MTFCA Forum

New style Starter Switch fix

Saturday a week ago, I drove our Model T for the first time, only 14 feet and stopped because the garage door was closed. On the next attempt, I pressed the starter switch and it stuck with the starter spinning. After some "excitement" I got it off. This was a new starter switch that I got about six years ago and have since read on the forum, is junk. I almost bought an original style switch but it needed fixing too. Here is my one week journey in many photos:

I removed it and took the switch apart. More correctly, I opened it and pieces fell out. The spring is too tight for the rest of the components. The discs look too thin.
The top piece, if (when) it were to fail would drop the discs and close the circuit. This thing failed to do its job. I decided to drill a hole, using the flange as a bit guide.

The top got cut off as I didn't need it.
Going to tap a #10-32 and use a screw to hold the pieces on better than they were before. Nope, not gonna happen. Broke the tap. Drilling out the top to remove the hex bar. I will re-use the top only. Beginning to use a 1/4"-20 carriage bolt as a replacement.

It fits great. And the top is not tilted like it was when brand new.
Acquired a coupling nut 1/4"-20 and use another 1/4" (upgraded size) for the disc on the bottom. Will the spring will fit? How far to screw into the coupling nut? The hex hole is too small at the moment. A file took care of that.

The tabs were loose. Tighten for now and address later. A screw for the bottom disc. A nut to hold the top tight but the spring needs to be wider at the top. And yet a little more open to surround the nut. A little help from some red.

This was once a computer heat sink but you can source copper from elsewhere. Shave off the top side where the fins were. Using the toy as a template. Cut off wheel and then a coping saw to cut it out. Going to reuse the insulator and add a washer to protect it from the force of the spring or stepping action.

The lower screw needs to hold this in place without grounding it out. More help from red on the coupling nut. Tracing a better insulator for the main housing. This black plastic came from a battery backup that powers computer servers. This will prevent grounding out if the disc twists up on one side. Trimming to fit the top insulator.

Will the screw fit? We are not finished and I hope you know why. Is there interference? Screw gets its head diameter reduced by 1/16".
The square of the carriage was removed. Cutting a slot. Cutting it shorter to fit inside the coupling nut. It's easier to fix thread burs if you already have a nut in place and then just remove it.

Will the bottom screw go in enough to clamp the pieces? Pieces from left to right as they will be assembled. ID is 1/4". OD needs to be 3/8". Drilled copper to 3/8" and test fit. Cutting off the excess.

Does the 1/4" screw fit?
Will it be insulated now? Assembly. The coupling nut stuck. So, tapping the hex hole upward. Removed the rounded edge. Problem solved. Removing paint. Why?

Four on the bottom. Four button ups on the side and grind. Spring is still too tight. Looking for Ohms everywhere, switch at rest and pressed down. Testing but no red yet. Did not bend the tabs yet either.

Working out the work-in on the tabs. Annealed. Is this a drain hole I see? A little bit more. Or is it a relief cut for the screw? It's both. So many issues with the new switch are being addressed.

The screw head center has been surfaced.
Got some help again from red. Bending over the tabs. Will they break? They did not.
Some paint. Used two wrenches to attach the positive cables so as to not spin the nuts internally.
Does it arc when the battery cut off is on? No.
Does it stick down and not return? No.
What is the travel distance? About 1/8" - 3/16".
Does the car start? Yes. We shall see if it lasts longer than a new starter switch.
If I find more problems, then I'll let you know how I resolve them.
Suggestions are certainly welcome.

Dang, I like this Vern.
IF I see this correctly, you can turn the copper contact disc with the "knob" on top for new contact points?
Always neat "outside the box" info and thank you!

The original switches have a laminated, copper plated spring steel bridging piece on the plunger. This helps to disengage the plunger when your foot is lifted. The disc setup as shown will be depending solely on the spring return on the plunger to break contact, so it needs to be quite strong.
You might want to find an original switch as a back-up for your good work.

Allan from down under.

Allan wrote: ↑

Sun Mar 03, 2024 5:51 am

The original switches have a laminated, copper plated spring steel...

Allan from down under.

I believe they were beryllium copper.

Man that’s a lot of work and it still might weld itself together just relying on the spring. I’d use it to power a ford type starter relay hidden under the floor. You could use low voltage to power thenrelay or even use it to complete a ground to activate it. Nice work though.

I appreciate how this thread has a step by step approach. A simple to the point title and Completion of the job before posting. This will make a topic search easier and help as a reference to anyone trying to fix there own problem later. Thank you for taking the time and patience to present it this way. And great work trying to solve a current new age part problem!
Bryant

I have repaired or cleaned up original starter switch’s on my 3 T’s plus a couple more I’ve picked up as spares. I’ve read on the forum about the newer repos and how cheap made they are. Your post in repairing and rebuilding one is a good thing for folks who want to save a repo switch and how to make them better.
Another thing it shows is how cheap these things are made. The originals were simply just better made with good materials and well worth spending time to repair them when necessary. It’s always a good idea to pick up the original starter switch’s when you can at swap meets rusty or not. They are built like tanks and will last a very long time.

Looks like beryllium copper it is Jerry. Is that the same stuff used in coilbox contacts? Learned something new today.

Allan from down under.

Allan wrote: ↑

Sun Mar 03, 2024 11:54 pm

Looks like beryllium copper it is Jerry. Is that the same stuff used in coilbox contacts? Learned something new today.

Allan from down under.

Allan,

Yes, I believe it is the same stuff. They may also be phosphor bronze.

That was a great restoration write up! Thanks for taking the time and effort!


As to starter switches, these are my observations. First, I have repaired a few switches. Not claiming that makes me an expert. (Probably nobody else would claim that of me either ) The original style switch uses a multi layered "leaf spring" style moveable contact. My thought is that, when pushing down on the plunger, the leaf spring contact, after initially touching the studs, does a bit of flexing. Like any leaf spring, when it flexes, its arch somewhat flattens out and the spring elongates slightly. When the pressure is removed from the plunger, the spring re-arches and pulls away from the contact studs. As it re-arches, the spring length once again shortens up a bit. The significance of the small change in spring length, is that in doing so, any tendency for the leaf spring contact to weld itself to the contact studs is overcome by the leaf spring pulling laterally away from the stud, while at the same time being pulled upwards by the coil spring. In my mind at least, that's what's going on. To not have that lateral rubbing force on the contacts, due to the flexure of the moveable leaf spring contact, may lead to welding/sticking of contacts.


Borrowed image from the classifieds, (thanks Melba Nolan!)