I put my original speedo into the tacho dash so I could keep my originals K's and also because it was a 5 speed cluster and didn't have the speed sensor on the back of the speedo and it wouldn't kick down without it.
I found this problem after i changed my dash out, i believe that the speedo was faulty because it was reading the wrong speed + not clocking over km's. So i pulled it all out again and put my original speedo in there, now shows correct speed, clicks over the km's and what not.
Oh, and i also forgot to turn my lights off after testing the lighting harness was pushed in correctly, so at 11 when i went out to my car to start it up, wouldnt go...and because of where i park the car, right up against a fence we had to tow the bloody thing out with my girlfriends dads van...major hassles