What's Inside: Combination Switch (Turn Signals/Wipers)

[usury]

Prelude
Have you ever taken anything apart and wished you had taken better notes or photos? I have.

This post is part of a continuing series of posts that detail the internal construction of various things. This is not intended to be step-by-step instructions for repair/removal/disassembly/etc. Rather, I hope this post (and future posts) can serve as a reference for people who would like visual clues in making their own repairs.


Part 1 of 3

Tantalizing Exploded View

Insides Exploded

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This is the "Combo Switch" from a 1987 Porsche 944. This version has the cruise control lever but NOT headlight washers. I understand the same/similar switch assembly is used on 928's and possibly some 1980's 911's?



Removing Rivets
Seven rivets must be removed, circled in green. The three Phillips-head screws are the ones that normally attach the interior plastic cover. They are threaded through their holes only as a way for me to not lose them.

Don't touch the rivet for the horn contact. It is attached to a long brass pin that goes all the way through the switch housing and comes out the back side.

I used a Dremel sanding drum. This will produce fine brass dust. Be certain to thoroughly clean the interior of the switch prior to reassembly. You'll find decades-old lubricating grease inside that ought to be replaced, so a thorough cleaning was already part of the project.

Rivets, before

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Rivets, after

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I chamfered the holes as I went in preparation for reassembly, though you can really do the chamfering at any time. Ultimately I used M4x0.7 x8mm long machine screws with a countersunk heads. I also tapped corresponding threads into the plastic switch housing. This solution is strong and works better that using small wood/sheet-metal screws instead (which I had tried for the first reassembly).

Grinding Rivets and Chamfering

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Disassembly
This switch is spring loaded. It will fly apart. I say it has a high "boing factor".

The photo above showing all the rivets removed also shows small wires threaded through a few of the holes. The wires are simply twisted together beneath the switch housing. The wires allow the metal plate to restrain the internal components until you carefully and deliberately intend everything to come apart.

Loosen the wires and start walking the metal plate away from the plastic housing. This allows for the controlled release of spring tension that otherwise would make you look for parts all over your workbench. Take care as the brass pin for the horn contact is quite long. Here you can see the nylon "cancellation tab" beginning to escape, still attached to its springs.

Walk the Cover Off

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Cover Plate Removed

Cover plate removed

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The turn signal side has two brass contact arms each with its own spring. (Those brass contact arms are responsible for hi-beams and flash-to-pass separately.) The windshield wiper side has a single brass contact arm also with a similar spring, not shown. (That brass contact arm does the windshield washer pump.)

Springs

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Inside and Outside Contacts

Inside

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Outside

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Part 1 of 3

[usury]

Part 2 of 3

Windshield Wiper/Washer Side

Wiper Stalk

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Wiper Stalk Nose

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Part 2 of 3

[ROB III]

These are GREAT!
Thank You.

[usury]

Part 3 of 3

Turn Signals and Hi-Beam Side

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Broken "Wings"
By the time I decided a repair was necessary, my turn signals were no longer consistently latching into position. I'd have to hold the stalk in the direction I was trying to indicate in order for my turn signals to remain on. I think the loose "broken wing" was getting in the way inside the switch housing. This was quite annoying, of course. Naturally, my turn signals couldn't self-cancel if they wouldn't even stay on.

There are little plastic "wings" on the internal business-end of the turn signal stalk. One of my wings was broken, and the other cracked. I found the broken wing wedged inside the switch housing. This first photo collage shows the condition of the plastic business-end part upon initial disassembly.

Broken Wings

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Here is the same part with the wings Crazy-Glued in place. (To be clear, Crazy-Glue is NOT a good way to repair this part.)

Glued Wings

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(I had Attempted a Repair which only "kinda worked"™. In fact, I had so much build-up of plastic in the attempt that whenever I used my left turn signal, my hi-beams also activated. Not flashing, just on. My repair had bumped the "flash-to-pass" contact into action when turning left. Not a lot of clearance inside the switch housing.)



Hi-Beams and Flash To Pass
The spring-loaded tip of the stalk itself engages with a separate nylon component that resides inside the plastic "business end". In the first pic, the dowel pin that connects the stalk to the business end can be seen. It could easily be removed and placed somewhere safe so it can be reused.

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Details and Measurements
In case you misplace a spring, or find any broken, here are some measurements. The "tooth" (circled in green) that retains the square nylon turn signal latch must be installed in a way that it engages with its slot. The tooth is very small and would be easy to miss.

Turn Signal Latch

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Copper Contact

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Dowel Pin

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Cancellation Tab
The larger nub (circled in green) must be positioned facing the metal cover plate when reassembling. It engages with an oval notch exactly matching its size. The smaller nub engages with the pocket on the top of the "business end" of the turn signal stalk.

Cancellation Tab

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Reassembly
Reassembly is a whole 'nother thing. It's not difficult after a dozen practice runs and/or with the help of another person. I'll describe that as part of my 3D Printed Repair Part. I haven't released the *.STL yet, though I do have the part installed in my car.

Part 3 of 3

[notny41]

very nice writeup - reminds me of when i pulled mine apart for a good cleaning

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[VegasBoxers]

Does anyone make a rebuild kit for the turn signal switch assembly?

I don't have a 3D printer and I haven't learned enough to know how to run one. I'd rather buy a pre-printed kit with all the parts already made.

Scott

[usury]

Does anyone make a rebuild kit for the turn signal switch assembly?

I'm currently running a prototype of the 3D printed repair part I designed to address the broken wings. I still have a couple of things to iron out though. I vaguely remember posting a short video of it in operation on my workbench.

I may be willing to sell a kit at some point, and/or post the model here on Carpokes with some non-commercial diy-friendly license. Maybe I'll even offer a service to rebuild the switch assembly.

The part itself would benefit from modern engineering resins and a resin printer. Though I printed my mostly good good prototype in ASA on a filament printer with decent luck already.

As the weather has reliably turned to rain in the Pacific Northwest, it's a perfect time of year for taking the car apart and tweaking this part.

[Tom]

Does anyone make a rebuild kit for the turn signal switch assembly?

I'm currently running a prototype of the 3D printed repair part I designed to address the broken wings. I still have a couple of things to iron out though. I vaguely remember posting a short video of it in operation on my workbench.

I may be willing to sell a kit at some point, and/or post the model here on Carpokes with some non-commercial diy-friendly license. Maybe I'll even offer a service to rebuild the switch assembly.

The part itself would benefit from modern engineering resins and a resin printer. Though I printed my mostly good good prototype in ASA on a filament printer with decent luck already.

As the weather has reliably turned to rain in the Pacific Northwest, it's a perfect time of year for taking the car apart and tweaking this part.

If you end up posting an STL, I'd be happy to print it for you on my From Labs resin printer. In the olden days (couple years ago) resin printers were a pretty big jump above FDM printers. They are still much better when you need injection-mold-like surfaces, but with the advent of enclosed core xy (aka Bambu) I find myself using the Form Labs printer less and less for stuff like this.

Also, as for licensing, thats one reason I prefer to post my stuff here on carpokes From our terms of service:

Any and all 3D-Print files (such as STL files) available for download on the Website are provided under and are subject to the Creative Commons Attribution Non-Commercial No-Derivatives 4.0 International Public License (as may be updated from time-to-time), the text of which is may be found in this link: https://creativecommons.org/licenses/by ... galcode.en; and is hereby incorporated into these terms as if set forth fully herein. Attribution must include a link to the page within www.carpokes.com where the file can be downloaded, and such link must be prominently displayed in close proximity to any description of the file or to any image of the object the file contains. Other than as may be expressly stated herein, any and all documents, files, 3D-Print files, How-To Articles, posts, messages, pictures, videos, or other data accessible from the Website (“Site Content”) is available solely for the personal, non-commercial use of the Carpokean who accesses it

[07turbeaux]

WOW! Very cool. Is that part no longer available through Porsche or aftermarket like Pelican or Automotion?

[07turbeaux]

Rarely do I not document processes at least not since the advent of camera phones. Trips to hardware store go so much smoother!