what rpm should i be at in third gear going 30 cuz im at 2100rpm do i have different gears? because my friend has the same car and we went right next each other at 30 and he was at 1700rpm

 

I highly doubt you have the stock 3.42's, might have 3.73's, I can't remember where I'm at in third at 30, but I'll find out soon for ya.

 

ok thanks but yea just let me know cuz my speedo is off by 10mph on the high way

 

http://f-body.org/gears/

 

you have 3.73's you buddy have 3.42's

 

94-02 T56 in 3rd gear at a true 30MPH and turning 2,100rpm, with stock tire diameter would have 4.10's.

But, the stock tach typically reads higher than actual engine rpm. If your speedo is off by 10 MPH, is it reading 10 MPH higher or lower than true speed? And is it 10 MPH off at 30 MPH, or at some other speed? A speedo that is inaccurate because of the wrong gear ratio being programmed into the PCM is going to be "off" by a percentage, not by a fixed number of MPH.

 

An easy way to tell what gears you have is to make sure that your friend's speedometer isn't off and have both of you hop on the highway.

Once your friend's sppedometer is at 70 M.P.H. (or whoever's speedometer is more accurate), put your car in 4th gear and look at your RPMs.

Whatever RPM you are at, divide the number by 1,000 and, in most cases, this is your gear ratio.

To make it easier to understand:

My car at 70 M.P.H. and in fourth gear, is just a hair over 3,400 RPMs, we'll say 3,420 RPMs just to make it easier.

So then I would do 3,420/1,000 = 3.42

The 3.42 is, more than likely, my gear ratio. And since I have stock gears (3.42), this method seems to work so far

 

ok ill try that next time on the highway but my speedo says 80 but my friend in his stock magnum said we were goin 70 and if i remember i tried to drop it in third at 70 and it was at like 5000 so i had to put it in fourth to race him

 

I'm kinda late getting back to ya, but I'm lower that 2100 at 30 in 3rd, so you probably do have 4.10's

 

ok thanks

 

So then your speedometer is almost 15% off...

More than likely, you have 4.10's (if not, 3.73's).

Just try hopping on the highway and do 70, or in your case "80", put the car in fourth gear and see what RPM you're at.

That's the easiest way to know what gear you have.