C2 rear-end gear ratio?

How do I determine the gear ratio in my 63 250hp 4spd- are there #'s on the
housing or 3rd member? It don't believe it has posi-track. Thanx- lib

There are numbers on the housing but the standard rear gear for the
250-300 hp 4 speed cars was 3.36:1. No it is not posi. All this is off
if someone changed the piece.

PDeen

On Jan 7, 10:27 am, "lib" > wrote:
> How do I determine the gear ratio in my 63 250hp 4spd- are there #'s on the
> housing or 3rd member? It don't believe it has posi-track. Thanx- lib

lib wrote:
> How do I determine the gear ratio in my 63 250hp 4spd- are there #'s on the
> housing or 3rd member? It don't believe it has posi-track. Thanx- lib
>
>
Look for a sheet metal tag attached to one of the differential cover bolts;
if present it has a stamped 2-letter code indicating the ratio. I think
a 63 250hp
ordered with a 4spd would have come stock with a 3.08 non-posi., code "CZ".
If by chance it originally had a 3-spd (3,540 cars came that way, most
of them
probably 250hp) and the 4spd was added after purchase, it would have had
code "CA",
the code for 3.36 non-posi, the most common ratio in '63; "CB for 3.36
posi,
"CC" for 3.55 posi, "CD" for 3.70 posi., "CE" for 4.11 posi, "CF" for
4.56 posi,
"CJ for 3.08 posi, "CX" for 3.70 non-posi.
Don't ask me why they didn't just stamp the ratio plus a "P" where
applicable.

Or, place a chalk mark on the sidewall of a rear tire, at the bottom
(with the car on level pavement in neutral),
and another chalk mark on the driveshaft or a driveshaft U-joint where
you can see it if you look under the car.
Have someone slowly push the car forward for a count of 3 tire
revolutions while you scoot
along on a mechanics dolly counting how many times the driveshaft mark
makes a revolution;
divide the driveshaft revolution count by the tire revolution count and
you'll have the ratio.
The more tire revolutions you make, the more accurate this method would be.
3 tire revolutions would be 9.24 driveshaft revolutions if the ratio is
3:08, 10.1 at 3:36, 10.65 at 3:55, 12.33 at 4:11.
9 tire revolutions (multiply the above numbers by 3) would be about 27
3/4 driveshaft revolutions at 3:08 ratio, etc.
If you jacked the car up from beneath the differential and had 2 friends
rotate the rear wheels in unison
in the same direction, calling out the revolution count while you count
driveshaft revolutions as outlined above,
you'd accomplish the same thing, perhaps a bit more safely.... but you
may find that the half-shaft
U-joints have some interference when the rear wheels are hanging all the
way down

In article >,
WayneC > wrote:

> Look for a sheet metal tag attached to one of the differential cover bolts;

The metal tag may have been, but none of my C-2s had one. I've always
found the code stamped into the flange where the axle cover mates to the
housing - on the bottom surface closest to the roadway.

Here's waving to ya - \||||

Owen
___

'67BB & '72BB

-- not affiliated with JLA forum in any way -- alt.autos.corvette is
original posting --
___

"To know the world intimately is the beginning of caring."
-- Ann Hayman Zwinger

Thanx for the info. I appreciate it- lib


"Barking Rats" > wrote in message
...
> In article >,
> WayneC > wrote:
>
>> Look for a sheet metal tag attached to one of the differential cover
>> bolts;
>
> The metal tag may have been, but none of my C-2s had one. I've always
> found the code stamped into the flange where the axle cover mates to the
> housing - on the bottom surface closest to the roadway.
>
> Here's waving to ya - \||||
>
> Owen
> ___
>
> '67BB & '72BB
>
> -- not affiliated with JLA forum in any way -- alt.autos.corvette is
> original posting --
> ___
>
> "To know the world intimately is the beginning of caring."
> -- Ann Hayman Zwinger
>