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Allison Tow Haul Question

D

DMitch

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Location
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When towing ny 5TH wheel I use tow haul until I get to about 50 then take it out. My understanding is that tow haul raises shift points and pressure within the transmission. Is that correct, and am I hurting the transmission by not using tow haul on the highway?

Thanks,
Dan
 
Once your in high gear and the TC is locked it doesn't mater if T/H is on or off it's all the same.
I leave mine on.
 
Tow haul raises the shift points and locks TC in every gear after the shift except 1st,also in allowing for better braking on down grades. This helps in towing heavy loads in helps control operating temperature by locking the TC.


Once your in OD and TC locked it makes no difference if your in Tow Haul or not.
 
MACKIN said:
Tow haul raises the shift points and locks TC in every gear after the shift except 1st,also in allowing for better braking on down grades. This helps in towing heavy loads in helps control operating temperature by locking the TC.


Once your in OD and TC locked it makes no difference if your in Tow Haul or not.
Click to expand...

Absolutely correct Mack and it does not raise pressure.
 
Okay maybe a dumb question but why is it that when I ma in tow haul on the highway with 15-20,000 trailer and the truck kicks down to 4th it holds it along time, but if I want it to get back to OD all I hav e to do is click it off let it shift and then click it back on. I thought these Alli's had "shift stabilization in tow haul. And out of tow haul it will hunt for what ever gear it wants freely and then try and up shift again only to have to downshift again. I know that is what my sister 03 LB7 does anyway.
 
by taking it out of tow haul mode you are defeating the shift stabilization you are talking about. The reason it's not shifting higher is because it senses the large load and knows it won't be able to maintain highway speed if it upshifts.

out of tow mode it will upshift as soon as it can. In "normal" mode you're essentially telling the tranny that the truck is empty and not towing anything. If you are towing something w/o tow/haul on then it will be shifting around a lot because it's trying to maximize fuel economy for an empty truck but then can't maintain speed so it will downshift again.
 
So then you should always run tow haul the hole time you tow correct? Liek DMICH is takeing his out of tow haul as soon as he hits 50, I am not sure what his highways are like but here in the midwest in the flint hills these trucks need all the help they can get. So we alway leave our truck in tow haul for the hole time we are pullin.
 
Once I get in the truck from hooking up the trailer, the first thing I do before I shift into gear is put it in T/H. I won't take it out of it until I unhook or when the truck turns off when I get where I am going. I would think taking the truck out of T/H once you hit 50 would defeat the purpose of the system. I also enjoy (quite a bit) the assisted braking you get when you are in T/H as well. Very helpful when towing and you start heading down a decent grade.
 
big block 88 said:
So then you should always run tow haul the hole time you tow correct? Liek DMICH is takeing his out of tow haul as soon as he hits 50, I am not sure what his highways are like but here in the midwest in the flint hills these trucks need all the help they can get. So we alway leave our truck in tow haul for the hole time we are pullin.
Click to expand...

The only time I ever momentarily turn off tow/haul is when I'm cruising at highway speeds on flat ground but not quite going fast enough to shift to 5th. I should also say that's with medium to light loads. If I'm towing heavy then tow/haul says on until I unhitch.
 
Can't you adjust the shift points in T/H mode?I know I need to read my manual more but I thought it said something about this.
 
I like tow haul, i also like OD Disable for hitting big hills, helps keep me from wearing the brakes as much.
 
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