The Stovebolt Site Forums The Shop Area Driveline T 5 speedo gears

I have a Camaro V8 T5 NWC with a .73 O/D installed in my 62 Chev one ton with a 4.57 rear end and 30 in. tires . I finally got around to finding a speedo cable long enough to reach the speedo out put .
My question is which drive gear on the main shaft would make the most sense to install as a starting point , as the the driven gear can be changed a lot easier to get my factory speedo to as close to accurate speeds as possible . I have both red and blue drive gears as well as matching driven gears .
I had to pull the trans. to address a noisy through out bearing and am taking this opportunity to install this missing gear . This is something I'd prefer not to do on a regular basis .

John

You need to do the calculations on THIS website.
You will need to know the rear tire diameter, and rear axle gear.
Plug the numbers in. The blue drive gear has 7 teeth. The red has 9.
The driven gears come in different tooth counts but you MUST make sure the DRIVEN gear you need is actually manufactured and available from vendors.
https://www.tciauto.com/speedometer-gear-calculator

Thanks Lugnutz , I searched on line and found one of your posts which had the above info .
The site recommended a 7 tooth drive gear (blue) and a 21 tooth driven gear (red) of which I have both and now I need only to install the trans. and test .

Thanks John

Finally got all the appropriate bits installed in my T5 and as its a V8 main box I replaced the original main shaft with a s10 main shaft in order to align the drive gear with the driven gear . Although I've only managed about 200 mile so far all seems to be well . It matches my GPS. speed fairly well until about 55 MPH. then the needle gets wonkey . It flutters around a fair bit until I get to a speed I can maintain then it calms down a bit .

I suspect the speedo is getting into unfamiliar territory as with the original gearing it probably never topped 55 Mph.

The cable is new so I suspect the issue is in the speedo and I don't know of any way to correct this .
For the time being I guess I'll just wait and see .

John