Someone on FB translated the full article:
A bit of bedtime reading for die-hard 400F die-hards
Sankei Giken Kogyo, an independent parts manufacturer that manufactures genuine mufflers, metal, and resin parts for motorcycles and automobiles, is offering a limited number of mufflers for the Honda CB400FOUR, which was released in the 1970s and is still very popular in the out-of-print car market. Sell. The reproduction muffler, which was faithfully reproduced by the original parts manufacturer using original drawings and manufacturing methods, is attracting a lot of attention as a genuine Reiwa part, even though it is a reproduction part. We will tell you about the story of how this product was born, how it was manufactured in the Showa and Reiwa eras, and the voice of Uematsu, an out-of-print car specialty store that sells this muffler, to tell you about the story of the birth of 4into1, with its elegant form and beautiful chrome plating.
Among the many out-of-print cars, the Honda CB400FOUR (hereinafter referred to as Yonfour) has received overwhelmingly high praise in the mid-size class. Based on the existing model CB350FOUR, the displacement was expanded to 408cc engine (a 398cc version was later added), and the cafe racer style was created by a low steering wheel and a sporty exterior that did not have any frills. It is one of the most popular models of the epoch and quickly became a popular model in its class.
One of the parts that symbolizes the Yonfoa is the 4into1 muffler, which combines four exhaust pipes into one. A collective muffler for a 4-cylinder engine is a common part these days, but at the time Yonfore made its debut, it was standard for a 4-cylinder car to have four mufflers, with the exception of collective mufflers for racing and some custom parts.
The muffler was manufactured as a genuine part by Sankei Giken Kogyo Co., Ltd. (hereinafter referred to as Sankei), an independent parts manufacturer that manufactures genuine mufflers and frame parts mainly for Honda vehicles. In 2024, half a century after the birth of Yonfoa, Sankei will produce a limited edition 4into1 muffler that is exactly the same as the one that was installed when the car was new.
Various repair parts are essential to maintaining a motorcycle and passing it on to future generations, and motorcycle manufacturers sometimes supply some functional parts. However, in the case of out-of-print cars that have been manufactured for many years, there are many parts that are no longer on sale. In particular, there are many cases where large exterior parts such as fuel tanks and mufflers are discontinued relatively soon after vehicle production and sales are completed. Of course, Honda has already discontinued sales of genuine mufflers for Yonfoa.
Why is it being reproduced now? There are two factors behind this. One is user feedback. Yonfoa continues to be very popular both domestically and internationally, and a certain number remain on the market, matching the trend of a growing preference for genuine cars over out-of-print cars. The other purpose is to create products within Sankei and pass on technology.
Since the full-scale introduction of 3D and CAD to industrial product development and manufacturing sites in the late 1980s, the face of so-called "manufacturing" has changed completely, and it is now commonplace for everything from prototyping to performance evaluation to be done virtually. ing. At the stage of producing a prototype, the specifications are determined down to the last detail, which is efficient, but it cannot be denied that development, which is done in front of a computer using a keyboard and mouse, makes it difficult to get a feel for how things are actually made.
Particularly for parts manufacturers like Sankei, the problem arises that simply making products according to the drawings sent by partner manufacturers reduces opportunities to overcome problems and develop problem-solving skills within the company. If an employee who knows the company's history of developing products through trial and error leaves the company, that technology will be lost. Such tangible and intangible assets and know-how are the assets of a manufacturing company, and in light of the spirit of ``Knowing the past, learning from the past,'' the remanufacturing of the muffler for Yonfore was judged to be optimal.
Due to its popularity in the out-of-print car market and the spirit of learning from the past and inheriting the manufacturing culture within Sankei, a project to reproduce the muffler for Yonfour started at the end of 2021. It was at the end of 1974 that the Yonfore, which was the first commercially available car to be equipped with a 4-into-1 muffler, was put on the market, but what was the manufacturing process used at that time?
The person who developed the styling of the Yonfour was Honda's late designer Masaya Sato. While renewing the style of the CB series up to that point and emphasizing an agile image, the muffler is now 4 into 1 instead of the 4 independent type, and the silencer is not the monochrome type where the left and right halves are welded in the center. The desire for tapered winding is also included in the rendering.
However, surprisingly, Honda did not submit any drawings for specific parts such as the layout of the exhaust pipes and the design of the assembly parts, and Sankei engineers created the product through prototyping and created the drawings. Development progressed through repeated meetings with Honda's designers and engineers.
For example, Sankei engineers initially planned to develop the area where four exhaust pipes line up under the clutch cover on the right side of the engine in the direction of putting the four pipes together. However, the oil pan for the CB350FOUR, which is the basis for the Yonfour engine, has a large downward protrusion, and if the exhaust pipes were grouped together under the engine, the minimum ground clearance would be insufficient. In the later CB550FOUR-II, the gathering part was placed under the right side step, but if this layout was adopted in the Yonfour, the bank angle during cornering would be insufficient. So, as a last resort, we came up with a flat, globe-shaped gathering part shape.
On the other hand, Honda's engineers changed the shape of the oil pan for the CB350FOUR oil pan in areas where it would inevitably interfere with the muffler. The 4into1 gathering part for Yongfore is a symbolic part of this muffler, but it was actually a shape created by Sankei engineers as a result of trial and error.
The silencer, which has a gentle taper angle from the gathering part to the tail end, is also the result of the efforts of Sankei engineers. The designer requested that a tapered silencer would look better on the Yonfora, which pursues a light and sporty image, but at the time Sankei had no experience in producing such long tapered pipes.
Therefore, the engineers began by making a jig for tapered winding, and gradually acquired the technology to wind long pipes, realizing a silencer that met the designer's wishes, and this became the first equipment for a mass-produced commercial vehicle. It is said that the Showa era manufacturing process, which started and stopped repeatedly in the early 1970s, was clearly recorded in the minutes of meetings between engineers and designers at the time.
The core styling was done by Honda's designers, and Sankei was in charge of the specific muffler structure, including the specifications.The muffler for the Yonfore was born, and Honda approved Sankei as a muffler manufacturer, and the muffler body was The SANKEI logo will be engraved separately from the HONDA logo.
By the way, the SANKEI logo that is still in use today was personally created by Mr. Sato, who designed the Yonfor, as a way of expressing gratitude for the hard work of the Sankei engineering team. This is also the case with the fact that the current SANKEI font bears some resemblance to the 400FOUR font on Yonfoa's side cover. For Sankei, the muffler for Yonfora is not only a part made from a relationship between orders and orders, but also an epoch-making event in that the company was actively involved in its development.
Although the genuine muffler for Yonfour is a Sankei product that has been approved by Honda, it is not currently sold as a genuine Honda part. Although there is a growing momentum for reprinting within Sankei, it is rare for genuine parts that have been discontinued to be sold again. In particular, Sankei is still a parts manufacturer that manufactures genuine parts for Honda vehicles, so of course they are sharing information with Honda during this project.
Generally speaking, demand for genuine parts gradually declines after a long period of time has passed since their release. If a new car was selling 1,000 units a year when it was released, but only 50 units are selling 20 years later, the production costs will increase for the manufacturer who supplies the parts, regardless of the vehicle manufacturer, to maintain production equipment for 50 units. Directly connected to. It would be nice if the cost could be passed on to the genuine parts price, but there are cases where the parts manufacturer cannot meet the genuine parts prices set by the motorcycle manufacturer.
No matter how popular it is, given the number of Yomfores remaining on the market and the demand for them, it would be impossible for Honda itself to sell them as genuine parts. That's why the framework was established for Sankei to sell the product itself after obtaining approval from Honda.
The 300 sets that will be manufactured this time is a very small quantity for Sankei, which mainly manufactures mufflers in mass production. However, it can be said that this was achieved not only because of the business but also because of the manufacturer's theme of ``warming the past and learning new things.'' However, since it was a genuine part that had been approved by Honda and was sold with the Honda logo on it, there was apparently strong pressure to avoid causing trouble to Honda due to complaints from end users.
The molds used to manufacture genuine parts had already been disposed of in 2009, so when manufacturing the muffler for the Yonfore, the first thing the development team looked for was the original drawings. A method such as reverse engineering, which involves 3D scanning the actual item and converting it into data, could be considered, but as explained in the previous section, this muffler was designed and drawn by Sankei, so in order to completely reproduce it, it would be necessary to go back to the drawings. This is the best option.
CB400FOUR｜MufflerImages (13)
A diagram of the internal structure of the muffler that was published in the catalog. As this was the biggest selling point of Yonfoa, its internal structure is explained in detail.
Fortunately, the drawings were discovered, but the challenge for modern engineers is how to interpret the two-dimensional drawings, which were drawn in an era before computers and 3D. This is because the blueprints include the dimensions of each part, but do not represent the three-dimensional curved surface. In the 1970s, it was common practice to bring a wooden mold made from a drawing to a designer, and after careful consideration and adding the designer's sensibilities, the shape was finalized.
What was helpful here was CAD data created by 3D scanning the mass-produced muffler at the time. By comparing and contrasting two-dimensional drawings and CAD data, we created a three-dimensional image from the drawings and attempted to recreate the feelings and sensibilities of designers and engineers more than half a century ago.
Even so, the prototype mold was unable to completely reproduce the delicate shape of the product at the time, and the mold was revised several times, but as long as the SANKEI and HONDA logos were included, it would not interfere with any part of the car body. There was a responsibility to not just be satisfied with the muffler's functionality as long as it could be installed and functioned as a muffler.
In developing the project to completely restore the genuine muffler from that time, we encountered some difficulties because technology and processing had evolved since then. One of them is the internal structure of the exhaust pipe.
The chrome-plated exhaust pipe has a double layer structure at a certain distance from the cylinder head side to prevent the surface plating from being damaged by exhaust heat. This itself has not changed since then, but in the 1970s, when multiple parts were welded together to make a single exhaust pipe, double pipes were used for high-temperature parts, and different molds were used in the middle. In contrast to welding a single pipe bent with a single pipe, in modern manufacturing methods, the double pipe is continuously bent using an NC bender from the exhaust port to the gathering point, so the double pipe is bent in the middle of the pipe. It cannot be changed in one go.
It is not possible to tell from the outside whether the exhaust pipe is a double pipe or a single pipe, and making the entire exhaust pipe a double pipe also improves the durability of the plating. Although there was an opinion that a heavy pipe would be fine, the manufacturing department was not satisfied with the idea, so they devised a manufacturing method and created a double pipe part way through using the Ultra C class method.
On the other hand, the part where the exhaust pipes come together was a problem because the texture was different from that time. At that time and even now, the assembly parts are formed by pressing material plates and welded parts are chrome-plated without polishing the base, but as the quality of the material itself has improved, the modern version has a glossy finish after plating. He says his condition has improved.
Although there are probably few users who are dissatisfied with the shiny chrome plating, some members of the development team said that the genuine parts at the time were not as smooth and shiny as this. However, since it would be unnatural to roughen the surface with post-treatments such as sandblasting or shot peening, the material was chrome plated without any modification.
The manufacturing department in the 1970s also paid close attention to the weld bead width of the tapered sign body and silencer end piece. Designer Mr. Sato instructed them to polish the weld marks so that the seams would not be visible, but because the material is thin, the heat from polishing inevitably distorts the body and end pieces.
Therefore, in response to the design request that the welding bead should be made as narrow as possible and the welding marks should be made visible without treatment, the Sankei engineering team ordered welding machines not only from Japanese manufacturers but also from overseas manufacturers. We pursued a narrow bead. This commitment has been carried over to the newly remanufactured muffler, which has a much narrower weld bead
than a typical production car muffler.
As a side note, this weld bead width is one of the points that distinguishes the muffler when the Yonfore was manufactured as a new car from the muffler that was sold as a part in later years. During the production of new cars, the Sankei factory also had a production line for Yonfoa mufflers, and welded narrow bead widths using welding machines from overseas manufacturers. However, once a new car is no longer manufactured and is treated as a repair part, the production line disappears and a different welding machine is used than in mass production, so the bead width is wider than the muffler installed on a new car.
The thickness, length, and position of the pipe that penetrates the separator inside the multi-stage expansion silencer have been reproduced exactly as per the blueprints, and the same anti-corrosion paint used at the time has been used inside. There are probably few riders who clearly remember the exhaust sound of new cars in 1974, but the sound is clearly quieter than the well-maintained cars of the time, and in cars that have not been well maintained, it is more likely to be due to engine noise than exhaust noise. Sometimes I'm more concerned about it, and I'm so moved that I wonder if this is the sound of a genuine new muffler.
As we have explained so far, just because the company has manufacturing drawings from half a century ago and has a track record of manufacturing genuine mufflers, it does not mean that it will be easy to produce the same product as back then. It may be an exaggeration to say that the manufacturer's prestige is on the line, but I commend Sankei's development team for reproducing a perfect genuine muffler based on the theme of learning from the past and making new things in the field of manufacturing, which has changed too much between the Showa and Reiwa eras. It should be done.
However, as a company, we cannot ignore economic rationality in the face of noble ideals. The two numbers they came up with were ``300 units produced'' and ``tax-excluded price of 198,000 yen.'' Generally speaking, the unit price of industrial products decreases as the production volume increases, but no matter how popular Yonfoa is, it cannot be compared to new model mufflers, which are manufactured in tens of thousands of units over many years.
As for the circumstances at the manufacturing site, as the number of products manufactured increases, the molds for molding the materials must be mass-produced, which creates a dilemma that will lead to an increase in product prices unless they are manufactured in even larger quantities. After considering the balance between quality and cost, we came up with a production number of 300 pieces and a price of 198,000 yen (excluding tax). For reference, the new price of a genuine exhaust pipe + silencer for the Honda CB400 Super Four around 2020 is over 220,000 yen, and genuine used mufflers for the Honda CB400 Super Four are sold for over 100,000 yen on online auctions. From a user's perspective, it can be said to be a bargain price.
In addition, this reprinted genuine muffler for Yonfour will be sold directly by Sankei rather than through Honda's genuine parts network. However, Sankei is a manufacturer and does not have a sales department, so several shops handle sales. One of them is Uematsu, which has been handling out-of-print cars for over 30 years. The company has a wealth of experience handling Yonfoa, which is the most popular model in the mid-size class, and Sankei wants customers to enjoy the sound and style by actually installing it on their vehicles, rather than using it as a decoration or for resale. We agreed.
Models that are popular in the out-of-print car market always have their own unique characteristics that attract the attention of riders. For Yonfoa, which took the world by storm with its stylish cafe racer style, the 4into1, the first commercially available car, is an indispensable icon. A genuine muffler born in the Reiwa era that perfectly reproduces the sensibilities of the Showa era designers and the techniques of the craftsmen will be a valuable gem not only from the point of view of long-time users but also from the perspective of passing on the craftsmanship
https://young-machine.com/2024/01/25/508206/...
