What gears do I have

[Stangcobra1122]

Hey guys, was wondering how I can figure out what gears are in my rear end without dropping my diff, first and second feel really short and my highway cruising speed(70mph) is just south of 3k rpm in 5th so I'm leaning towards 4.10s, but is there any simple way to figure out what I have so I can reflash the car so that my speedo is accurate.
thanks.

 

[98 N/A 4V]

Jack the rear up. Put a mark on the drive shaft and a mark on the inside of the tire. Rotate the tire 1 full revolution and count the number of times the drive shaft turns. If goes just over 4 times then you have 4.10's. If it goes about a 4.5x then you may have 4.56's. FWIW I have 4.56's and at 70mph I'm just under 3k.

 

[Stangcobra1122]

I'm considering just reflashing it over and over again with different gears in the tune and seeing which are correct, since my jack doesnt work with this car (too low)

 

[Darkc0bra]

4.56 should be close. I know when I am on the highway I am at 3k at 80mph and I have 4.10's.

 

[Trip]

you need to put in exact numbers, plus tire and wheel size......but looks like you may have 4.56..........check this link


Gear Ratio Calc

 

[Stangcobra1122]

My trans in an 01 is a 3650 right? or is it a t45

 

[TBCobra]

3650

 

[Stangcobra1122]

3650 isnt on that gear website, is 3550 close enough or is that not gonna fly

 

[01yellercobra]

I think the T45 has the same .67 overdrive as the 3650.

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[3B99SVT]

Check your speed in 4th. I'm pretty sure the T45 and 3650 both have 1:1 4th gears.

 

[01yellercobra]

Check your speed in 4th. I'm pretty sure the T45 and 3650 both have 1:1 4th gears.

All the transmissions are 1:1 in 4th. At least up until 2011.

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[3B99SVT]

All the transmissions are 1:1 in 4th. At least up until 2011.

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I've never heard of a tranny w/o a 1:1 4th gear ratio -- I just wanted to cover the possibility that they're different. And testing the speed in 4th would take out all uncertainty for identifying the diff gear ratio. So which 2011 trannys aren't 1:1 that you know of?

 

[3Stang]

Maybe 4:30s?

 

[fangs99]

The MT-82 in the 2011+ cars has a 1:1 5th
They are a 6 speed with only 1 over drive

 

[Stangcobra1122]

it wound up being off by 2-3 mph when I switched the ratio to...4.00
weird right

 

[3B99SVT]

The MT-82 in the 2011+ cars has a 1:1 5th
They are a 6 speed with only 1 over drive

So that explains my thoughts on a drive I took in MO. I got to drive my friend's new 5.0 during Christmas vacation when he twisted his ankle jumping a ditch while we were disc golfing. I only got to go through the first three gears and had to be relatively smooth to not jerk him around, but I did notice that the gear ratios were very close. The car pulled almost as hard as my old '91 5.0 in the lower rpms too! But it's soooo nice not to have a car payment!!!

 

[fangs99]

The new 5.0's get there MPH from the tall 3.15 rear gears. Kinda like the old 5.0's t-5 trans 3.37 1st gear but with a 3.08 rearend gear.