Ruby dynamo problem.....Continues

[Denis Sweeney]

Having successfully found broken wire on the dynamo, the "easiest" (ha ha) solution was to change out the damaged item and replace it with a recently refurbed dynamo, simples!
All went back together well and even got the timing reasonably accurate for the engine to start and run on about the third pull which is normal for Ruby, she ran fairly lumpy but most disturbingly there was a distinct, never heard before, rattling emanating from the the front of the engine.
I adjusted the timing until the engine ran fairly normally but still this rattle from the front end which even my good lady commented on.
I was pretty convinced it was from the front end and not having had the rattle before, decided it had to be to do with the new unit and so removed the dynamo and compared drive gears.
The attached photo shows the original dynamo right and the re-conned version on the left and to me it is clear that the width of the teeth at their outer edges on the original are significantly thicker than those on the re-conned unit, which to me would mean the teeth would be a loose fit in the mating gear, hence the rattle??
Am I right in thinking that this would cause a rattle and am I right in thinking that I should be ok to change the gears over to run with the re-conned dynamo but with the old drive gear??
Sorry the  pic is on a word doc but cannot seem to get pics on the site as the files always appear to be too large.

Cheers Denis S

[Nick Salmon]

This is your photo Dennis. Hope that helps others advice.

There should be no problem swapping over the gear. The one on the left looks very worn on the teeth but the image is not entirely clear.

[Nick Turley]

Hi Denis - I think you may have answered the question yourself.
It is difficult to tell for sure, the gear on the left looks to be scrap.
Pulling them off and swapping them round seems like a good call.

[Howard Wright]

Hi Denis

When you do swap them over make sure the gears have a small amount of backlash (4 thou is ideal). Too little backlash can not only ruin the dynamo drive gear but also the cam gear and crank pinion. Don’t ask me how I know this  .

If you do have too little backlash you can add a thicker gasket to the dynamo mounting tower. Too much backlash and you may need to linish the base of the tower.

Cheers

Howard

[Bob Culver]

With backlash tested in the tightest position. Is the one on the left a discarded alternator conversion gear?

[Denis Sweeney]

No Bob, the one on the left is a dynamo I had rebuilt as a spare, but has its original gear.
The one on the right is one that was fitted to the engine when originally purchased, that was tested during the restoration and used with minimal work and was working well with no noisy rattling until it failed recently with a broken internal wire.
Question to Howard and Bob if I may, how do I check the backlash on drive gear?
Cheers

[Howard Wright]

Hi Denis

You can just about get a feeler gauge between the teeth when poking it through the small inspection plate.  I find it easier to make up a few small lengths of shim steel of various thicknesses rather than a proprietary feeler gauge.

Cheers

Howard

[Tiger]

Hello Denis
I have just completed many hours on my Dynamo
Not quite back on the car and charging
However my advice would be to retain your original Dynamo because you know this has perfect
meshing with your engine.
You would need to carry out a small repair as stated before
The needed repair is very straightforward so if you prefer get a known specialist to carry this out.
PS The alternator reference I think refers to gears supplied which were inferior to the Austin ones.
I hope this helps and happy to chat further if you like
Regards
Tim

[Peter Clayton]

Dennis, you can reduce the image file size by using this program. I find about 20% is good for most pictures.    https://www.img2go.com/compress-image

[Denis Sweeney]

Thanks folks for all the comments, my naivety with regards all things electric knows no bounds, and so was wary of tackling repairing the broken wire on the original dynamo, it seemed a bit of a bodge, but having both dynamos on the bench and stuck between for me a rock and a hard place, decided to give the repair a go, and success.
Did not appreciate the wire simply ran from the brush to the D terminal and so was able to re-use the original fixing and simply soldered in a new wire, shrink wrapped it and fed it through to the terminal, simples doh!
All back together again now, running smoothly, and no rattles.
I also noted when I first removed the original dynamo that all the fixings on the dynamo were loose and the paper gasket, soaked in oil, slipped straight off. So with a new gasket plus some hylomer and all bolts tight I seem to have cured a significant oil leak too.
Thanks again for the comments and to Peter for the tip on photos
Cheers