maxshuty

Anyone here with a V6 upgraded to 3.55 or 3.73's recorded the actual drop in MPG? If it's more than 3mpg I dont know if it would be worth it, although yes the power and acceleration would be awesome, I use my car as a DD... I've put 17-18K miles on my car and I haven't even had it a year yet... Do the math on that and a 3MPG difference adds up to quite a bit of money. Anyone have any numbers??

schapman

I'd say mine dropped 2 mpg.

maxshuty

Not bad.

So if I get anything other than 3.31 I'll need a tuner? So in that case it would just be wise to go buy a cai+tuner then too huh? And then to make up for the loss in MPG I could upload an economy tune, right?

157dB

You gotta pay to play.
It dont work both ways at the same time....
You wont notice any more take-off
with 3.55s as opposed to 3.31s.
It takes 3.73s or better to notice the difference...

maxshuty

Interesting...

tx_zstang

Mine dropped 1-2mpg mainly because of a 'heaver foot' during acceleration! The actual highway mpg difference was < 1mpg.

And while many people are recommending an 8.8, you can also very likely find a taken-of 7.5 like yours, for a couple hundred bucks. If you dont plan to add power nor do a gear change, that would be the lowest-price way out.

Check locally in craigslist, around your state/area, and there's always someone selling a 7.5 somewhere on some forum.

As far as junkyard, you could find either an 8.8 or 7.5. As mentioned, the 8.8 will need a $25 or so pinion flange (and it needs to be installed properly), and the 8.8 will bolt right up in place of your 7.5.
if the gears are the same (stock), you won't even need a tuner (the tuner is needed to tell the computer what gear ratio you have so the speedometer and other calculations are accurate).

157dB

Higher gears allow taller tires without the speedo recalibration...
Fill in those rear fenderwells with some meats instead of skinnys...

Derf00

as stated do not have the dealer fix it, replace it with a new or take off 8.8.

Mattwood440

Why would you be out of warranty? That's powertrain which goes for 5 year or 60k.

http://www.motorcraftservice.com/pub.../07frdwa5u.pdf


Covered: Rear-Wheel Drive:
axle shafts, bearings (front and rear), center support bearing, drive axle
housing (including all internal parts), drive shaft, propeller shafts, retainers,
supports, seals and gaskets, universal and constant velocity joints.

Unless you've modified the drivetrain and didn't have a dealer do it, you're good. That dealer you mentioned maybe shady and will definitely need to be reported to Ford and the BBB or state if you're in fact covered, because bad dealers are half the reason the US auto makers are looked down upon.

maxshuty

This is covered under limited warranty?!
The dealer told me that it wasn't...

Edit-
I just went to a mechanic who we go through with all of our repairs (things that aren't covered under warranty), he's a trusted guy and he told lifted the car and took out the magnetic bolt in the rear end and showed me metal shards in there. He also said it should be covered under powertrain warranty. Hmmm...
I'm calling up a different dealership here in a little bit to see what they have to say about it.

Edit again-
Just called a different dealership and they said the rearend isn't covered under powertrain warranty...
I really dont understand why it's not, can anyone elaborate on this for me?