6 hours ago, kats said:

Hi Alan, I saw the BAT comments. I am sure this thread will definitely clear the myth.  It’s a lot easier to clear than clearing Mr. Goertz myth .

Ha ha! I'm always hopeful, but not so sure. I think we will see people talking about "plastic" steering wheels for many years yet. I still see Goertz getting credit for something he never touched (including the MF10 Toyota 2000GT).

6 hours ago, kats said:

I did a bit search for IZUMI , I found this article , https://www.nttd-es.co.jp/magazine/backnumber/no9/no09-izumi.html

I think that was just a few years before being merged into Autoliv . This article is very interesting and proved their very high quality and skilled engineering. 

Also I found an interesting another blog , https://ameblo.jp/1119-4195/entry-12213393088.html

A gentleman talking about IZUMI steering wheel. His friend whose father was a president of IZUMI , 常泉彦三郎

Excellent! And the president had such a great classical name too, almost like from a Taiga drama. So we can see where the 'Izumi' name came from. Thank you!

One of my key motivations with this thread is to somehow give due credit to Izumi for their fine work. And yes, I do think it is fine work. When I think about it, I don't know how they managed to make these steering wheels for Nissan at an acceptable cost. There's a lot of processing in there.  

Many of the parts suppliers for our cars were independent companies who specialised in their particular fields, often to an almost artisanal level. I have seen this many times in Japan. Such companies still exist, but their craftsmen have been retiring and/or dying out whilst bigger companies gobble them up. It would be sad to think that companies like Izumi came and went without people like us - who literally lay hands on their work when we interact with our cars - even knowing their name.

5 hours ago, Zed Head said:

So, definitely not just "plastic" unless you consider the wings of a stealth fighter to be plastic.  But, not really wood either.  A high-tech, for the time, product designed to look like wood but be better than wood. 

I hear what you are saying, but I'm still going to push back.

Izumi called these steering wheels 'wood'. They had already been making moulded plastic steering wheels - as seen on earlier, more utilitarian Nissan models - for many years. They would not have bothered using wood/wood fibre unless they were going to make a point of it. There were plenty of other - synthetic, readily available, repeatable - materials available for them to use as the reinforcement component, so why wood fibre?

The answer is staring us in the face. It was because they were engaging is mass-producing something that would otherwise be regarded as a hand-made item, as seen from contemporary specialist makers like Bluemels, Springalex, Moto-Lita, Nardi, MOMO, Les Leston and their ilk.

They used wood because they were specifically making wood-rimmed steering wheels for these cars.

 

     

Some more photos from my 'autopsy'. This time from the outer surface of the rim where 50+ years of use has worn through the outer layer and revealed a naturally-grained surface below it: 

21 hours ago, HS30-H said:

 Is there a split line/joint in the CSP's rim?  

No Alan, very much like the wheel in this thread, including the images above. I started restoring mine a while ago, so I know every inch well. The CSP steering wheel has painted black on the inside edge of the 3 slots cut into the satin polished 3 spokes, so points to a finish proceedure after molding as with the '69-73 wheel. Probably the same as the hub of the wheel, painted after.

Maybe an idea for a thread covering all those manufacturers who supplied Nissan with parts for the S30Z, the likes of Niles, for example.

Edited August 9, 20222 yr by RIP260Z
added bit

35 minutes ago, RIP260Z said:

No Alan, very much like the wheel in this thread, including the images above. I started restoring mine a while ago, so I know every inch well. The CSP steering wheel has painted black on the inside edge of the 3 slots cut into the satin polished 3 spokes, so points to a finish proceedure after molding as with the '69-73 wheel. Probably the same as the hub of the wheel, painted after.

Good stuff Ian, thank you.

Looking more closely at the CSP311's wheel, it does indeed look very similar to the rim type used on the S30s. I saved this photo from the Silvia that sold in Australia last year, and which shows some partial de-lamination (sun damage?) of the wheel rim which is quite revealing I think:

 

My description was based around "how do they get the steel in to the wood and keep it there?", how do they keep the wood from regaining its original form, and the hot technologies of the time.  It certainly could be wood.  Steam bending/forming is an ancient ship building technique.

Resin infusion of wood is a thing also.  So it might have started as a solid piece of wood but had resin infused to lock it in to shape once it was formed.

If I was doing the forensics I would look very closely at where the steel contacts the wood.  The inside not the outside.  The fine details around the weld beads and where the spokes enter might tell a story.  You could also burn a piece and see what it smells like and how it smokes.  Polymers/plastics have a distinctive odor when they burn and tend to produce a black smoke.

Many ways to get there, probably many technologies involved, probably combined to get the desired end result.

https://en.wikipedia.org/wiki/Steam_bending

https://en.wikipedia.org/wiki/Impregnation_resin#:~:text=The impregnation of resins into,into a solid substance state.

 

"If I was doing the forensics I would look very closely at where the steel contacts the wood.  The inside not the outside.  The fine details around the weld beads and where the spokes enter might tell a story."

36 minutes ago, Zed Head said:

My description was based around "how do they get the steel in to the wood and keep it there?", how do they keep the wood from regaining its original form, and the hot technologies of the time.  It certainly could be wood.  Steam bending/forming is an ancient ship building technique.

Resin infusion of wood is a thing also.

Already covered in post #6 of this thread, I'd say.

36 minutes ago, Zed Head said:

So it might have started as a solid piece of wood but had resin infused to lock it in to shape once it was formed.

Izumi - and Matsuo san - mentioned that the wood was processed in 'fibre' (conjoined strands, oriented lengthways) form. It is not a solid piece of wood in the way that traditional, mostly hand-made wood rim steering wheels used to be. The only hint (and it is only a hint....) of any seam or join I can detect is on the inside edge, where I think there is a faint line. It may be some sort of mould tooling joint line, which would make sense.

36 minutes ago, Zed Head said:

If I was doing the forensics I would look very closely at where the steel contacts the wood.  The inside not the outside.  The fine details around the weld beads and where the spokes enter might tell a story.

Just such a view is visible from the photos in the first post. The final photo homes in on an imprinted 'negative' of the welded joint between a spoke and the outer steel hoop. There's still 'grain' visible, but the impression of the welded joint is pushed into it. You can also clearly see the dark and smooth area where the wood material was pressed around the main part of the steel hoop. I would expect the steel spokes and hoop to conduct more heat than the wood and the resin, and we know that the mould tooling itself was hot. That seems to be one of the things that affects the surfaces most in contact with the metal.

 

36 minutes ago, Zed Head said:

You could also burn a piece and see what it smells like and how it smokes.  Polymers/plastics have a distinctive odor when they burn and tend to produce a black smoke.

I already did this, with two results. First I burned a section with the outer (shiny, dark) layer in situ and got grey smoke and a distinctive smell. Then I chipped off some of the more obvious wood inner and burned that on its own. Much lighter smoke and a very typical burning wood smell. The burned black wood can be used to write and draw, like a piece of charcoal.

The material is incredibly tough. It was hard to remove from the steel rim (although it was not adhered to it) and difficult to split the material into smaller pieces. It wants to split with its circumferential grain and it is very resistant to breaking across it. It makes me think of some sort of hardwood, like Indian Rosewood. 

 

     

17 minutes ago, HS30-H said:

Already covered in post #6 of this thread, I'd say.

Actually, you didn't really say much in that post.  A few names to research if a person wanted to, quotes of someone else's posts.  Kind of thin.  No details, just references to broad processes.

Anyway, manufacturing of parts like this is an interesting topic, when you get in to the fine details.  Where the technology becomes more like art.  Overall, in this case, it seems that the process of forming the wood was almost too good.  So good that the final product seems like plastic.

 

Interesting that Nissan/Datsun never referred to it as a wooden steering wheel in their sales brochures of technical publications. Jaguar refer to theirs as "wood-rim" steering wheel. The 240Z brochure refers to it as "Racing type" steering wheel.

1 hour ago, Zed Head said:

Actually, you didn't really say much in that post.  A few names to research if a person wanted to, quotes of someone else's posts.  Kind of thin.  No details, just references to broad processes.

No need for details in that context. I think pretty much everybody is familiar with bentwood furniture and the general concept of materials such as MDF. Part of my job involves sourcing and exporting vintage 20th Century modernist furniture, so I'm up to speed with the processes and materials that 26th-Z was referencing. I don't think I need to explain any tongue-in-cheek banter between myself and 26th-Z to you either.

1 hour ago, Zed Head said:

Anyway, manufacturing of parts like this is an interesting topic, when you get in to the fine details.  Where the technology becomes more like art.  Overall, in this case, it seems that the process of forming the wood was almost too good.  So good that the final product seems like plastic.

I agree with you about the art (or perhaps craft...) but if the final product really does seem like plastic to you, then I can't help you. I think it is bizarre for somebody to look closely at one of these wheels, look at the photos on this thread, and still talk about 'plastic'. 

50 minutes ago, SpeedRoo said:

Interesting that Nissan/Datsun never referred to it as a wooden steering wheel in their sales brochures of technical publications.

Are you sure about that?