Dynamo woes

[JoeRowing]

In the ongoing saga, I thought I had solved all of ruby's issues but alas, not only is the head coming off tomorrow to further investigate the sticking valve issues but it's not charging for love nor money

If I join the two terminals of the dynamo and test against earth I only get 5v. I've tried flashing it but no joy. Brushes or something else?

On a related note, has anyone tried those stealth dynamaters? A stealth alternator might do the job nicely.

[David Stepney]

I note on your other thread 'Ignition Light on All the Time', that you discovered that the cutout points had not opened. This may have destroyed the residual magnetism in the dynamo field windings core.

Assuming that your Ruby is Positive earth, attaching a lead to the dynamo body from the positive side and 'flashing' the F terminal to a lead from the negative side of the battery may restore it back to working order.

If this doesn't work, I suggest that you have the dynamo overhauled by someone who knows what they are doing. I note that there has been some discussion within these annals about dynamators and their reliability or lack thereof. Personally I would not be tempted down that route. My own car is used regularly and, during last winter, was used as my daily driver for some six weeks whilst the modern was undergoing repair. The dynamo seemed to cope well despite a lot of night time work and I never had a flat battery during that time.

[JoeRowing]

Thanks David - the dynamators look good but I ultimately want this to be a reliable as possible as we have some long trips in mind.

I have -ve earth, am I right to think the instructions are reversed in that case?

Hmm the -ve earth might be why the fuel gauge doesn't work..

[David Stepney]

Yes, if your car is negative earth, then my instructions should be reversed. However, I think your car should be positive earth. I am under the impression that the cars changed from negative to positive earth upon the introduction of the Ruby in 1934, but I am happy to be corrected on this.

[JoeRowing]

I'll double check but I'm 95% sure it's negative earth - i'd guess it was changed in the 90s. The electrics are not great though. I'm half tempted to rip it out and start again.

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Thanks David - the dynamators look good but I ultimately want this to be a reliable as possible as we have some long trips in mind.

I have -ve earth, am I right to think the instructions are reversed in that case?

Hmm the -ve earth might be why the fuel gauge doesn't work..

I think you're right in general, as always, the car at hand is a special case.

[Tony Press]

Here is where we would have a page of Dynamo story from Bob Culver 

[Hugh Barnes]

As I understand it, the Dynamators from Accuspark are no longer available. At the time they seemed an idea with potential, but with the improvement and availibilty of LED bulbs now, seems rather to have made them unneccesary...

[JoeRowing]

Thanks Hugh.

I'll try flashing it again after taking it apart and checking the brushes are all ok.

[andrew34ruby]

Yes, if your car is negative earth, then my instructions should be reversed. However, I think your car should be positive earth. I am under the impression that the cars changed from negative to positive earth upon the introduction of the Ruby in 1934, but I am happy to be corrected on this.

Sorry to correct you David but I think the change to positive earth was a bit later. Looking in 'The Austin Seven the motor for the million' R J Wyatt tells us that Ruby production started in July or August 1934, but the polarity change was introduced in December 1935.

My Ruby has always been negative earth, first registered December '34.

[John Cornforth]

Hi

Just a quick few points.

Many cars will have been changed from positive to negative earth during their lifetime.

The fuel gauge is not polarity sensitive, neither is the cutout.

You might want to clean the dynamo commutator and check the brushes are sliding freely before tackling anything else.