Klaxon vs Mixo Stritone horns

[NorthernThrux]

Thanks Steve, That is consistent with the discussions I've had with my restorer, Robert Gross. In fact, other than the replacement of "Klaxon" with "Mixo", the rest of the lettering is identical, as are the part numbers. Both are branded as Stritone, not surprisingly.
I've seen dozens of Mixos and rarely a Klaxon, so this also ties in with the relative rarity of the RS Klaxon horn.

I purchased a Klaxon in error. Which is kinda like saying I bought a bar of silver that turned out to be gold.

Ravi

[NorthernThrux]

Nope. Just a part number which is the same for many years of horns. The part number is the same as on a Mixo. Only the brand name is different.

Ravi

[NorthernThrux]

First two are Klaxon, as correct for '73 RS models from what I've learned.
Second two are Mixo, as correct for post banjo T, E and S models, including my '73S.

Identical Stritone lettering and trade mark/numbering markings on the right of the Stritone label. Mixo vs Klaxon branding on the left.

Ravi

[Gearby]

So is there a high or low label on the end of the Klaxon horn?

[RSTarga]

Haut=High

Has anyone noted if the tonality is exact between the Mixo or the Klaxon? On both low and high? If so, does anybody know when the changes may have occurred?

[Gearby]

Haut is actually French for top. Although it can be used for high, I suspect that marking at the base of the horn actually means top. Klaxon is French for horn. If there isn't a high or low marking on the bell of the klaxon horn, then I suspect the klaxon was to be used by itself whereas the mixo was to be used in a pair. I realize the klaxon may have been used as a pair but if theyre not marked high or low then they probably all had the same sound. I also would suspect that the klaxon had a different sound then the mixo horns. If there is a high or low on the klaxon then forget everything I just said. Lol

[NorthernThrux]

So is there a high or low label on the end of the Klaxon horn?

Yes. identical for both Klaxon and Mixo as well. In 4 languages. Low, Grave, Tief, Basso on the low and High, Aigu, Alto, Hoch on the high. As noted Haut=Top in French (Haute or Haut Couture for example). What I'd call 12 o'clock in referencing the marks.

To repeat, the horns are identical other than the Klaxon Mixo labels at 9 o'clock. Right down to the embossed part numbers. An interesting mystery.

Ravi

[sttoronto]

Anyone know which one is the date code and how to read it?

[911MRP]

Bosch are date coded using normal Bosch three digit system but don’t believe the Stritone of either brand are dated. Pretty sure the switch to the new brand was in response to regulations regarding horns that were coming into effect mid Jan 1973.


The regulation required the audible warning devices fitted to motor vehicles to conform to newly introduced standards and meet certain tests. They had to carry a mark This regulation took effect beginning 1973 . That’s why cars from around December got the Stritone so that they would be legal by time delivered and registered after Jan 15th
On this thread some time ago I touched upon the reason why Stritone superseded the banjo:

https://www.early911sregistry.org/fo...ose-interested

I shared material from my references to help nail down the date of change of supplier away from their major partner Bosch’s so called banjo. A produce that had been used on some models for a number of years. thj and as corroborated by on “transporting-patterns” appears to fit with the regulation introduction minus a month or so for lead times.


Parts are superseded and new suppliers approved for many reasons. One important reason being when new regulations from international and national bodies take effect. This particular change is almost certainly triggered by the new regulation regarding horns being introduced mid jan 73.

This is a summary of the regulation


The new regulation 28 of 1973 specifically required the E number to be imprinted on the horn as proof of certification of the part also to indicate the horns on vehicle now conformed to the particular technical tests of that are set out in detail in the many pages of the new regulation.

I note it mentions regional but I haven’t read the full detail to see if / when
this rolled out across the various markets. Pretty safe assumption that this regulation was the trigger to the change in this particular component. The reason we see Stritone with e2 mark appear from around December I suppose. Cars being built would need to be compliant as each market adopts the regulation. The change would be done with appropriate lead time as no prizes
for shipping non-compliant product!

In the automotive industry engineering and global operations matters are planned managed and controlled very tightly by specialists and subject to strict procedures etc. Ask me how I know

Porsche in 1973 no doubt had a good handle on the complexities and dynamic nature of their multinational business given they too were both an automotive OEM as well as providing consulting engineering to other OEMs. Patterns that can be observed these days by “train spotting” details extant on some old cars may not always totally clear fifty-years-on given what’s happened through their life but there was no doubt method in the madness of why done in the day.

A new datapoint that very broadly dates Stritone is the fact Mixo existed without E mark existed. I know that because I once had an orphan pair of Mixo sans E Mark. This is one photo of them I kept — note there is no E mark and the wording is slightly different to those that for the E-Mark :


I expect that pair preceded the new regulation. Their form was
identical to the Stritone ones seen on 911 in early 73 other than not E Marked! Don’t know about internals

So what? Perhaps the Stritone makers were fortunate to have a product already quite close to already the meeting the emerging regulation in their range? Mixo and Klaxon who made Stritone would have been aware on advance of the changing regulations as being on top of such things is business as usual. The fact the E mark appears where one didn’t exist before shows they took actions to get the certification and were allowed to use the E mark. However I’ve not ever seen the Bosch fanfare as used on Porsche to 72 with any E mark — Bosch would of course have had the new regulation on their radar too. They could have had it on their product development roadmap to get compliance in time. But given the lack of E-mark on
their so called Banjo suggests they didn’t bother to do so. Maybe with the new regulation n Bosch chose to rationalise the horn range and wind down that particular banjo shaped product line? Obviously this regulation change wasn’t just Porsche — it was for all audible warning devices in the affected regions— in fact Porsche unit volumes were probably quite small beer to the tier one suppliers compared to the scale consumption of true volume automakers.

Would be interested to know what the latest date code is on the Bosch banjos seen on Porsche but perhaps that line wound down and retired by Bosch rather than investing in making it compliant. Particularly if the banjo design was old and would have need major work and maybe new tooling to pass the new regulations to gain certification? Who knows but maybe on absence of Emarked Bosch banjo perhaps the usual supply partner advised Porsche they wouldn’t be making an E marked complaint horn of that type triggering Porsche procurement to look elsewhere for new suppliers with suitably complaint e marked products. They'd have done with lead time to deliver sufficient inventory lineside late calendar 1972 so cars could be built with appropriate horn. Maybe there was passing if the regulation was rolled out at rodent time in market such that some inventory of banjo could be useful.

I was a schoolboy in 72/3 so some of this is just surmising what might have happened — however Porsche obviously would have needed to address the regulatory change at end of calendar 72. Certainly seems they did so with the two types of Stritones. Suitably E marked to have cars mid January in affected regions. Thereafter Stritone type were used for many ears but not afaik dated. Red then much later black

So to OP question while not date coded there are at least three broad eras of the Stritones 1) Pre E marked Stritone ( never used in 911); 2) red E2 marked Stritone of Mixo and Klaxon manufacture girst fitted to 911 from December 72; 3) many years later black Stritones that are somewhat similar but not in detail and colour incorrect for calendar 73 TES & RS.

Steve