# Tow Haul Concern?



## garyb1st (Dec 6, 2007)

Don't know if this has been discussed or if there is a more appropriate forum but this is scary. I was talking to a friend who pulls a 25' Airstream. His TV is a 2006 Ford F250 Crew Cab Diesel. Basically the same vehicle I have except mine is a year older and I have a long bed. To put things in perspective, the airstream weighs about the same as my 28KRS. So we both have adequate TV's for our respective trailers. We're both around 75% of GCVW.

My friend was driving between the Coast Highway and US 101 on one of the mountain passes North of San Francisco. It was raining and the road was a bit slick. There was about a 600' drop on one side. He was driving in Tow Haul mode when he began his decent. Now I'm not clear on the next part but knowing how the tow haul mode works, I assume he stepped on the brakes to slow the vehicle while in the decent. When I do this, there is a lag between the time I apply the brakes and when the truck down shifts. When it does, the shift can be abrupt. My guess is that when the truck down shifted, the drive wheels slowed considerably even though additional pressure was not applied to the brakes. Not sensing the added braking pressure, the trailer didn't slow at the same rate the truck did. When that happened, the trailer started to slide to one side. Not wanting to go over the edge, my friend didn't attempt to straighten the trailer. Instead he let the trailer jack and both the TV and trailer eventually came to a stop. He didn't say how fast he was going when this happened, but his new down hill speed is 35 MPH. Not sure of the extent but both the Ford and Airstream sustained damage. Fortunately neither he nor his wife were injured.

I wouldn't call my friend a newbie since he's put about 10,000 miles on his trailer. But most of that was from one coast to coast trip. He lives near the West Coast and has traveled a number of mountain passes without incident.

After thinking about it, I'm not sure what I would do in a similar situation. Aside from keeping the downhill speed at 35 MPH, if the trailer starts to jack, I don't have a clue as to what I should do. If any of you seasoned drivers have any thoughts, I'd appreciate the input.

Thanks

Gary


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## shake1969 (Sep 21, 2004)

Maybe the guy's rig really was overweight. Most are and don't know it.

Enough force would have to be placed onto the rear of the TV to break the rear tires loose when the downshift happened. That would've been alot of force. If he had been running a proportional braking system, application could have stopped the rig and straightened things out, maybe. But with a 600 foot drop nearby, who knows if any of us would've been cool enough to pull out of a mess like that.

Slow down, reduce weight, and make sure you have a W/D hitch and it is properly setup. That's all I got.

Dave


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## outbackgeorgia (Jan 28, 2004)

35 in the rain with sick roads is still too fast


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## swanny (Oct 31, 2007)

don't know how much this means for this incident but, I read a post on dieselplace about a guy that had a chevy with a dmax / allison. he had it i T/H without a trailer in tow. the roads were wet and as he started to round a curve the truck down shitfed and almost spun his out. the tranny down shift is pretty effective i guess


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## GarethsDad (Apr 4, 2007)

I have a 06 ford f350 psd at work and we use it to haul the excavator. In the tow haul mode when you let off of the gas peddle the truck activates the engine brake. If you do not apply the brake peddle ( activating the trailer brakes) the trailer will be moving faster than the truck. Our truck has the built in brake controller. James


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## GoVols (Oct 7, 2005)

swanny said:


> I read a post on dieselplace about a guy that had a chevy with a dmax / allison. he had it i T/H without a trailer in tow. the roads were wet and as he started to round a curve the truck down shitfed and almost spun his out.


Why would anyone use tow/haul when NOT pulling a trailer?









I think more brake pressure would have straightened out the trailer, or a manual intervention of the trailer brakes. Then followed afterwards with an underwear replacement!


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## aplvlykat (Jan 25, 2004)

I know this would be frightening in the rain and going downhill but this is what I have always been told to do. When the TT starts to sway then you give the truck some gas and hit the emergency or manual brake control lever and then use the TT brakes to come to a stop. When speeding up the TV and braking the TT it will straighten everything back into line. This is why it is important to mount the controller within easy reach and be able to get to the manual brake lever with one hand. I just don't know how this would work going downhill in the rain. Kirk


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## hatcityhosehauler (Feb 13, 2004)

The wet roads are the key to this great mystery in my opinion. It is recommended, at least in the fire service, that when roads are slick, to disable engine brakes, Jake Brakes, or transmission retarders, and just drive slower. All of these devices can cause the drive wheels to slow rapidly, and cause the grip with the road to be broken, inducing a slide/skid.

Just my two cents.

Tim


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## 2500Ram (Oct 30, 2005)

aplvlykat said:


> I know this would be frightening in the rain and going downhill but this is what I have always been told to do. When the TT starts to sway then you give the truck some gas and hit the emergency or manual brake control lever and then use the TT brakes to come to a stop. When speeding up the TV and braking the TT it will straighten everything back into line. This is why it is important to mount the controller within easy reach and be able to get to the manual brake lever with one hand. I just don't know how this would work going downhill in the rain. Kirk


x2

Again the rain, slick roads and downhill all play into the situation but this is what I've been told.


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## CamperAndy (Aug 26, 2004)

I use Tow/Haul when not towing as I like the shift points and the speed that the torque converter locks up.

To the OP the problem was not tow haul but the fact he did not manually apply the brakes when it started side ways.


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## nynethead (Sep 23, 2005)

not actually being there in the situation one can only speculate, but what is the setting on his brake controller, on the prodigy you have the 1,2,3 seetings for trailer weight. He might have it set a 1 and needs to be 2 or 3.


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## tdvffjohn (Mar 10, 2005)

hatcityhosehauler said:


> The wet roads are the key to this great mystery in my opinion. It is recommended, at least in the fire service, that when roads are slick, to disable engine brakes, Jake Brakes, or transmission retarders, and just drive slower. All of these devices can cause the drive wheels to slow rapidly, and cause the grip with the road to be broken, inducing a slide/skid.
> 
> Just my two cents.
> 
> Tim


X2.......the sudden downshift of the trans and on wet roads caused the rear wheels to get a reaction and with the trailer pushing with the set up at an angle (meaning a slight turn) it caused the jackknife.

Accelerating might have pulled him out of it but when you are going down a steep hill already, by accelerating, you would need to hit the brakes again to slow down soon . Sounds like he was a no win situation when it started and he did a good job of protecting his family.

I rarely used my tow haul mode last summer including I 70 in Colorado because of the quick drop into a lower gear and then the high rpm s that followed. I try to start from the very top at the speed I want to stay at all the way down, maintaining a speed is easier of the brakes than slowing down to lower speed on a hill.

John


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## OregonCampin (Mar 9, 2007)

tdvffjohn said:


> I try to start from the very top at the speed I want to stay at all the way down, maintaining a speed is easier of the brakes than slowing down to lower speed on a hill.


This is what we do on Oregon mountian passes - this is what my DH taught me to do - keeps the breaks from getting over heated and failing on you when you really need them. We do not have Tow/Haul mode on the F350, but do gear down at the top of the hill and keep it there till we reach the bottom - I like controlling my own shifting on the steep mountian passes.


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## garyb1st (Dec 6, 2007)

swanny said:


> don't know how much this means for this incident but, I read a post on dieselplace about a guy that had a chevy with a dmax / allison. he had it i T/H without a trailer in tow. the roads were wet and as he started to round a curve the truck down shitfed and almost spun his out. the tranny down shift is pretty effective i guess


This is exactly what happened. I talked to my friend again and he told me when the trailer started jacking, he was in a sharp turn on a significant down grade. He was only going about 30 MPH. Speeding up was out of the question. He didn't have it in 4 wheel drive and doesn't know if that would have made a difference. I think we both feel that manually down shifting to 2nd before hitting the grade, would have prevented the problem.


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## garyb1st (Dec 6, 2007)

hatcityhosehauler said:


> The wet roads are the key to this great mystery in my opinion. It is recommended, at least in the fire service, that when roads are slick, to disable engine brakes, Jake Brakes, or transmission retarders, and just drive slower. All of these devices can cause the drive wheels to slow rapidly, and cause the grip with the road to be broken, inducing a slide/skid.
> 
> Just my two cents.
> 
> Tim


This makes a lot of cents. Sorry about the pun. I'm definitely taking it out of tow haul in any kind of weather. Any thoughts on using 4 wheel drive? I know it works in snow but don't have a clue when driving on ice or wet roads.


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## garyb1st (Dec 6, 2007)

CamperAndy said:


> I use Tow/Haul when not towing as I like the shift points and the speed that the torque converter locks up.
> 
> To the OP the problem was not tow haul but the fact he did not manually apply the brakes when it started side ways.


I've always used Tow/Haul on steep grades. Easier on the brakes and keeps my 8000lb Super Duty from picking up too much speed. That's with a full load of fuel, my DW and me.

We talked about manually applying the trailer brakes but wasn't sure that would help. Is that the recommended procedure?


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## garyb1st (Dec 6, 2007)

nynethead said:


> not actually being there in the situation one can only speculate, but what is the setting on his brake controller, on the prodigy you have the 1,2,3 seetings for trailer weight. He might have it set a 1 and needs to be 2 or 3.


The brake controller setting on our Super Duties goes from 05 to 10 in 05 increments. When I picked up the trailer, the salesman told me to take the truck with trailer in tow to a level lot and let the truck roll forward at slow idol. Adjust the controller setting until it's high enough to slow the truck and trailer by manually activating the controller. Next let the truck and trailer roll at idol and apply the truck brakes. If the trailer tugs, the increase the setting. If it pushes the truck, decrease the setting. Before leaving the dealers lot I tried this. Manually activating the brake controller did not stop the truck at any setting. We thought we might have an electrical issue. After two hours making sure the trailer brakes were operating properly we gave up and decided to take it to the Ford dealer and have them check it out. On the way home I manually applied the controller at about 25 MPH. It worked fine. I'll have the dealer check it out before I take the trailer on our first trip.


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## garyb1st (Dec 6, 2007)

tdvffjohn said:


> The wet roads are the key to this great mystery in my opinion. It is recommended, at least in the fire service, that when roads are slick, to disable engine brakes, Jake Brakes, or transmission retarders, and just drive slower. All of these devices can cause the drive wheels to slow rapidly, and cause the grip with the road to be broken, inducing a slide/skid.
> 
> Just my two cents.
> 
> Tim


X2.......the sudden downshift of the trans and on wet roads caused the rear wheels to get a reaction and with the trailer pushing with the set up at an angle (meaning a slight turn) it caused the jackknife.

Accelerating might have pulled him out of it but when you are going down a steep hill already, by accelerating, you would need to hit the brakes again to slow down soon . Sounds like he was a no win situation when it started and he did a good job of protecting his family.

I rarely used my tow haul mode last summer including I 70 in Colorado because of the quick drop into a lower gear and then the high rpm s that followed. I try to start from the very top at the speed I want to stay at all the way down, maintaining a speed is easier of the brakes than slowing down to lower speed on a hill.

John
[/quote]

The bigger issue was the tight curve he was in. Accelerating was not an option.

Starting at a slower speed makes sense. But if the grade is steep, what about manually downshift to a lower gear? I do that to reduce brake ware. But I don't know if that's hard on the Tranny.


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## LarryTheOutback (Jun 15, 2005)

garyb1st said:


> Manually activating the brake controller did not stop the truck at any setting.


It won't stop the truck, but it will help stretch the trailer back into line behind the truck, especially when combined with a slight increase in truck speed as mentioned before. That said, it might not have helped much in this situation as the speed was too high on this hill and tight curve.

Ed


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## Scoutr2 (Aug 21, 2006)

The Tow/Haul mode causes the electronic transmission control (BCM, on GM vehicles) to use a different shift map for transmission operation - changing the shifting points. As you accelerate, the transmission upshifts a little later, at a higher engine RPM for each shift. As you decelerate, it works in reverse - the engine RPM will jump up much higher when you downshift to the next lower gear. That action will cause the wheels to slow down rapidly for a short time until the engine cranks back up to the higher engine RPM. And that will cause undesirable results on slippery downgrades (as your friend discovered).

My advice (since you asked) is to turn OFF the Tow/Haul mode in that set of circumstances - when towing downhill with slippery underfooting. The transmission will still downshift, but at different points, and the engine RPM will not be as high after the shift. This will still cause undesirable results under the same conditions, but they will not be as drastic.

I'm guessing that he is using the brake controller that Ford puts in their vehicles at the factory. I don't know much about those controllers, but I use the Prodigy, which lets me set the controller so that the trailer brakes apply a little harder and a little ahead of the truck's brakes. That serves to help prevent the trailer from passing the truck in a downhill or hard braking situation.

Just my $.03. (The high price of fuel has also driven up the cost of my advice!) For what it's worth . . .

Mike


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## hazmat456 (Jul 26, 2007)

I routinely haul up to 20,000 lbs with a 04 F-350 and never use the tow/haul mode it is too disruptive and unpredictable, when going downhill I will manually shift into 2 or 1 at the top of the hill and manually use trailer brakes first then truck brakes. These trucks have plenty of power and using a engine brake on anything but a clean dry hard surface can be dangerous


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## Reverie (Aug 9, 2004)

I have been lurking on this thread trying to understand it. Someday I hope to have a larger truck and having one with Tow/Haul Mode is high on my list.

1. Why would anyone pull a large trailer if their Brake Controller had no authority, especially no manual authority, over the trailer? I don't mean this as a criticism but as a genuine question.

2. I'm inclined to believe the trailer must have had significant weight issues because for the trailer wheels to break free at 30 mph indicates to me that the trailer was "carrying" a great deal of inertia into the curve. If the trailer is not overloaded than the braking of the vehicle had to be very significant.

3. Can Tow/Haul Mode generate that much braking force? I always thought it had a fairly smooth transition but since I don't own one it is just speculation on my part.

Reverie


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## CamperAndy (Aug 26, 2004)

Reverie said:


> I have been lurking on this thread trying to understand it. Someday I hope to have a larger truck and having one with Tow/Haul Mode is high on my list.
> 
> 1. Why would anyone pull a large trailer if their Brake Controller had no authority, especially no manual authority, over the trailer? I don't mean this as a criticism but as a genuine question.
> 
> ...


I will answer #3, It is like doing a quick down shift with a manual transmission. The torque converter stays locked up and since you are off the gas the engine RPM will start off being down low and rapidly go up as the rear wheels spin the the engine up with the lower gear. When not in Tow Haul the torque convert will not stay locked at that low of a speed and the down shift if there is one will be a lot softer.

I personally leave mine in tow haul but down shift manually at the tow to ride the lower gear down.


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