When You have the dash out, can You take a photo of the regulator itself; which is directly behind the post or the rear, of the dash; where it is labelled +10V. If the regulator looks discoloured or broken in some way, I would suggest replacing it with a solid state one. Once You have a +10V voltage there; with no load (fuel or temp guages) applied, You can then add one at a time, & see whether, the +10V supply voltage slumps or drops.

Cheers Banjo   

Sorry for the very late reply banjo. Jave had many other things to fix so i forgot about it. But i Have pulled the dash apart multiple times and it doesnt seem discoloured or broken at all. I'm thinking it could also be the blue sheet on the cluster as it only gets voltage when the regulator is in just the right spot, as it has to be touching it just right for it to work. Also I have another question fkr you. Do you know whether between having a 5 speed gearbox, 4 speed speedo cable, and 3 speed auto cluster whether that may put the speedo out over 60kmh. I'm asking this as my speedo is out but only over 60. 100kmh by speedo is about 85kmh and 120kmh by speedo is about 100kmh. 

 

Cheers 79rolla 

Sorry, I don't know the answer to that one, as I've never come across that previously. My KE30 2 door sedan; started life, with a 3 speed automatic gearbox; which shortly thereafter, got changed to a 5 speed manual gearbox. I never noticed that it made any difference to the speedo readings.  My believe is that the speedo drive comes off the final shaft out of the gearbox; & the gear ratios have no affect on it at all. The only difference I can see making any difference to the speedo reading; is if the diff ratio has been changed, at some time; or larger wheels & tyres have been fitted.  Wouldn't be hard to work out, how far out the speedo reading would be, if you knew the orgininal & replacing diff ratios. Gets a little bit more complicated, if you change wheel & tyres sizes, as well as the differential ratio. Others on here may have gone through this exercise, & may like to comment.

Cheers Banjo

P.S. I'm guessing You have removed the speedo cable; checked it for breaks or wear, & also the little nylon gear, that slides into the rear of the gearbox.

Edited July 4Jul 4 by Banjo

"My believe is that the speedo drive comes off the final shaft out of the gearbox; & the gear ratios have no affect on it at all. "

Yep.  ..and if you swap the gearbox to one with a different number of speedo teeth you have to swap the nylon gear too, or it will chew itself to bits quite quickly.

Diff and tyres will put it out by a percentage, so 20% on yours, which is a lot for tyres are they are generally a similar diameter. Same for a diff ratio change, you could swap a 4.3 to a 4.1 and feel the difference immediately, and that's only 5%. They would have fitted a 5.1 ratio to give a 20% over-read, and the motor would be screaming at 100kph. If it was a ratio from g'box or diff change, the 20% at 100kph would give you 12kph error at 60kph.

So, maybe something inside the speedo where the magnet spins and turns the needle against a very weak spring. Things like the distance from the magnet to the needle.

Anyway, start by pulling the cable out, hanging it up on a wire and put a drop or few of oil in the top every time you walk past..

Cheers banjo and altezzaclub. The only thing that has been changed that I know of is the wheels, which i changed my self. It went from a 155/80/13 to a 205/60/13 tire. Thats all thats changed that I know of. Its still got the factory auto diff though. So I'm thinking it could be that throwing it out but I don't know. But I will have a look for damage on the speedo cable. 

Cheers 79rolla 

Edited July 4Jul 4 by 79rolla

Well, you're dead right with those tyres, tiresize.com says 90mph becomes 89.6..!  You can count the diff ratio by jacking up one rear wheel and turning the driveshaft by hand, the KE70 auto diff is 4.3, the manual's is 4.1, still a much smaller error than you see.