Gear ratio

[deathcrew]

Can anyone give me an idea of what gear ratio is in my car-440 mild cam 10-1 727 auto 8.75 rear 28in diameter tires on rear-55 mph off of my gps turning 3100 rpm.
Thanks,Don

 

[Meep-Meep]

How accurate is your speedometer and how loose is your converter? My car has 3.55's and at 70 I'm at 3500 RPM with 27" tires and a TCI 11" converter. 55 MPH I should be around 2800 RPM. You might have 3.55 or 3.23 but not sure.

 

[deathcrew]

First off I made a mistake the GPS said 50 mph and the tack was at 3100 RPM's. I have a 2800 stall converter and was using my GPS for a MPH reading because the speedo in the car was reading over 100 mph.

 

[Cranky]

My calculator says you have a 5.13 gear in there....but if you have a SureGrip, you can raise the rear and rotate the wheels and count how many times the driveshaft turns to one rev of the tire and get a good idea....

 

[deathcrew]

Thanks man I'll try that.

 

[deathcrew]

My calculator says you have a 5.13 gear in there....but if you have a SureGrip, you can raise the rear and rotate the wheels and count how many times the driveshaft turns to one rev of the tire and get a good idea....

Did you mean 4.13?

 

[Meep-Meep]

The stall converter may slip too much to get an accurate calculation on RPM vs. MPH. Better to count or just pull it out and inspect it.

 

[deathcrew]

The stall converter may slip too much to get an accurate calculation on RPM vs. MPH. Better to count or just pull it out and inspect it.

Thanks man,I was thinking about taking it to the local 1/8 mile track this sunday just to see what she will do. Probably embarrass myself pretty good (haven't ran a car down the strip in over 20 years!!:sleepy2:That will be me at the light:sixpack:and me afterwards!!

 

[Cranky]

3100 rpm is a lot for 50 mph in high gear. I ran a 4.56 in a small block Cuda on the street some years back and my rpm was pretty high too and I also used a 28" tire...but the calculator says you have around a 5.13 gear....and I plugged in the numbers in 3 different calculators and they were all within the same range. If your converter is slipping, you might have a 4.88 gear.

 

[Meep-Meep]

Thanks man,I was thinking about taking it to the local 1/8 mile track this sunday just to see what she will do. Probably embarrass myself pretty good (haven't ran a car down the strip in over 20 years!!:sleepy2:That will be me at the light:sixpack:and me afterwards!!

I know the feeling!