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-   -   8C 2900 B question (https://www.alfabb.com/bb/forums/limited-production-1910-1949/674524-8c-2900-b-question.html)

MALDI 01-28-2019 09:29 AM

8C 2900 B question
 
In the post linked below it states that the 1938 8C 2900 B has "a suspension designed by Porsche."

Can anyone confirm this? I was unaware that Porsche did any design work for Alfa Romeo.

https://carbuzz.com/news/rare-unrest...ver-20-million

PSk 01-28-2019 09:46 AM

I think they mean a suspension design first used/designed by Porsche on the Auto Union, i.e. front is by trailing arm's, like a VW Beetle.

Pete

MALDI 01-28-2019 10:45 AM

Thanks.

So "a trailing arm suspension first used by Auto Union" would be more accurate.

PSk 01-28-2019 11:26 AM

Quote:

Originally Posted by MALDI (Post 8368092)
Thanks.

So "a trailing arm suspension first used by Auto Union" would be more accurate.

Agree, note also that Ferdinand Porsche invented the torsion bar suspension.

I do not believe that Ferdinand Porsche was actually involved with the design of any Alfa Romeos.
Pete

PSk 01-28-2019 11:42 AM

1 Attachment(s)
You can see the Auto Union/Porsche design of front suspension in this photo of a 8C-35 (from https://www.ultimatecarpage.com/img/...-35-22091.html), which apparently the front suspension of a 8C 2900B is based on:

Pete

tubut 01-28-2019 12:10 PM

As I had the luck to be following the restoration of the 8C 2900B that won Pebble Beach last year, I believe I can share some of Simon Moore's notions regarding Porsche (and add some of my own).

It appears that Alfa realized in late 1934, as production of the 8C 2300 wound down, that a new suspension design was necessary to stay competitive (both in races and in the top-of-the-line sportscar market), and so Jano began a new design for an independent suspension of all four wheels.

There seem to be two Porsche project numbers that pertain to Alfa Romeo (project #63 for the front suspension, and project #69 for the rear suspension), but, while Simon Moore indicated at some point that Porsche sold rights to Alfa, I was told by people doing research in the Porsche archives that there seems to be no documentation about the exact scope of work and/or Porsche's involvement in the suspension design. Then again, Simon mentioned an original drawing dated 01-May-1935 that I have not seen, and to me it's unclear whether that was a Porsche or Alfa Romeo drawing.

The situation gets even murkier when one takes into consideration the "knee action" front suspension design patented by André Dubonnet and compares it to the 8C 2900 front suspension. Also unclear to me is whether or not, or to what degree, Porsche project #69 related to the gearbox and final drive of the transaxle rather than the quite ingenious 8C 2900 rear axle suspension geometry.

My personal opinion is that the notion of "suspension designed by Porsche" probably stretches too far. I have a hunch that there probably was too much pride in Alfa to completely outsource such an important aspect of car design, and a much more likely or plausible scenario would have been that Jano and Alfa made the initial design, and then approached Porsche to get a second and/or expert opinion about its design -- and for verifying their (Alfa's) calculations.

Let's hope that some day more documentation is found that clarifies what Porsche's exact involvement with the 8C 2900 suspension was.

PSk 01-28-2019 02:30 PM

Quote:

Originally Posted by tubut (Post 8368124)
As I had the luck to be following the restoration of the 8C 2900B that won Pebble Beach last year, I believe I can share some of Simon Moore's notions regarding Porsche (and add some of my own).

It appears that Alfa realized in late 1934, as production of the 8C 2300 wound down, that a new suspension design was necessary to stay competitive (both in races and in the top-of-the-line sportscar market), and so Jano began a new design for an independent suspension of all four wheels.

There seem to be two Porsche project numbers that pertain to Alfa Romeo (project #63 for the front suspension, and project #69 for the rear suspension), but, while Simon Moore indicated at some point that Porsche sold rights to Alfa, I was told by people doing research in the Porsche archives that there seems to be no documentation about the exact scope of work and/or Porsche's involvement in the suspension design. Then again, Simon mentioned an original drawing dated 01-May-1935 that I have not seen, and to me it's unclear whether that was a Porsche or Alfa Romeo drawing.

Very interesting. Note also that Porsche was a fan of swing axle rear suspension, and I think, the 8C 2900B uses that concept.

Quote:

The situation gets even murkier when one takes into consideration the "knee action" front suspension design patented by André Dubonnet and compares it to the 8C 2900 front suspension
Some P3's were fitted with the Dubonnet independent front suspension.

Ferdinand Porsche was a consultant engineer, so I guess it is not impossible that Alfa Romeo consulted him. He was renown as a suspension designer, although drivers of the Auto Union might disagree with that ;)

Note also many racing cars of that period had front suspension like that (BRM v16, and of course the 158/9 Alfetta, both a long time later to name a couple). I think other than the Dubonnet system it was one of the early independent front designs.
Pete

tubut 01-28-2019 05:08 PM

3 Attachment(s)
Quote:

Originally Posted by PSk (Post 8368190)
Very interesting. Note also that Porsche was a fan of swing axle rear suspension, and I think, the 8C 2900B uses that concept.

Yes, that is correct. The transaxle is attached to the frame and doesn't move (remember, the drive shaft turns at engine RPM). The swing axles are supported by a transverse leaf spring and dual-jointed trailing arms (on the outside of the frame rails) that also dynamically adjust the toe-in of the rear wheels throughout the suspension travel range.

The front suspension and steering are pretty sophisticated, too.

These cars are interesting and beautiful when you see them at events -- but absolutely stunning when one can study them from underneath on a hoist.

Attachment 1547624

Attachment 1547626

Attachment 1547628

PSk 01-28-2019 05:44 PM

Thank you so much for those 2 photos!

Pete

Max Pershyn 01-28-2019 09:12 PM

2 Attachment(s)
tubut,
sorry for off topic. I know the question is not for you but you might answer.

Does the car have any original part? Everything seems made nowadays except the engine sump and front suspension. I would not call it restoration :)

Just compare with the museum car.

PSk 01-28-2019 10:18 PM

Museum car is dirty and potentially under sealed.

If you cleaned it up it would look the same
Pete

Max Pershyn 01-29-2019 05:22 AM

Quote:

Originally Posted by PSk (Post 8368352)
Museum car is dirty and potentially under sealed.

If you cleaned it up it would look the same
Pete

Pete,
Museum car is original and looks the same as it it was made (because the engine was broken the car has not been used). Take a look at pictures from Fusi or any other book with a period photos. Cars have never been shiny underneath, the parts were rusty, unpainted, etc. The car from tubut post looks like Easter egg, it is perfect it looks like just made but not preserved. I understand it as American way of restoration (to make cars better than they were new). European school is to keep original parts, keep patina and preserve the originality. Take a look at cars from Lo Presto collection, they restored in a different way.

pescara 01-29-2019 08:59 AM

Maldi : it is possible that the suspension was designed by Porsche and that Jano has recovered the outline to fit the car. To copy each other's ideas is still done today in the automotive world.

The goal is to succeed the project, what managed Jano wtih immense talent, an incomparable brio...


Tubut : I am a little puzzled by a picture. It seems to have some "glass wood" coming out of a sill ? Could you explain me what part I am looking in this picture ? :nerd:

Chris

PSk 01-29-2019 09:40 AM

If I owned a 8C 2900B it would be immaculate everywhere ... and correct in details. The 8C 2900B is simply the best car ever made, **** right I'd passionately love it. I'd clean it with a tooth brush!

My 1750GTV will be immaculate everywhere when its restoration is finished, but correct.

While I appreciate some components were never painted by the factory, that does not mean you need them to look rusty. There is no law against cleaning your car ...
Pete

Max Pershyn 01-29-2019 10:50 AM

Quote:

Originally Posted by PSk (Post 8368498)
If I owned a 8C 2900B it would be immaculate everywhere ... and correct in details. The 8C 2900B is simply the best car ever made, **** right I'd passionately love it. I'd clean it with a tooth brush!

My 1750GTV will be immaculate everywhere when its restoration is finished, but correct.

While I appreciate some components were never painted by the factory, that does not mean you need them to look rusty. There is no law against cleaning your car ...
Pete

To clean them it's fine but to paint that was unpainted from the factory? FIVA will not approve it :)
I think FIVA is not involved in a judging of American concourses, this is the reason why over restored (I mean better than original) cars always win.

Pete, please read this.
http://www.fiva.org/wp-content/uploa...OK-ENGLISH.pdf

By FIVA standards the 2900 from Tubut pictures is FR =“free reconstruction” (reconstruction without using any historic model in terms of form, material or work technique. The part however fulfils the technical function of an historic component utilised earlier).
Or NB =“newly built” an accurate as possible a copy in terms of form, materials and make, reproduced directly from a documented original).

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