Interesting discovery about 308 GTB headlight switch..

That's what I'm trying to figure out how to do. Do we have three basic pieces (two halves of the knob plus the round donut piece on the stalk end)? I can try prying it apart with an X-acto (inside a plastic bag so I don't lose any pieces but I'm not sure where to start.

 

Mike,
I've found that if you hold the stalk & firmly pull straight out on the twist knob, it'll pop out of the keeper ring at the knob's base. Prying using a knife, screwdriver, etc. generally chews up both the bottom of the knob, & the keeper ring.

I can generally stop the pull before the knob comes out far enough for the detent ball to take off like a BB, but still use a plastic bag.

I've only seen a few problems with the actual insides of the twist knob, they're listed in order of liklihood:

Your QV will have the newer mechanism with a pair of contacts coming out like a V, then the ends form a U.
The knob has a small blade molded on the inside. When the knob is in the off position, the blade spreads the legs of the U apart, opening the contacts. In the on position, the blade is parallel to the legs letting them touch.

1) Bad connection of one of the wires. Usually a poor solder joint to one of the contact legs. Suspect this is your problem.

(BTW, the older switches have rivited crimp contacts & I've seen bad crimps).

2) The blade has broken off of the inside of the knob. It's possible to reattach it (See Carmen's post in the old FCHAT). I have a mold for the QV & 328 knobs, & can readily make a mold for the older knob.

3) The detent groove in the knob has become worn, or the detent ball & spring are missing.

4)The blades have gotten bent because of 3).

5) The plastic switch body is broken. The body is the piece that holds the contacts & is molded one the shaft. This is very rare. I don't currently have a mold or master part, but can make one if yours is broken.

Just keep all the pieces & send them to me. I'll reassemble them & make a mold from them.

BTW, I fix more than 3x8/Mondial switches. I currently have the column switches from a '67 330GTC & a Maserati Bora in for broken stalk replacement.

 

Could not find Carmen's old post that shows how to repair the inside end of the ligth stalk. I think this is my problem.
Thanks for your your help Verell.

 

That was exactly it -- one of the solder joints had broken loose allowing the contact to shift position.

 

Verell is the king of the Ferrari light stalk!

 

Verell:
the headlight switch on the 308 is the same as a 365GTC4. Can you diagnose the extent of the problem from the followng photos?

MANY thanks!

http://home.earthlink.net/~f365gtc4/images/Switch%20Detent%201.jpg
http://home.earthlink.net/~f365gtc4/images/Switch.jpg
http://home.earthlink.net/~f365gtc4/images/SwitchInterior1.JPG
http://home.earthlink.net/~f365gtc4/images/SwitchInterior2.jpg

 

Bryan,
Please describe the symptoms, what does/doesn't work?

I didn't see anything obviously bad with the inside of the twist knob, but as you know, it's very hard to see down inside there.

Also, a couple of photos of the contacts on the end of the headlight shaft might be helpful.

 

agree - as most of
Verell's posts, a bookmarked fav reference thread

 

http://home.earthlink.net/~f365gtc4/images/SwitchContacts.jpg

I can turn the lights on by pinching the contacts manually. I suppose it's posible that nothing is wrong except that the ball and detent just fell out.

 

Since the contacts work OK, it's mechanical. As you say, maybe the ball & detent just got out of place. First thing is to try reassembling it & see if it's OK.

I'ts been a long time since I worked on that particular style of headlight twist switch, but I don't remember anything particularly touchy, prone to wear or breaking.