Speedometer Gears
Thread Starter
Racer
Joined: Oct 2006
Posts: 396
Likes: 3
From: Buffalo New York
Speedometer Gears
My speedo reads 20% low. I have an 18 tooth driven gear, 3.36 rear gears, and 235-60-15 tires. It makes no sense. An 18 tooth gear is the smallest out there. Am I missing something? By the way, it's a '76 L-48 with a 4 speed.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
I had a similar issue with my speedo.... was reading about 30% low.
Mine was fixed by restoring the speedo drive mechanism in the gauge.
I believe the standard factory calibration is 1000 rpm cable speed should read 60mph. Try attaching a drill (with a known drill speed) to the speedo cable (gearbox end) and see what your speedo displays.
The speedo mechanism may just need a bit of lubrication, or recalibration.
cheers
tom
Mine was fixed by restoring the speedo drive mechanism in the gauge.
I believe the standard factory calibration is 1000 rpm cable speed should read 60mph. Try attaching a drill (with a known drill speed) to the speedo cable (gearbox end) and see what your speedo displays.
The speedo mechanism may just need a bit of lubrication, or recalibration.
cheers
tom
Le Mans Master
Joined: Oct 2000
Posts: 7,831
Likes: 5
From: Austin TX
There are threads about this... Black Magic made a calculator you can use to see what you need. I tried it with your tire size and it says you need a 21 - if you have the large drive gear.
http://forums.corvetteforum.com/show...74&postcount=4
This thread (also by Black Magic) should tell you what drive gear you have:
http://forums.corvetteforum.com/show...eedometer+gear
http://forums.corvetteforum.com/show...74&postcount=4
This thread (also by Black Magic) should tell you what drive gear you have:
http://forums.corvetteforum.com/show...eedometer+gear
