Can't recall what gears are in my car

[dspaulding70]

Please don't laugh!

We went back and forth trying to decide between 3.23 and 3.55 and a couple of years later now and we cannot recall which one's we finally went with.  I should have taken better notes.  Anyway, trying to determine which one I have.  I know that when I drive 60 mph, the rpm's are about 2600.  Standard 15in tires.

Have a 440 with 727.

Any guess?

[Just 6T9 CHGR]

I'd guesstimate 3.23's

Try this calculator to get more accuracy....

http://www.ringpinion.com/Calc_RPM.aspx

[maxwellwedge]

Jack 'er up spin the wheel one full turn and count how many times the yoke spins around. 

[Finn]

^Agreed^

[maxwellwedge]

Please don't laugh!

We went back and forth trying to decide between 3.23 and 3.55 and a couple of years later now and we cannot recall which one's we finally went with.  I should have taken better notes.  Anyway, trying to determine which one I have.  I know that when I drive 60 mph, the rpm's are about 2600.  Standard 15in tires.

Have a 440 with 727.

Any guess?

I wouldn't go with your speedo reading - your speedo gear could be wrong for your gears and tire height as well.

[c00nhunterjoe]

what is a standard 15 inch tire?  use gps to get an accurate speed and what size are your tires?

[Runner]

Jack 'er up spin the wheel one full turn and count how many times the yoke spins around.  

 I agree, unless its an open rearend then jack one tire and spin the tire 2 revolutions and count how many times the yoke spins.  


  this a really nice calculator for figuring out pinon speedo gears. http://tciauto.com/Products/TechInfo/speedo_gears.asp

  i agree on the gps. im acually pretty suprised at how acurate this old speedos are when you use the right speedo gear. (at least in my junk up to 70 mph)

[Runner]

Please don't laugh!

We went back and forth trying to decide between 3.23 and 3.55 and a couple of years later now and we cannot recall which one's we finally went with.  I should have taken better notes.  Anyway, trying to determine which one I have.  I know that when I drive 60 mph, the rpm's are about 2600.  Standard 15in tires.

Have a 440 with 727.

Any guess?

I wouldn't go with your speedo reading - your speedo gear could be wrong for your gears and tire height as well.

again i agree. if you had 2.76 gears in before the change and didint switch to the correct speedo gear then yoen the math will still show a 2.76 gear using tire, rpm, and mph.  also i dont know what tach your using but not all of them are acurate