speedometer cable
Thread Starter
Racer
Joined: May 2021
Posts: 331
Likes: 15
From: Las Vegas
speedometer cable
In a 77 corvette, are there 2 speedometer cables one called lower and the other called higher? I thought there was only one long one from the cluster to the trans. I don't have cruise control. mine is a 4 speed manual. Also, I changed the stock 370 rear end gears to 390 gears. Do I need to change the speedometer gear to a different one? If so, anybody know what color?
Safety Car
Joined: Oct 2007
Posts: 4,360
Likes: 1,724
From: Seattle Area Washington
With a manual transmission single cable.
If my math is correct:
Currently you have a 4 speed and I'm assuming it is original to the car?
Current Drive Gear would be a 7 tooth and green...
With a 3.70 ratio and Bf Goodrich 255 60 15 tires and a outer diameter of 27.1"
Your Driven gear now should be a 19.27 tooth, well that's not possible so lets round it off to a 20 tooth...
Same Drive Gear and Tire outer diameter with a 3.90 ratio is 20.3 tooth...
Your current driven gear if Blue is a 20 tooth so no change is needed...
If my math is correct:
Currently you have a 4 speed and I'm assuming it is original to the car?
Current Drive Gear would be a 7 tooth and green...
With a 3.70 ratio and Bf Goodrich 255 60 15 tires and a outer diameter of 27.1"
Your Driven gear now should be a 19.27 tooth, well that's not possible so lets round it off to a 20 tooth...
Same Drive Gear and Tire outer diameter with a 3.90 ratio is 20.3 tooth...
Your current driven gear if Blue is a 20 tooth so no change is needed...
Race Director
Joined: Nov 2006
Posts: 13,151
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From: Sunshine Coast, Queensland, Australia
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Cruise-In VIII Veteran
I have a 77 manual. No cruise. On piece cable. My ex had a 77 auto with cruise. 2 cables.
I once replaced my cable. Ordered from one of the vendors 20 years ago. Don't remember which one.
I run a brown gear. 3:37-1 rear gear. so, cant comment on which one. Other than run your GPS on your phone at a steady highway speed and check it.
I once replaced my cable. Ordered from one of the vendors 20 years ago. Don't remember which one.
I run a brown gear. 3:37-1 rear gear. so, cant comment on which one. Other than run your GPS on your phone at a steady highway speed and check it.
