Stater sw sticks closed.

[Bill Goddard]

I have had the starter switch stick closed twice now. Does anyone know why this happens? The starter is a 12v conversion. Thanks Bill G

[Will N]

I've had that happen several times. One theory is that the repro switches use a copper contact bar, whereas the orignals were a bronze alloy. The copper isn't as "springy" as the bronze, and therefore doesn't spring back away from the copper button on the starter when you let up on the switch. The arcing that results welds the contacts together. I've taken to inserting a section of rubber hose under the copper contact bar to act as a spring to help separate the contacts.

I've also noticed that the welding tends to happen more often when the battery doesn't have a full charge to it. I can't explain why that might be, but since I've been using the Battery Tender charger on the car when it's not in use, the incidents of welding have stopped.

[Willie Krash]

Low batteries lacking sufficient voltage can weld contacts. The simple view is voltage pushes and current is quantity. Kind of how electric stoves work, or water moving very slowly thru a radiator. A battery capable of say 350 amps at 9.5V will start a V8, the same current at 4V burns and melts contractors. The current "lays" there too long and produces heat.

[H. L. Chauvin]

FWIW: An experience.

Had it happen on (2) "new" repro starter switches.

The problem on both of mine was that the female threaded starter switch plunger that receives the male threaded starter switch rod was manufactured at an incorrect angle; hence, when connected to the starter switch rod, it would be pressed downward where it would bind & hang up on the starter switch's bottom of the metal body hole after depressing the starter switch rod.

After this binding occurred, the rod could not bounce back up.

If one uses a Dremel tool, the round opening in the metal starter switch body can be carefully & slightly enlarged such that absolutely "no" binding occurs.

To "see" what is happening:

A. Place a piece of vertical cardboard on top of the starter & with a pencil, draw the angle of the starter rod exiting the floor board; and,

B. Compare this rod angle to the starter switch's plunger; and,

c. Then remove metal from the round starter switch body hole until the starter switch plunger is at the correct angle & slides up & down easily where absolutely "no" binding occurs.

Just another experience to share.

[Tom Wesenberg]

I agree that the low battery is often the cause of welded contacts. I've also seen the switch with the wrong push rod angle as Henry just mentioned. That's why I like to restore original parts when possible, instead of buying repro parts. Sometimes you can buy the repro part and use some of it's parts to fix the original part.

[JackA]

Sponsored Links (Register now to hide all advertisements)

Back EMF?

[Big hammer]

Low battery volts Longer time on starter More heat welding
the contact points Maybe anyway I installed a stainless steel
strip under the cheap copper strip now it springs off the starter
button :-) I will replace switch with an original someday maybe