Ignition switch autopsy

[Save Old Iron 1,573]

Well, I started to do some work on my C160 auto that's been sitting for a while waiting for a total rebuild.

The ignition switch felt funny and did not always engage the starter.

So off the switch came and directly onto the newly acquired metal lathe I bought a few weeks back. Can't tell you how much I miss the sound of milling metal in the morning.

Anyway.............

I wanted to get a view of the inner workings of the ignition switch and see how this puppy works and what could fail inside.

So I skimmed off the crimped portion of the body of the switch that holds the contact assembly

and separated the switch body

from the contact assembly

the reason the key switch did not have the right "feel" is visually evident in the next photo - the copper contact on the right side of the switch body is sitting down against the black plastic key receptacle. The left side contact is shown picked up to reveal a spring underneath the contact. The right side contact has a broken spring underneath the contact body.

Picture in your mind, these two copper triangle shaped contact pads riding around on the circular contact pad as you turn the ignition switch. As you turn the switch to different positions, the contacts bridge different pads on the round contact circuit board. Different positions enable different contact to receive battery voltage.

cleaned up the grease from the contact assembly

and cleaned the copper traces on the contacts to show the level of corrosion present on the copper traces

Next the switch rotor is disassembled from the metal switch body

So why do good switches go bad? Not upbringing. I say it's the environment they live in.

CORRODED EXTERNAL SWITCH CONTACTS

the level of corrosion seen in the circuit board external contact shows how the wiring terminals could loose contacts with the switch terminals - rust "expands" as it grows, pushing away the wiring terminals from the switch terminals.

ARCING OF THE INNER SWITCH CONTACTS

not really present in this switch (but photoshopped in), any heavy arcing / sparking across the switch contact "pads" could easily make the function associated with that pad become erratic. The blasting away of the pad metal by the arcing destroys the contact with the switch contacts.

MECHANICAL DEFECTS

seen in the photos above, broken contact springs or broken contacts on the round circuit board.

[Kelly 1,035]

I just did the same thing last week, not as nice as you did, but all the same took it apart replaced a broken spring with one out of a ball point pen cut to fit, cleaned all the contacts, added some dialectic grease and reassembled, works like new.

[Save Old Iron 1,573]

I guess this just falls into the same category that everything else does in this household - nothing leaves here in one piece - ignition switch, hair dryer or Ipod, everything gets taken apart.

I suppose this switch could easily be made functional if I could find an elegant way or reattaching the terminal circuit board.

A ballpoint pen spring would work just fine. I did not plan on saving the switch just satisfying a curiosity to see what's inside and check to see if a shot of contact cleaner would actually help. In this case, it would not have helped.

Thanks Kelly, at least I know I'm not the only one who lives in this tortured little world of "gotta know what's inside" :D

[Duff 206]

Thanks Kelly, at least I know I'm not the only one who lives in this tortured little world of "gotta know what's inside"

Inquiring squirrels just gotta know!

Duff :wh:

[Kelly 1,035]

Well mine was on a orig. ign. switch for a early case tractor very hard to find then after fixing it, I found I had a NOS one hiding on a shelve.

[Duff 206]

Well mine was on a orig. ign. switch for a early case tractor very hard to find then after fixing it, I found I had a NOS one hiding on a shelve.

So you've still got the NOS one in reserve! Sounds like a win-win to me!

Duff :D

[Kelly 1,035]

Yes and no I have a guy as we speak driving up from OH to buy the tractor and the spare parts :D

[KC9KAS 4,744]

S.O.I., you do an excellent job of showing and explaining in your posts.

I am mechanical & electrical inclined , but many on here are self-admittedly NOT , and your efforts have to be a really big help to those that need a little more help.

Keep up the good work and thanks from everyone !

[rickv1957 77]

I would have to agree with KC9KAS,way to go Chuck!! Rick

[rmaynard 16,690]

For the average Joe, this is why they made this sign:

Bob

[MikesRJ 558]

S.O.I. (sigh) What a guy ... :D

[Save Old Iron 1,573]

For the average Joe, this is why they made this sign:

besides,

who wants to be an "average guy" ?

[squonk 44,860]

I just did the same thing last week, not as nice as you did, but all the same took it apart replaced a broken spring with one out of a ball point pen cut to fit, cleaned all the contacts, added some dialectic grease and reassembled, works like new.

I had a Kawasaki bike that had a hazard flasher switch that was broke. I really didn't care about it. I sold it to a electrician I work with. I told him the only thing on the bike that was bad was the switch. He fixed with a pen spring. :USA:

[SAM58 31]

Chuck,

where do you find all the squirrel pics? are they just local squirrels?

All the squirrels worry about here are their nuts... :thumbs:

[Coadster32 793]

Just rebuilt my 551 switch two days ago. Looks pretty similar. I agree with the enviornment theroy. I just uncrimped and re-crimped. Works good now. (Don't know for how long though) :D

[Don1977 605]

For the average Joe, this is why they made this sign:

Bob

We don't read warnings or instruction. If it's there and not working it has to come apart.

[64s 83]

Chuck, Do you have a source for the return spring? I took apart some switches a year ago but can't find replacement springs . Thanks, George

[Save Old Iron 1,573]

George, I haven't really tried to source one. I can't believe it would be that difficult to find one in a "spring" catalog

but seriously, this particular switch is not going back together as I machined it apart on a lathe. I imagine you might be able to wedge the back cover off a bad switch - replace the springs and polish up the contacts and save a few bucks. The spring that came out of this one looked very much like a ball point pen spring. How about the McMaster - Carr catalog ?

That is partially why I do these autopsies .... to discover if some original, irreplaceable switches, solenoids, etc are repairable. Some day these parts are going to get scarce and expensive. Maybe not ignition switches, but other items such as Tecky stators and ignition modules, RR's etc. If you can fix a $30 switch with a $2 spring and some epoxy and get a reasonably reliable repair, I'm all for that

I just found a source for parts for the 1970's style C series rectifier regulators. I am convinced these RR's can be repaired for around $20 and some elbow grease.

Stay tuned too - next weeks SOI University will be pulling apart a defective starter solenoid !!

[VinsRJ 723]

I would have just thrown it away and bought a "Cheena" switch :thumbs:

[buckrancher 2,695]

I just found a source for parts for the 1970's style C series rectifier regulators. I am convinced these RR's can be repaired for around $20 and some elbow grease.

Me too brand new ones for $20.00 on E-Bay

and I'll save the elbow grease for something else :thumbs:

[Coadster32 793]

Stay tuned too - next weeks SOI University will be pulling apart a defective starter solenoid !!

I'll be watchng for that post. :thumbs:

[horsefeathers 15]

Old_Iron, Have a 310 8 the PO added a push start button.

So I'am sure that the ingintion switch looks like your photo shop pic!

You realy do have all the bases covered including "short"stop!(pun intended!)

SOI University! Tuition! Free to RS members!

What a deal in these hard econmic times!

Free education! You can't beat that dead horse!

Sign me up for some courses!

You should get some T-ee shirts made up!

PROPERTY OF SOI UNIVERSITY!

(the shocking truth of getting zapped!)

HORSEFEATHERS!