jymbee
Well-known member
I use Tow/Haul haul mode often when going down hills but it's not clear to me how it's intended to work when going up hills. Does it just reduce the amount of downshifting, or... ?
Basic Tow/Haul question
- Thread starter jymbee
- Start date
The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
Roy M
Well-known member
It will downshift sooner and wait longer to shift up.
nibroc
Well-known member
that's if ya got an auto trans :
Utclmjmpr
Well-known member
If your rolling along in top gear,, and slip it into tow/ haul,, your tach. will raise about 6 to 8 hundred RPM to give you more power when needed.. That's the difference and the reason your mileage will be reduced..>>>Dan
Ex-Calif
Well-known member
In some transmission it inhibits the "top gear" which is usually an overdrive gear.
Gary RV_Wizard
Site Team
I think his 2012 coach has a Ford V10 engine and the Ford 5-speed auto tranny (5R110). Tow-haul on that is smart and should not drop you out of the top gear (overdrive) unless the engine load actually demands more power. It's not just an OD on/off switch as was present on the earlier 4-speed (4R100 tranny), so doesn't inhibit OD. Therefore the rpms won't increase if cruising along on a fairly level stretch, but it should downshift quickly when a grade in encountered and stay in the lower gear(s) longer than with the normal mode shift pattern. That's what eliminates the gear "hunting" that disystox mentioned.
One source of confusion is that Ford's Tow-Haul works differently on high-torque diesel engines than on gas V8 or V10's. The engine performs differently, both up and down hill, so the Tow-Haul management is programmed differently to match the engine performance. It's the same switch, in the same location, but it changes engine/tranny management in different ways.
OP
OP
jymbee
Well-known member
Gary RV_Wizard said:
Yep, should have mentioned that-- Ford V10 5 speed. Starting to understand, at least in theory, what Tow/Haul is designed to do going up a hill.
There has been times when after descending a grade I failed to shut off the Tow/Haul only to notice it some time later. I assume that this is not that much of an issue?
Final point is that I have finally purchased the 5 Star Tune system and will be installing that before the next trip and in order to evaluate how effective that is I just wanted to make sure I was clear on all the issues involved.
Thanks much to all for the input!
OP
OP
jymbee
Well-known member
Ok, one final question-- the name "Tow/Haul". I assume that describes the basic use of the system-- going up and going down grades. But when going down, are you "towing" or "hauling"? To my way of thinking both names imply the same thing. Never really understood the derivation of the term! ???
Larry N.
Well-known member
To me, towing is pulling a second vehicle along with you, while hauling is carrying more stuff on board. But it's a minor distinction. :jymbee said:
Utclmjmpr
Well-known member
I always thought that "tow" was to pull behind a towable device as in a trailer of some description.. To "haul" as in using a pick-up for it's intended use, would be hauling a heavy load in the back.. It could be either or both..>>>Dan
Timmy_B
Active member
- Joined
- May 20, 2017
- Posts
- 35
jymbee said:
I have the V10 Gas but have the 6 speed. Having used it a couple times with large UHaul trucks, I was familiar with it before we picked up our Class A. It is very helpful on the downhills, as well as the ups. If you tap or lightly apply your brakes, it will automatically drop down to 5th. If you do it again (and the revs won't take it above where the computer will allow it to go) it will drop to 4th. If you then press your cruise (speed) control, it will stay in that gear all the way down the grade. If you want to cancel that and have the transmission shift back into 5th or 6th, simply kill the Tow/Haul button. Once you get used to it, you will not want to go without it.
OP
OP
jymbee
Well-known member
Timmy_B said:
That's interesting. I never thought of using cruise in that manner. I will definitely give it a try next time out and see if it works the same way with our 5 speed. Thanks!
Timmy_B
Active member
- Joined
- May 20, 2017
- Posts
- 35
jymbee said:
I forgot to mention, it also will do this when you are on the exit ramp. It helps slow you down much faster with less brake pressure. If you're not prepared for it, though, the engine suddenly revving up to above 4K can be disconcerting, so make sure you're aware that it will happen.
A Traveler
Well-known member
- Joined
- Aug 25, 2014
- Posts
- 651
The tow/haul function basically does this:
That?s it.
- When accelerating, it tells the transmission to upshift later, to allow the engine to develop more horsepower.
- When decelerating, it tells the transmission to downshift sooner, to allow the engine to develop more engine braking power.
That?s it.
Gary RV_Wizard
Site Team
Could be either or both, so don't try to read a lot into the labels. Both Tow & Haul are simply indicative of extra load (weight) conditions that can be aided by a change in the engine & transmission management algorithm. It makes no difference whether you are towing the extra load or carrying (hauling) it.
A further thought... Because of its heavy body, a motorhome is always operating near its max design load (GVWR), so in essence is always "hauling", even without a toad in tow. The rear axle gearing is designed to handle that as "normal", but most any grade above 2%-3% will benefit from the optimization of tow/haul mode.
Ex-Calif
Well-known member
As Gary And others said, the tow/haul and cruise continue to get smarter. My 2012 Jeep isn?t that smart but cruise is cool. It will sense over speed and downshift. Very useful going down a long grade with a base weight of 4500. More so when hauling a 5000 pound trailer...
To your question about shutting it off. Probably no harm but good practice to switch out. With electronic boxes shift points will change and likely ding mileage a bit... but of towing heavy, even on the flat it is useful.
To your question about shutting it off. Probably no harm but good practice to switch out. With electronic boxes shift points will change and likely ding mileage a bit... but of towing heavy, even on the flat it is useful.
