Boomerweps
Hills of PA
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A minor trick with the F150 10 speed on hills:
If you set the cruise control before the top of the hill going down, it will aggressively downshift to maintain speed 5mph or so above the set speed. I’ve not tried this towing.
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mkirsch
Rochester, NY
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Thinking about this more, and I'm wondering if you are expecting the truck to automatically maintain speed.
It doesn't work that way. If you get it into "grade braking mode" with much of a trailer on, and just let it go, it will keep downshifting and downshifting trying to maintain speed.
You need to use brakes, and you need to stay ahead of the transmission to keep it from overcompensating. Once it starts dropping gears and overrevving the only solution it to pop it out of tow/haul and start over.
Putting 10-ply tires on half ton trucks since aught-four.
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Grit dog
Black Diamond, WA
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Boomerweps wrote:A minor trick with the F150 10 speed on hills:
If you set the cruise control before the top of the hill going down, it will aggressively downshift to maintain speed 5mph or so above the set speed. I’ve not tried this towing.
It works towing as well. Until the revs can’t keep up with the acceleration. On a Chevy anyway, with the same trans.
Most newer transmissions with smart tow/haul do that as well. Even my clunky ole 68rfe.
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Turtle n Peeps
California
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Modern computer controlled trucks do not over rev. It's impossible because of the computer.
Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.
Let it rev.
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wnjj
Cornelius, Oregon
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Turtle n Peeps wrote:Modern computer controlled trucks do not over rev. It's impossible because of the computer.
Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.
Let it rev.
Truck pulls hold these meetings too. I used to help my uncle who owned a pulling sled business. There was one local truck that had a moderately built 454 that spun 9000 RPM when pulling.
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Lantley
Ellicott City, Maryland
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Turtle n Peeps wrote:Modern computer controlled trucks do not over rev. It's impossible because of the computer.
Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.
Let it rev.
I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.
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Turtle n Peeps
California
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Lantley wrote:
I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.
Any modern diesel truck or gas truck for that matter, cuts all fuel off to the injectors while going down hill. There is no heat being made because there is no combustion going on. This has been going on since 1994.......at least for GM.
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Lantley
Ellicott City, Maryland
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Turtle n Peeps wrote:Lantley wrote:
I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.
Any modern diesel truck or gas truck for that matter, cuts all fuel off to the injectors while going down hill. There is no heat being made because there is no combustion going on. This has been going on since 1994.......at least for GM.
That all sounds good, I don't dispute your claim. But that 2007 truck would definitely overheat if you let it. I managed to control the overheating by not letting the truck rev as much on steep declines.
Again it had an after market exhaust brake that could had been faulty and ultimately caused the problem.
My 2019 has a factory exhaust brake and does not have that issue.
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JRscooby
Indepmo
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Lantley wrote:Turtle n Peeps wrote:Lantley wrote:
I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.
Any modern diesel truck or gas truck for that matter, cuts all fuel off to the injectors while going down hill. There is no heat being made because there is no combustion going on. This has been going on since 1994.......at least for GM.
That all sounds good, I don't dispute your claim. But that 2007 truck would definitely overheat if you let it. I managed to control the overheating by not letting the truck rev as much on steep declines.
Again it had an after market exhaust brake that could had been faulty and ultimately caused the problem.
My 2019 has a factory exhaust brake and does not have that issue.
To slow a vehicle, a lot of energy must be transformed to heat, and dissipated. Now does it go out thru brakes or engine and drivetrain?
Personally, I know engine temps will drop fast when jake shuts off, and transmission/rearends will cool quickly if soft-pedal for few miles, and the system designed to stop is still in best working order if faced with emergency.
Now something that many overlook is how to reduce the amount of energy that must be dissipated. It takes much less braking, service or engine, to reduce speed from 40 to 30 than 60 to 50MPH. Let speed drop to well below safe as you near start of downhill, then hold the lower speed until near bottom.
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mkirsch
Rochester, NY
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Turtle n Peeps wrote:Modern computer controlled trucks do not over rev. It's impossible because of the computer.
Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.
Let it rev.
That's true when you're stomping on the go pedal, but is it when you are being pushed down a grade by a big trailer with your foot off the gas?
When you're being pushed you can cut the ignition all you want and it's not going to limit anything. The only thing that will bring RPMs down is an upshift, and I don't know of anyone who has let their rig go that far to see what would happen.
For science, I've let my 8.1L/Allison go to 5000 before I hit the brakes, and there was no indication of it upshifting or doing anything but dropping another gear in a futile attempt to maintain speed by engine alone.
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