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The perfect gear?
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Posted by: OldFart

I got the 05 back from warranty repair today (they rebuilt the entire rear-end). Since they were already into the rear end for the repair, I had them install 3.73 gears at the same time.

I put about 100 miles on it, some traffic, some highway and I find:

1. It's much stronger. I don't know what the exact torque gain is but you can sure feel it.

2. I'm up shifting sooner and using 5th gear more often. At least at first glance, it appears that I may actually get better fuel economy than with the stock 3.55 gears because of this. I still need to get the odometer reset for the new gears and until I do, the verdict is out on this issue. Right now it says I've gained about 2.5 mpg but that is just the odometer thinking I've traveled further than I actually have.

If it turns out that I break even on fuel economy, the 3.73's may be the perfect gear for the 05 manual. More torque and decent economy - who could ask for more.

OldFart

Posted by: Mac

The perfect gear? Boy, that's a hard call but I'm sure leaning your way also, even tho most of my driving (400 miles a week just going to work) is on the Interstate. Had guys at one of the Ranger swap sites going the opposite way thinking reduced RPM at cruse would give them better mpg. Engines usually are more efficient at producing power around 3300 rpm (does not translate to better mileage). You can end up with not enough power to pull 5th gear with the power you need.
Mac

Posted by: Aussie XAXB

Not knowing crap about the newer Mustangs, I presume your speedometer is electronic and the shop already made the adjustment for the new gear? If so I would be surprised if the odometer is controlled seperately so you may be getting an accurate fuel mileage reading.

Steve

Posted by: OldFart

Quote:

Originally Posted by Aussie XAXB

Not knowing crap about the newer Mustangs, I presume your speedometer is electronic and the shop already made the adjustment for the new gear? If so I would be surprised if the odometer is controlled seperately so you may be getting an accurate fuel mileage reading.

Steve

Thanks for making me think. (You're good about doing that.)

I'm pretty sure the dealer didn't do anything other than rebuild the rear-end. (Since I told the tech I was running a custom program and didn't want it changed.)

I was under the impression that I'd have to have my favorite tuners re-flash the computer to correct for the new gears. They are pretty straight-up folks and wouldn't tell me I needed another tune if I don't, so I'll call them and post a follow-up.

Thanks Aussie,
OldFart

Posted by: OldFart

Quote:

Originally Posted by OldFart

Yep, if you change gears the computer does need to be reflashed to correct the odometer and the mph.

OldFart

Posted by: KartRacer39

I think if you change tire sizes as well Old Fart, On my 05 had to change for Tires here. And definately my tuner only since i have custom program for Vortech

Posted by: dustindu4

I got 4.10s and they're pretty good. I already had a predator tuner to adjust my speedo so that wasnt an issue for me.

Posted by: OldFart

Quote:

Originally Posted by dustindu4

I got 4.10s and they're pretty good. I already had a predator tuner to adjust my speedo so that wasnt an issue for me.

Since I prefer custom programing, rather than a hand-held tuner, I'll be sticking with that. Custom programing has worked very well for me.

But you are both right. You need a re-flash for both tire size change or gear change if you want the speedo and odometer to read correctly.

OldFart