Hi, i have just done a manual swap on my 91 Auto TT and fitted a NA gearbox, iam now having issues with the speedo not displaying the correct speed, when i start the car and  move the car forwards a tiny bit  it will show 20 mph  or more and stay there until i turn the car off i pulled out the speed sensor and it has the the red cog on it.

My question is do i need to fit the blue TT cog to get the speed to display correct or is there another issue

 

Thanks for the help

Is this a UK zed or Jap spec? 

If Jap spec, do you know if the clocks are using a conversion mod to clock in miles rather than kilometres! 

 

This is  jap spec  i think the clocks were replaced by a previous owner as there is a old receipt in the service history  saying "converted from kph to mph having a uk spec instrument cluster fitted"

Also, what rear diff are you running?

If NA with NA gearbox, you'll need NA speed sensor. 

6 minutes ago, Aff68 said:

Also, what rear diff are you running?

If NA with NA gearbox, you'll need NA speed sensor. 

Hi i think the diff is still stock so the standard TT diff

 

 

Ah ok mate. I read somewhere that if its an NA gearbox with TT diff, then the speed calibration would be off. So definitely try the TT cog in the speed sensor which will have the correct calibration. 

Just a quick update to let people know ...

I never did sort it out... However i am 99% sure now that it is the actual dial/dash that is the problem as i use a device called the utcomp pro which can display speed and rpm and distance as it piggybacks off the speed sensor itself and it shows the correct readings/information therefore rulling out a speed senor issue and leaving me to assume its the dials themself that is the issue

Hope that helps anyone 

You can adjust the speedo by using little potentiometers on the back of the clocks.

 

and this may help too

http://www.mytwinturbo.com/custom/speedometer-calibration-comparison.htm