Speedo is wayyy off: what gears do I have?

[Xcessiv]

Hi!

The speedo on my Stang GT 2001 (T3650) is wayyy off. At ~2000 RPM at 75 mph (speedo), I'm in reality going at 55-57 mph according to the cars following me.

There were some threads with links to calculate everything, but I didn't find them. What gears do I have?

Thanks

 

[98stangv8]

i would "guess" 3.73's...but that is just a guess...

how do you not know what gears you are running? did you just buy the car that way?

 

[UVBNHAD]

If it's not gears have you swapped out the guages lately? If you don't do the needles right they will be way off.

 

[Xcessiv]

i would "guess" 3.73's...but that is just a guess...

how do you not know what gears you are running? did you just buy the car that way?

Yep, I bought the car that way.

 

[Xcessiv]

If it's not gears have you swapped out the guages lately? If you don't do the needles right they will be way off.

Nope! Everything's all original.

 

[Cobra Jay]

Hi!

The speedo on my Stang GT 2001 (T3650) is wayyy off. At ~2000 RPM at 75 mph (speedo), I'm in reality going at 55-57 mph according to the cars following me.

There were some threads with links to calculate everything, but I didn't find them. What gears do I have?

Thanks

If you're still running 245/45/17's that gives you a tire height of 25.6811.
Assuming you're in O.D.(5th gear)

Tire Height=25.6

O.D. ratio =.62

RPM=1925(2000 on tach)

MPH=55

R&P ratio= 4.30


or

Tier Height=25.6

O.D. ratio=.62

RPM=1902(2000 on tach)

MPH=57

R&P ratio=4.10


www.randysringandpinion.com
It's hard to tell because you havn't been to specific and your cars tachometer won't give you a 100% exact reading.

Jack the rear of the car up off the ground and put some jack stands under it to support the car.

Make a mark on a tire and 1 on the driveshaft.

Have someone rotate the tire one complete revolution while you count how many times the drive shaft rotates. A little over 4 would=4.10 a little over 4 1/4 turns on the D/S= 4.30

hope this helps.

 

[Xcessiv]

Wow! This is exactly the kind of answer that I was looking for.

Thanks alot!

 

[Xcessiv]

I'm just anxious to see how this will translate the main driveability of the car in daily driving. I really don't think that 4.30s make your car faster.

I think that I'll look for some Nittos DR...

 

[Cobra Jay]

I really don't think that 4.30s make your car faster.

I think that I'll look for some Nittos DR...

Go drive a stock Stang with 3.27's and then one with 3.73's,4.10's or 4.30's and then tell me that the gears do nothing for them!

Stay away from the Nitto DrR's. Get some BFG or M/T Dr's!

 

[Xcessiv]

Go drive a stock Stang with 3.27's and then one with 3.73's,4.10's or 4.30's and then tell me that the gears do nothing for them!

Stay away from the Nitto DrR's. Get some BFG or M/T Dr's!

Ok... I gotta admit that it really wakes up the car. I was just wondering if I could get any traction on the street when wanting to play a bit.

 

[Xcessiv]

I did the driveshaft test today and I officially have some 4.10s under there. I'm pretty happy, I was planning to install theses anyway.

Now, I just gotta learn how to drive this beast on standing starts.