172 Ph1 Speedo Reading Low!

[Isambard]

Hi all,
I have searched around the forums quite a bit and cannot find the same problem as I seem to have!
I have done several tests against my sat-nav, and when I am driving at 30mph, the speedo reads 25. This 5-mile inaccuracy persists through all speeds as far as I can tell.
Obviously if i were to follow the speedo's reading of 30, I would be driving at 35, and likely get caught for speeding, so I would like to try and solve it!
So far, I have checked that the wheels/tyres are standard size, which they are, and have also replaced the speed sensor connected to the gearbox. This has not changed the readings
Has anyone ever come across this strange issue, or have any ideas how to solve it?
Apologies if this is posted in the wrong section.

 

[Dan@SJM]

Sounds like the clocks have been apart and the needle hasn't been put back in the correct place

 

[Isambard]

I forgot to mention that at low speeds (probably sub 5mph) the needle doesn't move at all-would that line up with what you have suggested? Thanks for the idea anyway!

 

[Dan@SJM]

Yup

 

[Ol’ Tarby]

Yeah I agree with Dan.

I had the clocks in my CTR apart for some reason which I forget, but I put the rpm needle back on and it was way out. I had to hook up my code reader to read the live engine speed and then try and push the needle back on in the right place.

 

[Isambard]

Ok great thanks guys... now to find out how to get at the clocks :-S

 

[Isambard]

Ok over the weekend i managed to get at the clocks. I tried to pull the needle off to reposition it, but it wouldn't come off.
I then tried turning it round by about 5mph but this doesn't seem to have worked either.
Am i missing something? Does the needle unscrew from the back or something like that?

 

[Ol’ Tarby]

Use a fork and gently pri it off

 

[Isambard]

Its definitely not screwed on at the back or anything? I do NOT want to break it!

 

[Ol’ Tarby]

Pretty sure they aren't. The needle is just pushed on. @McGherkin will know

 

[Isambard]

Finally found a reference:
http://www.cliosport.net/threads/how-to-changing-the-colour-of-the-dash-clocks.461910/
Just had to think outside the box for how to actually find it!

 

[McGherkin]

^yeah, just pushed on. When you put them back on, turn the spindle anticlockwise until it hits the lower stop, then put the needle on halfway up and push it down to 0. If you go too far, you'll have to go right back up the gauge and push it against the top stop before you try it again.

 

[Isambard]

Thanks!
When you say 'halfway up', do you mean pointing horizontally?

 

[McGherkin]

Doesn't matter, as long as you can push it down to 0.

 

[Isambard]

Ok thanks, I'll have another go and let you know how I get on!

 

[McGherkin]

Fork method is for the win. If you've got a fairly skinny fork you can slide the prongs either side of the needle.

 

[Isambard]

Hang on... where about's is the top stop?
To simply re-align the needle can I not push it all the way round past the top stop (as you describe), and then adjust it back down using the lower stop... meaning I wouldn't have to actually pull the needle off?

 

[Isambard]

This seems to have fixed the problem! Thanks all for the help!

 

[McGherkin]

Hang on... where about's is the top stop?
To simply re-align the needle can I not push it all the way round past the top stop (as you describe), and then adjust it back down using the lower stop... meaning I wouldn't have to actually pull the needle off?

You've obviously solved it now but in case anyone else sees this then yes, that's what I was getting at.