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  View original topic: speedometer question.
Gonšalo Torres Sat Nov 05, 2022 1:05 pm

Hello everyone.
I'm repairing a speedometer bug and this is the first time I've seen these holes in an odometer wheel frame.



it's normal? what is the function?
Taking into account that the most modern ones don't have these holes anymore, it's the first time I've seen this.



If anyone can help. Thanks.

Zwitterkafer Sun Nov 06, 2022 8:39 am

I've seen those too. My guess is that the holes were drilled there on purpose as part of a calibration process. The more holes you drill, the weaker the interaction between the rotating magnet and the metal cup. I would leave it alone and not worry about it.

Oh, and welcome to The Samba!

Gonšalo Torres Sun Nov 06, 2022 9:09 am

Zwitterkafer wrote: I've seen those too. My guess is that the holes were drilled there on purpose as part of a calibration process. The more holes you drill, the weaker the interaction between the rotating magnet and the metal cup. I would leave it alone and not worry about it.

Oh, and welcome to The Samba!

Yes, my first guess is that this is a calibration adjustment. but it doesn't make much sense. this piece must be as watertight as possible and as balanced from the point of view of magnetism. These holes break that logic. This piece is one of the first and I understand that VDO was still taking the first steps in the design of speedometers. My fear now is to remove the needle to treat the piece and unbalance the object. I'll have to mark it as best as possible or replace this piece with a more modern one, without holes...

mdege Sun Nov 06, 2022 9:27 am

Holes like those are usually for balancing a rotating mass.

Zwitterkafer Sun Nov 06, 2022 11:40 am

The speedo needle cup only travels slowly through an arc and never rotates fast enough that a tiny weight imbalance would matter. The holes in the cup make perfect sense, and compensate for a rotating magnet that was a little too strong. Water should not get inside the speedo in the first place, and any holes in the cup are irrelevant in this regard. I suggest cleaning the cup with a few spritzes of alcohol and avoid removing the needle if at all possible. Another problem to avoid would be metallic debris attracted to the rotating magnet.....such debris must be painstakingly removed.

Gonšalo Torres Mon Nov 07, 2022 7:57 am

Well I understand. By the way, here on the forum is there any document that shows the variants of the vdo speedometers that were being placed in the bug / samba? I saw in a post an excerpt of a sheet that seemed to have some models and was grouped by year. Does anyone have this document they could provide?
Thanks in advance.

Zwitterkafer Mon Nov 07, 2022 8:42 am

Good question. As a starting point, there is a guide to Beetle speedometers by year, on the Wolfsburg West site.

St_Rand Thu May 11, 2023 4:16 pm

How did you get the face off? Specifically, how did you remove the little flange that the needle presses into?



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