Do I have a gear?

Question · Dec 15, 2005

How can I tell if my car has a 3:73 in it or not? My first gear can only get to 35. It's right at the red line at that point. Do you guys think I still have the stock gear, or does this mean I have a 3:73, or a 3:55? I'm basically just trying to figure out how long my first gear should be, assuming it's a stock gear. Thanks for the help.

triggz · Dec 15, 2005

What year/model is your car? If it a mach1 it will have 3.55s. 99-04s have 3.27s stock, and 94-98s can have 2.73s or 3.08s.

Theres no way to tell you exactly what gear you have without knowing your year model, tire size and transmission type, and exactly what MPH vs RPM you see.

The definitive way to tell is to jack the rear of the car up, put a paint mark on the driveshaft and start rotating the tires. For every 1 rotation of the tires, the drive shaft will make X number of rotations, X being your gearing.

IE, if your car has 3.27s, 1 rotation of the wheels equals 3.27 rotations of the driveshaft. You can also do more than one rotation of the wheels and then divide the number you get by X number of wheel rotations for better clarity.. 3 wheel rotations = 9.8 of the driveshaft with 3.27s, but will be 11.25 with 3.73s.

trinity_gt · Dec 15, 2005

According to my quick calcs, with a 3.38 1st gear (Tremec 3650) and a 3.73 rear, together with "standard" 245/45R17 tires, you'd see about 5950RPM at 35MPH in 1st gear. With 3.27s you'd see just 5216RPM. 3.55s would give 5660 and 4.10s would give 6539RPM.

I'd venture you've got 3.73s in there assuming your tach & speedo are both reasonably accurate.

BlackenedSVT · Dec 15, 2005

Just for refference, the 94-98 cars had 3 options in gears. my 98GT came with 3 gear options in that year and they were 2.73, 3.08 or 3.27. All automatic GTs from 94-98 had 3.27 rear end gears i believe. I know when i swapped to 4.10s in my (automatic) 98GT, the mechanic pulled out 3.27s =)

Outlaw97GT · Dec 15, 2005

UDTBadkarma said:
Just for refference, the 94-98 cars had 3 options in gears. my 98GT came with 3 gear options in that year and they were 2.73, 3.08 or 3.27. All automatic GTs from 94-98 had 3.27 rear end gears i believe. I know when i swapped to 4.10s in my (automatic) 98GT, the mechanic pulled out 3.27s =)

My 97 auto has 3.08's, 3.27 was an option for all 96-98 GT's

Just do what triggs said, jack the rear of the car have a friend spin your
tire "1" time and you count how many times you driveshaft goes around.

If it only goes around a hair over 3 times = 3.08's or what ever size gear you
have.
Or pull the cover and count the teeth and divide together. Dont trust the tag
if you got the car used, might have been changed.

Question · Dec 15, 2005

It's a 99 GT. It moves pretty good for just exhaust. It's very loud and seems to pull pretty good down low, which is why I was curious. There is no way to tell if the guy who had it put a 3:73 in it. Which seems pretty logical, since he has this really loud exhaust without any cats or anything...At 35MPH the car is right at red line. Almost 6. Does anyone else have a 99-04 GT with a stock gear, that is different from mine in first gear?

By the way, the car does have standard tires. (245/45/17) Stock rims and tires.

Venom_Nitrous · Dec 15, 2005

Question said:
It's a 99 GT. It moves pretty good for just exhaust. It's very loud and seems to pull pretty good down low, which is why I was curious. There is no way to tell if the guy who had it put a 3:73 in it. Which seems pretty logical, since he has this really loud exhaust without any cats or anything...At 35MPH the car is right at red line. Almost 6. Does anyone else have a 99-04 GT with a stock gear, that is different from mine in first gear?

By the way, the car does have standard tires. (245/45/17) Stock rims and tires.

3.27's

1LowGT · Dec 15, 2005

my 98 gt auto had 3.08s

CanadaStang · Dec 15, 2005

Question said:
How can I tell if my car has a 3:73 in it or not? My first gear can only get to 35. It's right at the red line at that point. Do you guys think I still have the stock gear, or does this mean I have a 3:73, or a 3:55? I'm basically just trying to figure out how long my first gear should be, assuming it's a stock gear. Thanks for the help.

OMG!!! Mr. Lt1 bought a......a...... Mustang???

[Twitch] · Dec 15, 2005

3.27 T45 in First gear at 6000rpm > 41.598073050691 MPH
3.73 T45 in First gear at 6000rpm > 36.468015784386 MPH

Tire size is 245/45/17

mrvax · Dec 16, 2005

UDTBadkarma said:
Just for refference, the 94-98 cars had 3 options in gears. my 98GT came with 3 gear options in that year and they were 2.73, 3.08 or 3.27. All automatic GTs from 94-98 had 3.27 rear end gears i believe. I know when i swapped to 4.10s in my (automatic) 98GT, the mechanic pulled out 3.27s =)

1996-1998GT
--------------
2.73=maunal
3.08=auto
3.27=optional for either

Stang|ess · Dec 16, 2005

What's your rpm in 5th at 55 mpg?

Question · Dec 16, 2005

[Twitch] said:
3.27 T45 in First gear at 6000rpm > 41.598073050691 MPH
3.73 T45 in First gear at 6000rpm > 36.468015784386 MPH

Tire size is 245/45/17

So, this would assume I have a 3:73. Where did you get this information by the way? Is there a link? There is no way my car can go 41 MPH in first gear...

Question · Dec 16, 2005

Stang|ess said:
What's your rpm in 5th at 55 mpg?

I'm going to go and find that out right now. You mean 55mph, right? All of a sudden were talking about gas, lol.

CanadaStang · Dec 16, 2005

Question said:
So, this would assume I have a 3:73. Where did you get this information by the way? Is there a link? There is no way my car can go 41 MPH in first gear...

This should help:
http://www.wcfords.com/stuff/calcs/EGTcalc/egtcalc.php

Question · Dec 16, 2005

Alright, at 55 mph my car is over 1500 rpms. I would say, 1600 rpms or so...

Question · Dec 16, 2005

CanadaStang said:
This should help:
http://www.wcfords.com/stuff/calcs/EGTcalc/egtcalc.php

Maybe I'm dumb, but I can't figure out that thing...

trailblazr81 · Dec 16, 2005

Its simple, fill out the stuff you know, pick yer gear n tranny then it calculates whatever field you left open.

The 55 MPH at 1600 RPM would be the 3.27's if its a T45 or TR3650.
Go buy some 4.10's.

Outlaw97GT · Dec 16, 2005

Question said:
Maybe I'm dumb, but I can't figure out that thing...

You have a 99 GT Im assuming its a 5sd since you didnt say, and Im also assuming you have 245/45/17 tires. If so and if you were at 55 mph in 5th gear(Im assuming again) at 1600 rpm here is your gear size=Result:
Rear End Ratio = 3.3172798206155

That means you have 3.27's...

imblown-ru · Dec 16, 2005

hmm so my mustang can theoretically do 209 mph? thats what that webpage says...im gonna go try

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