Chevy Towhaul

[exav8tr]

I have a 2005 duramax/alllison and the tow haul. When decending, should I down shift to 3rd or let the tow haul control my down hill speed?

[wingerphil]

From one Phil to another

Just hit your brakes to slow down to the desired down hill speed and your tranny will downshift and hold that speed. The first time it you do it is a little un-nerving because it sounds like the engine is racing and gonna jump out of the truck but this is normal. The allison will hold the speed just fine and is one great tranny!!

[Mudchief]

I normally do as Wingerphil does but have also done it manually. Like Phil states you will think it is going to come out of there. In the mountains I have had mine pushing 4000 rpm but the truck manual says it will not hurt the engine. It sure saves your brakes.

[Illini Trekker]

Let the Allison do the work, come into the hill slow then use the brake firmly to slow you down. Someone has posted a brake and wait ratio to let the brakes cool down but that will all vary with the different hill grade and distance.SeeYa

[Bob Pasternak]

If I let my engine go to 4000 RPM, I'd have engine all over the county!! 3000 max on Cummins.

[rrheik]

Like stated before leave in Tow/Haul and hold down the brake for a tic and it works great. Went all over Utah, Montana, and Idaho last summer, and Mr. Allsion worked great getting me down some pretty steep mountains. On my way back to Montana now, and feel really comfortable about descending after last year's experience. First time I descended I had my doubts and figured I would get a good white knuckle test, but quickly realized I could relax and enjoy the beautiful scenery. However, I am now stuck in San Antonio because I sprained my rightr ankle badly, and can't drive, and my DW doesn't drive, so we will be stranded until next week, and then off to the mountains in Montana. You will find going up and down the steep grades a breeze. Just enjoy your trip.

bob

[Cat320]

Put it in T/H and leave it alone...it is smarter than we are.

[Mudchief]

Bob Pasternar, the manual on page 2-31 states the grade braking is designed to work in the dashed red zone of the tack without hurting the unit. That is 3300-4800 rpm. When I was pushing 4K I was on a 12.5% grade. On a 7-9% it is about 3000-3300.

[Delaine and Lindy]

Cat 320 your correct again..... I have owned 5 GM trucks with Duramax/Allison, and when I'm towing the 5er it stays in tow haul mode. And when not towing with the the manual shift on the 07's its very useful when your just running around. GBY...

pparamore, we had a 2005 and we pulled all thru the rockies and the D/A combo was awesome.....

[Mac]

This is my first D/A combo, we had a gasser prior to this. We live in Colorado and my wife always was worried about going down the hill (I was worried about over heating going up). But I'll tell you this is almost unbelievable, we've pulled a couple passes already and that transmission is a godsend and the Duramax pulls uphill like crazy. In short, we're both pleased, beyond words!

mac

[mobrownies]

I do not rely on the tow haul mode. I smoked all eight brakes coming down a steep grade in Vermont. I pulled over till things cooled down, then turned the two haul off, put it in second gear and did not have any problems making it the rest of the way down.

I do use the tow haul in town or in rolling hills to minimize shifting. It does make the transmission run cooler.

[Montana Sky]

I set the tow haul and forget about it. I start the crest of the grade at 25mph and let the tranny take it from there. I also use the "stabbing" brake method to slow the rig down, otherwise the Allison does all the work for me.

[jpkelpe]

We just got back from a trip through West Virginia and let the Allison and Tow Haul do its work. Worked great. We had stopped at a rest stop and a trucker who had been behind us told us we needed to check our brake lights because he never saw them on--he was amazed when we told him we hadn't used the brakes.

[bncinwv]

Now for a total novice question on the Allison, when using tow/haul should the gear selector be in D. More particularly are there occasions where we should be using M??? Even without tow/haul on, how are the experienced drivers using the gears. The only thing I know for sure (I think) is that M-6 is overdrive?? By the way, jpkelpe, hope you took one of the more scenic routes through our mountains!!
Bingo

[Delaine and Lindy]

Great question, M-6 just lets you control the shifts up or down. I normally when under the 5er I let the tow haul take care of the shifts. Even the M-6 has shift points. The Allison is a proven transmission and has been in Trucks for a long time. If you use the tow haul it will take care of the Duramax also. I have pulled a lot of gears but the Allison is the best Transmission thats on the market today (my opinion). GBY...

[Steve and Brenda]

I made an error on our last trip. After engaging the T/H mode while leaving the campsite, we made a stop at the site's office. Forgot to set the T/H mode when restarting the engine. Was driving through town to the interstate and when coming to a stoplight and to our horror I WAS NOT SLOWING DOWN LIKE NORMAL!!! Almost hit the tiny car in front of us even though the boost setting on the Prodigy Controller was set to B2.

I don't know if there's an advantage in mountainous terrain but I swear by T/H and the way the tranny assists in speed governance in Texas' mildly rolling hill country.

[jpkelpe]

Yes, BIngo, we were adventuresome and drove Hiway 50 from Parkersburg to Winchester, VA--beautiful scenery--sort of a narrow road and the steep grades were much longer than we had expected. On our way home we came over I64 which was also beautiful

[2007dura]

quote:Originally posted by bncinwv

Now for a total novice question on the Allison, when using tow/haul should the gear selector be in D. More particularly are there occasions where we should be using M??? Even without tow/haul on, how are the experienced drivers using the gears. The only thing I know for sure (I think) is that M-6 is overdrive?? By the way, jpkelpe, hope you took one of the more scenic routes through our mountains!!
Bingo

I use tow/haul everytime I am towing, and 95% of the time use "D". I use the "M" feature occasionally when towing in the mountains(I live in western NC) and encounter traffic on climbs which causes the tranny to keep going from one gear back to another. I will put it in the gear I want, say "4", and can keep the RPM's in the range I like to tow in. As for overdrive, the Allison actually has 2 overdrives, 5th and 6th gears. When in tow/haul, you have to be around 63 MPH to get in 6th.

[Ozzie]

What a timely discussion...I have been test driving the allisons...