smiggleburger
Palm City, Florida
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Can anyone explain the magic that Ford uses with their new 6 speed auto to get a 9000lb tow capacity from both the 3.31 and 3.73 gears?
2008 Expedition - Heavy Duty Tow 6 Speed Auto
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VintageRacer
Dundas, Ontario
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Probably they accept lower performance standards that they may have done before. Just because it will tow it doesn't mean it will perform well, or even acceptably, when towing it.
Brian
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brownja
connecticut
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I believe the motor is a little more powerful and the chassis is a little bit lighter. Most of the improvement would come going from 4 to 6 gears.
That allows a shorter first gear and smaller jumps between the gears.
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jb
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Terryallan
NC
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smiggleburger wrote:Can anyone explain the magic that Ford uses with their new 6 speed auto to get a 9000lb tow capacity from both the 3.31 and 3.73 gears?
Actually I believe the 3.73 is rated for less. But the reason is. The 6 speed will just pick the gear it needs to do it's thing. It may tow in 3rd, or 4th. Just because there are 6 gears there. Don't mean it has to use all of them.
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skipnchar
Topeka Kansas USA
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First of all, Ford does not rate it's transmission to tow anything. The rating is for the entire truck. It SEEMS that every time Ford posts ANY tow ratings folks come out of the woodwork to claim "they can't do that". Why would you or anyone CARE WHAT Ford chooses to do with their warranty? ANY tow rating is simply the weight that the manufacturer has assigned as being OK to tow while they continue to honor warranty claims. Since MY old 4 speed transmission model has a 10,000 lb. tow rating and a 3,050 lb. payload I a bit surprised they didn't rate it for MORE weight. It's pretty obvious that Ford KNOWS that it'll take the loads they rate it for. My guess is that they're just TESTING it and will eventually get the tow rating back up where it's been simce 2004.
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SemperFiCop
USA
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All 2008 Standard 119 inch WB Expeditions come with the 3.31 Rear Axle
There is an Optional 3.73 Rear Axle for $75
The Heavy Duty Tow Package Option is $350
The EL has the Standard 3.73 Rear Axle
The 3.31 Rear Axle with HD Tow Rated for 9,200
The Optional 3.73 Rear Axle with HD Tow ONLY Rated for 9,050
You lose 150 with the Optional 3.73 Rear Axle,
Go Figure... 
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Keith99RS
Suffield, CT
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Same way the Titan tows 9,500lbs with 3.31's. 6 speed transmission allows change in the final drive ratio with a lower 1st gear..
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Lariat trucker
Sticksville, TX
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The way it was explained to me: The EL weighs more than the STD wheelbase model so the tow rating was modified to compensate for the extra weight of the EL. For 2008 (it was for the 2005-2007) the 3.73 is NOT available in the STD wheelbase Expedition. I went through a very frustrating situation on my 2008 Expedition. Ford made a customer concession and put the 3.73 gears in my 2008. The gear change really helped the towing and although we decided to go with a Class A I would recommend that upgrade to anybody who expects to tow anything over 6000#s with an Expedition.
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NickG
Warren, Michigan
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Well, my 2004 van with a 6.0 liter, 4 spd trans, and a 3.73 gear is rated at 7900 lbs towing. That is just 1100 lbs away from 9000 lbs.
But equipped with the 4.10 gear, the rating jumps to 9900 lbs.
So four years later with industry-wide improvements in engines, plus a trans with two additional gears... I certainly see nothing obtuse with the current ratings for that package.
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mkirsch
Rochester, NY
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No magic to it. It's what I've been saying right along, that it's not just the rear end ratio, it's the combination of transmission ratio and rear end ratio.
The gears in a 3.31 axle are actually STRONGER than a 3.73, because the teeth are larger and deeper. A 4.88 ratio has very shallow, small teeth compared to a 3.08. It's all a matter of degrees.
If the shaft can take the torque, you can get your gear reduction in the transmission by adding a shorter 1st gear, and still get good empty highway economy with the lower ratio axle in overdrive.
Toyota goes the other way with the new Tundras. IIRC they've got a 4.31 rear axle ratio, and double-overdrive in the 6 speed transmission.
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