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here is the scoop, I have been towing trailers for years just never with an auto diesel. The gas motors I have had I have never taken the thing out of overdrive and no problems whatsoever. Just for grins I put the trans in tow/haul mode with about 4,000 lbs worth of trailer and WOW. The shift firmness was awesome, and the first time I hit the brakes the thing started downshifting on its own and slowing the truck down it was great. My question is, is all that shifting bad for it,or since that is what it is made to do just roll with it. Thanks for your opinions and knowledge in this matter
 

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Allison built it to stand up to the abuse of towing, but all bets are off with a tuner.
 

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queso;1552344; said:
here is the scoop, I have been towing trailers for years just never with an auto diesel. The gas motors I have had I have never taken the thing out of overdrive and no problems whatsoever. Just for grins I put the trans in tow/haul mode with about 4,000 lbs worth of trailer and WOW. The shift firmness was awesome, and the first time I hit the brakes the thing started downshifting on its own and slowing the truck down it was great. My question is, is all that shifting bad for it,or since that is what it is made to do just roll with it. Thanks for your opinions and knowledge in this matter
Roll with it and enjoy........... It's an Allison.

DEWFPO
 

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Nothing bad...........

DEWFPO
 

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Tow/Haul

With no load, no trailer, it likely will not grade brake. Need some weight in the box, or on the hitch to get it to grade brake. It usually has to gain a bit of speed while you are riding the brakes - like a load would push you down a steep hill - before grade brake cuts in. Or be standing very hard on the brakes...empty you are into a panick stop. Not likely to happen with on load. Often use truck empty as a car. Use tow/haul in rolling hills, just for the shifting and shift points. Generally don't get grade braking when empty.

Manual says if the anti lock brakes cut in, it will already have released the grade braking.
 

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In haul mode it will downshift and brake with no extra load. In 2wd in snow it seems to shift smooth enough not to break the rear loose, but it has drifted a bot on me. It has shifted down 3 gears smoothly on snow, downhill 5%, around a mountain hairpin without issue. In 4wd, there is no issue at all and I do use it without load. I can almost drive the pass in blizzard conditions without brakes, and I like always being on the power.
As far as I can tell, the truck does not know or care how much weight it's hauling, simply alters the shifts points; up some 700 rpm.
 

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Empty 3500 LBZ w/ the 6spd Allison, tow haul on the off ramps, just a slight touch of the brake it will down shift. Drove dad's truck tonight and did it on the off ramp on i-95 here in Florida.

Kev
 

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Tow Haul

Higher shift points is ordinary tow haul situation.

With enough load pushing you down the hill, some brake pressure, varies with amount you have to control the speed on a particular downgrad, it will grade brake (down shift) to put the RPM over 4000 IF needed to control the speed. On a long grade once it has shifted, maybe second gear at 65 MPH, the engine is roaring, speed under control, you can take your foot off the brake, just let it run to the bottom. Nice stuff and sure saves the brakes. Have to power up to get it to release or it will pull the speed right down once on the flat.
 

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:exactly:

That is why I bought the D/A. And the dealer gave me a truck in the deal for free:D
 

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Manual says that tow haul hurts mileage and that you don't really need it under 75% (16,500 lbs) of GCWR. I'm loving that I have an allison but when I pull my 5'er and I'm in traffice tow haul drives me crazy! The constant downshifting makes it annoying as sometime you just want to coast.
 

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I pull a loaded 22' trailer with a terramite t5c two buckets and a loaded tool box. I would say I was pulling around 4500 pounds. Should I be using the tow/haul or not? I use it when I am on smaller roads for braking purposes but not on the interstate. I love the way it shifts and brakes, but I am affraid of "wearing it out" especially if I dont need to be using, any thoughts?
 

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Tow/Haul

I use tow haul as stated above but also to keep the convertor locked so the trany doesn't heat as quickly. I understand that tow haul locks the convertor for second through fifth. With the trailer on I use it ALL the time at ALL speeds. Without the trailer I use it for convieniance.
 

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No, it's perfectly normal operation in T/H mode.

DEWFPO
 
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