Have you guys ever heard of a Speedometer correction adaptor that will correct for oversized tires on an 1979 Escort Mk2 4 speed transmission using a Cortina speedo? Where does one go to get such an item? The cable goes into the transmission with a "C" clip. I need to slow down the speedo about 10%. Russ

There are such things as "ratio adaptors" (do a google) but it's unlikely you'll get one to fit i think.
Probably easier / cheaper to either have your speedo re-calibrated or go to an electronoic set up, Burton do electronic output adaptors

you could just take the gauge apart, then print off a new face on a computer printer and stick it on. You could do a google search and use one of the many examples on the web (like these pic's) and just modify one on paintshop to suit your speedo and speed range. If you get another car to drive along with you and flash their lights at say 30, 50 & 70 mph and have a passenger mark the dial positions with tipex then you know where the numbers should be.

Why have a drab boring normal dial when you could have anything you want??

I'd have a nude girl on mine but herself would kill me

[Edited on 29/5/09 by Mr Whippy]
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& seeing where you are...

you have far too much free time ...

Thanks. I had no idea a speedometer could be re-calibrated. I'll check into that. I thought about the new face but the mileage would still be off. Russ

You may be able to get a different speedo drive gear, i know there are a few available for the type 9 box so may also be for the 4 speed.
Paul.

As Paul has already suggested changing the driven gear for the speedo drive in the gear box should sort your problem IF you can find the right part. Easy to change without dismantling the gear box. I'm not sure but I think our HGVs (trucks to you) have to have a tachogragh fitted which sometimes needs the speedo calibrating using some sort of gears in the cable , Might be of use ? I have had a Mini speedo serviced and recalabrated by Speedy Cables, some one near you may offer the same service.