Hey everybody, I have a 2012 GT brembo package/3.73 gears from the factory. Does anyone know if I can swap AM’s 3.31 gear kit in the Torsen diff and will I need any extra parts? I do have aftermarket 19 inch wheels also.

 

Judging from your question I am guessing that you've never swapped gears in a rear end before. The short answer is that yes you can swap out the 3.73's for the 3.31's. The longer answer is that the proper clearances between the ring and pinon are critical for quiet running and long life. At a minimum you will need a new crush sleeve in order to set pinion bearing preload and a shim pack to set pinion depth and ring gear backlash. New bolts, factory will work, but I would use ARP's, are always a good idea. It is possible for someone with no previous experience to do this, but if you can find an experienced mechanic to supervise or walk you through it I would do it. Lacking that, there are videos online that can be very helpful. I would watch more than one,since some are definitely better than others. Some of the auto enthusiast magazines sometimes have good step by step instructions, just be sure that it's for a Ford 8.8 rear end since while they all have some commonalities the different makes and models have important individual differences. Good luck.

 

You might want to do the full rebuild while you are at it, I think there is a "kit" available with all of the parts; not sure of the price difference but probably is worth it to have all of the parts available.

Like SilrBult suggested, the installation is tricky and is best done by someone who knows exactly what they are doing . . . . if you have a good drivetrain/transmission shop in your area, it is probably worth the money to pay them to do it for you.

I think you will like the change, I always thought that 3.73 was a bit too short/steep for comfortable daily driving with the MT82 transmission ratios.

 

Thanks guys I appreciate the answers! I am going to have a reputable shop near me do it, they installed 4.10s in my old mustang and that went smooth. I was just going to buy the ford performance 3.31 gear kit off of American Muscle, I need the installation kit and oil right?