use to always down shift to 4th. On Saluida, 7% grade, west bound on I26 it was a 3rd gear climb with out the juice, with the Juice its a 4th gear at 60mph.

[MaxDMax]

I have been towing a 13,500lb 5th wheel (loaded) which puts me at around 21,500 gross including truck, cargo, my family and trailer. I have a 3500 Duramax and always use the tow haul button while towing. I have noted that if I am in 5th gear all the time there is no difference in my transmission temperatures with tow haul on or off, however as soon as the truck is required to shift due to grades the temperature climbs quickly without tow haul on. My transmission temperature will go over 200 very quickly without it on, but never reaches 200 in tow haul. I live right in the middle of the Appalachian Mountains in Ky. and need/love the Allison grade-braking feature. It is not unusual for my RPMs to come close to red line on very steep down hills under braking. I think this is one of the best features of our trucks.

[ 08-15-2002: Message edited by: MaxDMax ]</p>

[sonofagun]

Greg,

I like the tow/haul mode but I have found the trans won't hold 5th gear as well when in that mode. I turn it on and off as I tow (not a lot) to get the benefit of lower gearing when the engine/tans will pull it. Diesels are made to work a lower rpms. I ALWAYS use it when going up or down meaningful grades (especially down). I have watched the trans temp carefully and don't see any difference when I'm moving down the highway in 5th without tow/haul or 4th with it on. One is working the torque converter a little harder but the other has the rpms higher. I have opted for the better fuel mileage as long as the trans temps don't rise.

Good luck,
Bob

[jeffbentleyreich]

I couldn't keep my RPMs from going well into the red line while using Tow/Haul. I was going appx. 50 down a straight steep downhill. I finally gave up and crawled down at about 35??

[BigO]

Your owners manual will tell you to use tow haul when you are at 3/4 of your GCWR. (Gross Combination Weight Rating)

[Greg Watkins]

The trip was a HUGE success. I carried my TT, 4 men, and enough supplies to feed an army through the Western NC mountains this past weekend. I used T/H for the majority of the trip. Truck pulled OUTSTANDING !!! Transmission temp stayed under 200 the whole trip and I couldn't tell any difference in the RPM's once I got it into 5th gear. (I tried turning the T/H off and on during the flat parts of the ride to see if it made a difference. Didn't appear too make much if any difference.) I made this same run last year with my 2k Suburban with the 5.3 engine. There are a few hills that absolutely KILLED the Suburban. Those same hills were cake this trip. The guys riding with even commented on the fact that we were passing people going up the hill instead of being passed :~&gt; Overall very pleased. A little better then 10 MPG for the towing part of the trip. This includes the mountains and 65-70 MPH on the flat stuff.

But the best part came on the way back. I was cruising in the slow lane, going down the backside of a mountain, when a Dodge pulling a TT similar to mine passed by. The driver looked to be pretty happy to be passing a diesel (especially a chevy diesel I'm sure) as he went by. Then we started back up hill. Not only did I pass him, but 2 other D/A's passed him (and me) as well. I never saw the guy again once we hit the uphill part of the mountains, but it was fun running with 2 other D/A's (one towing TT, one not) through the hills :~&gt;

Thanks for the info,

greg

[TBC]

I had the pleasure of passing a F**d and a D***e in the Rocky Mountains on some steep long grades. I topped out on the passes running 65-70 mph and still increasing speed. I used to really stuggle up those same passes in my 454 Suburban and other trucks with 350's in them. It was pure joy to be able to pull into the passing lane and go on past the other diesels. What a truck and mine is stock except for a K&N filter.

[builder 52]

Been reading this forum for weeks now but this is my first post. I have an 02 D/A with 4500 miles
on it with 2200 of them towing a 27' fifth wheel weighing about 10,000 lbs. Adding 2 atv's on a trailer behind it adds about 1500 lbs. When I pull a 6% grade fully loaded the trans pulls down to third gear and runs rpm's at 3000 at 55 mph.My engine temps climb to 220 deg.F . The trans will not shift to fourth gear. Seems like fourth gear would run about 2500 rpm's ,into the torque band, and lower engine temps. Any ideas on holding fourth gear? Thanks

[FirstDiesel]

Sounds like you need to get some JUICE to me. smile.gif

[JEBar]

Builder ... Juice addition would help (it did mine) but with the temperatures you are running would suggest addition of an EGT gauge .... would be interesting to see just what temps you are running...Jim

[Lone Eagle]

Builder52, I live in Tremonton and pull a 10K 5th wheel also. Give me a call @ 257-3375. Maybe I can help. Later! Lone Eagle smile.gif

[Russ Denman]

Builder 52,

I personally don't hold over 2500 RPMS. If she won't hold 4th or 5th, keep her in 3rd at 2500 until you hit the crest, you'll stay cooler that way and get better fuel milage.

There have been times when I know it will hold 5th but I had it in cruise and got behind the power curve. Once there, Tow/Haul won't let it up-shift so I pop it out of Tow/Haul, let it up-shift then put it back into Tow/Haul.

Russ ;)