Replacing center "brush" contact on Square 4 distributor

[pauldridge]

While recommissioning my '53 MK II Sq 4, I noticed that the center contact (graphite?) in the distributor had broken off and the spring was hanging partially out. That explains my failure to start the beast on last attempt some 6-8 months ago.

I was pleased to see that Draganfly had a brand new complete distributor cap in stock at reasonable price, and I had it in hand here in Texas in little over a week!

I also ordered a replacement center contact brush assembly (contact and spring) with the hopes of repairing the original cap as a spare.

My problem is I can't figure out how to get the old one out and new one installed? It appears the assembly has to be pressed in from the OUTSIDE of the dizzy body. Do I try to grab that exterior copper contact and pull it out, or drive out the whole thing from inside with a thin punch, or ??

Any help would be appreciated.
Phil Auldridge
Austin, TX

[will_curry]

With all the Lucas caps I've met that centre pickup pushes in from the inside.
The brass stub to which the HT cable from the coil connects is moulded into
the bakelite of the cap in the form of a sleeve and it's into that sleeve that the spring goes.
Twisting the spring so the spring tightens as you push or pull helps things.

If I remember correctly the graphite in these pickups is harder than that used in magnetos
and will damage the slipring if used there.

[ian williams]

hi Paul;
with most of the carbon brushes ive dealt with they have a tapered spring below them that grips in the socket it sits in and the spring grips the end of the brush spigot , when you put the spring and brush in you put both in at same time and rotate the brush as you do it .
youll see that one particular rotation will make it "looser" and drop in whereas other way it will go tighter.

if you have the brush broken and are removing it i used a small drill down into it , ie 2mm and then a small screw to try and get a grip to the brush , then pull the brush out whilst rotating/twisting it .

if you are left with spring still inside the socket after removing brush you can use another screw to catch up in the spring and pull it out [may stretch it though !!] , or you can just push and rotate the brush into the existing spring if all is clear inside of old brush carbon ..

greensparkplug company sell a fair few carbon brushes and springs for many distributor caps .

all the best
ian

[pauldridge]

Thanks for these helpful comments.
Without this, I would likely have destroyed my old cap trying to remove from the wrong side (wouldn't be the first time!)
Phil