For most this will be old hat or useless info for the pros. I broke my first headlight switch and lost parts from my second headlight switch. I always wished someone would have wrote one of these up. Since I still haven't gotten over it yet... here it is: To start you need to remove your switch: http://www.jalopyjournal.com/forum/...emy-head-light-switch-gm.680308/#post-7560489 I have two switches the one on the left is from 1957 the one on the right is from 1959. If you look close on the 1957 one you will notice an aluminum screw that attaches the switch contact with the dome light switch contact (left bottom). If you look at the 1959 one you'll notice no screw because it is spot welded. The one from 57 is easier to break down and clean though they are otherwise the same.
I started by taking off the three top screws off and carefully removing the plate because there are springs inside that want to shoot out. Once I had that apart I was careful to set all the parts aside and unscrewed the aluminum screw I mentioned above. At this point everything was apart and got a bath and scrub in a nice grease cutting dish detergent. Whatever grease I couldn't get off I used some brake cleaner and promptly re-cleaned the part in the soapy water. All metal parts were lightly cleaned with a brass bristle brush. There are two metal contacts that act as a circuit breaker on the switch, I cleaned those with some emery. You will notice them if you look on the right and left under side of the body.
Once everything was cleaned, de-greased and dry I started to put the switch back together. I started with the main body and the dome switch. The dome switch contact goes under the main body contact then the aluminum screw goes back in.
Next was what I call the block, the block is upside down right now. The four springs go in first then slide in the the contacts. I put di-electric grease on those contacts before mating them to the main body in the next step. Now is when the tricky part starts. Flip the switch upside down and lower it on the block, the hole in the block facing front of switch. Now holding the block in flip the switch again and put it down.
To install the knob catch, slide the spring in the round hole and the holder down on top of it. Notice the little grooves in the side wall (right photo) they are very important in a future step. Next is what I call the clicker, two rounded cups on each end of the spring with a metal rod going through it. This is what makes the clicking noise when you turn your lights on. Take note of where it goes, the grooves in the side wall under it and just put it aside for now.
Now for the dome switch moving parts. The plastic tube gets a spring then the brass plate. The little brass tabs on the brass plate need to face away from the spring underneath it. Next was where I needed three hands and patience so you'll have to use your imagination. I used tape to hold the dome light moving parts to the dome light switch really tightly. Tight is very important to allow the plate to fit over it. Next I took the clicker and very carefully squeezed it between the groves along the side walls. I finessed the plate over the spring and front of the dome switch. **I find it easier to lower the plate from the nub side (where the 4th plate screw would have been) while holding down the spring. Have your screws handy and try to get them all on but not tightened down completely yet. Cut the tape to release the dome switch plastic and fit it around the hole in the plate and tighten the screws down. Take note of the springed rivet we will use this in the next step.
Now you need to install your knob and test it. Slowly push the knob into the plastic part of the dome light switch. There is a corresponding flat stop on both the knob rod and the plastic domeswitch part. Push really easily until you hear clicks. If you only hear one click you need to pull out and press down the springed rivet to allow the rod to lock in. Do not force the rod in or you risk breaking stuff. If all is well you should hear two clicks open and close. If you hear rattling or don't hear two clicks you may need to take the top plate off and re-do the clicker springs. At the end I used most of the 1957 switch and cannibalized parts from the 1959 switch. You might ask why I went through the trouble when I can get a re-popped one for $35. Answer, I have taken apart at least two of these and I can tell you that what was made years ago is way better than the garbage they are re-popping. I am using a re-popped switch that I picked up when I broke my first one. I will be replacing it with the 1957 switch. I'll cannibalize the re-pop for parts I broke or stole from the 1959 and keep the 1959 as a spare.
FWIW, once they went to that design, they used it right up to 1996 classic vans, changing only the plug and knob. They all mount the same and the basic design is the same. So you may be able to use a newer one for parts, or if you're not afraid of changing the wiring around just replace it outright. Just keep your original knob and shaft and dash bezel -
not quite...the modern switch with the triangle shaped shaft was a later design. there are several differences in how the two mount and how the knob/shaft fit, and the guts are completely different.
My original '49 was getting balky, especially with the rotary dimmer so I hit it with WD-40 and it works like new.
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