I Was looking at loading up a FX4 as a possible 09 f150 to buy. but I just noticed that you can only get the fx4 with the 3.73 rear end gearing???? My question is how much would that actually hurt your gas mileage over the 3.55's ...

greg

 

I heard it was a max of 2mpg. No idea if this is an accurate figure for the f150's as this was from other sites when i was compaireing what ratio to go for.

 

I don't think it's anywhere close to two MPG's. It's probably more like a .25 at the most if any.

Ford tested the 3.15-1 gearing to get all their 20 MPG rating. There is no way the 3.73 gets 2 MPG worse than the 3.55. With that logic the 3.15 would get 6 or more better than the 3.73 and that's not the case.

The 3.73 is a much better all around gearing than the 3.55. I'd get the 3.73's.

 

You could be right as i was on forums that wernt nothing to do with f150's they were towing forums. I wanted to know what difference i would see towing a 8000lb trailer with a 3.73 compaired to a 3.55 and most people were saying 1-2mpg difference. So i went for the 3.55 and it tows my trailer very ell.

 

Well I don't tow all that often, and if I do it is just a car trailer a couple time a year to the track, otherwise the motorcycle goes in the bed along with everything else...so would the 3.55's be a better gearing for me?

 

I was told time after time that i should go for the 3.73 for my trailer. The thing is i wanted powerfold mirrors and not the massive tow mirrors so i went for the 3.55 after all. All i can say is that it has no problem towing my trailer fully loaded. Im sure the 3.73 would be great if you towed 8000+lb day in day out but for 95% of people i guess the 3.55 is fine when they tow very rarely. I tow my trailer everyday and it copes just fine. I dont even need to use tow/haul mode.

 

thanks for the info...I think I will end with the 3.55s...but I guess my last question is what is the difference between the limited slip and the non-limited slip rear...is that just traction control?

 

Sort of....its a set of clutches in the rear axle that limits slippage across the rear axles....its my opinion that trucks SHOULD NOT BE BUILT WITH OUT LIMITED SLIP AXLES

 

Get the 3.73s. Overall it won't hurt your economy. If it hurts you on the highway, it will help in the city. Also get the limited slip.

Every review I've read has either said that the 5.4 seems "taxed" (Motor Trend) in normal driving or just hasn't mentioned engine power. So I'd give it all the help you can with the 3.73s. All the shootouts against the other brands also used 3.73s.

So far I've had 2 F150s with 3.55s and I'll never have that ratio again. I find it barely adequate empty on my 2000 and the 09 5.4 only has 15 more ft/lbs and is heavier.

Mike

 

I ordered my Platinum with the 3.73 Limited Slip gears and I am getting about 13.1 MPG's. It would probably get closer to the sticker of 14 but I have a heavy foot at stop signs. It towed my enclosed snowmobile trailer to NY like it was not even back there!

 

A buddy of mine has an '08 3.73 5.4 4x4 screw, I've got an '08 3.55 5.4 4x4 screw. His has a little better kick in the pants at take off mine gets between .5 to 1 mpg better than his. If your talking '09 FX4 not only is it the 3.73 its the only trim level that gets the E-locker which for me would be well worth the slight mpg differance.

just my .02


Steven

 

well really I am going to probably end up with a king ranch 4x4...I was just thinking about loading a fx4...but it sounds like if i find a king ranch with 3.73's I should pick it up..but as of right now my dealer can't find in with the color I want(Royal Red). He said that he found two with CA emmissions which they are not allowed to sell here in VA...but he is still looking for me

I think I am going to wait for one to come around with the 3.73s...unless of course the price is right and it has 3.55s

 

The figure i was given seems about right then. I am getting just short of 14.8mpg on all city driving so far and about 19.1 highway and i also have a heavy foot compaired to most cars leaveing the same light. I think the 3.73 is worth it if you want the massive mirrors and better towing for heavy weights but if you towing anything like what i tow (8000+lb) day in day out then you will be very happy with the 3.55. I know i am. Have no problem keeping with traffic and getting around the mountain roads here.

 

If you are getting an 09 why don't you just order one the way you want it?

 

then they got me by the *****, I got quoted a 42,500 out the door price by the manager...if you order it and put a 1k non refundable down payment on it and then you try and deal they don't care to deal as much then and they don't have to take it...

from my understanding...correct me if I am worng..

If I can order it and agree on a price before ordering then that is exactly what I would do