*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: You know what they say about common sense-it ain't so common!
I am planing on towing my 25 Grady White about 4 hrs. on flat country. My question is shoud i leave the tranny in over drive? I have the 6.0 liter v8, 373 gears, tow haul mode on tranny. Boat must weight in at 7000lbs or more. Don't want to burn up my wifes car and don't want to ride all the way down in my regular cab diesel. Any first hand knowledge would be appreciated.
I tow a 23ft boat with with a Yukon XL. Same power as you've got with the Suburban. I towed it 4hrs last month on flat land (Florida). I left it in over drive to keep the RPM's down. I usually get 13mpg, but that trip cost me. I only got 8mpg. But hey, you got to pay if want to play. I would'nt worry, you've got all the truck you need.
I tow near the same weight with same truck, except differential gear ratio is 4.10. Tried with and without "trailer mode" engaged. On flat road there is no difference, but on hilly roads transmission stays cooler (have temp gage) when engaged. Somewhat better fuel economy in overdrive (if you can call it economy - 8.6 Mi/Gal).
I would use "trailer mode" if towing for 4 Hrs.
We have a certified GM tech that keeps his boat next to ours and I asked him about towing with our Silverado 2500 HD 6.0 liter.From what he told me the only problem they have with the motor/ tranny's in these thing is people towing in O/D.He told me to make sure that it is in tow/haul mode when pulling the boat.Maybe he was blowing hot air but all he does at the dealership is bench work rebuilding transmissions etc.I also asking about the piston slap and he told me that they have seen no problems related to it what so ever.... so far.Great motor with lots of power but hungry for fuel.
Check your owners manual and I think it might have something in there about towing with the tow/haul mode or swing by your dealership and talk to the service manger and he will give you the straight info.
Ok here is where I offer my usual. Anything can tow anthing at the right speed and in the right gear. Brakes are often the limiting factors. In terms of the engine just chose gears that are keeping the rpms higher than normal and not lugging. Slow up hills if necessary. WATCH THOSE BRAKES. Special rules apply for Diesels - just stay in the recommended rpm range and even with those there is less wear in the higher end of the range - even though there may be less torque in the diesel...You other folks - don't try this at home - this "keep the rpms down" thing is only applicable (somewhat) to diesels.
good luck and have a safe trip.
__________________ 1st Cav Div Air Assault Infantry RVN
-Can Do........ and .......Carry On -
I've taken several long (6 - 14 hour) trips towing with my 2002 8.1 Suburban. I used cruise control in tow/haul mode and the transmission stayed cool, even towing up mountains on 100 degree days.
Put it in tow/haul mode and let the tranny figure it out :-)
I have a 8.1 4.10 2500. I use the tow mode when on long hauls with hills. On interstate when tranny is not apt to downshift alot, I tow without tow mode. Mine and doorone's boat (Aquasport 21.5 Ospry Sport) are lighter than the grady you will be pulling and our motors are larger, so if I were you I would use the tow mode (especially since it is your wifes truck)
I regularly tow my 24' Albe (which probably weighs in just over 7,000 lbs) behind a 2001 Suburban with the 5.3 and Autoride suspension. Leave it in overdrive and use the tow/haul mode, run 65 with cruise control on. Mostly flat with some hilly areas. Trip is 2 1/2-3 hours. No problems.
I have towed my rig with the 2500-6.0 and 2500HD 8.1/Allison. The 6.0 will gear seek to much pulling the weight of your boat, I would drop it in third and/or use T/H mode, the T/H mode will decrease gear seek. I run the 8.1 in 5th as long as I am on flat ground and not running into a strong head wind, the T-top loves a head wind.
I would bet your owners manual will say to NOT tow in OD. It simply makes the tranny shift more often which builds up heat which is enemy number one of the transmission. Heck I tow with a 350 dually and don't even use over drive. Do it enough times and odds are you will be looking for a new tranmission.
Nowhere in my oweners manual does it say not to tow in OD. It only specifies to tow in the tow/haul mode. It may even say thatit should be in OD, I'll have to go back and look.
The purpose of tow/haul mode is to manage the shifting patterns in a way that is suitable to towing. This includes when/if OD should be selected in any given situation.
So, put it in tow/haul, select D, and off you go...
I'll buy that because you have the tow/haul mode. A truck without it will say to not tow in OD. When I am talking about OD I am talking about the little button that you can push to put it in one higher gear. That is not something you want to do when towing. With TH, drive is the right gear.
Petersr2, Is there a reason you choose not to use the tow haul button? I pulled a similar boat as you down to the Keys with the 8.1L/3.73 combo and was very pleased with the transmission's performance (fuel economy is a different story!). I left mine in T/H the whole time.
Yep, you can use over drive With the 4L80E or Allison. Read your own manual though. Even my 96- Z71 manual said I could, I would still put the tranny in 3 if there was gear seek and usally did so.
It seems that it stays in Overdrive more 'without' the button pushed. I basically like to test things to see the results. I have not found any difference between the On/Off button on flat roads. If someone had more information about what the switch actually does to the trany (change shift points, stiffen shifts,etc.) then I might change the way I do things. My Bronco, with a 302, has to be in tow mode all of the time. The Bronco basically stays in fourth when the button is pushed. I just think(and I might be wrong) that my Suburban is way more than I need, thus it does not even know the boat is back there on a flat interstate. Larger Boat, Different roads, start and stop, etc. will change this. I also have not done a fuel comparison on using the button vs. not. I towed this boat from Houston to Richmond VA, and did not have the button on most of the time.
Tow/Haul firms shifts and makes the Truck hold gears longer, I dont use it that much now. I am not sugesting others to not use it either. I have watched the trans temp and it does not make much differance. I did use this feature with the 6.0/4l80E trans combo because it did not have any where neer the Torque the 8.1 has and would gear seek into a head wind. The Tow/haul mode does help with grade breaking, I would use it for that alone in hilly conditions.
Towing with 2500 Suburban 
1st Cav Div Air Assault Infantry RVN
