Bosch horn restoration

[Markp]

Is anyone offering restoration services for Bosch horns? Mark-Seattle

[Peter van Es]

Do a search on this forum. There are some reproduction units available, that people are happy with.

Peter

1970 280SL. Also known as 'admin@sl113.org' and organiser of the Technical Manual.

[hands_aus]

Michael Salemi was doing some resoration to these Bosch horns.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[mdsalemi]

It's not an easy task, I'm afraid.  My restoration, if you would like to call it that, was to dispose of the case's insides and fit smaller Bosch horns inside.

You can get pretty darn good Hella and Chinese models for something like $100 or so.  You can then get Bosch horn tags and install them for a more accurate look; but unless you are trying to fool a Concours judge, I wouldn't bother with the latter.

http://www.rallylights.com/hella/horns.asp  Scroll down this link to find Hella horns that look like the old Bosch ones, and these are at a reasonable price.

http://cgi.ebay.com/ebaymotors/BOSCH-STYLE-HORN-MERCEDES-PORSCHE-VW-12V-NEW_W0QQcmdZViewItemQQcategoryZ38655QQihZ002QQitemZ120213999937QQrdZ1QQsspagenameZWDVW  This guy, expresspart, sells an offshore horn that looks pretty good.

NLA-635-001-00  That's the part number at http://www.stoddard.com/parts.shtml for their horn kit.

That should be all you need.  If you actually want to try and take your horn apart and restore it, I do have a technical guide (not written by me however) that has some information on how to do it.  The challenge in doing so is a lot of the horn's innards are press-fit into the rear of the clamshell case, and thus you can't properly paint of powder coat it; you can do the front grill however.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[tuultyme]

How closely do these replacement horns sound like the original horns?  I was contemplating putting something like these on my daily driver and then when I come upon another Pagoda maybe they would recognize the sound rather then looking at me funny as I wave to get their attention.  It might also help if we could come up with a Gang (group) sign that could be recognized by all.

Bruce; 268Blaugrun(green) 1970 280SL; IL

[mdsalemi]

Well, it's a good question.

How does a reasonably well kept horn, albeit 40 years old, sound today as compared to when new?  I don't know, but I can't believe after this life underneath a Pagoda it sounds identical.  That being said:

The official Bosch data, for what its worth, indicates we had two tones, middle and high, indicated by a 3/4 or 9/10 suffix designation on the horn tag.  The 3/4 were on early cars, the 9/10 were on later cars.  

3 or 9: 290 Hz Tone
4 or 10: 345 Hz. Tone

The Hella horns mentioned in the previous post are 310 Hz. and 380 Hz. respectively, so for sure these will sound a bit higher.  However it looks like they have an adjustment screw, so you might be able to lower the tones on them--how much?  I don't know.  Buy a pair and let us know.

The Hellas also don't have a tag on them so you'll have to drill and tap the covers if you want to make them look like Bosch.  They are also 130mm in diameter whereas the Bosch horns are 155mm so there is a little bit of a difference.

I don't know what those expresspart horns specs are, but if one looks closely at the tag on the image, they match the Bosch 290/345 combo.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[zoegrlh]

I have a 1970 280SL European spacs, which came with Hellas "trumpet/tuba type" horns as original equipment.  Does anyone else have these types of horns installed?
Bob

Robert Hyatt
Williamsburg, VA.

1970 280SL, Red on Silver,4-speed, Euro spec; 1999 C230 Kompresser Sport, Black on Black; 1990 Miata, Black on Red, 5 Speed

[Bob G ✝︎]

A couple of weekends ago on a rainy Sunday. I attended a Porsche swap meet in Irvine and noticed a set of restored Bosch horns idenical to ours. I cannot remember the name of the company as I was shoving business cards in my jacket with notes about who did what. I remember asking if they would restore my horns with brakests and they said they would and turn them . Cost If I remember was $400.00 not really that high if they say what they do, looked like they been around along time. I will look through my business cars you can send me a PM off line if you are  intrested.
I also purchased a set of repoduction hella horns Super T horns, they sound the same. So unless you are planning on having the Concours experience of judges scrutnizing every detail of your car. You might wantto settle for the afterr market horns and put your orginals away for now.
Bob Geco

[66andBlue]

Hi regierytyznll,
after you refurbish/repair the horns, how do you tune them to the correct frequency of 290Hz and 345Hz? Do you have frequency meter or do you just do it "by ear"?

Alfred
1966 blue 230SL automatic

[66andBlue]

Hi, thanks for sharing your skills, I am sure we'll call for more help soon.  I had hoped that you might have known of a better tuning trick.
 
Here is what happened when I refurbished my horns.  I had tried to do it by ear too
but it didn't sound right. So one of my neighbors, who plays the
saxophone helped out. One day - when we thought the rest of the neighbors were at work or shopping  
he came by and played an "F" (= 349Hz) while I turned the tuning knob
on the "high" horn. And then we repeated the procedure, he playing a
"D" (=294Hz) and I tuning the "low" horn.
After we were satisfied with the result, and having scared a few cats,
the city police arrived in my drive way. They had received a complaint
for "disturbing the peace".  It took awhile to convince them that all
that happened was that he had tried to teach me how to play a saxophone.  

Alfred
1966 blue 230SL automatic

[mulrik]

Hi zoegrlh
I think I have the same trumpet horns that you are mentioning. i always wondered whether they were original or not. Do you have a picture of them. I can't access my car for the moment, so unfortunately I cannot provide a picture of mine.

Best,
Ulrik


'67 250 SL Papyrus White 113043-10-000023