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Old 06-08-2016, 05:07 AM   #1
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Brand: Thor Motor Coach
State: Missouri
Posts: 11
THOR #4471
Transmission winding up before upshifting

I drive a 2016 Ford Hurricane 29' Thor motorhome.
When accelerating from a stop, the tranny winds up to 3400rpm before shifting into 2nd gear, then winds up to 4200rpm before shifting into 3rd gear. This happens on both flat roads and on the hills.
It has been taken to the Ford Dealer, and they hooked it up to a machine and said that it is operating correctly.
When driving with the cruise control on at 65 mph on a flat road, when it encounters a hill it will downshift from overdrive to 3rd gear and wind out to 3400rpm, then drop down into 2nd gear and max out the tach to 6000rpm if you don't immediately tap the brake or turn the cruise control off.
I have heard that there is an article in some RV magazine that talks about these issues and recommends an aftermarket component that can be installed on the transmission to correct the problem.
Does anyone know which magazine and which month the article appears, or what the component is and who carries it?
I've searched the web with all the search words i could think of, but I can't find it.
Thanks
scooterdudetim1
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Old 06-08-2016, 11:30 AM   #2
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Brand: Thor Motor Coach
Model: Vegas 24.1
State: North Carolina
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THOR #2142
Scooter,


Are you talking about a 5Star Tune-up? I am toying with this upgrade later this summer.


Check out:
http://5startuning.com/product/ford-6-8l-v10-rv-motor-home-only-x4-power-flash-device/


Doc

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Old 06-08-2016, 12:33 PM   #3
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What is the problem? The V-10 is an overhead cam engine designed to run at high RPMs.

The 5-star tune won't change that unless you specifically ask them to lower the redline (which they will do: They will happily make any changes you want for your custom tune).
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Old 06-08-2016, 12:45 PM   #4
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Jamie,

Thanks...live and learn.

Doc
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Old 06-08-2016, 01:59 PM   #5
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Brand: Still Looking
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Quote:
Originally Posted by scooterdudetim1 View Post
.....cut....

It has been taken to the Ford Dealer, and they hooked it up to a machine and said that it is operating correctly.
When driving with the cruise control on at 65 mph on a flat road, when it encounters a hill it will downshift from overdrive to 3rd gear and wind out to 3400rpm, then drop down into 2nd gear and max out the tach to 6000rpm if you don't immediately tap the brake or turn the cruise control off.
I have heard that there is an article in some RV magazine that talks about these issues and recommends an aftermarket component that can be installed on the transmission to correct the problem.

....cut.....
Most motorhome engines rev higher simply because they need to in order to develop more power. That doesn't necessarily mean there is anything wrong.

The usual problem is that the driver expects it to drive like a car, and it won't. "Tuning" can mostly change the way it "feels" but it will never change the laws of physics. I hate to be blunt, but the answer is in the numbers.

Your motorhome weighs roughly the same as five cars the size of a Honda Accord. Now imagine driving an Accord with a tiny 1.3-liter engine rated at 70 HP and 90 lb-ft of torque. If you load up the family and head down the road, it will seem as slow as molasses, right?

When it doesn't accelerate as expected, most of us will just give it more throttle, which is very normal, but results in the computer determining it needs to allow engine to rev higher to give you the power you asked for.

The same happens on hills. The very low power-to-weight ratio makes it "IMPOSSIBLE" for the motorhome to maintain highway cruising speed up a steep hill, so it has to downshift to a lower gear. The ONLY way to avoid much higher RPMs is to slow down a bunch. That will result in a lower gear and moderate RPMs. And it pays for driver to anticipate and turn off cruise control before reaching the hill.

Tuning an engine may make incremental changes that you may like, but for the most part Ford tunes the drivetrain taking a lot of factors into account. If there was a lot to be gained without hurting anything, why wouldn't Ford engineers do it from the start?


One other thing. Your 2016 may have been built on a 2015 Ford chassis, which could have the 5R110 transmission instead of newer 6R140. I would look it up if you don't already know. If so, gear spacing can be much wider between some shifts, leading to higher RPMs more often. But even if you have a 6-speed, it won't accelerate or climb like a car. It's best for driver to adapt to driving the relatively underpowered motorhome.
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Old 06-08-2016, 02:50 PM   #6
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Transmission winding up

Jamie,
Thanks so much for the very informative reply. Sounds like one just needs to learn how to drive the transmission. I appreciate your response.
Scooterdudetim1
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