Tires and speedo
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
Use this calculator...it will tell you how much your speedometer will be off and then you can decide what to do about it. http://www.miata.net/garage/tirecalc.html
To adjust your speedometer there's a piece that gets changed that the cable fits into. I think they're color coated and can be purchased from suppliers. They're really intended to compensate for different rear axle ratios since tire sizes on C3's was pretty fixed.
To adjust your speedometer there's a piece that gets changed that the cable fits into. I think they're color coated and can be purchased from suppliers. They're really intended to compensate for different rear axle ratios since tire sizes on C3's was pretty fixed.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
You need to use a GPS (navigator) or time mile markers to find out what speed you are actually going when speedo is set at 60 mph. For every 3-4 mph that you are 'low' of actual speed, you should reduce 1 tooth from whatever speedo drive gear you remove from the transmission. For every 3-4 mph that you are 'higher' than actual speed, you should add 1 tooth to that gear.
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
It's a plastic 'driven' gear that costs a whole 10 bucks and takes 5 minutes to R&R once you get the car up in the air.
http://corvette-parts.zip-corvette.c...en%20Gear&rk=7
http://corvette-parts.zip-corvette.c...en%20Gear&rk=7
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