Speedometer under-reading 20km/h

[Guimak]

Hello. I'm new here. 

I signed up because i can't find a solution or cause anywhere for this.

I have a skoda felicia 1.9D from 1999. It had no problems, the speed was correct with the gps. But the odometer was stuck, soo i sent to fixe it. But when it return something was off. The odometer works but the speedometer was reading 20km/h less than it should at any speed. Soo as soon i start driving the speedometer starts to rise. example: at 120km/h (gps), it reads 100km/h... something that didn't happen before i sent it to fix the odometer.

 

And now the garage i sent my car to fix doesn't want to take responsabilities and no other mechanics know how to fixed it.

 

Any ideias please??

[KenONeill]

Well, is the odometer reading correctly or is it also 20% low? If they're both slow/short then I'd suspect the drive cable.

 

If the odometer is correct you may have to go legal, and we can't advise you on that without knowing (country level) where you live!

[RicardoM]

Wrong answer, Ken. You have send Guimak on a wild-goose chase. There is nothing wrong with the bowden cable.

 

Guimak, for somebody to gain access to the odometer, it has to remove (among other things) the needle of the speedometer. This operation must be preceded by marking the position of the rotating disc/cup that drives the needle at a known speed, let's say 50 km/h, in relation to the housing of the speedometer. Only then the needle can be removed by lifting it. The needle is pressed fit on an axle. As you can imagine, at installation time the needle could be pressed on the axle in whatever position, as it is no slot on the axle for guiding the needle. That is why we had to mark a known position of the needle, so that we have a reference (calibration) for installation.

 

Now, since the clever mechanics that worked on your car didn't know that and moreover they have the audacity to refuse fixing their mistake, you are on your own and you have to recalibrate the speedometer yourself. In the absence of a calibration jig, the only solution that I know of is to remove the needle and reinsert it initially some 10-15 degrees clockwise in comparison to initial position. It is a trial and error job. I did it having the mask of the instrument cluster removed. The protective transparent plastic of the cluster has to be removed too. The idea is to have quick access to the needle while doing a test ride. See where the needle sits at 50 km/h on the GPS and fit the needle accordingly. Good luck!

[Guimak]

1 hour ago, RicardoM said:

Wrong answer, Ken. You have send Guimak on a wild-goose chase. There is nothing wrong with the bowden cable.

 

Guimak, for somebody to gain access to the odometer, it has to remove (among other things) the needle of the speedometer. This operation must be preceded by marking the position of the rotating disc/cup that drives the needle at a known speed, let's say 50 km/h, in relation to the housing of the speedometer. Only then the needle can be removed by lifting it. The needle is pressed fit on an axle. As you can imagine, at installation time the needle could be pressed on the axle in whatever position, as it is no slot on the axle for guiding the needle. That is why we had to mark a known position of the needle, so that we have a reference (calibration) for installation.

 

Now, since the clever mechanics that worked on your car didn't know that and moreover they have the audacity to refuse fixing their mistake, you are on your own and you have to recalibrate the speedometer yourself. In the absence of a calibration jig, the only solution that I know of is to remove the needle and reinsert it initially some 10-15 degrees clockwise in comparison to initial position. It is a trial and error job. I did it having the mask of the instrument cluster removed. The protective transparent plastic of the cluster has to be removed too. The idea is to have quick access to the needle while doing a test ride. See where the needle sits at 50 km/h on the GPS and fit the needle accordingly. Good luck!

 

 

Thanks for awnsering. But i realise now i did a huge mistake  on explaining myself. It dos not under-read, but i over-reads. So a 120km/h (gps) the speedometer marks 140km/h.

I don't know if it's the same solution.

 

So i need to remove the plastic proteting the dashboard, for that i need disconnect the dashboard, remove the plastic, connecting the dashboard again and them with the car at a know speed, remove the needle and fit where it should be. 
To remove the needle, i just need to pick it up and remove, nice and easy, or is there something to unscrew.

But when it's time to put the plastic again isn't it going to descalibrate?

[RicardoM]

7 hours ago, Guimak said:

But i realise now i did a huge mistake  on explaining myself. It dos not under-read, but i over-reads.

Not a huge mistake but obviously important. The mechanics inserted the needle flush with the stopping pin at 20 km/h. In fact the needle should push a little against the stopping pin helped by the return spring. See photos below for details.

 

 

8 hours ago, Guimak said:

To remove the needle, i just need to pick it up and remove, nice and easy, or is there something to unscrew.

No unscrew. Use for instance the two parts of a clothespin as two opposed levers below the black disc of the needle and push up evenly.

 

8 hours ago, Guimak said:

But when it's time to put the plastic again isn't it going to descalibrate?

I didn't mean the clear plastic below the gray mask of the speedometer. I meant the clear plastic that protects the entire instrument cluster.

[Guimak]

32 minutes ago, RicardoM said:

 

 

No unscrew. Use for instance the two parts of a clothespin as two opposed levers below the black disc of the needle and push up evenly.

 

 

Soo i remove the cluster:

 

 

When removing the needle...It's easier to do this by removing this plastic cover and gaining access to the needle, or removing all the speedometer/odometer out?

 

Another question, does it have space so that i can pass over the stoping pin without totally disconnecting the needle? ( i know, if you said soo it must have space).

Do i need to do this with the cluster/speedometer attach to the speedo cable from the transmission, or i can do all this and then attach?

 

By the way. You have been giving me a huge help, i wasted like months trying to figure this out with mechanics and google.

 

Edited 5 May, 2017 by Guimak

[RicardoM]

1 hour ago, Guimak said:

When removing the needle...It's easier to do this by removing this plastic cover and gaining access to the needle?

Yes. Depending on the thickness of your index fingers, you'll learn to pull out the needle by hand.

1 hour ago, Guimak said:

Another question, does it have space so that i can pass over the stoping pin without totally disconnecting the needle?

Yes. By the way, the pin can be removed too with a pair of pliers if you think it's easier.

1 hour ago, Guimak said:

Do i need to do this with the cluster/speedometer attach to the speedo cable from the transmission, or i can do all this and then attach?

You will have to detach first the cable at the speedo drive end.

1 hour ago, Guimak said:

I wasted like months trying to figure this out with mechanics and google.

Months?

[Guimak]

2 hours ago, RicardoM said:

Yes. Depending on the thickness of your index fingers, you'll learn to pull out the needle by hand.

Yes. By the way, the pin can be removed too with a pair of pliers if you think it's easier.

You will have to detach first the cable at the speedo drive end.

Months?

 

Yeah. Not a very common car here in Portugal.

Soo

1.Remove the cluster

2.Remove plastic cover

3.Remove Needle
4.Insert the needle below the mark of 20km/h (as if it where on 0 km/h)
5.Twist and pass over the stopping pin
6.Push all the way in
7.Connect everything back together

I'll give it a try in two days and give feedback.
Thank you soo much!

[RicardoM]

14 hours ago, Guimak said:

7.Connect everything back together

Don't expect fitting the needle correctly (bang on with the GPS) from the first try.

 

PS

No need to quote my entire post to reply. The topic gets unnecessary long. Use the Quick reply form at the bottom of the page.

[Guimak]

Noted

 

So i did it! Finally. At first try i manage to get it right with an error of maybe 3 or 2kmh above the gps. Lucky me? ahah.

 

At first i had dificulties to pop out the needle, it was really tight and i was afraid of breaking something. But after a few minutes i managed to get it out. It's all working now.

Thank you soo much RicardoM.

[RicardoM]

7 hours ago, Guimak said:

At first i had dificulties to pop out the needle, it was really tight and i was afraid of breaking something.

Sometimes it helps growing some fingernails

7 hours ago, Guimak said:

It's all working now. Thank you soo much RicardoM.

Well done! No problem.