I just bought an 06 f150 fx4. Just towed my boat for the first time with it (about 7000lb total) and I store it on some land I own by the lake... to get to where I park it, I have to climb a pretty steep dirt/loose rock road. I always used 4 low with my other vehicle (89 GMC K5 Jimmy), and the Jimmy would climb the hill barely breaking a sweat...The f150 definitely seemed like it took a lot more effort to do it... Both trucks have 3.73 gears. Not trying to start a Ford vs GM thing here, just wondering if the newer trucks don't have the low end grunt like the older ones, or do Fords not have the same granny 4 low gears or what.

 

I might be wrong here, but is it possible that the gear raito in the low on the chevy was lower than the one on the ford?

like maybe the chevy was a 1:1 and the ford is not?

Tire size can change it too.

 

only been in 4 lo once, and it didnt seem to be that low to me. my jeep i had had a noticeably low 4low, so it could be that we have a higher 4 lo gear.

cant forget the 1st gear ratio in the trans too, thats pretty tall. 2.84 i think. if that gmc has a 4l60e or whatever its probably lower to boot.

all these apply:

trans gearing
transfercase gearing
rear end ratio

 

The drive by wire may have something to do with it too.

 

Being the GMC is an 89, its a 700r4, 3.06 first gear, pretty low gear. probably a factor. But I'm thinking the transfer case is way lower than the Ford. I guess to its a balancing act to try to build a nice comfortable truck that gets 18-20mpg on the highway vs something that can tow a house.

 

Might be the drive by wire as glc stated along with the Ford torque management control.

 

Also - a Jimmy is a lot lighter than a F-150 - what engine was in it? If it was a 350, that's got tons of low end torque.

 

It indeed is a 350. I'm sure it is lighter, but I wouldn't say it is a lot lighter since the older trucks have more steel in the doors, hood, etc...I can close the tailgate on my f150 with 2 fingers, it takes two arms to close the tailgate on the Jimmy. I also have 33"BFG on the Jimmy vs stock size tires on the f150.

 

[QUOTE=Redstinger;4418381.I can close the tailgate on my f150 with 2 fingers, f150.[/QUOTE]

tailgate assist :P take it off and carry it around..weighs a bit more

 

Think I figured out the issue. Today I had the truck in 4 low and pulled the gear selector down to "1" instead of "D"....man I found the power...so all this this time, the truck has been starting in 2nd gear on 4 low. This would explain why it didn't feel as powerful as the Jimmy. Is this supposed to be this way? Is this the Ford computer starting in 2nd gear because it is managing torque or something in 4 Low.

 

You are comparing 2 different beasts. I experience the same thing with my '77 chevy shortbed. Major differences:

Jimmy vs. F150

lightweight vs. heavy beast
short wheelbase vs. long wheelbase
drive by wire vs. carb
straight front axle w/ maybe lockers vs. CV shafts w/ open diff
different gear ratios
different engines w/ different torque curves

Plus, any half ton pulling 7000 pounds uphill is going to work hard doing it.

4-low gives it a lower gear ratio through the transfer case, so yes the computer might be using 2nd gear but Im not really sure. 4-low in "1" should give you gobs of torque even just feathering the gas.

 

Damn right!

 

Likely not starting in 2nd ...
... but if you have it in 4-LO and start away with the load with the trans in Drive (or O-Drive) ...
... it shifts into 2nd really fast, almost as soon as you start moving unless really working it hard so likely you were pulling the hill in 2nd all that time.

If you want to hold 1st, hold it in 1st.

Also note that with Ford, if you ever do pull it back into 2nd (or shift up to 2nd from 1st) , you will force the trans into 2nd even if starting from dead stop with 7K behind it.

Fords been like that for as long as I can recall, at least back into the '60s. I think my uncle's '61 Starliner 390 with Cruise-O-Matic even did it.

Great when driving on some slick ice ....
.... not great when trying to start a big load on a big hill.

 

Actually, the old Cruise-o-Matics had D2, D1, and L. D2 was a 2nd gear start, shifts to 3rd. L was 1st if you pulled it in below about 25 mph, above 25 it was 2nd, and would grab 1st slowing down through 25. When they went to PRND21 then 2 was a full manual 2nd.

 

my trans guy has always told me that when you use that 1 on the selector it not only holds it to first, but it kicks in another set of clutches that you wouldnt have by being in d.