8% grade descent

[PatsRock]

Newbie Here. F350 and 37' fifth wheel.

Yesterday I went down an 8 degree slope and left it in Tow Haul while using the breaks on trailer and truck to slow me down. I was thinking I might have been better off starting in 2nd gear at the top of the hill.

What is the correct strategy for braking on a big descent?

[Mr__Cob]

Howdy All,

Regardless of transmission type, "IF" you need to use your service brakes to slow down while descending a steep grade, use the method professional truckers use; use enough pressure on your brake pedal to drop 5mph in 3 seconds then let up, repeat as needed. The trick is to NOT getting going to fast to begin with, start out slow from the top and be in control all the way down without burning up your brakes. If you don't have some type of exhaust brake, GET ONE, its the best money you'll ever spend.

[john_bet]

Most of the post sound all to complicated for me. So far I have not found a 6-7% grade that I can't pull in 3rd at not less than 48 mph turning about 2700 rpm. I push my button to drop out of o/d to 3rd and lock up t/c again and go. That's all I have needed so far from my '04.5 Dodge/Cummins. Personally I can't afford an exhaust brake add on or a newer truck at this time so I drive within limits of what I own and it has worked very well in our travel all across the northern part of this fine country. JME.

[jffnkrn]

As stated earlier, lots of good suggestions and experience. For me, when approaching the grade, signs will tell me, I put truck in a lower gear depending on the grade, mine has tow/haul mode or manual override. Then I control my speed, if a steeper grade, for me about 8%, I keep it slow, maybe 45 to 50. When I start getting closer to the 50 or 55, I use breaks firm and steady to slow down to the slower speed, 35 to 40, then let er coast until I regain a speed that is getting close to uncomfortable, then slow er down again. In over 16 years, never had an trouble with this except the idiots that fly by you and flip you off because you were going slower. I can honestly say I am not one of those laying over a hill side, in a run away truck ramp or sitting at the bottom of the hill getting a ticket or with overheated brakes. Just take your time and keep your rig under a comfortable control. Good Luck & Be Safe ! ! !

[lbrjet]

My tranny will drop to first in T/H. Happened once in Utah last year coming down a twisty 12% grade. Mostly held me at 30 MPH but still had to brake a little for the 25 MPH curves.

[Tystevens]

Note that T/H won't cause the transmission to downshift to 1st for braking purposes in any make or model as far as I'm aware. If the hills are steep and you need 1st gear, you need to manually downshift.

The process is simple. Just downshift enough so that you aren't speeding up anymore! Your truck won't shift into a gear too low for the current speed, so you don't have to worry about that.

[coolbreeze01]

PatsRock wrote:
Newbie Here. F350 and 37' fifth wheel.

Yesterday I went down an 8 degree slope and left it in Tow Haul while using the breaks on trailer and truck to slow me down. I was thinking I might have been better off starting in 2nd gear at the top of the hill.

What is the correct strategy for braking on a big descent?

1st or 2nd would have been a good idea. Buy an exhaust brake!!

[myredracer]

Besides all the T/H stuff:

I know that you should try and stay off the brakes as much as possible, but if I knew we were going to be heading into territory with steep downhill grades, I'd want to know in advance that our TT brakes are in good working order and that the BC is adjusted properly. Too many things can go wrong with brakes on a TT and when you do brake, you'll want to be able to count on both the TV & TT brakes working for you.

I also think it's important make sure to slow down well in advance of a corner before you enter it. You don't want to find yourself in a corner and having too much speed going down a steep incline. Max. posted speeds for corners are based on the heaviest, longest and most difficult of vehicles and rigs so if you enter at corner at or less than the posted speed, you'll get around the corner(s) fine.

We went up and down a mountain pass last week of 10% and 4,000 ft. (I know not bad compared to some). The road on the way down was quite twisty, rough and narrow in sections at 50 - 60 mph. We had shocks installed earlier this year and this was the first real test of them. It is way easier to control the truck now and the TV and TT together are much "tighter" and a lot more predictable.

I love the T/H on our '09 F250 and it's great going up or down steeper roads. Don't know if our V10 works better for engine braking over a V8 but the engine braking is quite effective.

[BurbMan]

Gdetrailer wrote:
Each vehicle has it's own characteristics, one vehicles "2nd gear" just may be 3rd gear or another vehicles 1st gear. So there IS NO SET IN STONE RULE as to what speed or gear to be in..

BurbMan wrote:
I would slow enough to drop into 2nd at the top of the hill, possible 1st depending on how twisty/turny. Leave it in tow/haul, that provides additional engine braking. I know on the burb 2nd gear limits speed to 45, 1st gear to about 30 on these steep grades. As long as no sharp curves I am OK at 45.

Personally I can’t believe all the ideas tossed into this thread!

I wasn't going to reply any more but there is so much utter nonsense being posted which is simply going to make more confusion..

Not sure why you are picking on my post, I clearly stated that those values apply to MY SPECIFIC VEHICLE. I drive my vehicle according to what my owner's manual says and OP should do the same.

[ReneeG]

Gdetrailer - thanks for your posting. When the OP asked about descent in Tow/Haul mode and I noted the year of his TV in his signature (or was it post), my response was based on using the Ford's Tow/Haul mode braking feature. It works and should be used. Although we know to always engage Tow/Haul mode when towing, even on flat land, our transmission guy advises it.

[blt2ski]

8% is pretty minor in grade. I'd hold direct if a long interstate style road with long curves. With curves the gear below for 35-45 with a diesel. 2 gears below direct in most gassers. I was usually in the gear below to go down the 35 mph 11% grade to the North of my house, same with the 9% going south from my house.

Its when you get on the 15-25% grades on local city and county roads around Seattle etc those usually get me worried. 8% unless there is a hairpin, nothing to worry about. Or try the 6 miles from Timberline to government camps 10% grade with 2" of compact snow and ice, blowing 30 with gusts to 50 mph. That will get your knickers up! Chains on all 4 of the truck, two of four on trailer. No problems.....I even lived to write and tell about it!

Note to self, do not type using smart phone, it is WAY dumber than I.
marty on edit.........

[Turtle_n_Peeps]

Dave Mck wrote:
Am I correct in figuring grades? An 8% grade drops or rises 8 feet over a 100 foot span?

Yes.

[dave17352]

My tow haul and exhaust brake work wonderfully. Yet on hair pin turns on steep grades with with 10 mph speed limits I still use the manual selector between 1st and 2nd gear. That also works wonderfully. That's what it is there for.

[Dave_Mck]

Am I correct in figuring grades? An 8% grade drops or rises 8 feet over a 100 foot span?

[Gdetrailer]

BurbMan wrote:
I would slow enough to drop into 2nd at the top of the hill, possible 1st depending on how twisty/turny. Leave it in tow/haul, that provides additional engine braking. I know on the burb 2nd gear limits speed to 45, 1st gear to about 30 on these steep grades. As long as no sharp curves I am OK at 45.

Personally I can’t believe all the ideas tossed into this thread!

I wasn't going to reply any more but there is so much utter nonsense being posted which is simply going to make more confusion..

Each vehicle has it's own characteristics, one vehicles "2nd gear" just may be 3rd gear or another vehicles 1st gear. So there IS NO SET IN STONE RULE as to what speed or gear to be in..

Tow/Haul MAKES this much easier to tow and takes a lot of guess work out of it..

Folks READ THE MANUAL.

PATSROCK, you did not give the year of your truck but here is the Owners manual for our 2006 F250.

Pay attention the points I bolded.

2006 F250 Owners Manual Link

Pages 176-178..

Understanding the shift positions of the 5–speed automatic
transmission

This vehicle is equipped with an adaptive Transmission Shift Strategy.
Adaptive Shift Strategy offers the optimal transmission operation and
shift quality. When the vehicle’s battery has been disconnected for any type of service or repair, the transmission will need to relearn the normal shift strategy parameters, much like having to reset your radio stations when your vehicle battery has been disconnected.

The Adaptive Transmission Strategy allows the transmission to relearn these operating parameters. This learning process could take several transmission upshifts and downshifts; during this learning process, slightly firmer shifts may occur. After this learning process, normal shift feel and shift scheduling will resume.


D (Overdrive) with Tow/Haul OFF

D (Overdrive) with Tow/Haul OFF is the normal driving position for the
best fuel economy. The overdrive function allows automatic upshifts and downshifts through gears one through five.

D (Overdrive) with Tow/Haul ON
The Tow/Haul feature improves transmission operation when towing a
trailer or a heavy load. All transmission gear ranges are available when using Tow/Haul.

To activate Tow/Haul, press the
button on the end of the gearshift
lever.

The TOW HAUL indicator light will
illuminate in the instrument cluster.

Tow/Haul delays upshifts to reduce frequency of transmission shifting.

Tow/Haul also provides engine braking in all forward gears when the
transmission is in the D (Overdrive) position; this engine braking will slow the vehicle and assist the driver in controlling the vehicle when descending a grade.

Depending on driving conditions and load conditions, the transmission may downshift, slow the vehicle and control the vehicle speed when descending a hill, without the accelerator pedal being pressed. The amount of downshift braking provided will vary based upon the amount the brake pedal is depressed.

To deactivate the Tow/Haul feature and return to normal driving mode,
press the button on the end of the gearshift lever. The TOW HAUL light
will no longer be illuminated.

When you shut-off and restart the engine, the transmission will
automatically return to normal D (Overdrive) mode (Tow/Haul OFF).

Do not use the Tow/Haul feature when driving in icy or slippery
conditions as the increased engine braking can cause the rear
wheels to slide and the vehicle to swing around with the possible loss
of vehicle control

The transmission will not downshift into 1 (First) at high speeds; it
will downshift to a lower gear and then shift into 1 (First) when the
vehicle reaches slower speeds


Over the years Ford has made significant enhancement changes to the Tow/Haul feature, our 2013 the Tow/Haul works even better than the 2006 version.

To be very clear, these transmissions NEED to be placed in Tow/Haul AND KEPT IN TOW/HAUL while towing.

This allows the transmission to RELEARN AND ADAPT to the load. Randomly turning on/off Tow/haul or manually downshifting when you think you need or don’t need it makes no sense and you are not taking FULL advantage of the Tow/Haul feature. Not to mention the transmission NEVER learns and adapts CORRECTLY to your towing conditions when you are constantly overriding the Tow/Haul feature.

In order for the Tow/Haul feature to work CORRECTLY you MUST keep the Tow/Haul ON.

If you keep the Tow/Haul on it WILL AUTOMATICALLY DOWNSHIFT FOR YOU. This is DEPENDING ON DRIVING CONDITIONS AND LOAD CONDITIONS.

The AMOUNT of downshift braking WILL VARY BASED ON THE AMOUNT OF BRAKE PEDAL PRESSURE (IE how many gears it downshifts).

If Tow/Haul does not automatically downshift you simply Press on the BRAKE PEDAL, the more pressure you apply the more aggressive the downshift will be.

Keeping in mind that the transmission WILL NOT DOWNSHIFT to the next lower gear if your speed is excessive for the next lower gear to protect the engine and transmission. You cannot override this feature even if you manually select a gear, the transmission will only downshift when it is safe to do so. In other words if you are 4th and select 1st it will only go to 3rd until the speed has reduced enough to safely shift to 2nd and so on..

PATSROCK, READ YOUR MANUAL.

The highway system ALSO GIVES you advanced notice of any steep grades so all you need to do is to be aware of them. When you SEE a down hill grade sign and before you start down the grade, let off the throttle THE WHOLE WAY (LIFT YOUR FOOT OFF THE THROTTLE PEDAL). This will allow you to lose some speed and let the Tow/haul do its job (you must let up on the throttle to get Tow/Haul to downshift).

If you feel the downshift is not happening fast enough or it has downshifted and is gaining speed simply press on the brake pedal until it downshifts to the next lower gear.. When it downshifts you can let up on the brake and simply watch to see the speed is no longer increasing.

You MAY need to apply brakes periodically on long grades to maintain a safe speed but you should not need to continuously ride the brakes nor be pressing hard the whole grade as long as the Tow/Haul has downshifted far enough.. If you do have to use the brakes Tow/Haul SHOULD downshift to a lower gear all the way down to 1st IF NEEDED provided the RPMs are within the safe area to do so.

The last time I manually downshifted was with my 2003 F250 which did not have tow/haul..

The highway systems will also have signs posted for truckers which often will post max safe speeds for truckers, towing heavy as you are you should HEED the posted trucker speed limits for those grades. Unlike a lot of RV "towers" I tend to fall in line with the truckers when going down long steep grades and maintain similar speeds as they are doing.

Not to mention that if there is hairpin turns and such those will have posted truck speeds.

You can at any time find Ford Owners manuals online..

FORD TRUCK OWNERS MANUALS