Speedometer error
Thread Starter
Racer
Joined: Oct 2013
Posts: 362
Likes: 11
From: MARSHALLVILLE OHIO
Speedometer error
My newly acquired 79 has an issue with the speedometer. I first realized it the first day I got it. Coming home from a cruise in I was holding up traffic. I checked it with a GPS and my son shot it with radar. 50 mph is indicated as 70 on the speedo. Can anyone suggest a fix. Or do I change the speedo gear, and which teeth. As far as I know everything is stock including the tire size.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
First step is always to verify whether the odometer is registering correctly or not.
If it is, the drive gears are correct but the speedo head is out of calibration. It needs to be removed and sent to a shop.
If the odometer has the same % error as the speedometer, verify the driven gear in the transmission.
If it is, the drive gears are correct but the speedo head is out of calibration. It needs to be removed and sent to a shop.
If the odometer has the same % error as the speedometer, verify the driven gear in the transmission.
Racer
Joined: Nov 2011
Posts: 374
Likes: 21
From: Charleston SC
This will probably confuse the issue, but I think you want to go UP on the tooth count if I read your post right. (Speedo reads: 70, actual: 50). I do agree with the one tooth per 5mph. The driven gear change is cheap and easy so it's worth a shot. You can usually find the driven gear locally. Have a wonnerful weekend, Bill
Racer
Joined: Sep 2012
Posts: 420
Likes: 0
My 74 has the same problem shows about 20 miles more then the actual speed
I did a test today by measuring a mile then took the vette and at the .7 mark it already had a mile on the odometer
It shows 83000 miles now I'm wondering how much less it actually has
I did a test today by measuring a mile then took the vette and at the .7 mark it already had a mile on the odometer
It shows 83000 miles now I'm wondering how much less it actually has
