Chummy rewired.

March 9th, 2015

I’ve been very slack again. I’ve done nothing on the special for ages and only minor things on the Chummy. I’ve just changed jobs again and am now working from home so hopefully I will have more time to do thing but until I’ve done my first month and start getting paid again I won’t have any money! And I have been terribly distracted learning all about Bletchley Park and Turing Bombes and building an ENIGMA machine into a wristwatch!

Joss has been making progress on his car though and a few weeks ago when I went round he has his fuel tank mounted.


I have done some small jobs though. I replaced the rear shock friction material and bushes and the front radius rod mounting cups with new ones. Unsurprisingly on this car when I removed the rear shocks I found both sides had been bodged. Both have sections welded into the middle of them.

IMG_3167_1 IMG_3169_1

There was some discussion on the friends site about the brass discs that go under the friction material and what difference it makes. I was going to do some measurements to see what difference it makes to the friction but I forgot that on the earlier cars the centre part of the shock is attached to the chassis so doing any sensible measurement would be tricky. So I didn’t bother!

I also finally redid all the wiring. I also worked out why it had shorted. I took apart the cutout to test it and found it in really poor shape. It has a steel base and just some of that almost cardboard like material as insulation. That was all soggy and missing in some places meaning one of the brass rivets attached to one end of the coil was shorting to the case. Since the case is ground and the coil is attached to positive that was a direct short. That explains why all the wiring had burnt out and melted right along it’s length.


As the coil was no good I stripped it off the base and instead am using a large Schottky diode instead of a cutout. I mounted that to the base (insulated from it with a mica washer) to act as a heatsink.

IMG_3190_1_1 IMG_3194_1

With the cover on it all looks fine. I wasn’t really worrying too much about making the wiring look original anyway as it’s just a temporary thing for now until I decide what to ultimately do with the car. I just made it neat and out of the way. I replaced all the wiring in the end. I do still need to tweak the dynamo brushes. I am not worrying about Summer/Winter settings. I am going to set the brush up so the battery is just charging at road speeds. It means if I need to use the lights the battery will be discharging but given I don’t use the car at night that shouldn’t be an issue. And I have a nice battery charger at home!

One thing I did was put grommets in the holes that the wire to the rear light ran through. There were four holes through various bulk heads obviously drilled by someone blind or stupid (actually my money is on both). Of the four three of them went though something they shouldn’t have.

IMG_3201_1 IMG_3203_1 IMG_3200_1

I tidied the edges off the holes up (they were very rough and sharp) and fitted rubber grommets then ran the wire though those. With all that done I was finally able to take the car for a WOF which it got luckily. It does drive much better with the rear shocks done and the radius arms mounting point all tightened up.

Next weekend is the annual Roycroft Trophy meet at Hampton downs. I am hoping that starts to motivate me to finish mine soon.


One Response to “Chummy rewired.”

  1. Renaud in Brittany Says:

    Hi Simon,
    Pleased to have you back!
    Enigma stuff is fascinating but don’t let you get distracted from cars too much!
    (though I’m a taker to a link about your Enigma work if any!)

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