How to caliberate speedo

[mr928]

Does anyone know how to caliberate the speedo? Dat521gatherer was nice enough to send me a working speedo/ odometer but it's off by about 15%. I'm sure I can take it to a speedo shop to adjust but i thought I'd check here first to see if anyone has tried this on their own.

 

[wayno]

I don't beleave you can ajust the speedo, what you have to do is change the speedo gear in the transmission.

[DanielC]

You get different pinion gears that go into the transmission, that match the rear axle ratio. Has your 521 by any chance had a transmission changed to a five speed, or a different rear axle ratio?

[mr928]

Very interesting but my current speedo works well and is very accurate but the odometer does not work. My 521 is all stock to the best of my knowledge and judging by the top speed in 4th the gearing appears to be stock.

[mr928]

Ok I took it by the place that repaired my original one and he recalibrated it by adjusting the spring tension.

[darrel]

My experience in calibrating speedometers are with zx speedometers. They all work the same way. The cable turns the numbers and a magnet drags the needle around. What the speedo shops do it change the strength of the magnet so it matches whatever is stamped on the face plate. I brought in the speedo head to the local shop here with the 130 mph face on my '82 turbo. This way I still had the 6 place odometer using the '79 spdo face. The '79 spdo head has only a 5 place mile reading. The numbers on the '79 odo are larger than the '82 head.

 

The spring tension he adjusted was for the stop at zero. Some use a peg, but mine was a spring.

 

 

The best thing about getting it recalibrated was that he did it for free.