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-   -   What gear do you use - downhill w/ trailer? (http://www.f150forum.com/f82/what-gear-do-you-use-downhill-w-trailer-264380/)

ccc150 06-25-2014 02:27 PM

What gear do you use - downhill w/ trailer?
 
Have not pulled an RV yet with my '13 EB SCAB but will be next month. With out a trailer I have noticed in the EB you need to be down to at least 3rd gear before you get any real engine braking, with 2nd even more. What gear do you all use going down a steep, like 7%, grade? What speed can you drop down in to 2nd with out hurting the tranny?

brulaz 06-29-2014 09:44 AM

It's not only the grade but the speed limit and whether there's hair-pin turns every half mile or so.

Coming down the west side of Newfound Gap in the Great Smoky Mountains National Park, I was in 2nd. Would brake to 20mph for each hair-pin, then the grade would accelerate the rig to 40mph before the next hairpin, so would have to brake again. Speed limt was 35mph.

Eventually the truck brakes started cooking/smelling so I started manually using the trailer brakes to help out. Probably should have pulled over half way down to let things cool off.

Think you could down shift to 2nd at 40mph. Probably the tranny won't do it if it's too extreme.

On grades like this you can't just use Tow/Haul as it will upshift into 3rd between the hair-pins once you take your foot off the brake.

But on steep grades on most Interstates without the hairpins and higher speed limits, Tow/Haul has put me into 3rd with the first brake application and that's usually good enough, even on a 7% grade, if the speed limit is 60-70mph.

jcain 06-29-2014 03:03 PM

The down fall to the little EB workhorse is that it has little to no engine braking. I always ran my trailer brake gain a click higher during large descents. Brake in 10mph increments. ie: speed limit is 55, I'd brake to 45 then let it coast back to 55 and re apply brakes. You have to let things cool down or you'll be a runaway rig before you know it.

brulaz 06-29-2014 04:05 PM

Quote:

Originally Posted by jcain (Post 3572220)
...
I always ran my trailer brake gain a click higher during large descents.
...

This is a good point. Typically you set your trailer brakes to just below lock up when at normal temperatures. Good for one-time emergency stops.

But not good for long periods of repetitive braking. Those drums are going to warm up, expand and need more juice to get the same stopping force. On that downhill run described above, I had just adjusted the brakes a couple of days before. They would lock at 8, so I set them at 7.5. But by the time I got to the bottom of the hill, I had them at 9.5 and could probably have gone to 10 without lockup. Yes, they were *hot*, as were the truck's brakes.

Disk brakes on the trailer would be nicer!

Laramieskibum 07-13-2014 02:46 PM

below 30mph I'm in first gear. plenty of engine breaking there for speeds around 30mph. I let it rev to 500rpm below redline then take it down to 3000rpm and let it build again. This gives the brakes a chance to cool before the next application. 7% grades with switch backs, 7,100lb travel trailer and full truck (150lbs over rear axle rating).


ecoboost does have compression braking, you just need to get it up at high rpm (>3,000, more like 4,000+). Truck/trailer will feel like its getting away from you until you let it rev, then it will hold you back. If it doesn't hold you back once you rev it up, your going to fast, gear down 1 gear then let it rev back up. If that's too slow than too bad, better than smoking the brakes, go that speed. Let the engine compression you need determine the speed. I've never had hot brakes on any pass in Colorado, Wyoming, Utah (done nearly all of them with this load, interstate (I70,I80,I15), highway (out of vernal, out of grand junction, south pass wy, Teton pass wy), and long sections of steep dirt roads (20mph or less I'm in 4x4 low to help gear down).


Checked my brakes while switching the snow tires/rims out and they look just fine after 62k, 15k+ of that towing 'heavy' and all tows involve a pass/grade here. Tow/haul works too good on the parleys canyon section of I-80 east of park city when empty, I find my self hitting the accelerator. That is probably a 10 mile 3-7% grade.


It's too bad we don't have selectable front hubs, two wheel drive low would give you more options at slow speeds on pavement.

Laramieskibum 07-13-2014 02:57 PM

Quote:

Originally Posted by brulaz (Post 3571843)
It's not only the grade but the speed limit and whether there's hair-pin turns every half mile or so.

Coming down the west side of Newfound Gap in the Great Smoky Mountains National Park, I was in 2nd. Would brake to 20mph for each hair-pin, then the grade would accelerate the rig to 40mph before the next hairpin, so would have to brake again. Speed limt was 35mph.

Eventually the truck brakes started cooking/smelling so I started manually using the trailer brakes to help out. Probably should have pulled over half way down to let things cool off.

Think you could down shift to 2nd at 40mph. Probably the tranny won't do it if it's too extreme.

On grades like this you can't just use Tow/Haul as it will upshift into 3rd between the hair-pins once you take your foot off the brake.

But on steep grades on most Interstates without the hairpins and higher speed limits, Tow/Haul has put me into 3rd with the first brake application and that's usually good enough, even on a 7% grade, if the speed limit is 60-70mph.


If speed limit was 35mph I'd be in 1st gear and just go below the speed limit rather than smoke the brakes on truck and trailer in 2nd. We have similar grades/speeds here. 1st gear will go in at 29mph or so, plus it has a lot more gear reduction than second. Try first gear next time, you will like it. I take all steep highway / non interstate grades <35mph or so in 1st gear.

ccc150 07-13-2014 10:17 PM

Quote:

Originally Posted by Laramieskibum (Post 3594243)
below 30mph I'm in first gear. plenty of engine breaking there for speeds around 30mph. I let it rev to 500rpm below redline then take it down to 3000rpm and let it build again. This gives the brakes a chance to cool before the next application. 7% grades with switch backs, 7,100lb travel trailer and full truck (150lbs over rear axle rating).


ecoboost does have compression braking, you just need to get it up at high rpm (>3,000, more like 4,000+). Truck/trailer will feel like its getting away from you until you let it rev, then it will hold you back. If it doesn't hold you back once you rev it up, your going to fast, gear down 1 gear then let it rev back up. If that's too slow than too bad, better than smoking the brakes, go that speed. Let the engine compression you need determine the speed. I've never had hot brakes on any pass in Colorado, Wyoming, Utah (done nearly all of them with this load, interstate (I70,I80,I15), highway (out of vernal, out of grand junction, south pass wy, Teton pass wy), and long sections of steep dirt roads (20mph or less I'm in 4x4 low to help gear down).


Checked my brakes while switching the snow tires/rims out and they look just fine after 62k, 15k+ of that towing 'heavy' and all tows involve a pass/grade here. Tow/haul works too good on the parleys canyon section of I-80 east of park city when empty, I find my self hitting the accelerator. That is probably a 10 mile 3-7% grade.


It's too bad we don't have selectable front hubs, two wheel drive low would give you more options at slow speeds on pavement.



That was what I was really looking for when I started this thread. I really wanted to see if going to first gear would be OK coming down steep grades.

Laramieskibum 07-13-2014 11:14 PM

Quote:

Originally Posted by ccc150 (Post 3594999)
That was what I was really looking for when I started this thread. I really wanted to see if going to first gear would be OK coming down steep grades.

It's the only way for me, at speeds lower than 35mph (3.73 gears). Won't go into first till something like 25-29mph. 1st has pretty deep gearing on our trucks, more bang for your buck, 2nd does nothing at lower speeds. 2nd gear doesn't rev up until way over 40 mph.

brulaz 07-14-2014 08:09 AM

Since I only do this once a year in the Smokies, I'm not that worried about wear-and-tear. The brakes have checked out fine since.

If such steep slopes were routine, I might be more worried about wear-and-tear on the tranny at those high revs in first. But ultimately, I'd be looking for a different truck, with a different gearing or an engine with more braking at lower rpm.

Laramieskibum 07-14-2014 10:29 PM

Quote:

Originally Posted by brulaz (Post 3595511)
Since I only do this once a year in the Smokies, I'm not that worried about wear-and-tear. The brakes have checked out fine since.

If such steep slopes were routine, I might be more worried about wear-and-tear on the tranny at those high revs in first. But ultimately, I'd be looking for a different truck, with a different gearing or an engine with more braking at lower rpm.

Not much for hills in Ontario (barely above sea level?), or even in between, but roads like you see in the Smokies are the norm for every trip in the mountain west. I'm am looking at a 1ton if further improvements to this truck don't pan out but not due to lack of braking power from the engine but overheating while towing at altitude our steep grades. Towing here starts at 4-6,000' and ends at 9,000' for us at the end of the climb, inside of a 2 hr drive, usually the last 30 minutes of the drive, every trip. Normally aspirated engines are pigs here compared to their sea level breathern and I cannot yet justify the $10,000 additonal cost in a diesel....yet...slowly wearing down as the heat issues with the ecoboost continue to surface and I"m not the only one, many of us in the mountain west with ecoboosts are having problems but not with transmissions breaking due to engine braking. See thread in 2011+ forum on this site. Forced induction is high on my list, and the options are limited - ecoboost, ecodiesel, or hd diesel....

I'm not willing to give up on the F-150, this truck pulls like a no other gasser in the high alt valley floors and even on the hills, just needs some help in the cooling department. If I can't solve it, cummins bound in a few years...

Not sure I understand how this is any harder on the tranny? 40mph down hill vs 40mph on the high way should be seeing the same loads and speeds inside the transmission? So long as it remains cool, which it does when engine braking like this. Maybe in tension rather than strain? If every person in the mountain west just used their brakes and did not engine brake there would be alot of work for the brake monkeys.

I do not agree that engine braking at below redline RPM's adds any statistical engine damage. In other words 10 minutes at an average of even 5,000rpm is probably nothing compared to the trucks lifetime damage from sitting idling in the drive way / stop lights / traffic / ect, or in my trucks case:

50,000miles of 80mph interstate driving
15,000 miles of 65mph highway towing
<500miles of steep grade towing, of which 250miles are engine breaking down hill, on the high side (assumes 4-5 steep trips per year)

So 1-2% of its miles are spent at high rpm, with no fuel being added, and sufficent cooling to keep temps down, all the while receiving good cool oil.


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