1972/73 RS Carrera Cars: Use of thinner steel Light weight

[bell 904]

Hi I am a private Porsche enthusiast and new to 1972/73 RS Carrera cars. I am a bit confused about the use of thinner (0,80mm) steel in the manufacture of 1972/73 RS Carrera cars and about the use of the term "light weight". Therefore, I would very much appreciate a response to my following questions:

1.) Did the use of thinner steel (0,80 mm) depend on the type of car (M471,M472,M 491) or on the production date?
2.) Is there a(n) (official) record for which VINs thinner steel (0,80 mm) was used?
3.) Was the use of thinner steel limited to the manufacture of Type M471 (S) and M491 (RSR) cars,or
4.) were also type M472 cars manufactured using thinner (0,80 mm) steel?
5.) Were all Type M 471 cars manufactured with thinner (0,80 mm) steel?
6.) Does the use of term "light weight" under common understanding refer to type M 471 only or to all cars for which thinner steel (0,80 mm) was used?

Thank you for your assistance

bell 904

[69Sman]

I'm sure my answers will be contradicted, and that you will get MANY MANY conflicting replies. However, to the best of (well researched) knowledge:

Hi I am a private Porsche enthusiast and new to 1972/73 RS Carrera cars. I am a bit confused about the use of thinner (0,80mm) steel in the manufacture of 1972/73 RS Carrera cars and about the use of the term "light weight". Therefore, I would very much appreciate a response to my following questions:

1.) Did the use of thinner steel (0,80 mm) depend on the type of car (M471,M472,M 491) or on the production date? ANSWER: The thinner sheet metal was used up regardless of 'M' status. IT was more or less date based.

2.) Is there a(n) (official) record for which VINs thinner steel (0,80 mm) was used? ANSWER: It is widely believed that right around chassis #1036 the thin sheets started to run out, and/or around April/May 1973.

3.) Was the use of thinner steel limited to the manufacture of Type M471 (S) and M491 (RSR) cars,or
were also type M472 cars manufactured using thinner (0,80 mm) steel? ANSWER: M472 cars were fitted with the thin sheets, as long as it was available.

5.) Were all Type M 471 cars manufactured with thinner (0,80 mm) steel? ANSWER: No, not the later cars, to the best of my knowledge.

6.) Does the use of term "light weight" under common understanding refer to type M 471 only or to all cars for which thinner steel (0,80 mm) was used? ANSWER: To M471.

Thank you for your assistance

bell 904

[bell 904]

Thanks for the very helpful reply

[Robert5995]

Bell -

If I were you, I would round up one of the Konradscheim Carerra RS books. It will answer lots of questions!

- Rob

[davep]

Okay, I'll stick my neck out here.
As I understand it, Porsche had to build a certain # of cars to a specification in order for it to be homologated for a particular racing class. Initially 500 were proposed, then a second lot of 500 then finally 1500 plus. The first 1000 were built, weighed on a certified scale and thus the series was homolgated. After weighing, the cars went back and were converted to M471/M472/M491 or not. Thus at least the first 1000 had to be built with thin gauge steel regardless of final type. So far as we know, only the RS got the lightweight panels along with reinforcements. The production # does not distinguish between the "RS body type" and the regular coupe. After the 1000 cars were built the factory used up the remaining lightweight panels, and not all cars got a complete set. The last 500 cars almost certainly had the standard panels with rare exceptions possible, and these could be M471 or M472 or M491. So far as we know there was no official record after the first 1000 cars. So an RS lightweight would only refer to all cars for which thinner steel (0,80 mm) was used.
This post is just one I selected out of a thread of about 140 pages:
http://www.early911sregistry.org/for...l=1#post883236
It would be best to read the whole thread.

[LongRanger]

. . . Porsche Classik release . . .

http://www.early911sregistry.org/for...auge-rs-panels


. . . and already NLA?




.........................................

[911MRP]

The few (7?) lighter panel parts that Porsche Classic released a few years ago were just a subset of the thinner gauge panels used on the first ~ 1000 that Davep and 69Sman refer to. There were other thin guage panels used on those ~1000 lighter-weight chassis used to achieve the homologation goals. Twelve thin guage panels is what factory used according to an old document list I've seen on this point.

Thinner panels in some cases like roof and door skin are quite evident if a relaxed owner allows hands on . Other thin panels were less accessible spots, even of owner is willing to prod around.

So an RS lightweight would only refer to all cars for which thinner steel was used.
This post is just one I selected out of a thread of about 140 pages:
http://www.early911sregistry.org/for...l=1#post883236
It would be best to read the whole thread.

I agree but don't expect this distinction in normal usage as "lightweight" has become misused and at times misleading term rather than the original terms Sport and Touring or M471 or M472. RS"L" meant Touring in 72/3 for crying out loud but term RSL is sometimes used now for M471 by some as long term owner Jeff once pointed out! The original question did ask about common understanding of " lightweight" however.

This extract from factory RS Technische Information sheet dated 25 October 1972 the month of the launch of the model does not use designation "lightweight" for the Carrera RS Sport -- so I would propose on this forum we don't use either as we should be beyond "common (mis) understanding" particularly when the term becomes potentially misleading given how the bodyshell panels and vehicle configuration evolved.


When I hear somone refer any and every M471 as "lightweight" it confers on them the same credibility as the person who loudly declared the nice RHD M472 recently returned from NZ to UK was a replica! Or folks who still think the RS were all white. Etc

I would however expect on this knowledgable specialist forum like Davep is proposing to have the ability to discuss the different configurations and variations of Carrera RS as it evolved clearly. If the different font size of toolkit wrenches is now quite clear after lengthy thread debate I'm optimistic the factory deliberately choosing to source and fit twelve different thin gauge panels for ~1000 cars at time of building and weighing each body shell to be lighter weight for homologation purposes isn't too insignificant detail to fathom . Agree there will be some with mix during transition around 1036 that wil not be known. But later on almost certainly no light panels left so why call ALL these M471 lightweight. Lightweight in early RS goes beyond the gauge of a dozen panels, regular paint not dimpled paint on the early cars eg rear chassis rails, plastic horn push, front crossmember and so forth. All M472 by implication if not lightweight are heavyweight... Really? Heavier in weight due to customer M472 conversion order trim granted but still these are the lightweight bodyshell the factory homologated because each chassis was demonstrably proven to be a lightweight at Stuttgart scales and recorded so by FIA. Subsequent chassis not ( usually) so. In fact most (if not all) of those 500 later chassis known to be not built lightweight bodyshell due to e.g. metal gauge, dimpled paint in those areas, different rear bumper, series rear quarter window, change to cross member and so forth.

There maybe were a few oddities among late ones if some theories on specific homologation purpose among late examples is ever categorically proven and undoubtedly some got made with mixture as limited thin panels run out but... beyond that mid 1000-1100 range by default these days any and every m471 labelled "lightweight" just being accepted terminology ... hmm!

Don't see "lightweight" term used in the factory 73 model price list for M471 so why should they be called that now?
There was a list price for the Carrera RS without paying for M471 or M472 but that configuration is not designated "homologation" in any in- period price list or literature I've seen yet -- it is simply the Carrera RS. For whatever reason a few owners chose to forego conversion maybe even happy to live with e.g. compromised 165 tyres on a 150 mph car or mired likely do own work post delivery to change the mist basic cinfigurstion to suit their intended purpose.

Regardless ~1000 of them were documented as being weighed when presented at scales with light bodyshells evidence to achieve homologation goal ..but hundreds of other examples later on in were not!

Frankly I still don't know what to make of this in the kundendienst-information for RS which has a different fahrzeuge after chassis 1000. Rather sends a signal that after the 1000 was made the factory considered those with vin above somehow different -- something that is mirrored in how they moved to use standard series ordering procedure and consolidated to more normal series production processes once the limited edition homologation purposes cars were accounted for. There is to my mind evidence of a difference in essence between first 500 plus 500 and remainer that is another topic much broader than thin panels. A cynic might say factory was (for majority of them) milking the unexpected success of the homologation cars but taking profit by eliminating the complexity of initial limited homologation series cars by simply moving to the operating norm in things like procedure, process, components when compared to the earlier specially managed limited edition of ~ 1000 .

Later almost certainly heavier chassis made with much more regular series production methods / components in M471 trim called "lightweights" are considered more valuable than those specially designed, built and controlled first or second series RS ... really? Go figure!




S

[davep]

I guess that part of my thought process was that the first 1000 were weighed and recorded for purposes of homologation. At the time of weighing, the cars would have been outfitted as lightweights. After the weights were recorded and the cars converted to customer specification I presume that many would lose the overall lightweight status; the chassis would remain untouched, but the trim would gain weight. There are many shades of grey here; and absolutes are treacherous.

[69Sman]

I have a document from Porsche regarding all this. I scanned and posted it once, LONG AGO. I will try and dig it up, and post again. It basically states what I already stated: thin gauge steel started to run out around chassis #1036, and it was used up on post chassis 1036 until it ran out completely, and then the regular gauge steel was used. NOBODY KNOWS how many cars numbered 1000-1500 actually received thin gauge panels, and/or how MANY panels were thin vs. regular. NOBODY KNOWS.....if you really want to know? Invent a time machine.

[911MRP]

Agree we will never truly know about the details and supply pragmatics of that period of transition just over the 1036 mark but beyond the "say for argument and ease of maths there were roughly 80-90 " transitional examples, few would argue that (m)any of the remaining ~500 or so of that third series categorically got full complement of thin lighter panels. If any light panels at all. No lightweight bodyshell for them then, not in same sense of those previous ~1000 examples that certifiably to FIA did.

Don't doubt at all that vin 1036 specifically defined a milestone point in RS model lifecycle (for example thin gauge parts depletion and or formal end of second series run of 500 having achieved the original homologation goals).

The figure of just over 1000 seems logical given the 360 0011 start number, the production sequence varying from stamped vin sequence. 500 plus 500 were sufficient as proof to FIA to achieve the two group homologations plus presumably a few as buffer. Between vin 1035>6 certainly seems to have some significance in other vintage factory paperwork I've seen dating back to original model research ....but those were not in a technical bulletin format.

I have a document from Porsche regarding all this. I scanned and posted it once, LONG AGO. I will try and dig it up, and post again. It basically states what I already stated: thin gauge steel started to run out around chassis #1036

It would be interesting to see your factory bulletin previously posted that refers to 1036. Document didn't come up in search of Early S prior posts today but the search for it shows it was alluded to in several threads ...old post and its attachment seems to have gone missing? The actual factory wording in that technical bulletin would be interesting to read directly if it can be reposted per the kind offer to do so?

Cheers

Steve