How To: Rebuild Starter Pushbutton Switch

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Sep 30, 2008
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Sapulpa, OK
I've seen a number of references to starter pushbutton switches not working properly, sticking and not returning to the neutral position. My switch started to malfunction over a year ago and I was able to manually move the switch back into the neutral position to get the headlight to turn back on. Recently, the switch began to stick and was hard to move, so hence the project to rebuild the switch. Plus it doesn't seem that the switch mechanism is readily available except as part of the complete RH throttle assembly. Here's what I did to repair my switch..............

I'm assuming that everyone can get to the point of removing the RH throttle unit and removing the parts from the lower half of the throttle unit.


This is the spring that I removed from the switch.................the tail has been broken off causing the switch
to loose it's anchor point for the spring action.

Pushbutton interior.jpg

This is the underside of the pushbutton switch body showing the steel ball bearing which is spring
loaded and the recess for the spring. There is a black plastic post that was broken off in the hole
shown above. The switch pivots about this point and the spring loaded ball provides alignment and upward force
to keep the switch contacts in contact with the upper switch plate.


This is the bottom part of the switch housing..............the arrow points to where the plastic
pivot post was located on the part. This location needs to be drilled out to accept a new
pivot post for the push button.

Drill hole in base.jpg

By clamping the push button switch body to the lower frame using the steel ball as an alignment device, I was able
to drill a 3/32" hole into the bottom frame piece and maintain precise alignment between the two parts.

Drilled hole in bottom frame.jpg

Drilled hole in the bottom frame for the push button switch pivot shaft.

Drill hole in contact plate.jpg

This is drilling the hole in the top contact plate for the switch. Again I clamped the parts together to keep alignment
as precise as I could to keep the switch from binding.

The only part I haven't shown is the winding of the torsion spring for the switch. Basically, I'm trying to duplicate the switch as closely as possible. I measured the diameter of the wire which was around 0.021" and I ended up buying 0.025" piano wire at the local Hobby Lobby store, 3 pieces at 12" long for $1.99. I tried several different drill bit sizes as mandrels to wind the spring on. I ended up using a 5/32" drill bit as the mandrel. I drilled a hole in a piece of hard word and put the drill bit in the hole. I fastened one end of the wire to the board with a small screw and washer near the drill bit. I then wound the wire around the drill bit in a counter clockwise direction until I had 5 coils and then went further until the ends of the spring matched the old spring. 5/32" is slightly larger than needed but it does produce a spring(0.025") that will fit into the switch body. I trim both ends of the spring to fit into the body and to match the part that catches the lower body. I spent several hours doing this.

I forgot to take a picture of the switch body with the 3/32" pivot shaft installed. I left enough sticking out on both sides so that it would be securely captured in the lower body piece and the top contact plate. I fastened the pivot shaft to the push button with Super Glue so that the shaft would be easier to install and not having to mess around with it dropping out of the switch body.

The final step is the re-assembly of the switch and if you have short term memory loss then you should have taken some pictures of the switch mechanism when you took it apart. After you carefully get the switch body positioned in the lower switch frame and then installed the top contact plate on top and now is the fun part of getting this assembly back into the throttle housing. Needless to say, this is a tedious and pain staking process and is best done when you are in the proper frame of mind and haven't had too much to drink.

I am pleased to say that after reassembly my switch work just fine after a few limbering up movements. Spring pressure feels really good and the switch contacts were in excellent shape and should last another 20 years. My only big concern was getting enough spring tension and I moved the arm on the torsion spring a little bit more in the direction of more movement that the original spring so that more pressure was being applied, approximately another 20 - 40 degrees in angular displacement as compared to original spring.

Hope this can be done but it's not on my fun list of things to do.
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Mar 14, 2010
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Chandler, Arizona
Really nice write-up. This one should be stickied. Rarely does one of these switch assemblies need to be replaced. They will last at least two generations. You just showed how to extend it through another generation!

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