'41 Accessory knob

[valk]

I'm going to hook up my fogs lights to the LEFT hand accessory knob because the righthand accessory knob is already occupied by an electric fuel pump.  So all my knobs have an allen head screw tucked on the underside of the knobs to release them EXCEPT the lefthand accessory knob. It has the indentation for the screw but was never drilled out. Does anybody know how to release the lefthand accessory knob so it can be used? 

Thank you,

Peter

[FLYER15015]

PM Matt Harwood on this one, as he is the '41 guru.

Q= do you see a "flat" anywhere on the switch shaft,

That usually means that there is a flat spring in the knob.

If so you can usually just pull it straight off.

 

Mike in Colorado

[Matt Harwood]

Mike is 100% correct. The ACCESSORY knobs are just held in place by a piece of spring steel, which is secured to the knob with a screw on the back of the knob (my first ACCESSORY knob wasn't usable because we drilled the set screw hole at the wrong angle and the replacement I bought on eBay didn't have the spring, which is the one shown below). You shouldn't need the spring and it may make the knob difficult to pull out. You'll need to drill out the hole and tap it for a set screw to hold the knob secure on the end of your switch's shaft. Here are some photos of my accessory switch and the hole I drilled to make it work. Your switch shaft should have a smaller diameter area just before the end where the set screw will secure the knob so it can't just slide off.

 

Hole already drilled and tapped.

 

Switch showing where the set screw is secured.

 

In the dash.

Edited September 20, 2019 by Matt Harwood (see edit history)

[neil morse]

Hi Peter:

 

The accessory knobs are held in by a spring clip, but they are very tight.  You need to go in from the back and loosen the screw that holds the spring clip to the knob.

[neil morse]

Matt and I posted at the same time.  Between the two of us, I think we've answered your questions.  At first I thought you were talking about taking out the accessory knob and using an actual "Fog Lights" knob (which are made from unobtanium, but sometimes can be found).  I was going to tell you that wouldn't work on the left side since the Fog Light knob is made to fit on the right side.  But I'm now thinking that Matt has the correct interpretation and that you are planning to adapt the accessory knob to use for your fog lights.  Let us know which it is, and also I'd be curious to know where you found a switch for your fog lights whether or not you have a knob.

[valk]

Thanks Boys. Matt has the right interpretation.  I'm still a bit fogged regarding how to remove the knob. Do I just pull mightily on the knob or loosen/remove the "spring clip" screw behind the dash?? I can't picture what the spring clip looks like. With all the other switches in place, there is not much room to see or manuver - I may need an old dental mirror to see what's going on.  Once out, though, I drill and tap the hole for a set screw and install on the shaft. Thanks so much for the info and pics.  If I ever get a fog light knob, I guess I'll have to swap the accessory switches around. 

 

Also, is there a correct way to route the lamp wires to the switch? I was just going to snake them along the sides of the engine compartment where the harness is.  And any pointers where to tap into power? I will study Matt's write up again but I think I may roll the dice and not install a relay.  Neil, I got the switch from the same Buick forum member who sold me the lights. He PMed me when I expressed an interest in finding some. PM me and I can give you more details. 

Thanks sincerely,

Peter

[Matt Harwood]

Just yank it out. It'll feel like it won't budge but then it'll give up and pop out. 

[valk]

Bingo! Thanks Matt. This pic shows both the clip and the untapped set screw hole. I'm on my way...

Peter

[neil morse]

3 hours ago, valk said:

I may need an old dental mirror to see what's going on. 

 

Sounds like you were able to extract the tooth without a mirror!  I probably confused you, but when I dismantled the dash on my car, I was afraid to just yank on the accessory knobs and found that loosening that screw (which is readily accessible from the back) made it a lot easier to get the knobs off.

 

For what it's worth, the fog lights on my car are powered by a wire on the "accessory" pole of the ignition switch, and there is no relay.  I am actually in the process of rewiring my car, as you may know, and I'm probably going to just run a single "correct" cloth insulated wire out along the side of the engine compartment, as you suggest, fitting the wire into the same clips for the main harness.  Then I will solder a "Y" connection after the wire disappears behind the grill, and run the wires out the bottom the grill to the two lights.  That's the way it was done previously on my car, but with modern wire.  I'd love to have those mounts that Grampa showed where you can conceal the wire in the mount, but I don't know where to get them.  With Matt's assistance, I just bought two new mounts off Ebay that are the correct height to get my lights above the bumper.  It will look a whole lot better.  I have also run a dedicated ground from each light to the bumper support.

[Matt Harwood]

I pulled power for mine from the BAT terminal on the voltage regulator. That's a full +6V direct from the battery and it's a heavy enough 10-gauge wire to handle the load of the fog lights. That's a better solution than the ignition switch.

 

 

It probably isn't a problem on a car with a robust ignition system like our Buicks, but you never know. I've had cars in my shop that didn't run correctly or would stall randomly because people were powering other accessories from the ignition and those accessories eventually pulled enough juice away from the ignition to cause running problems. Very difficult to trace those problems.

 

In fact, we had a car in the shop last week that would stall every time you used the power windows, seat, or top. Turns out that someone decided that the ignition switch was a suitable place to pull power for the giant hydraulic pump that runs the windows, top, and seat. Whenever it was on, there was no power left for the ignition and the car would stall. Not good in traffic if you decided to get a bit more comfortable. The ignition switch and key got so hot that it actually burned my son's fingers as he was turning it on and off to help me diagnose the problem. The insulation on the grossly undersized 14-gauge wire eventually melted and dripped onto the floor. Check it out:

 

 

So find a good spot to pull power that isn't under the dash or the ignition switch. This winter I'm going to run a bus bar in my Limited to power all the accessories so they've got big wires and fuses to be safe. I'll have all the clean electricity I need for the lights, radio, and other electrical accessories.

 

Edited September 21, 2019 by Matt Harwood (see edit history)

[Bloo]

18 minutes ago, Matt Harwood said:

I pulled power for mine from the BAT terminal on the voltage regulator. That's a full +6V direct from the battery and it's a heavy enough 10-gauge wire to handle the load of the fog lights. That's a better solution than the ignition switch.

 

And once again, Matt Harwood nails it. The highest voltage point in the system (when the system is charging) is the armature terminal of the generator. The "BAT" terminal is as close as you can get to to the armature terminal without upsetting the regulation. The next stop on the way to the battery is the ammeter. If you wind up on the other side of the ammeter somehow, then any current the fog lights draw will register as "charge" current, which of course it isn't. There is literally no better place to connect a light bulb than the "BAT" terminal of the voltage regulator.

 

If you need/want them to go off with the ignition, I would add a relay. It's better not to stress an antique ignition switch.

 

Edited September 21, 2019 by Bloo (see edit history)

[neil morse]

Okay, thank you guys, I am learning something on this forum, as usual.  The fog lights on my car were added by former owner (whom I call "Mr. Goodwrench"), and he obviously had no idea what he was doing.  I will change the set up on my fogs.

[valk]

Great stuff, thanks again. Call me Capt Obvious, but I want to run this by you guys. As you can see in one of Matt's pictures above, the switch has 3 terminals, 2 behind the fuse and 1 off by itself. The 2 together behind the fuse are for the lights and the other for power, right? I was just going to connect the light wires directly to the 2 terminals behind the fuse and, per Matt, a direct wire between the voltage reg "Bat" terminal and the remaining terminal on the switch.  Is that right? 

[Matt Harwood]

36 minutes ago, valk said:

Great stuff, thanks again. Call me Capt Obvious, but I want to run this by you guys. As you can see in one of Matt's pictures above, the switch has 3 terminals, 2 behind the fuse and 1 off by itself. The 2 together behind the fuse are for the lights and the other for power, right? I was just going to connect the light wires directly to the 2 terminals behind the fuse and, per Matt, a direct wire between the voltage reg "Bat" terminal and the remaining terminal on the switch.  Is that right? 

 

No, the original-style fog light switch with three terminals is designed to turn off the fog lights when the headlights are on. The factory only wanted them working with parking lights. I did a little experimenting with my switch and a continuity tester and found that the two terminals you want to use for it to be a simple ON/OFF switch are as shown:

 

 

The third terminal is for the power feed to the headlights and is off when the others are on. It isn't used unless you want to wire in the power to your headlights there so power is killed to the headlights when you turn on the fogs. I didn't want that so I skipped it. There's only one power wire for two fog lights so you have to split it at some point, preferably up front by the lights so they're easy to remove if necessary. 

[valk]

Thanks Matt. I'm sure you're right but it seems to me that wiring them the way I suggest would also work and allow me to run the lights independent of the headlight/parking light circuit. My lights came with enough wire on both of them to route back to the switch so I can hook both lights up directly, and I wouldn't have to splice a single wire into 2. I may be totally wrong on this and hope Grandpa, Bloo or others will weigh in. 

[Matt Harwood]

3 hours ago, valk said:

Thanks Matt. I'm sure you're right but it seems to me that wiring them the way I suggest would also work and allow me to run the lights independent of the headlight/parking light circuit. My lights came with enough wire on both of them to route back to the switch so I can hook both lights up directly, and I wouldn't have to splice a single wire into 2. I may be totally wrong on this and hope Grandpa, Bloo or others will weigh in. 

 

That won't work. That OEM fog light switch with three terminals is NOT an ON/OFF switch, it's a diverter switch. +6V in on the top, and either of the two rear terminals can be on, but not both. If you hook it up as you propose, with the hot on top and each of the rear terminals going to one of the fog lights, when you turn the switch on (pull it out), the light connected to the right-hand terminal will turn on. When you turn it "off" (push it in), the fog light connected to the left-hand terminal will turn on and the first one will turn off. Does that make sense? Depending on the position of the switch, only one of those terminals is hot if there's power in at the top, but not both at the same time. As I said, you can do some continuity testing to confirm this. My photo above shows how to connect the wires if you want the in position to be OFF and the out position to be ON. Using the other rear terminal means in will be ON and out will be OFF.

 

None of it has anything to do with headlights unless you hook it up the way the factory would have, which either kills the fogs when you turn on the hi-beams, or kills the headlights/hi-beams when the fogs are on. I haven't been able to find any documentation either way, but that's exactly what this 3-post switch is designed to do: kill one set of lights when another is turned on. If I had to guess, I would say that the factory ran the output from the headlight switch to the top post of the fog light switch, then out the left-hand terminal to the headlight junction block and/or hi-beam switch. That way the headlights would work normally, but pulling out the fog light switch would kill power to the headlights and/or hi-beams and divert the power to the fogs. This would also mean that you'd have taillights when the fogs were on, which is how I wired mine. Regardless, as long as you supply a separate source of +6V power to the top terminal, hooking it up the way I show above will allow you to turn on the fog lights independent of headlights/parking lights.

 

I also wouldn't run two separate wires all the way through the car and dashboard just to connect them to the switch separately. What happens should you ever need to remove the fog light? You'll have to pull out all that wire that you've snaked through the body and dash, then run it back in there to reconnect it when you reinstall the light. Use a junction block or a simple splice closer to the lights to make this easy--done correctly there are no reliability issues. One 12-gauge wire will easily handle the 8.5 or so amps that both fog lights will draw (2 lights x 25 watts ÷ 6 volts = 8.3 amps), there's no need for a separate wire for each light until you need to split it to reach the housings. I used separate wires in my installation only to the relay, which is under the hood and that was exactly for this reason--if I ever need to remove the fog lights, I can simply disconnect that wire and pull it out easily.

 

 

Edited September 21, 2019 by Matt Harwood (see edit history)

[valk]

Thanks Matt for your thoughtful reply. I'm a dufus when it comes to electrical stuff and appreciate your help. I gotta run but will study your responce when I get back. 

Peter

[Bloo]

I'm gonna have to defer to Matt on this, as I have no 1941 manual. I do remember when Matt posted about this when he discovered it, and it does seem a bit bizarre.

 

I can understand having them go off with high beam, even quite a few modern cars do that. Foglights are wide and low and are effectively "extreme" low beams. There is no need or sensible reason to run fogs with high beams, and they draw current, and some old car charging systems don't really provide enough current (though that is less of a problem after 1940).

 

IIRC that isn't what happened. ALL the headlights went off with the fog lights on (didn't they Matt?). That is sort of bizarre. I can imagine wanting to run the foglights alone, but I can also imagine wanting to run them with low beams. The only reason i can EVEN imagine is that with foglights only you would have no light at the back of the car, unless you remembered to turn on the parking lights also. Maybe Buick was trying to make it idiot proof? I don't know, but I'm not crazy about it, and I would rather have it the way Matt wired it.

 

Regarding running the two foglight wires all the way to the switch (or relay), there is nothing ELECTRICALLY wrong with that (it's even a tiny bit better, but that is splitting small parts of hairs....). Given Matt's description of the switch, you would have to stack both wires on the same screw. It would indeed be a pain to take back apart.

 

Just don't put any splices or terminal blocks out in the breeze. Your connections should run into the car far enough that they don't get wet. I see bullet connectors hanging out in the breeze on foglights and I sort of cringe. On a more modern car, if you get behind the core support, its pretty dry. I'm not sure where a good dry spot is on the 41.

 

I had a 70s Alfa Romeo that had signal lights hanging out on the bumper like fog lights. The wires ran through a grommet, and there was a connector just inside the body. The area was still more or less open to the elements (and probably wheel splash too). Those connectors would rot and fall apart about every 6-12 months, requiring both halves of all three spades to be replaced. They COULD have used a foot more wire and put those connectors up behind the core support where it is dry, and that is how I fixed mine and a few others.

 

Less connections are better. If you are going to add some, pick a dry spot.

 

 

 

 

Edited September 21, 2019 by Bloo (see edit history)

[valk]

Thanks much guys - I get it now. I intend to wire them up like Matt's so I can run them independent of all the other lights. Thanks for taking the time to explain it to me. 

Peter

[Guest]

Cudos Matt! That is an excellent writeup and clear photo shoot! One explanation for turning off the headlights when using "fogs" is why they are yellow and lower at all. It would seem to defeat the purpose of the fog lighting to leave the bright reflective white headlights on when all they would do is reflect against the fog vapour in front of the car, serving to reduce visibility. Just a "swag"(scientific wild ass guess!)  :-)

Edited September 23, 2019 by Guest (see edit history)

[FLYER15015]

Well now I feel deprived.

Us poor '40 guys don't have an "accessory" switch.

I had to run a fused 10 gage wire from the battery up under the dash and hooked up the "Trippes" and the fogs to a 3 way toggle (on-off-on) under the dash.

Can't have them both on at the same time, 'cause it's hard on the old generator, but they are on their own system so to speak.

[valk]

Here's a stupid simple schematic of wiring the fogs without the relay - is this correct? 

[Matt Harwood]

That should work just fine.

[valk]

Thanks Matt. And just for giggles, here's one WITH the relay:

 

[valk]

Matt, 

How did you drill and tap the accessory knob in that one can't get a clear, straight shot at the pilot hole without the bit fouling on the edge of the housing? I see how one can miss the sweet spot and ruin the knob. I see no alternative but to start with a really small bit and try and widen the hole gradually so as to not mangle the housing. 

[valk]

The pic looks like there is plenty of room to get a straight shot at the hole but it's deceiving and the bit can't go straight in without bumping up against thre housing. 

[Matt Harwood]

1 hour ago, valk said:

Matt, 

How did you drill and tap the accessory knob in that one can't get a clear, straight shot at the pilot hole without the bit fouling on the edge of the housing? I see how one can miss the sweet spot and ruin the knob. I see no alternative but to start with a really small bit and try and widen the hole gradually so as to not mangle the housing. 

 

 

Dr. Francini did bugger the first one we tried. Fortunately, ACCESSORY knobs are relatively easy to find on eBay. On the second one, I did it in two steps--a small and then final. The conical seat there will help you guide it and you lose that if you do too many passes. Just drill one small pilot hole so you have a guide for the final size (I don't recall the drill size, but I think the set screw I used was a #8). The angle is not super critical, just close enough so the set screw can lock on to the shaft. Francini totally missed, he was too vertical with his drill, so it didn't contact the shaft at all. Keep it angled down as close to the edge of the knob (I put a few layers of masking tape in case the drill nicked it) and it should be fine.

 

If you do miss, you can probably go a size or two larger on the set screw--the larger diameter should eventually contact the shaft and lock on. Not too much bigger, but enough to make things work. I didn't think of that until just now, but that's what I should have tried before buying a new knob.

 

 

Edited September 25, 2019 by Matt Harwood (see edit history)

[valk]

Thanks man. I'll give it a shot.