I have an 81 corvette that has the stock 85mph speedometer, and i have heard that they used to make some kind of convertion thing that you hook up to your speedometer cable at the transmission, and it allows you to go off of you kph so that you have a 135 mph limit. they were really popular when the corvettes had an 85 mph speedometer, but i wouldn't know the first place to look to get one. if anyone knows, can u please reply to this, or e-mail me at Kryptonight07@yahoo.com
thanks

I've never heard of that type of conversion. I know there are Vette shops that will take your OE speedometer and change the face of it to read 140 or 160 mph, and rebuild and calibrate the innards for you. I believe the conversion runs about $175-$200.

My '78 came with a metric speedometer since it was a Canadian car. I bought a used MPH speedometer and installed it with no problems at all. It works just fine. You change from your 85 mph to a 140 speedo with no problems...the speedometer cable is the same for all. What can change is the small internal gear for various rear axle ratios.

Gunslinger
Frederick, MD
'78 L82

Ya, i have heard of places that change the face of the speedometer, and i was talking to a guy that has owned quit a few vettes, and he was telling me that they had that thing back when he owned his, so i was just wondering if anyone had heard if it was still around. well if you ever hear about one, let me know, thanks

what about the speed sensor on the back side of the speedo..does this device cause any problems when changing?

When I changed the speedometer head on my car, I experienced no problems at all outside of some needle bounce it already had. Changing the cruise control transducer took care of that.

Why bother.
You can order a direct replacement 140 mph speedometer from John at REDLINE GAUGE AND CLOCK REPAIR.
The replacement is under 60.00 with your exchange.

This, (IMO)is the best dollar for dollar upgrade I've ever done.

Sorry I don't have the phone number, but there's plenty of posts regarding this, run a search,

thanks for the info Craig, i knew a place to get a replacement that was 140 mph, but it costs about $145. thanks for telling me about this place. can't wait to see how fast i am going!