3.55 vs 3.73 gears on 4x4 Ecoboost
03-18-2012, 10:53 PM
#1
3.55 vs 3.73 gears on 4x4 Ecoboost
What is the MPG difference with city vs highway? I've read too that unloaded the truck is actually quicker getting up to speed with the 3.55 gears. Has anyone compaired the two?
03-19-2012, 07:29 AM
#2
V-8 Sounds Great
Although my *** dyno is not an official source of information, I test drove a 3.73 before I decided on my 3.55. I didn't feel any difference in acceleration. I chose the 3.55 for lower highway rpms. 2100 rpm at 70mph was too much for me. I did race an FX4 on a "closed course" and we were dead on equal the whole time all the way to 100
03-19-2012, 08:28 AM
#3
Originally Posted by boosted150
Although my *** dyno is not an official source of information, I test drove a 3.73 before I decided on my 3.55. I didn't feel any difference in acceleration. I chose the 3.55 for lower highway rpms. 2100 rpm at 70mph was too much for me. I did race an FX4 on a "closed course" and we were dead on equal the whole time all the way to 100
03-19-2012, 09:10 AM
#5
I test drove both gear ratios and could not tell a difference between the two. I don't pull anything super heavy...normally 3000 to 4000lbs not very often... so no point on getting the higher ratio for me. Plus with the 3.55 I get a little better mpg and still have plenty of get up and go power. My last tank of gas was 18.3 mpg normal driving 50/50 city/highway.
03-19-2012, 09:18 AM
#6
There will be a whopping 90-100 rpm difference between the two at 65 mph.
If you're considering the 3.73s, go ahead and get them. I'll probably repeat this until I'm blue in the face, but there's not enough mileage difference between the two ratios to get worked up over.
These trucks have a high enough 2nd overdrive that my F150 is actually about the same engine speed in 6th gear with a 3.73 gear, as my Wrangler is with 3.07 gears and 30" tires at 65 mph. Take it for what its worth, but do remember that Ford wants a heck of a lot less money to upgrade to 3.73s on a new vehicle than what it would cost to replace them yourself (particularly on a 4wd truck!) down the road. Having driven plenty of under-geared vehicles (my Wrangler being one of them, but not saying that the 3.55 is inadequate for this engine) in my time, get the lowest possible ratio that fits your needs today, and what you think you'll need in the future. If you decide on larger tires at some point, you may be kicking yourself for not getting the 3.73s.
If you're considering the 3.73s, go ahead and get them. I'll probably repeat this until I'm blue in the face, but there's not enough mileage difference between the two ratios to get worked up over.
These trucks have a high enough 2nd overdrive that my F150 is actually about the same engine speed in 6th gear with a 3.73 gear, as my Wrangler is with 3.07 gears and 30" tires at 65 mph. Take it for what its worth, but do remember that Ford wants a heck of a lot less money to upgrade to 3.73s on a new vehicle than what it would cost to replace them yourself (particularly on a 4wd truck!) down the road. Having driven plenty of under-geared vehicles (my Wrangler being one of them, but not saying that the 3.55 is inadequate for this engine) in my time, get the lowest possible ratio that fits your needs today, and what you think you'll need in the future. If you decide on larger tires at some point, you may be kicking yourself for not getting the 3.73s.
Last edited by byoungblood; 03-19-2012 at 09:21 AM.
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03-19-2012, 06:52 PM
#8
Performance and mileage will be virtually indistinguishable between the two ratios. Driving style will vastly overwhelm any difference between the 2 ratios.
03-19-2012, 07:18 PM
#9
Senior Member
Had both in 5.4 and about 1 mpg diff.