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Old 07-19-2019, 04:40 AM   #1
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Model: 2017 Miramar 34.2,
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THOR #14761
Unhappy F53 6 speed trans ( down shifting to soon)

Hi ALL - Frustrated with the torque flight transmission downshifting on simple hills , when not needed into 4 or 3 gear. The damn engine is going to come through the doghouse, is there anything that I can do . ( 5 star tune does not sound like the answer) I hand shift as much as possible for the uphills. But going down a grade, traffic following me and trying to get a running start on the next hill the trany does its thing if just tapping brakes and jumps to 4, 3
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Old 07-19-2019, 05:06 AM   #2
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Model: ACE 27.1
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Originally Posted by SANDDOG View Post
Hi ALL - Frustrated with the torque flight transmission downshifting on simple hills , when not needed into 4 or 3 gear. The damn engine is going to come through the doghouse, is there anything that I can do . ( 5 star tune does not sound like the answer) I hand shift as much as possible for the uphills. But going down a grade, traffic following me and trying to get a running start on the next hill the trany does its thing if just tapping brakes and jumps to 4, 3
Take it out of tow/haul mode and turn off the cruise control.
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Old 07-19-2019, 12:25 PM   #3
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Model: Windsport. 35M
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SANDOG

I know what you are experiencing. Donít tap the brakes. When you want to slow down, apply the brakes like you mean it, then release fully and quickly. Donít ride the brake pedal either. Keep your foot off it. It seems like just tapping the brakes tells the computer you want it to downshift. Remember, you are driving a truck not a car. Drive it like a truck. Let the computer and transmission do its job. Do a search on the forum for ďdownshiftingĒ. Lots of good info on proper driving techniques for this transmission.
Remember, Itís a truck. Donít expect it to drive like a car. Itís easy to forget if you donít drive it often. You have to learn how to apply the brakes and control the throttle properly. Sometimes if you want the transmission to upshift sooner you must let up on the throttle. This can feel counter intuitive until you get the hang of it.
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Old 07-19-2019, 01:39 PM   #4
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Simple math says that 320 HP in a 20,000-pound motorhome plus toad (more or less) will result in power to weight similar to putting a 64 HP engine in a 4,000-pound car. If you did, the transmission would be shifting a lot too and the engine would run close to redline on uphills.

Downshifting for engine braking has similar limitations. A 6.8L V10 may seem large, but relative to weight, itís like a 1.4L tiny gasoline engine trying to slow a 4,000-pound vehicle. Itís going to scream if driven like a normal car.

Easiest solution is to slow down on both uphills and downhills if one wants to keep RPMs much lower. On downhills itís often necessary to first apply brakes to slow down enough so that engine braking can provide enough braking force in a much lower gear to keep from speeding up again. Unfortunately, that means going downhill much slower than auto traffic.
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Old 07-19-2019, 02:57 PM   #5
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Hi Ted - yes I wish it was that easy , I rarely use Cruise only on level ground and have never used tow haul. Thanks though for the reply I appreciate it.
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Old 07-19-2019, 03:04 PM   #6
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THOR #14761
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Originally Posted by Chance View Post
Simple math says that 320 HP in a 20,000-pound motorhome plus toad (more or less) will result in power to weight similar to putting a 64 HP engine in a 4,000-pound car. If you did, the transmission would be shifting a lot too and the engine would run close to redline on uphills.

Downshifting for engine braking has similar limitations. A 6.8L V10 may seem large, but relative to weight, itís like a 1.4L tiny gasoline engine trying to slow a 4,000-pound vehicle. Itís going to scream if driven like a normal car.

Easiest solution is to slow down on both uphills and downhills if one wants to keep RPMs much lower. On downhills itís often necessary to first apply brakes to slow down enough so that engine braking can provide enough braking force in a much lower gear to keep from speeding up again. Unfortunately, that means going downhill much slower than auto traffic.
Thanks Chance I appreciate your reply and have driven heavy equipment for a long time and understand the weight ratio. Still think the transmission is over reacting to slight down hills changes when not necessary . It’s interesting when coasting at 55 on a slight downhill the tranny kicks in with no need for it too. No braking is needed frustrating but I’ll work on.
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Old 07-19-2019, 03:08 PM   #7
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Originally Posted by 16ACE27 View Post
Take it out of tow/haul mode and turn off the cruise control.
Quote:
Originally Posted by Shawn62 View Post
SANDOG

I know what you are experiencing. Donít tap the brakes. When you want to slow down, apply the brakes like you mean it, then release fully and quickly. Donít ride the brake pedal either. Keep your foot off it. It seems like just tapping the brakes tells the computer you want it to downshift. Remember, you are driving a truck not a car. Drive it like a truck. Let the computer and transmission do its job. Do a search on the forum for ďdownshiftingĒ. Lots of good info on proper driving techniques for this transmission.
Remember, Itís a truck. Donít expect it to drive like a car. Itís easy to forget if you donít drive it often. You have to learn how to apply the brakes and control the throttle properly. Sometimes if you want the transmission to upshift sooner you must let up on the throttle. This can feel counter intuitive until you get the hang of it.
I only try to keep it in check on slight grades and I hand shift as much as possible going uphill. I donít want to redline I just cruise it around 3000 RPMs maybe a little more for the uphill. But downhill that baby will drop into third gear 4300 Rís. I understand 6% grades down
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Old 07-19-2019, 04:39 PM   #8
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Why do you say "5 star.... is not the answer". I hear lots of good things about 5 star.... esp what it does for the tranny shifting.

It wont cure all your problems but it sounds like it might help??

I have not pulled the trigger yet for my E450 but its on my short list. I will post update on what I think about the shifting once I do so.

On smaller (but multiple hills) on the interstates.... I will let the RV speed up (if road is straight) going down the hill (like 75 + mph) to use the momentum for the next hill. Then I back off the throttle slowly until it gets down to about 65 mph, tranny may or may not shift (depending on how steep and long the hill is) but most of the time its just one gear .... so around 3000 RPM.

If the hill is much steeper (or longer) it will down shift again but usually im only doing 60 mph so the RPMs are at or below 4K. Then I repeat.

Its kinda fun but kinda a PITA if its more than 50 - 75 miles. But you get use to when they tranny likes to down shift so I try to keep the RPM's low enough to keep shifing to a minimum as I go up the hills.

On super steep (and curvey) you dont have this option. Do what they suggested above.

I sometimes will put the tranny in N to get out of that super low gear then put it back into D or D4. If the hill is not too long this works well.

But if super long you may need all of the trannies help to save your brakes.
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Old 07-19-2019, 05:09 PM   #9
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Model: 2018 24.1 AXISSIXxSIX
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THOR #13932
I'm kind 8f baffled by the drivability complaints especially by those who say they are past profession drivers or have an intimate knowledge of some sort. We live at 6500 ft. Our other house, just 3 hours away was at 447ft. We climb a lot, we descend a lot. A LOT more than is common.

We just drive the rv. I can outdrive any downshift, understand any rpm increase and I don't buy into the whole acceleration increase from a tuner kit you 'feel'. It sure does give you an increase but there aren't one percent, maybe even only a tenth of a percent of us that hold the peddle to the floor, hit max rpm and then do it some more, when leaving a fueling station. It's nice to read the stats it's nicer to be reality based.

I've done some really wild, stupidly expensive mods to my 24.1
That tuner at that price won't be one of them, and I have no issue with the 6speed.

Try driving the rv instead of letting it dictate to you.
Maybe it's because I don't have a degree, don't claim an enviable history with racing or heavy equipment. I DRIVE, as in command, the vehicle.

I haven't a complaint or a false sense of 'seat of the pants' performance increase.
The gas mileage increase the tuner won't say they really get?
It's the same association with the driver that a radar detector has. It's a mind game with yourself. You back off, unintentionally.
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