Odometer dead - usual cog issue

[Fuchs915]

Spotted during the MOT that the mileage hadn't moved as much as I was expecting.  Checked on the way home and it didn't budge.  Spent about 30 minutes carefully stripping the speedo down to get this.

Removed the clip from the undamaged cog and the damaged one just disintegrated, so much easier to remove!  Then spent ages counting and recounting and counting again so I could order the correct replacement wheel.  Should go back together easily enough, just need to see if I have a potentiometer on the electrickery board to adjust the over reading speedo, otherwise I'll go quick and dirty and set the needle a little further anticlockwise.

Simple job as long as you take your time, especially with removing speedo needle and with lifting the edge of the bezel.  I used a small half moon pick to start with to get the bezel rear edge lifted initially, and after going round 2-3 times with that, progressed to a small flat blade screwdriver for a bit more leverage.

 

Edited November 1, 2021 by Fuchs915
typo

[Siy]

"....otherwise I'll go quick and dirty and set the needle a little further anticlockwise."

 

Is this a thing then? My speedo reads too low... it will tell me that I am doing 60, when in fact I may be around 68mph... could get dangerous!

 

Is it possible to just reset where the needle sits initially, to slightly improve the readout? Obviously it wont be particularly accurate, especially at varying speeds - but I guess it may be better?

[Fuchs915]

17 minutes ago, Siy said:

"....otherwise I'll go quick and dirty and set the needle a little further anticlockwise."

 

Is this a thing then? My speedo reads too low... it will tell me that I am doing 60, when in fact I may be around 68mph... could get dangerous!

 

Is it possible to just reset where the needle sits initially, to slightly improve the readout? Obviously it wont be particularly accurate, especially at varying speeds - but I guess it may be better?

Yes, you can reposition the needle, it’s a friction fit on the spindle. I am going to see if I have a potentiometer on the circuit board as would expect that to be a better adjustment but if it doesn’t have one at least I will be able to get it reading a bit closer.

Hope that helps.

[strosek34]

I’ve just replaced my cog as well,  not too difficult, got it from EBay seller VFS911,  he has a chart of which cogs match the existing ones it turns plus Dia. Dimensions which does help,  mine is kilometre speedo so is different from a UK one.

I also reset the needle as mines always read too high.

£31.95 for a tiny cog is lot,  but such is life these days.

[Strictly]

VFS911 is me ;=) (aka VoFlo, formally Air Cooled Classics, all me)

All net proceeds to my own 911 rebuild, its just a hobby business these days, I don't do it for a living anymore. 12.5% discount on any item I sell, just contact me through PM rather than ebay. Ive not got that much (used) stuff left, a few bits here and there but not alot really left. 

Luke

 

[Busybee]

On an early car (67 912), my speedo needle bounces around continually. Say I'm aiming for 50mph, the needle bounces between 40 and 60 ish. Could that be a cog with a broken tooth? 

[strosek34]

That’s good to know Luke,  cog worked a treat and your info is good regarding the different gears.

 

Haith,  

Yours might be a cable operated Speedo,  so might just need the inner cable taking out and being cleaned and re-greased.

[Busybee]

8 minutes ago, strosek34 said:

Haith,  

Yours might be a cable operated Speedo,  so might just need the inner cable taking out and being cleaned and re-greased.

Cheers Steve. I'll look into an early car speedo setup. 👍

[Strictly]

I'm also thinking cable related, its also driven by another gear which bolts to the gearbox, but I would start with a cable. You could of course inspect your odometer gear, but I would do that last. I have that size if you need one in the end. 

[Devs]

I just wanted to add to this thread as I completed the replacement of the same cog on my 84 recently.

I purchased the replacement cog from eBay seller VFS911 which was perfect and using this video, followed all the instructions.   100% worth doing.

https://www.youtube.com/watch?v=pvm23fMcSEA&t=1625s&ab_channel=Charlie'sForeignCarService

[RichJones]

On 01/11/2021 at 20:33, Strictly said:

VFS911 is me ;=) (aka VoFlo, formally Air Cooled Classics, all me)

All net proceeds to my own 911 rebuild, its just a hobby business these days, I don't do it for a living anymore. 12.5% discount on any item I sell, just contact me through PM rather than ebay. Ive not got that much (used) stuff left, a few bits here and there but not alot really left. 

Luke

 

Hi there, my odometer has gone, I’m not very good at the diy replacement thing, do you know anyone I can send mine to for the cogs to be replaced please??
 

[Flat 6]

I used Rick Beauchemin, calls himself high lift productions. Great service and price for this same job.

Discussion here http://www.911uk.com/viewtopic.php?p=1351851

Sounds like Reap are also good.

Cheers,

Al

[RichJones]

Thanks for that but it looks like Rick is in Canada, probably better finding someone in uk.

 

[Ian Comerford]

Julian Reap http://www.reapautomotivedesign.com

[MarkJ]

jeez i swear my car is suffering in sympathy with a lot of the tech issues on here lately. Now my mileometer has stopped working! Only noticed this morning when i tried to reset the tacho to see how (little) far i'd get now on £50 fuel  quite handy in one way as my car is now stuck on 198k miles 

The speedo part works fine.

So i will also be at the mercy of getting someone else to fix it. Any Swiss watch makers on here? 

Edited March 22, 2022 by MarkJ

[Nige]

Not a Porsche specialist but they're UK based, I've used them effectively in the past although for custom cables, they've been around for yonks.

http://www.speedograph-richfield.com/html/inst_repairs.html

http://www.speedograph-richfield.com/

Although they really only show old boy English stuff, but might be worth an enquiry?

Website is from 56k modem days lolz

Edited March 22, 2022 by Nige

[Nige]

This UK outfit lists VDO/Porsche repairs

https://www.classicsparesengineering.co.uk/classic-spares-services

 

Just Googling, I have no experience.

https://octoclassic.com/product-category/porsche

 

[MarkJ]

thanks for the links Nige 👍 

No idea what something like this costs to sort out tbh. 

[Leicestershire]

It's a very easy repair.

Lots of how to guides + it's an opportunity to calibrate your speedometer.

[Pablo]

I’ve just done this job on my 993 recently, have a go yourself, it’s not difficult but just requires a little patience!

Edited March 24, 2022 by Pablo

[Lesworth]

Go on @MarkJ, you can do it!

[MarkJ]

1 hour ago, Lesworth said:

Go on @MarkJ, you can do it!

ha, its tempting i must admit. My trepidation is based on previous efforts with things like this where i try and prise it open and the innards fly everywhere !  i remember opening the ECU like i was a bomb disposal expert  

its probably only one cog that does the mileometer i expect as speedo works fine. Fuchs915's photo makes it look like a kids toy gubbins but i'm more fearful of breaking the glass or buggering up the speedo calibration. Can i just leave the needle alone and replace the (assumed) broken cog for the mileometer?

[Chris T]

Omegaman on here did a great job on both of mine. There is a knack to it, and then you need to select the correct gear set (there are several), install and re-assemble. I'd probably DIY it now but at that time it suited to send them away. He's Wiltshire based I think.

Chris

[omegaman]

Yeah go on @MarkJ You can do it 🙂 if you mess it up just send it to me and i'll sort it for you. Message me if you decide to tackle it yourself and need any tips. 

[Devs]

On 24/03/2022 at 15:18, MarkJ said:

ha, its tempting i must admit. My trepidation is based on previous efforts with things like this where i try and prise it open and the innards fly everywhere !  i remember opening the ECU like i was a bomb disposal expert  

its probably only one cog that does the mileometer i expect as speedo works fine. Fuchs915's photo makes it look like a kids toy gubbins but i'm more fearful of breaking the glass or buggering up the speedo calibration. Can i just leave the needle alone and replace the (assumed) broken cog for the mileometer?

I added a link to a video further up this thread which I used.    Needle has to be removed.    Have a watch and then have a try.