OK, i'm trying to figure my gear ratio out but i'm havin trouble. i used the calculator on the site but i don't think i did it right.
I have P225/60/R15 tires all round. I have a 700r4 tranny. At 70 MPH the tach is at 2450-2500 rpm. Any clue on what my ratio is? the calculater said something like 4.24 or somthing like that.

Thanks
Matt

 

i would say 3.73s... i have 3.42s and i sit at 2500 @ 70 mph...

 

Have you changed the fluid lately? Then youneed to take the cover off anyway, so you can do the overdue maintenance. While you're taking care of your car, take a look at the gear and see what it really is. All else is just a guess.

 

matto antoher option here that i encountered is . . .

your tach is off.

my tach is off by more than 3k by the time i get close to redline, i was very confused abou tthe gearing in my car, then i put it up on they dyno, and watched the tach connected to my #1 plug and watched the REAL rpm, and was able to just how far off a factory tach can be.

 

Although the point about probably needing to remove the diff cover and change the fluid is VERY TRUE, there are other ways.


One thing I think you're forgetting in your calculations is the fact that the 7004R has an Overdrive, so it's not a 1:1 gear ratio in 4th gear...


Try HERE for a good speed / gear ration calculator.


You can also look for the rearend stamping on the housing, which should tell you what the gears SHOULD be if they haven't been changed.


HTH