Hey guys, I need your help with this easy little task. Next time you are on the highway...take a look at your speedo and your tach. and let me know how fast you are going at 2000 rpm's and 3000 rpm's in MPH while you are in OD.

I am trying to figure out if my rearend is stock or not. Or if there may be a problem with my car. For me @:

2000 RPMs = 50 mph
3000 RPMs = 80 mph

Let me know....thanks!

 

You could always pop the cover and check the gears themselves; have you changed the fluid yet?

 

2000 in OD= 60 mph
3000 in 3rd= approx. 90-100 mph

You don't look stock. I can hit 80 mph at 2500 rpm.

 

TomP, yea a friend of mine and I were talking this weekend about it, and he was like "you could always count the teeth". So I figure that was a good idea, because no I haven't changed the fluid yet. Thanks for the info though.

How do gears work....ie, if they were 3.23's would there be 323 teeth....etc. I don't know very much about gears.

 

Lets take, for instance, my poor 3.73 rear with the blown posi that's sitting in the backyard. Count the # of teeth on the ring gear... my ring gear has 41 teeth. Count the # of teeth on the pinion gear, it has 11. Divide: 41 / 11 = 3.72727272 = 3.73.

The gears in that axle even say "GM 3.73:1" on 'em. I don't remember if my 3.42 axle gears say that.

 

1750 @ 60 mph
3000 @ about 100