3.55 vs 3.73 vs 4.10 Gear/Speed/RPM Spreadsheet - Ford Shelby Cobra GT500 Forum
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Old 11-27-2009, 06:37 PM
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Default 3.55 vs 3.73 vs 4.10 Gear/Speed/RPM Spreadsheet

I threw together a spreadsheet that helps me compare the RPM's and MPH for each gear to help me decide on which gear ratio I want to go with, and thought it may be helpful for others to see as well.

Right now I'm leaning towards keeping the motor stock with the exception of a VMP tune and "maybe" a set of headers, and put the rest of my nickels and dimes towards a Griggs GR40 suspension - but it won't be anytime soon.

If that's the route I go, then I'm thinking the 4.10 gears will give me a little more kick in the pants over the stock 3.55 gears, and still return decent RPM's while on a long road trip.

Specs below are for a 2010 GT500 with 26.85" tires (stock)...

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Old 11-27-2009, 08:15 PM
07Ebony 07Ebony is offline
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Default Re: 3.55 vs 3.73 vs 4.10 Gear/Speed/RPM Spreadsheet

I have two acquaintances with GT500's and they installed the 4.10 gears. They both agreed that it was too much. It made first gear almost useless and even second gear was hard to keep the tires planted and maintain a straight line when launching hard.

We have members on this site that do like the 4.10's but I believe that to run with them and maintain control when you plant your right foot that you will also need to mod the rear suspension.
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Old 11-28-2009, 06:07 AM
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Default Re: 3.55 vs 3.73 vs 4.10 Gear/Speed/RPM Spreadsheet

I'm still on the fence on which way to go as I'm afraid I won't feel a lot of difference with the 3.73. I also know if a lot of power mods are done it's better to stick with the stock gears.

Having said that, I was talking to my son's basketball coach on this very topic as he's a professional engineer that fabricates race cars for a living. He said anyone can get in a car and nail it, but it's the good driver that understands throttle control, and he recommended 4.10's all day long (especially with 5th and 6th being overdrive gears). Of course his opinion is like an asshole, everyone has one.

I remember my first street-legal motorcycle was a Ninja ZX9-R (this was well over a decade ago) and it was the first production bike to break into the 9's in stock form. Many people thought I was nuts starting off on such a powerful motorcycle (and many people thought I was nuts for even having a motorcycle), but I made myself respect the throttle and everything turned out fine. No way that bike would run a 9 second 1/4 mile under half throttle. However, once the bike was underway and rolling along in 3rd or 4th it was a huge grin factor to feel it blast from 50 to 120, and that's sort of what I'm shooting for with the GT500.
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Old 11-28-2009, 06:20 PM
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Default Re: 3.55 vs 3.73 vs 4.10 Gear/Speed/RPM Spreadsheet

Quote:
Originally Posted by TX STIG View Post
I'm still on the fence on which way to go as I'm afraid I won't feel a lot of difference with the 3.73. I also know if a lot of power mods are done it's better to stick with the stock gears.

Having said that, I was talking to my son's basketball coach on this very topic as he's a professional engineer that fabricates race cars for a living. He said anyone can get in a car and nail it, but it's the good driver that understands throttle control, and he recommended 4.10's all day long (especially with 5th and 6th being overdrive gears). Of course his opinion is like an asshole, everyone has one.

I remember my first street-legal motorcycle was a Ninja ZX9-R (this was well over a decade ago) and it was the first production bike to break into the 9's in stock form. Many people thought I was nuts starting off on such a powerful motorcycle (and many people thought I was nuts for even having a motorcycle), but I made myself respect the throttle and everything turned out fine. No way that bike would run a 9 second 1/4 mile under half throttle. However, once the bike was underway and rolling along in 3rd or 4th it was a huge grin factor to feel it blast from 50 to 120, and that's sort of what I'm shooting for with the GT500.
3.73s if you're only on the street with stock tire height.

4.10s if you're going to race it and use a taller (28") tire. My 4.10s with a 26.25" tire bang the limiter at the line (at 6,500-6,600 rpm) on a great pass.

28's will drop it down to around 4.00 and will be perfect.


Hope this helps

bj
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Old 11-28-2009, 07:35 PM
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Default Re: 3.55 vs 3.73 vs 4.10 Gear/Speed/RPM Spreadsheet

I spent almost the entire day driving the car around in the country and must say I really enjoyed the way it's geared (my first short road trip with the car). Too many people have said 4.10's are too much unless you're drag racing it (which I'm not doing), so I'm going to take the advice and leave it alone.

Thanks!
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