speedometer repair.

[Russlin]

Hello I hope that somebody might be kind enough to explain the workings of the PA speedometer as fitted to my 1928 Austin 7.
During a recent test run travelling at 45-50 mph the needle started to behave erratically for several seconds before returning to zero and occasionally assuming a new position on the dial. I have checked the cable drive at the gearbox and the cable itself, both are in working order. Could any of your readers please advise whether the speedo can be repaired and would parts be available Thank you.

[bob46320]

You say the cable is in working order - What did you mean by that ?  I have found that the "PA" is very susceptible to poor cables where the inner binds very slightly on the casing.  The workings of the "PA" are much like a Watts Governor where balance weights fly out as speed of rotation increases.  Other causes are loss of some of the balls from the ball races supporting this spinning assembly.
I did write an article in the PWA7 mag which I could e-mail to you if you send me a PM.
Bob

   
   

[Dave Wortley]

You may have lost your balls which was my problem about 30 years ago. Seriously if the balls have fallen out of the bearings I removed the remains of them and then screwed together the male and female parts of the bearing with a few thou running clearance. Worked ok since then ie for many miles.
Cheers,
Dave.

[JonE]

some more repair notes here. sorry, didnt see the PW ones...!
https://sevenrk.wordpress.com/2019/05/25...er-repair/

[Nick Turley]

I am certain you will find if you look at the drive entry of your speedo that the little square shaft will allow movement left to right.
If that is the case it needs new balls in the bearings. As said elsewhere in this thread  David Cochrane supplies them.

To repair as per the article on this thread you need calmness, patience, good eyesight, good lighting and a spotless bench to carry this out.
You can buy a great tool for removing the pointer, here are the details;-
https://www.ebay.co.uk/itm/Watch-Hand-Ha...2749.l2649

 Take your time with it - they are delicate!

If doing this worries you, send it to Richfield speedograph they do a great job bearings and a full service costs about £100 
http://www.speedograph-richfield.com

Hope you manage sort this out OK

[Stephen Barker]

Hello,

If you go to the Essex Austin Seven Club website- in the technical section are a couple of articles about Smiths speedo repair and rebuild, which may be of help.

https://ea7c.org/technical-advice/smiths-speedo-repair/

https://ea7c.org/technical-advice/smiths...o-rebuild/


Regards

Stephen

[Hugh Barnes]

Chris Clark, or his son Greg, will do this repair much cheaper than Speedograph Richfield, I would imagine. You can mail Greg at:

Claudia_louise17@hotmail.com

[Russlin]

Thanks to all for your helpful replies as to the workings of the PA speedometer. As the cable on my car is not frayed nor binding against its casing I expect to find that some of the balls have gone missing from their races.
This forum provides a wonderful service by experienced operators who are happy to share their expertise with others less knowledgeable.

[Malcolm Parker]

The speedo on my 1931 RL saloon has a gremlin.   It was rebuilt 20 years ago by Ron Bailey, ex Rolls Royce millwright, and was the most accurate speedo and odometer of any vehicle I have ever had.  It never ceases to amaze me how inaccurate many modern speedos are.  They tend to read fast so you think the performance is great and record higher mileages so you think the fuel consumption is also great. 
I digress.   The RL speedo was working perfectly one day then next day I found that it was still working but the needle was 20mph too slow, so it was reading 10mph at 30, 20mph at 40 and I was going a bit at 30mph. 
It has a newish cable and the odometer is working perfectly.
I don't think I've lost my balls (yet!) but is it simply that my pointer has drooped?

[David Witton]

I have used Chris Clark many times. He does a wonderful job and is very reasonable