The Stovebolt Site Forums The Shop Area The Electrical Bay stop light switch and horn

I have a 53 with a 235 engine. My brake lights are not working. The fuse
good. The stoplight switch is located on the firewall below the steer wheel shaft and is mounted with two threaded bolts. Do I need to pull the carpeting and remove the jute insulation to replace the switch?
Also,I need to install a horn but the two I have can't be mounted on the manifold or the oil filter. Apparently I don't have the correct brackets although I can't locate one that would work.

The offset bracket between the two horns should allow you to mount that horn on the right on the manifold, although it looks like it's missing the part that bolts to the horn (wider bolt spacing- see the attached pic.) Chevy produced an offset bracket similar to that to use when an oil filter was mounted on the manifold. It moves the horn forward a bit to prevent interference with the oil filter. Jim Carter sells a non-offset horn bracket, but not the offset one.
Yes, you'll need to pull back the carpeting and jute insulation to get to the screws for the brake light switch, but I'd use a multimeter to check it before condemning it. It could be something entirely different, such as a bad ground at the taillights. Do your troubleshooting first, then replace the part that you find bad.

Hi Scott,

I was in the same boat as you. Horn came in a box of parts but there was no bracket.

I have no idea why Jim Carter or anyone else sells the bracket for use on engines with no oil filter. I doubt many people are driving their restored trucks without oil filters.

Anyway, I found this horn on ebay that had been sitting at the bottom of Big Snake Lake for a few decades for $20.

I bought it just to get the bracket. Look around, you'll find one. If not, you can see that it would be pretty easy to fabricate a bent piece of metal that would work.

Scott, Since both these topics are more related to the electrics of the truck I've moved your thread over to the Electrical Bay for further discussion and helpful info. On the offset bracket, put an ad up in Truck Parts Wanted. You will probably find a fellow Bolter that may have an extra laying around that will be willing to help you out.

thanks and great idea!

I wanted to post a few more photos to clarify my situation. I posted the firewall as that is where the horn had been mounted.
As you can see my manifold is different.

thank you. From what I can find, in 54, the horn was mounted on the radiator support. My engine is a 54 , 235. Not sure how to mount but will look.
Good advice re the stoplight. Not sure how to check with a multibmeter - continuity light? but will trouble shoot.

Scott, Here is a good article with pictures from Jim Carter on 1948-53 Horn bracket locations and types. The pictures should help you see how it gets mounted. As others have mentioned, the offset bracket is the one used when an oil filter is installed. Your intake manifold looks to have the horn mounting tab on the forward runner (just behind the front oil filter U-clamp).

Perhaps your oil filter just needs to be moved back a little to make room for the horn. Will that Z bracket in your picture mount to the boss on the manifold?

One pin on the stoplight switch (doesn't make any difference which one) should have battery voltage all the time. Operate the switch's lever and make sure that the voltage doesn't change more that 1/10th of a volt. If the change is more than that, the problem is a poor connection between the switch and the battery. Fix that before continuing.

The other side of the switch should have no voltage until you press on the brake pedal (or you move the lever). Then it should have battery voltage. If so, and the brake lights do not come on, the problem is in the wiring from the switch to the brake light(s), the brake lights themselves or the ground to the brake lamps.

If the voltage is a volt or more less than it was without the switch "on" the switch is bad.

Thanks, but my manifold does not have a mounting "boss", it is there but no bolt holes (guess that is what it is called). Jim Carter states that in 54 (my engine), the horn was mounted to the radiator support.
At this point, since I may have to remove the carpet and jute to access the bolts for the stoplight switch and will probably mount the horn where it was originally on the firewall.

interesting... it looks like the mount boss on your manifold, the bolt holes were not open, then I see a bolt going through one.
Were the holes plugged up? My manifold boss does not have holes.

my boss does not have bolt holes.

is it possible that the problem is my turnsignal switch? I have an aftermarket turnsignal and although it flashes at the tail light, it no longer flashes at the swith itself and the arm droops when not in use when it used to stay in the neutral position.

USUALLY the brake lights and the turn signals on the rear of the truck use the same filament in the rear bulbs when turn signals are installed. IF (big if) the rear turn signals work, but the brake lights do not work, the likely point of failure could be either the brake light switch or the turn signal switch.

If the brake lights AND the turn signals don't work the failure is more likely in the turn signal switch.

I guess I should disassemble the turn signal switch.
On another topic, would this horn placement be OK?
I like the horn, this is where the old small horn was.
I would have to have a mounting bracket fabricated.

No reason it couldn't go there, I suppose. What about drilling the mounting holes on the manifold and put it there?

That seems pretty difficult. That boss is thick and I would probably have to remove the manifold to do it. Thoughts?

What about welding the bracket to the manifold boss?

Don't attempt welding on the cast iron manifold. If you haven't welded cast iron before, trust me you'd be better off buying a different manifold, because that one will likely be ruined. Drilling would be way easier, but you might need a longer than normal drill bit to do it. Cast iron drills pretty easily.
Interesting that Chevy saved a nickel by not drilling the manifold boss when they moved the horn to the radiator support.
Your firewall mounting bracket (assuming you'd fab it similar to the cardboard) would be pretty floppy. You'd need an angle brace to keep the horn from bouncing around.

Just thinking out loud here. If you are ok (?) with changing the orientation of the horn you want to use (pointing down instead of forward), you could bolt the existing Z-bracket to the firewall and the horn to that bracket. It might place the horn forward enough to clear all the things on the firewall and in the engine compartment. The horn doesn't care which way it's aimed to function. That heavy brace and orientation change should solve the "floppy" problem mentioned by Kevin.

Using the z bracket and mounting to the firewall ( that's where and old smaller horn was- firewall already has two bolt holes there)..might work . I will check.
Leaving town for 2 weeks but will resume project ASAP.
Appreciate your opinion.

Didn't realize the cast iron problem.
Do you think I could drill the holes without removing the manifold?
Leaving today for 2 weeks so resuming project ASAP.
Appreciate everyone's advice!

If you can get a straight run at it with a good cordless drill with a proper metal drilling bit, it should be pretty easy. Maybe move the oil filter out of the way temporarily. No need for the holes to be threaded. I attached my horn with 1/4" shoulder bolt and nut.

In an add-on to Otto's thought on moving the oil filter to drill, you can remove the front canister u-bolt to better expose the tab for drilling. The rear u-bolt will keep the filter secure while you drill away. Just be sure to mark your drill starting point so the through bolt will clear the canister u-bolt like in Otto's 2nd pic.

Guys, just looked at mounting the horn on the firewall pointing down and it seems it would work without the "Z" attachment to the mounting bracket...sure would be easier but mounting on the manifold looks better..
Maybe I could try drilling first to see how it goes.
I have to remove the original jute ( very dried out and fragile) to access stoplight switch which I think needs replacement so at same time I could bolt the horn on...
I like the manifold look better but will think on it...

Photos posted

Drilling the manifold boss will require you finding the correct offset bracket to mount the horn there. If it fits in the firewall location, then that would work fine.

I think there'd be plenty of room to drill the boss. As I mentioned you might need a slightly longer drill bit to keep the chuck from hitting the manifold. The attached pic shows a standard length 19/64" drill bit chucked all the way into the drill. You might be able to chuck the bit shallower and avoid hitting the manifold with the chuck.

Or use a bit extension.

https://www.amazon.com/Pieces-Drill...bon/dp/B08VGPFPCD/ref=asc_df_B08VGPFPCD/

Without removing the radiator, Otto, those bit extensions would be too long. There was maybe 3 inches between the back of my drill motor and the radiator. But you could cut one down.

Than you both for all advice. I think I will try drilling the Boss when I return early August.
Unlikely that the manifold would crack right. I have never drilled through cast.

Not likely to have a problem unless you try and drill the holes full size all at once. Be sure to use sharp bits and do the drilling in size stages. Drill speed too fast and/or trying to remove too much metal can lead to jammed/broken bits and most likely some busted knuckles. Take your time and let the drill bits do the work.

Wanted to give everyone that was so helpful regarding my horn issue. I got it mounted today and it sounds great!
Thanks again!
Scott

Scott, Glad to see you got it done and thanks for coming back and letting us know! Looks good and you didn’t have to mess with drilling the holes!

Otto, of course mine is a 216 in an 37 and I may have longer u bolts, but my oil filter mounts straddled the carburetor. This leaves the manifold horn mount area available .

37 GC, I guess the wiper motor vacuum port is plugged up behind the oil filter?

37GC and Otto, Just a note that you guys are kinda driving this conversation off-course. Scott already completed his horn mounting as mentioned above. Perhaps your new discussion needs to get moved to the Engine Shop?