Ford wants 150 bucks to recal my speedo.

So if my speedo says I'm going 60 mph with 4.10's, how fast am I really going? I used to have 3.31s.

And I LOVE the 4.10s!

 

You will be going quite a bit slower than the speedo shows.

You spent the buck for the gear but are wimping out on a speedo recal box?

Better yet, get a tune.

 

Since the speedo recal gadget reflashes my computer, couldn't ford use that to say I've used a tune and void my powertrain warranty?

That's why I leaning towards having Ford do it.

 

Have you done any highway driving with the 4.10s? How are you liking them in that respect? MPG? I bought 3.73s for my 2011 GT auto after a long debate on 3.73 vs 4.10, and still am tempted to try and switch them out for 4.10s before install .

 

Well, 90% of my driving is stop and go northern VA city driving, so I can't say. Plus my speedo is hella off, and I have no idea how much.

But holy crap, these things PULL. I start in 2nd gear and goto fourth for city driving and it's pretty smooth. Second gear was my "rocket gear" in the 3.31's, but with the 4.10 every gear is rocket gear!

Sorry I can't comment on highway mileage. These have only been in for a day and I rarely drive on the high way. I imagine it's not bad if you stay 65ish...but if you go 75-80 then I imagine it's harder on your fuel econ.

 

I do probably 80% city driving, 20% highway. Occasional long trips on the highway at ~80 mph. With 4.10s and my 275/35/20s that would be roughly around 2800 rpm, which is my only worry - that it would get irritating after a while. Keep us updated on how you like them... so tempted...

 

You're also putting more miles on the odometer than the car actually has.

 

You mean if I don't get a recal? Crap.

 

This........
I'd go right ahead and have it done by your Ford dealership. I'm having the same issue here...was driving at traffic speed on the highway yesterday and noticed that my speedometer was showing 100 whan in fact i was going about 75...WTF, so i put back the car to stock specs and redownloaded the Steeda '93 tune again and made sure that i adjusted the revs per mile for my size tire properly.
Crappy day today over here, so will try it tomorrow.

 

You've already made a change to your driveline, so if you are worried about warranty, changing the ECU to get the correct speedometer would be of lesser concern. I would also have your Ford dealership make the change.

 

The speedo recal box doesn't flash the computer.

It just wires in, in between the signal generator on the transmission and the PCM and alters the pulse count to trick the PCM and speedo to make it read correctly.

Is your car an auto or manual?

 

Wow. That was a leap. 1st gear must be pretty useless with the M6. Like granny gear in my F150 (unless I'm pullin' stumps and logs and such ).

 

At least we know of a guy that will never complain about hard 1st to 2nd shifts on his 2011 Mustang

 

 

you're going about 49 mph +/- a few decimals.

click here

put in 235/50/18 for tire size
3.31 for axle ratio
7000 for redline
3.66, 2.43, 1.69, 1.32, 1.00, .65 for 1st-6th gear
hit calculate
then change axle ratio to 4.10, hit calculate and the chart under the original one will have all the new speeds/gear/rpm

 

i have a speedo box from my 2003. its brand new, i used it for 100 miles maybe. Let me know. ill sell it like $50. Not sure if it will work on a 2011. its from ford racing. still in the package.

 

The way the automatic transmission is geared, I wouldn't want either of those.

 

Still loving the 4.10's.

I might not like it if I had to LOTS of high way driving at 80+ mph, but I was cruising along at 65 just fine. City driving is much more fun and there's power everywhere!

 

It is much easier than that !

3.31/4.10 x 60MPH = 48.4MPH

You are basically 20% slower than the speedo so putting 20% more miles than in reality

 

Its not bad at all. I have the 4.10's and travel 80 miles round trip a day. 80% highway and 20% city. And I have no trouble with it at all. 70-80 is perfect cruising and I still get about 20 -22 MPG. If you spend all day at 90+ than these gears are probably not for you. But in reality the amount of time I get to spend at those speeds is very little. However the car is still comfortable and quiet at those speeds even with the gt500 axlebacks.