Author Topic: Correct Finish to Bosch Horn Screws (Read 8039 times)

RobSirg · « **on:** January 15, 2019, 04:19:20 »

Hi All and Happy New Year,

Was not able to find this in my search - can someone tell me the correct finish to the outer screws (on the rim) on the Bosch Horns? Are they yellow CAD or Black/Dark Grey?

Mine are Black / Dark Grey - have seen yellow CAD which looks nicer but I don't wish to over-restore if that was not the original finish. I believe the 2 screws on either side of the name plate are Gal?

Appreciate your help.

Regards,

Rob

mdsalemi · « **Reply #1 on:** January 16, 2019, 21:38:39 »

How about rust?

Seriously Rob, the most unforgiving life of any part of this car is the horn! It lives just inches from the pavement, absorbing all manner of weather and abuse...I suspect mine were zinc plated steel whose color, if any, wore off decades ago...

...which is why the replacement kits from places like Stoddard use stainless steel fasteners.

66andBlue · « **Reply #2 on:** January 16, 2019, 22:55:09 »

Quote from: RobSirg on January 15, 2019, 04:19:20

.. - can someone tell me the correct finish to the outer screws (on the rim) on the Bosch Horns? Are they yellow CAD or Black/Dark Grey?...

Go to our tech manual: https://www.sl113.org/wiki/Electrical/Horns
open up the PDF that lists all the Bosch part numbers and you'll find that the screws for the horns in our cars were always black. (There is also a chromed version for horns in other types).
You can also find more info in my article in Pagoda World Number 21, 2017.

RobSirg · « **Reply #3 on:** January 16, 2019, 23:04:08 »

Thanks Mike,

I'm well aware of the salt on the Michigan roads having visited Kalamazoo many times in your winter - fortunately Aussie roads need no such treatment. In any case, the reason I have multiple Pagoda's is so I have some to drive (often) and one for show. This one is undergoing a full restoration and will spend its first few years in show, so it is not likely to enjoy a wet road for a while. I'm more interested in restoring it back to the way it left Stuttgart without going crazy (not going to try replicate orange peel exterior paint finish, etc). If stainless steel screws were the original finish I would gladly install them. I'm thinking maybe they were yellow CAD?

Here's where I am so far - engine was started last month after 3.5 years of work so far (don't ask why it is taking so long). Anyway, it purred like a kitten and passed the coin on the rocket cover test without having a proper tune. FYI - I am trying to replicate the photo taken by John (aka 49er) of his newly delivered manual 280SL(albeit mine is RHD) right down to the yellow caps on the battery. Thanks to John for his "holy grail" photos and for everyone on this forum to help with small details like this. Cheers. Rob

p.s - I am aware there are incorrect clamps, etc, in this photo as we still have some temporary installations. I will send photos for critique when it is more complete.

RobSirg · « **Reply #4 on:** January 16, 2019, 23:07:18 »

Thanks Alfred, that's great - and proves yet again that my Blue 1969 280SL is correct in every detail.

I did recall there was a good article in Pagoda World and tried to find it - then figured it was quicker to ask here.

Cheers

Rob

Garry · « **Reply #5 on:** January 17, 2019, 01:23:05 »

Rob,

That is looking extra good. When is. the first showing, MBCV Concourse?

RobSirg · « **Reply #6 on:** January 17, 2019, 03:29:18 »

Hi Garry - hope you are well!

I think I originally intended to show it at MBCV concours 2017 but I guess I am now on track for 2020.

Might even consider this year's Motorclassica if we have a good run. All chrome is done, all running gear installed (car drives), Hard top is complete, seats and doors trimmed. Just need external paint and then refit interior, soft-top and external trims and glass. I'm sure some tiny things will slow me down and hopefully we wont lose a part that is NLA.

I couldn't be happier with the engine - it revs so sweetly......didn't expect it could be that good.

….of course I didn't expect it would take this long or cost this much - at least I can see some light now.

49er · « **Reply #7 on:** January 17, 2019, 22:26:47 »

Hello Rob,
Your engine looks better then mine when it was new. Great job. And for what it's worth, here is a photo of one of my horns that is far from concourse shape. The two screws that hold the Bosch plate were zinc/cad and the outer rim screws are black. They still work perfectly and always fun to give them a toot (especially in tunnels)

John

RobSirg · « **Reply #8 on:** January 17, 2019, 23:13:30 »

Thanks John - nothing beats the original in my mind.

Will be sure to post more photo's once it is has progressed.

Cheers

wwheeler · « **Reply #9 on:** January 18, 2019, 00:53:41 »

It looks as if the outer screws on John's horn weren't plated before they were sprayed black along with the horn. My guess is that they were coated with black oxide which can be a good "primer" for top coats. So maybe they were black oxide and then painted along with the horn as an assembly. The screws holding the plate have faired better because of the plating. Very interesting and thanks for posting.

Peter h · « **Reply #10 on:** January 18, 2019, 11:07:32 »

The screws are black painted. The 2 screws on the plate are Chrom.
Peter

Shvegel · « **Reply #11 on:** January 18, 2019, 14:23:30 »

A million little details and we are just scratching the surface. I finally put a small plating line in my shop so I could do whatever finish is needed.

wwheeler · « **Reply #12 on:** January 18, 2019, 16:25:29 »

What sort of plating system are you using?

Shvegel · « **Reply #13 on:** January 19, 2019, 23:41:34 »

Caswell Zinc with my own home brew yellow chromate. With the home brew which is more concentrated I can yellow chromate screws hose ends etc that are supplied type 1 (clear/shiny) but were originally yellow chromate.

I think I contaminated my Zinc bath by using a heating element that had a bit of steel on it so I have to order more stuff.

I originally started with the intention of plating what I refer as the “unplatables” like the solenoids, atmospheric compensator etc but started to do more and more as time went on.

wwheeler · « **Reply #14 on:** January 20, 2019, 19:38:09 »

Interesting. I know what you are talking about re- the hose ends. So have you been successful with the solenoids and Baro compensator?

Shvegel · « **Reply #15 on:** January 22, 2019, 10:40:52 »

Baro compensator was easy. I just hung it upside down with the bath at the threads. I thought the solenoids were easy as I simply dried the out, Soaked them in fresh water, dried it out again and dropped it in oil working it back and forth but a couple weeks later the CSS was stuck beyond belief. I had a spare as a backup so I could experiment on the one I messed up. If I did another I would simply drill the back so I could really dry it out then patch it later. Since I know you are well down the road of being detail oriented I wanted to mention that the brass back insert on the CSS remains brass. I masked mine with a bit of tape before plating.

wwheeler · « **Reply #16 on:** January 22, 2019, 16:01:58 »

Excellent! Another cold weather project. Luckily the solenoids have the drain hole at the flange mount. That allows the oil from the IP to drain out when a certain level is reached inside the solenoid. Also handy for plating to let the fluid out.

What was your drying out procedure?

mbzse · « **Reply #17 on:** January 22, 2019, 18:10:14 »

Quote from: RobSirg

.../...can someone tell me the correct finish to the outer screws (on the rim) on the Bosch Horns?.../...

Already settled here by member 66andblue, Wallace and Peter h but anyway; here is a picture of a NOS Bosch horn similar to the ones in our Pagoda cars. From a current e-bay ad.
Black paint applied all over as can be seen. The ID plates with numbers in the middle attached later on in factory assembly process, by means of bright cad slothead M3 screws.

114015 · « **Reply #18 on:** January 22, 2019, 20:06:00 »

Perfect, Hans ...;
looks great.
Wanna have that look too...

Yours?
Where did you find that one?

All best,
Achim

Shvegel · « **Reply #19 on:** January 23, 2019, 09:26:49 »

Wallace,
I blew them out as best as I could then put them on top of my garage furnace. 150 degrees in a toaster oven would work too. If my wife only knew what went on when she is gone.

wwheeler · « **Reply #20 on:** January 23, 2019, 16:30:46 »

Quote from: Shvegel on January 23, 2019, 09:26:49

Wallace,
I blew them out as best as I could then put them on top of my garage furnace. 150 degrees in a toaster oven would work too. If my wife only knew what went on when she is gone.

What we need is a thread where everybody confesses all of the times they have used their household appliances to repair the cars. I can see it now...Honey, this bagel tastes like a solenoid. Do have any idea why?

Pawel66 · « **Reply #21 on:** January 24, 2019, 18:09:40 »

Quote from: wwheeler on January 23, 2019, 16:30:46

What we need is a thread where everybody confesses all of the times they have used their household appliances to repair the cars. I can see it now...Honey, this bagel tastes like a solenoid. Do have any idea why?

This would have to be password protected to prevent our partners come across it even accidentally. Serious damage threat.

Peter van Es · « **Reply #22 on:** January 25, 2019, 15:07:34 »

Quote from: Pawel66 on January 24, 2019, 18:09:40

This would have to be password protected to prevent our partners come across it even accidentally. Serious damage threat.

Just post it in the Full Member thread. Only full members can read it. Remember to log out from the forum -- and your PC -- when you leave your PC alone. Do use a password on your PC. Easy - peasy...

RobSirg · « **Reply #23 on:** February 03, 2019, 01:58:29 »

My admission:

I used the Dishwasher for the front headlight lens covers, and the Clothes Washing Machine (front loader) for my original seatbelts after taping bubble wrap over the buckles, etc…..worked a treat!

Also used black shoe polish to bring back life to my original firewall padding - but later recoated with a vinyl / fabric paint.

wwheeler · « **Reply #24 on:** February 04, 2019, 01:27:50 »

I am sure you feel better now. Right?

News:

Author Topic: Correct Finish to Bosch Horn Screws (Read 8039 times)