Dismantling Starter Button

[John P]

After many months trying to source a floor mounted starter button for my Ulsteroid at a sensible price I now have what I believe is probably the later version.

   

It was sold as being for refurbishment but I'm not really sure what to do.

It look like I need to clean up the brass disk which acts as a contact between the two brass pads and obviously give it all a thorough clean / paint but I'm not sure what to do about the pads themselves which I haven't yet tried to remove.

They appear to be insulated from the bottom and sides of the metal casing by what looks like a fibre cup but I'm concerned that if I try to dismantle the pads and threaded connectors this insulation will fall apart.   That being said it's not in that good a condition and there will presumably be quite a high current here.

Any suggestions how best to proceed.

   

   

You can probably see the state of the insulation in the photograph below and also note that one of the connecting studs appears to be bent.

John.

[GK5268]

I have the same problem, I have sort of dealt with it by using a different switch but retaining the shroud, so it looks similar - at some point, I may take the new switch apart and swap the knob for the original button, but as it stands, it does the job and it may well become one of those temporary fixes that are permanent!

Here is the switch I used:

https://www.ebay.co.uk/itm/Jeep-MB-GPW-C...2749.l2649

[JonE]

I think I asked the same questions about a year back and Ruairidh posted some helpful pictures. I'll have a look back later and see if I can locate...

[restorer]

Hi Have you thought about silicon, it is used to make moulds for tin soldier or you may find right shape in kitchen supplies.   David

[Dave Mann]

yes I was faced with a similar problem, on removing the two contacts the insulation disintegrated, a search of the recycling bin produced a milk container screw cap which fitted perfectly.

[John P]

Curiously, I had been thinking about looking for a plastic cap such as the milk container one used by Dave Mann but I was a little concerned it may tend to melt or even burn if there's any sparking when the switch operates.   I suppose some form of rigid (thermoset) plastic cap would be better.

I have now taken the rest of the switch apart but am confused how the insulation actually works.

The tops of the two contact pads are insulated from the base of the housing by the now defective fibre insulating "cup" but the threaded studs, which are a nominal 5/16" diameter, simply pass through clearance holes in the metal housing.   There is the remains of an insulating washer under the nut which secures the stud into the housing but no obvious insulation between the outside diameter of the stud and the edge of the clearance hole.

If this is how it was originally then the only thing preventing a dead short between the battery connection and earth is a minute air gap which seems very unlikely.

Any suggestions or am I missing the point of how the switch actually functions?

John.

[Colin Wilks]

The obvious solution would seem to be an insulating shoulder washer, which is perhaps what the original fibre job was. 5/16" is a gnat's off 8mm so perhaps hiding two of these might do the trick without frightening the purists?
https://rover.ebay.com/rover/0/0/0?mpre=...0481731718

[Dave Mann]

I did the repair many years ago and the plastic milk bottle top is still doing it's new job. you also need some insulating washers around the threaded section of the contacts to stop them contacting the body.

[John P]

Although I was a little sceptical I offered up a milk carton cap as per Dave Mann's suggestion and it fits almost perfectly, doesn't even require any trimming, so I think that's what I going to use.

I also found that what I thought were just clearance holes in the casing for the treaded studs to pass through are actually larger diameter holes lined with insulating rings so the design now makes sense to me.   That being said I may actually change these rings for some headed bushes as per Colin Wilks suggestion.

The only remaining issue will be obtaining or somehow making a shroud for the button.   I've only seen photographs of this part which make it look as though they were made either by spinning, or possibly pressed out, but in any case with a rolled edge where the button goes.   Obviously I can't replicate this rolled edge and not having a lathe means machining something which looks like a rolled edge won't be easy.   Any suggestions?

John.

[squeak]

You could try soldering a brass harness ring to a suitable washer

 https://www.greggrantsaddlery.com.au/sta...OQEALw_wcB