Adjusting Speedometer Reading

[William2]

My speedometer has always over read the speed by about 7 mph. I have just read a short article in a classic car magazine that after removing the speedo front glass and bezel it is possible to gently prize off the needle from the spindle and re-seat it in a different position instead of sending it away for re-calibration. Has anyone tried this method?

[ericbushby]

Hi William.
Look carefully on the speedo dial and you will see a small white dot at about minus 7 MPH.
This is a calibration mark and is the position at which the pointer should be fitted. If you gently prise your pointer anticlockwise past the springy zero stop it should rest at that dot.
After fitting, the pointer is gently prised past the zero stop to rest on `0`.
If the pointer has mistakenly been fitted at `0` this would account for your error.
Use or make two levers to pull the pointer off straight, protecting the paint on the dial. Put the pointer back on lightly and then press it gently on when satisfied.
Best of luck.
Eric in Burnley
1967 S3SE DHC

[davidj]

Something you might wish to consider; if you have different size tyres fitted now than when the car (and speedo) was built ie 155/80's fitted instead of the original 145/80's, the speedo will be slightly less accurate.

[Quart Meg Miles]

Something you might wish to consider; if you have different size tyres fitted now than when the car (and speedo) was built ie 155/80's fitted instead of the original 145/80's, the speedo will be slightly less accurate.

But then the error would get greater as the speed went up. I have standard everything but mine still reads 10 % [ percent] high so I've moved the needle to be correct at 30 mph. I know it will read 4 mph high at 70 etc.

The needle movement suggested by Eric is correct and I've done it to achieve my result. But if your movement to the proper position still gives the wrong result then move it by the amount which will give the correct reading, In fact do that anyway if your needle does not swing to the correct spot. Make some temporary mark, like sticky tape, of where the needle naturally zeros.to and move it on the shaft by 7 mph anticlockwise.

[William2]

Thank you for your replies. I will follow your instructions and see what happens. I assume that I only need to remove the chrome bezel and the glass to adjust the needle with the speedo removed from the dash??

[ericbushby]

Hi William.
Yes, remove the speedo first. Some wiring can be removed when the speedo is hanging out of the dash.
Be prepared to remove the trip reset knob and the steering wheel if necessary. The trip knob is held by a cross pin through the shaft.
I usually remove the steering wheel and the drivers seat to work behind the dash anyway.
The bezel and glass can be stubborn if they are original and have not been disturbed for fifty years. Mine was so bad that it took several days of occasional drops of release agent before the glass and seal would separate from the case without risking breakage. Other have said they had no problem.
I found putting the speedo back harder than taking it out.
Best of luck
Eric

[gjz30075]

Removing the needle can be a bugger. Use a fork to wedge it up,using the bend in the fork
as a fulcrum. Protect the gauge face with some thin cardboard.

[Quart Meg Miles]

If you are lucky you may be able to release the bezel before the unit leaves the dashboard, once released from behind. Try twisting the bezel when the speedo is loose and if it rotates eventually it will find the slots to release it, and with it the glass.

I didn't have that luck and having my steering wheel set very forward found it easiest to centre and remove it then loosen the clamp holding the wheel-surround in position and pull the that out as required. Get the trip knob out, as described, and ease the speedo out.

I removed my tight bezel by first easing the tags a little with a screwdriver, to make sure they were free, then slid a thin craft knife blade between the bezel rim and the speedo body all the way round it to remove all the grot. Perhaps I was lucky but I could then rotate the bezel, using a rubber sheet to grip it, until it aligned with the gap in the body rim. If necessary use WD40 or whatever. Good l luck

[William2]

I managed to prize off the speedo needle and reset it at about minus 10mph. I took the car out for a drive using my GPS to calibrate the speed difference. Great news my speedo now only over reads by 1-2 mph which is ideal.
Thanks again for all your help on this matter. I should have done this years ago!!

[ericbushby]

Hi William,
that`s great.
Thanks for the feedback.
Eric in Burnley

[Quart Meg Miles]

Hi William,
that`s great.
Thanks for the feedback.
Eric in Burnley

+1