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Discussion Starter #1
I can't find it now, but is there a recall or transmission software upgrade so the ED with 8spd tranny shifts into 8th gear at 55mph instead of 60mph????
 

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You are going to have me looking at the rpm and speed now.

Never heard of anything like that but it means little. One thing that make me wonder is rear-end ratio. The rpm at 55 on a 3:55 rear end would be lower than with the 3:92 rears. My take is it would be quite low in the powerband. That might not be a good thing as it would lug the engine.

Later today I'm gonna look and see just what it is with my 3:55's. Bet I would not want it in 8th at such a slow speed.
 

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Discussion Starter #3 (Edited)
Better fuel mileage in 8th at 55mphn cause it's the overdrive gear. 55 mph is what the manufacturer's use for their fuel mileage numbers.

So, take your vehicle to 55mph and set the cruise control and look at the MPG's readout on your truck. If it's under 20mpg it's stuck in 7th gear! So, hit the gas to make it shift into 8th gear or manually change the gear using the buttons on steering wheel...

And, yes the fuel mileage will suffer having a 3.92 rear vs the 3.55 ....
 

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Told you I was interested.

Watched as it shifted this afternoon. At about 49 mph my 3:55 rear end Eco. shifted into 8th. Took it to 55 mph and ...


That's like 1,350 rpm or something like that. Real low. Think it's below the reasonable torque curve of the engine. Like this the fuel flow shows it over 30 mpg. Just too low an rpm unless you like to play the fuel mileage game.
 

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Discussion Starter #5
I just took delivery of 14 Quad Cab 4x4 Laramie last night so I have to watch the rpms. Mine was closer to 1800 at 70mph. So, is this normal? I avg'd 25.6 coming home from dealer with 40% stop and go traffic and rest highway..
 

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Discussion Starter #7
Yep, exactly what I was showing. THanks

Now, if I can figure how to activate the NAVIGATION on the 8.4A???
Dang dealer wants like $700 to activiate it? It should be a simply software activiation feature...Anyone have any clues?
 

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Told you I was interested.

Watched as it shifted this afternoon. At about 49 mph my 3:55 rear end Eco. shifted into 8th. Took it to 55 mph and ...


That's like 1,350 rpm or something like that. Real low. Think it's below the reasonable torque curve of the engine. Like this the fuel flow shows it over 30 mpg. Just too low an rpm unless you like to play the fuel mileage game.

http://www.vmmotori.com/l630-dohc/automotive-en/v6-en/l-630-dohc.html

at 1350 you're making what, about 350-375 Nm (258-276 ft-lbs)
 

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Not my post so I don't want to take it over. That torque/horsepower chart sure fits the issue. Good information. Thanks.

Motor likes to run and pull between about 1,700 and 2,200 rpm's from my experience. "About" is the key word as I'm not as exact in my feelings as that chart is.

Keep things somewhere in that range and the motor is happy. Always like a happy motor.
 

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Not my post so I don't want to take it over. That torque/horsepower chart sure fits the issue. Good information. Thanks.

Motor likes to run and pull between about 1,700 and 2,200 rpm's from my experience. "About" is the key word as I'm not as exact in my feelings as that chart is.

Keep things somewhere in that range and the motor is happy. Always like a happy motor.
Good to hear it from someone with real world experience, hear this from many people over time will help to get an average of where it's experienced at.
 
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