How are people liking 4.09 gears in the MT82?

[7thlighter]

Update....I've called 3 Ford dealers over the past few weeks asking for an installation cost of the 4.09's. All of them said they'd check and let me know but none called back. I wonder if it's just bad luck or if they don't want to do this for some reason?

Also, did some calculations... 7000 rpm in my 3.73 car in 1st is 47 mph, with 4.09's it would be 43 mph. In 2nd it's 73 mph vs 66 mph, and in 3rd it's 108 mph vs 98 mph. So in terms of both 0-60 and 1/4 mile, you wouldn't have to add an extra shift if you went to 4.09's. Also, at peak 420 lb-ft of torque at 4600 rpm, the force applied to each tire patch would increase from about 2200 lbs to 2400 lbs, which would be the equivalent of increasing the peak torque from 420 to about 460. So the 4.09's seem like a pretty good mod if it's reasonably priced.

Thanks for taking the time to make those calculations. I was wondering about changing the gears and what that would do. What do you think it would do to the MPG?

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[Mikepol2]

My personal experience with mpg has had more to do with the landscape than gear ratios...my Mustangs have never been daily drivers, I've always had V-8 Chevy Silverados for winter and going to work. I've had trucks with 4.10, 3.73, and 3.42 gears, with no real noticeable change in mpg, but in western PA it's very hilly and there are a lot of traffic lights on the way to work. So I was actually using less gas pedal to climb hills when I had the 4.10s, and didn't do much highway driving. Guys who do a lot of highway driving in flat places like Oklahoma would probably tell you they notice a much bigger effect with higher gears.

BTW, found a local speed shop who said they'd install them for $125/hr and it would take almost a full day, so looking like about $800 plus parts for installation if I went with them. That $125/hr seems pretty steep, more expensive than dealers.

 

[7thlighter]

My personal experience with mpg has had more to do with the landscape than gear ratios...my Mustangs have never been daily drivers, I've always had V-8 Chevy Silverados for winter and going to work. I've had trucks with 4.10, 3.73, and 3.42 gears, with no real noticeable change in mpg, but in western PA it's very hilly and there are a lot of traffic lights on the way to work. So I was actually using less gas pedal to climb hills when I had the 4.10s, and didn't do much highway driving. Guys who do a lot of highway driving in flat places like Oklahoma would probably tell you they notice a much bigger effect with higher gears.

BTW, found a local speed shop who said they'd install them for $125/hr and it would take almost a full day, so looking like about $800 plus parts for installation if I went with them. That $125/hr seems pretty steep, more expensive than dealers.

Thanks Mike for taking the time. It looks like you gain more than what you give up. Not a bad proposition.

 

[Jetnoise]

Going from 3.55 to 3.73's will get you a butt meter kick but might not be all you seem to want.
Go a bump in .5 ratio either way is a reasonable cause & Effect.
I have used 3.73's in just about every toy. Love the ratio and my suggestion
There is always staying with the 3.55 and hunt for Gaines elsewhere

 

[Turbolag87]

Ive also been thinking of changing gears in my18. they seem way to long.. I was thinking 3.90s?

 

[Mikepol2]

Again all depends on what you personally do with your car... the fastest road I drive on is a 45 mph speed limit, and my "fun" driving is in 25 to 35 mph twisty areas (or the constant sniffing around from Subaru WRX's at stoplights). No track or dragstrip, or any highway driving. I emailed U.S. Gear asking if they ever plan to offer 4.30's, that would be my #1 choice but nobody sells them for the Super 8.8 yet.

Here's a gear calculator that you can play around with, to see what effect your gear size and tire size choice would have:

http://www.dragtimes.com/gear-ratio-calculator-mph-speed.php

 

[Turbolag87]

Again all depends on what you personally do with your car... the fastest road I drive on is a 45 mph speed limit, and my "fun" driving is in 25 to 35 mph twisty areas (or the constant sniffing around from Subaru WRX's at stoplights). No track or dragstrip, or any highway driving. I emailed U.S. Gear asking if they ever plan to offer 4.30's, that would be my #1 choice but nobody sells them for the Super 8.8 yet.

Here's a gear calculator that you can play around with, to see what effect your gear size and tire size choice would have:

http://www.dragtimes.com/gear-ratio-calculator-mph-speed.php

My car is basically a pure street car. I’ll be lucky to see the track once a yr . Just a little paro

 

[CNCLester]

I have 4.09 in my 18 pp manual. They make the car more snappy. I think if your drag racing the 3.73 is better as I was crossing finish in third at 7200 +. With 4.09 I shift to fourth about 150 ft before finish.
For autocross, the 4.09 is really good, keeps rpms between 4 & 7 k through most courses. Car comes off a dig well with drag tires. On my michilens at a 30 roll in first, if I punch it with traction control in sport mode it will spin first to shift, and then second for a bit. It's fun as hell imo.
I bought a second differential and installed the gears keeping my other diff on the shelf. Takes about 2.5 to 3 hours for me to swap them out using a lift and tranny post Jack

 

[Mikepol2]

I have 4.09 in my 18 pp manual. They make the car more snappy. I think if your drag racing the 3.73 is better as I was crossing finish in third at 7200 +. With 4.09 I shift to fourth about 150 ft before finish.
For autocross, the 4.09 is really good, keeps rpms between 4 & 7 k through most courses. Car comes off a dig well with drag tires. On my michilens at a 30 roll in first, if I punch it with traction control in sport mode it will spin first to shift, and then second for a bit. It's fun as hell imo.
I bought a second differential and installed the gears keeping my other diff on the shelf. Takes about 2.5 to 3 hours for me to swap them out using a lift and tranny post Jack

What speed/mph did you run with the 4.09's? Any other mods?

 

[CNCLester]

What speed/mph did you run with the 4.09's? Any other mods?

12.6 @ 113. Car needs driver mod for sure. This is the first manual I've run at the track and my launch technique sucks. My sixty ft was 1.9. I definitely can leave harder but am cautious of breaking a half shaft with drag radials. I need to get bias plies. There is a good bit more in the car.
Pmas, longtubes, Lund tune.

 

[Ghost50]

Good thread.

One of the first things I wanted to do was go up from my 3:73’s to the 4:09’s.

In all of my previous Mustangs I’ve ended up with either 73’s or 4:10’s. So as soon as I got my 19 I figured I’d do the same.

I’ve cooled on the idea simply because as others have mentioned the nature of gearing in the MT82.

As it stands now it feels like first gear is gone too quick for me with the 3:73’s. I’ve bounced it off the limiter a few times already when fooling around and getting on it.

I may give them a shot in the future though. I want to gather more info and read more feedback from people who have done the switch. Or maybe find someone whose done it and have them take me for a ride or let me drive it.

 

[Turbolag87]

once i add the reset of my mods in teh spring ill determine if i need the gear (3.90)

 

[Ebm]

Don't fear the gear!

 

[Mikepol2]

I have 4.09 in my 18 pp manual. They make the car more snappy. I think if your drag racing the 3.73 is better as I was crossing finish in third at 7200 +. With 4.09 I shift to fourth about 150 ft before finish.
For autocross, the 4.09 is really good, keeps rpms between 4 & 7 k through most courses. Car comes off a dig well with drag tires. On my michilens at a 30 roll in first, if I punch it with traction control in sport mode it will spin first to shift, and then second for a bit. It's fun as hell imo.
I bought a second differential and installed the gears keeping my other diff on the shelf. Takes about 2.5 to 3 hours for me to swap them out using a lift and tranny post Jack

My differential is at the shop getting the 4.09's installed, and now I'm trying to figure out what gear oil to use. Forum posts say the 75W85 installed in the car by Ford was mainly chosen for improved gas mileage. I emailed Optimum Performance Mustang asking what BG lube they recommend and they said 75W140 BG Ultra Guard LS because the 4.09's will put additional thermal load on the diff. What has your experience been?

 

[Sammy123]

My differential is at the shop getting the 4.09's installed, and now I'm trying to figure out what gear oil to use. Forum posts say the 75W85 installed in the car by Ford was mainly chosen for improved gas mileage. I emailed Optimum Performance Mustang asking what BG lube they recommend and they said 75W140 BG Ultra Guard LS because the 4.09's will put additional thermal load on the diff. What has your experience been?

How much did the shop charge for 4.09 installed?

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