Rear end ratio for mileage. - Ford Powerstroke Diesel Forum
User Tag List

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 26 Old 02-10-2010, 08:23 PM Thread Starter
Powerstroke.org Rookie
 
Join Date: Mar 2008
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Rear end ratio for mileage.

My 2008 F250 has 3.73 ratio, later on I understand 3.55 were available and now 3.31 ratio. Has anyone out there changed rear end ratio to gain mileage? My truck is Spartan tuned, cat-dpf delete,and banks ram air intake. I am getting around 14 -16 mpg, just looking for a little more! Thanks
mglight is offline  
post #2 of 26 Old 02-10-2010, 08:41 PM
Compression Ignition Addict
 
Join Date: Jan 2010
Location: Galveston, TX
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
I'd like to know this too

2003 F150 Lightning- Whipple 3.4l 659rwhp 711rwtq @18psi on 93

2008 F250 FX4- afe stage II, 5" Flo Pro, Elite- egr delete/wastegate/4" downpipe/cfm+/ported fuel rails
Innovative XRace-12.81@103.9; H&S Hot Damn- 13.13 @ 101.4 556 rwhp (Traded In)

2011 F150 King Ranch- Custom Status Air Suspension, 3-link (lays frame)
REDL1NE is offline  
post #3 of 26 Old 02-11-2010, 03:13 AM
Powerstroke.org Sponsor
 
powerstroker67's Avatar
 
Join Date: Mar 2008
Location: Chaplin, CT
Posts: 828
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
What size tire are you running?

What Spartan tune are you running?

What RPM do you drive the truck at? Keeping the truck under 2000 rpm helps fuel mileage, when it has the right tuning in it to make power down there in the rpm range.
powerstroker67 is offline  
post #4 of 26 Old 02-11-2010, 04:34 AM
Warheads on Foreheads
 
superdutydixie's Avatar
 
Join Date: Aug 2009
Location: Houghton, LA
Posts: 1,812
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
I've always been told that 3.55 are great for towing/MPGs.

09 F-250 Superduty CCSB
SOLD
superdutydixie is offline  
post #5 of 26 Old 02-11-2010, 05:07 AM Thread Starter
Powerstroke.org Rookie
 
Join Date: Mar 2008
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Spartan 210, stock tires, happy with the increases in mileage with the spartan tuning, if rear end would give more mileage I would like to consider it. When my truck was at dealer for warranty work, I asked service manager about changing rear end gears and he looked at me like he had never heard of such a thing.
mglight is offline  
post #6 of 26 Old 02-11-2010, 12:10 PM
Compression Ignition Addict
 
Join Date: Aug 2008
Location: Chambersburg PA
Posts: 530
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Send a message via Yahoo to skipnay
I know on 4.6L the 3.73's are alot better on fuel acconamy then the 3.55's unless you are on the flatest place on earth at all times and not towing anything.

2010 My Wife has 2 Full time JOBS NOW
2008 F250 H&S MiniMaxx, S&B CAI, and cat/pdf delete
2008 Brute Force 800 All hooked up 67hp to the wheels
2007 Got Married
2004 KFX 700 Stock Bore Kit XX cams
1990 Mustang Notch getting ready to hook it up
1988 Mustang GT 449hp to the wheels 6sp Getting a cage installed
skipnay is offline  
post #7 of 26 Old 02-13-2010, 10:15 AM
Premium Member
 
mor4wd's Avatar
 
Join Date: Jan 2010
Location: South Texas
Posts: 1,126
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 1
Thanked 10 Times in 9 Posts
Feedback Score: 0 reviews
Sounds like your Service Manager is an idiot. Find yourself a good axle shop and talk to them. The dealer would probably charge a fortune, plus if they don't do them regularly then they might not know how. If they do it wrong you'll get excessive heat and noise at best. There are probably other ratios available too from someone other than Ford. Just remember if your truck is 4wd then you'll need to do the front end also. You'll also need to recalibrate your speedometer.
mor4wd is offline  
post #8 of 26 Old 02-13-2010, 04:33 PM
Compression Ignition Addict
 
Iqoair's Avatar
 
Join Date: Dec 2008
Location: Calgary AB
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
You would probably never recoup the cost of changing everything over, also depends on what type of driving you do (City, highway, etc).

2013 F-350 Platinum
35" Toyo Mud Terrains on stock HD rims
2.5" leveling kit
Firestone Airbags
Bilstein 5100 shocks

Iqoair is offline  
post #9 of 26 Old 02-14-2010, 02:10 AM
Member
 
Join Date: Feb 2010
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
I read somewhere the 3.55 gets approx 0.5~0.9mpg better than the 3.73...best case conditions which probably means you'll see most gains only on highway driving.

Probably not worth the cost.

I'm pushing about 14.5mpg hand-calculated when I'm empty with a light foot in mixed-driving and if it hasn't been regening more than 15~20min per tank. Bone stock on 20" rims

Last edited by aquamans350; 02-14-2010 at 02:17 AM.
aquamans350 is offline  
post #10 of 26 Old 02-14-2010, 07:43 AM
Compression Ignition Addict
 
benjamin24's Avatar
 
Join Date: May 2009
Location: Mississippi
Posts: 1,128
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
It would cost ballpark $1200-1500 to have a good shop do a gear swap for you. Then you would have to have the truck reflashed or if running a tuner have it reprogrammed with the changes so thats gonna cost you too. I'd order a higher hp tune and try to keep my foot off the skinny pedal if I were you. If your average city and hwy combined is 15-16 I'd be very happy with an 8k lb truck.

09 Lariat Ultimate/Spartan/
AFE SS Exhaust/AFE Stage II/
Weathertech/Cervinis/Toyo/UWS


benjamin24 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome