rear axle ratio

[Bill K]

The car is a 1966, 4 speed with a .040" over bored 1600.
Until now the tachometer and speedometer never worked
because of broken cables. Confirmed the speed today at 55 MPH
and the engine is turning at 4,000 RPM at that speed. The standard
rear ratio is a 3.90. I suspect the ratio in this car is at least in the mid to
high 4 range (4.56-4.88). What ratio do you think is in this car?
Thank you in advance.
Bill

[spyder]

What size are the tires?

[cktrap]

This might help.

http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php

[theunz]

A 4:62 set was available, I bet if someone went that low they probably put in a LSD as well. Have you checked?

[spyder]

I used a 4.88 ring and pinion from a truck with a posi. It won't go too fast but gets there quick!

[SLOroadster]

It might have a 3.9 or a 4.11 in it. At 55 with 205/50/15s, a 5 spd (in 5th) and a 4.11 rear end, I'm turning about 3500 rpm according to the tach.

Will

[datsunfreak]

The car is a 1966, 4 speed with a .040" over bored 1600.
Until now the tachometer and speedometer never worked
because of broken cables. Confirmed the speed today at 55 MPH
and the engine is turning at 4,000 RPM at that speed. The standard
rear ratio is a 3.90. I suspect the ratio in this car is at least in the mid to
high 4 range (4.56-4.88). What ratio do you think is in this car?
Thank you in advance.
Bill

In a previous 1600 with a 205/50-15 tire, 4spd, and a 3.90 rear end, 4000rpm was closer to 66-68mph.

[theunz]

Well Bill, you could always just count the wheel to drive shaft revolutions and get a fairly accurate result.

[Toptech360]

The car is a 1966, 4 speed with a .040" over bored 1600.
Until now the tachometer and speedometer never worked
because of broken cables. Confirmed the speed today at 55 MPH
and the engine is turning at 4,000 RPM at that speed. The standard
rear ratio is a 3.90. I suspect the ratio in this car is at least in the mid to
high 4 range (4.56-4.88). What ratio do you think is in this car?
Thank you in advance.
Bill

In a previous 1600 with a 205/50-15 tire, 4spd, and a 3.90 rear end, 4000rpm was closer to 66-68mph.

Thats about where i am at with my 1500 and "stock" size tires. 60mph is about 3800 rpm. I do wish there was a 5th gear! Still better than my old land cruiser with foot long connecting rods and a 4k redline tho. Lol.