Will gears without a tune damage the transmission?
 

Simply put if you change the rear axle gears on an 05 + mustang without recalibrating the ECU will it damage the transmission.

I have heard some people say yes, but I cannot see it happening unless it is very different then earlier mustangs, I know some one with an 03 that has
driven his car with 3.73s for years without a recal.

No, gears are merely a mechanical piece of the puzzle that is behind the transmission, so as far as I know, they don't affect it. Probably want to recalibrate the speedo though.

*with further thought, I have no experience with how gears will affect an auto transmission. I wouldn't think it would affect it at all except that it will go through the RPM's faster. Couldn't hurt though with an auto just for the extra power and to firm up the shifts.

If you don't get the ECU reflashed. Your speedo and odometer will be off. The bigger the differance in gears the worse it'll be. Also with an automatic the shift points will be wrong and that will hurt your performance. If you don't want to buy a tuner you can get a dealership to reflash it but that would be a permanant thing.

+1111

A tunner is handy anyway for misc things such as calibrating speedometer, tune, check engine lights, codes check etc. Well worth the money. If you dont want to get one, then be cognizant of your speed cause your speedometer will be off and even worse if you have wheels different than stock size

I don't have a newer 2005 + mustang.
This was a hypothetical.
On another forum (non ford) a poster was having trouble with people telling him that installing gears in an 05+ mustang without a retune would grenade the transmission.
I don't know any of the tech for the newer models but it sounded utterly ridiculous to me.

I havn't hung around the froums for the newer cars but I imagine if gears without a retune would grenade a trans there would be floods of complaints.

I've known many people running pre 2005s for years without correcting via tune /speedcal/trans gear.

I just say your speedometer will be off

No damage to the PCM. Your speedometer will be off and your shift points won't be maximized to take advantage of the gears if you're an auto.

What he said!

So what was the "other" forum you were on?? Just curious :)

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