Mustang Club of Maryland

Well, I thought after the K & N filter, Bama Tune, and Barton short shifter I was done with mods.

Now I'm considering changing the rear end from a 2.73 to 3.73. Has anyone made this switch (2012 V6 manual vert). Would like to hear both pros and cons.

Since I would have the installation done by a Ford dealer (warranty concerns), how many hours of labor should I expect?

When i asked ford they told me around $800 just for labor. JPC wanted $600. BobT did it for around $300. i wouldn't have done gears on my 09 mustang v6 if i didn't go to bob.

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Thanks for the reply. Since my car is still under factory warranty it may be better to have a Ford dealer do the installation.

I've read that the change to 3.73 may cause gear whine. Have you experienced this?

Get motive 3.73 gears. No whine. but your going to need to tune your car to correct your speedometer from changing your gear ratio. on the 2010+ models, they can tell when you tune your car which voids your warranty.

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I don't know what "motive" means. I was planning to get the Ford Racing brand (from Ford). I was going to return to the stock tune prior to taking the car to the dealer. The dealer said they would adjust the computer module to reflect the new gears and adjust the speedometer to be accurate. I would then have to request Bama to provide me a new tune.

I'm trying to determine the rpms at 65 mph while in 6th gear.

ford racing gears are known to whine. Motive gears dont whine.
Also, you know they can still tell that your car has been tuned even when you return it to stock. Ive heard plenty of horror stories from ppl buying the 2011 mustang gt and getting a tune from bama. Then when #8 cylinder failed, Ford denied their warranty claim because they can see the car was tuned in the past.

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Interesting. I've read just the opposite - that the Motive brand is associated with whine while a qualified install of the Ford gears creates no whine.

With respect to the cylinder problem on the V8 some posts indicate that the problem was not caused by the tune and that Ford did in fact repair the vehicle. Also, please remember that I have a 6 cylinder.

Assuming I opt for the 373 gears, can anyone tell me what the rpms would be at, in 6th gear at 50mph, 60mph and 70mph?

Would 355 gears be a better choice?

I'll see if I can get you an excel file. I had a gear calc. spreadsheet and you can fin them online.

Boss Tire and Gear Calculator.xls [63 KiB]
Downloaded 264 times

Thanks for the spreadsheet. Couldn't figure it out.

After some research I'm thinking about abandoning the idea of 3.73 gears and going with the 3.31 gears. It appears that this choice would be more aligned with my driving stlye.

Still need to do more research.

Anyone care to comment on the 3.31 gears?

I personally am a fan of 3.73`s on most V8 cars. I would never go with anything other than 3.55 if I drove all highway and 3.73 if I wanted a good balance between power and RPM. I dont like high RPM`s on the highway. I like a nice low RPM to cruise but want the power to get going. If I had your car, I would go 3.55 with no doubts. Just my thoughts...

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1990 Mustang GT
http://www.ocstangs.com

So, you are saying I will still experience comfortably low rpms while highway cruising with the 3.55? Remember I don't have the V8. Any idea of rpms at 70mph? Once I get that number I can try those rpms in 5th gear to make sure it's liveable for me enough to go for the 3.55s

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James Heller
MCOM President

1967 Fastback 289, C4, Magnum 500 wheels, Long Tubes

1989 LX Notchback 5.0 supercharged SSP too much to list

2011 GT some basic bolt on goodies

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James Heller
MCOM President

1967 Fastback 289, C4, Magnum 500 wheels, Long Tubes

1989 LX Notchback 5.0 supercharged SSP too much to list

2011 GT some basic bolt on goodies