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Discussion Starter · #1 ·
Put deposit down on a '17 last week : ) I would like to replace the stock 3.73's with a 4.56 gear set---will work much better for my non-track use of the GT's rpm range---would allow two red-line shifts on the way to 100 mph vs only one for the stock gear set, still cruise at 80 mph at 2800 rpm in 6th---just think it would make for a better street setup. (Please give feedback if you deem a bad idea)

Ford Performance does not offer a 4.56 set for the IRS, and no web search turns up a set. Does anyone know of a supplier? just a matter of time? thanks! Jack
 

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Looks like a 4.10 will be the only higher ratio set available for the GT350 for some time. By the way, there is no way you can hit 100MPH in 2nd gear, you need to be in 3rd gear to reach that speed.
 

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Discussion Starter · #3 ·
thanks, Dave--Do you know who offers the 4.10's ? (my bad on the "one shift" statement--I thought one review had stated "2nd gear tops 100 mph--but did check an instrumented test this evening, and 2nd tops at 81 mph--good catch)
 

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Might want to drive the car before you decide the on a gear swap. The car has a low 1st gear. I think 410 or 456 would make 1st gear completely useless.
 

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Me too. Just picked mine up 2 days ago and still can't fine enough excuses to go for this or that...but unless you are purely talking 1/8 mile drag racing, no need for a lower 1st gear. I love this car!
 

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Old thread but both of my gear swaps in a GT500 came out noisey which is more common than not. You get gear whine and noise and having had it in two installs i would think twice

don
 

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Old thread but both of my gear swaps in a GT500 came out noisey which is more common than not. You get gear whine and noise and having had it in two installs i would think twice

don
I know this is an older thread, but that's not normal. Where did you get the gears from? The FR 4.10 I put in my Mach1 was as dead silent as the stock 3.55. I've heard of people having a whine with other brand gears.
 

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I work at a ford dealer and all gear sets were ordered from FRPP .... installed by the store

don
 

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Huh, wouldn't have expected whine then.
 

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Looks like a 4.10 will be the only higher ratio set available for the GT350 for some time. By the way, there is no way you can hit 100MPH in 2nd gear, you need to be in 3rd gear to reach that speed.
Ford Performance only offers 4.09 and I don't know of any 4.10 or 4.11 gear sets being offered for the GT-350 by any one else.
For my driving preferences and habits, the 4.09 would be better suited for me than the 3.73 gear set. I have lived with a loud rearend in a street/strip ride for the past 17 years and it has pushed me close to the limits of my meds. I would have to be assured of a quiet result before I could consider a gear swap.
 

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Put deposit down on a '17 last week : ) I would like to replace the stock 3.73's with a 4.56 gear set---will work much better for my non-track use of the GT's rpm range---would allow two red-line shifts on the way to 100 mph vs only one for the stock gear set, still cruise at 80 mph at 2800 rpm in 6th---just think it would make for a better street setup. (Please give feedback if you deem a bad idea)

Ford Performance does not offer a 4.56 set for the IRS, and no web search turns up a set. Does anyone know of a supplier? just a matter of time? thanks! Jack
Jack, you and I are of the same mind on this subject.
The Ford Performance Dept of Ford has a 4.09 gear set. They can be ordered and installed by your local Ford Dealer ship
Here are a few questions that will arise with a gear swap.
1) The GT-350 has differential lube cooler in conjunction with an outside radiator.
2) Ford engineers jumped through hoops to hide the vibration and cabin noise that is inherent with the Flat-Plane-Crank in the engine (affectionately known as the VooDoo engine). Changing the gear set might interfere the delicate balance of the engine drone and resonance.
3) Maybe the gearset will possibly interfere with the differential cooling system

Jack, besides my GT-350, I have a Street/Strip racer which has had two 4.10's (stock GM both broke). One set of 4.11's in a Moser 9-inch detroit locker. I now have 4.56's in the moser. The car is now a perfect toy.

I posted here, because I wanted to know if anyone has yet made that gear swap and if there were any issues.
 

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thanks, Dave--Do you know who offers the 4.10's ? (my bad on the "one shift" statement--I thought one review had stated "2nd gear tops 100 mph--but did check an instrumented test this evening, and 2nd tops at 81 mph--good catch)
Nobody offers 4.10's or 4.11's
Mustang Performance offers 4.09 for the GT350 $289 + speedometer adjuster
Ford Performance offers the 4.09 through the ford dealership for $189 + the cost of the speed sensor change
 
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