Quote:
Originally Posted by whbob
Bill, how does it pull on grades? I also have a 2720.
Also does it have an overdrive cut-out or does it adjust the shift points like GM's large vehicles? Do you pull in overdrive? Finally, do you use a weight distributing hitch? Thanks, whbob.
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Bob -
In the tall steep parts of the Rockies or the high Sierras, it does OK, but I'm not going to tell you that "I don't even know it's back there", as so many people do. The altitude decreases engine horsepower a lot, and the transmission can't really make up for that. If I recall correctly, the rule of thumb is 3% per thousand feet, so I start to feel it around 6-7,000 feet. However, the extra gears do make it easier to keep the RPM at a point where the engine has reasonable power, but isn't screaming. In my Explorer, on the flats, the transmission is programmed to keep the engine around 1800-2000 RPM. Climbing a steep high-altitude grade with the TM behind, I am willing to run it up to 4000 RPM, but seldom higher. Red line is 6500. If I were willing to go higher in RPM, then I could go faster on the hills, but I am unwilling to beat the engine. That's a personal choice, of course. I expect 200K out of my cars, even though I tow a lot.
The Explorer does not have a Tow/Haul mode that changes the shift points. I wish it did. I think that is a better approach, especially if there is also an Overdrive Lockout switch.
The Explorer does have an overdrive lockout switch. It actually locks out both 5th and 6th gears, and leaves me running in 4th. I don't mind that - if conditions warrant locking out overdrive, then 4th gear is probably where I would set it manually anyway.
I normally tow in 6th gear until the transmission begins to "hunt", or shift between 5th and 6th fairly often. Then I switch off. On our heavily-loaded twice-a-year cross-country trips, this gets us from Flagstaff to, say, Pittsburg. The Mogollon Rim in Arizona certainly causes hunting, and the rolling terrain in western Pennsylvania can do it, though not everywhere. Remember, of course, that the Explorer has a small V-8 (4.6L), so more shifting is to be expected compared to Wayne's 6-liter moose!
Interestingly, at least to me, the transmission runs cooler (I have a gauge) in 4th gear with the engine at 4000 RPM than it does if I fancy-foot and keep the tranny in a higher gear and the engine at a lower RPM.
To summarize, having more gears allows you to fine-tune the engine RPM to the road speed better. At 2000 RPM, the engine doesn't have much power. That's why the tranny tries to keep it there - to sip gas and give better fuel economy in daily driving. But if you need power to climb a grade, you have to increase the RPM, and a range of available gears allows you to do it better.
Yes, I use a Reese WDH. Wouldn't leave home without it.
Hope this helps.
Bill