An amusing mystery: 1971 911S Coupé

[davep]

So I was minding my business when a member asked a question regarding a 1971 911S engine serial #. The number he was seeing was well above the normal range of serial #'s for the manual transmission engine type 911/02 6310001 to 6311959, but not in the range of the race engines types 911/2x. It turns out that some scratches changed the appearance of a digit, so it was a false alarm.

However, to my alarm I noticed that the reported serial range of the engine type only amounted to a total of 1959 engines, while the total 911S bodies was 2198. The Coupé range from 9111300011to 9111301430 and the Targa range from 9111310011 to 9111310788; so 1420 + 778 = 2198. Normally the quantity of engines exceeds the quantity of bodies by a small percentage, so a shortage of about 250 engines is serious. The highest serial race engine I know of is only 11; so the race engines are not likely to make up the shortfall. What about the Sportomatic? The literature of the time says that the 1970 and 1971 911S was not fitted with a Sportomatic; but perhaps a few custom made cars were made for special customers. There is also the missing type # 911/05 that would fit perfectly with a Sportomatic 911S engine. However, an exhaustive search turns up no evidence of a Sportomatic 911S for these two years.

Well, it turns out that having collected data over 50 years from many sources allows me to see that the highest engine serial #'s matches well with the highest chassis numbers. So both the chassis ranges and the engine range seem to be correct. There does seem to be an interesting anomoly though; I have 112 chassis #'s over the 911S Coupé range, so about 8% of the range. The biggest gap between two cars is 66 except for a whopping 252 car gap between 9111300842 and 9111301094. A significant amount of prodding of my sources for information resulted in the discovery that 236 chassis from 9111300852 to 9111301087 were not built. No explanation is known. I believe the time period is late March or early April 1971.
Further research is being done to find the production numbers from the cars before and after the gap; also needed are the production and chassis numbers of other Porsche built coupes with similar production numbers, and the production and chassis numbers of all Porsche built coupes near the end of the chassis ranges. Everyone with a 1971 Porsche built coupe is encouraged to send me chassis #, production #, engine and transmission #'s and whatever date information is available. Full CoA's are welcome.

[Bullethead]

That 236 production numbers were possibly just skipped is fascinating, Dave... subscribed and looking forward to the explanation(s)!!

[Dougieboy1]

I have an explanation......

i know it is hard to believe but maybe, just maybe, Porsche sometimes makes a mistake.

I have been dying to contribute to a thread on fonts for chassis numbers but i know i run the risk of being shot down by the porsche perfectionists.....

I will be the heretic here, Porsche staff are people first, Porsche employees second. Sometimes people make mistakes.

Does that work?

[HughH]

When Dave raised this with me a short time ago I thought it may have been to put aside some Vin Numbers for homologation purposes - maybe the rear seat "modification" to make it a touring car or something like that BUT the 2.2T E and S were already homologated from 1970 with continual updates so that thought seems to have been a dead end (and anyway not enough Vin numbers are missing for a bunch of them to be "put aside" for a project that did not seem to get off the ground). In the 1970 MY they did a run of ST's mixed in with the normal S's although there was a bunch of them in that February/March 1970 period where most of the "run" for customers was built that they almost had consecutive numbers. However there is no evidence of there being a similar series competition cars being contemplated at that time although it was a time of economic downturn and some financial and managerial stress at Porsche.
I seems very unusual and it also seems to indicate that there were way fewer 71S coupes made than the vin numbers and records, books etc suggest.

[911MRP]

If they couldn't count to just above tens thousand no wonder they soon brought in external management and changed from a KG

No doubt historians will have minuteae details behind the attached but this is how Porsche reported the " business year" in a press release. Without a date range pertaining to that in the text unsure of the exact period covered although suggests accounting year. The release is undated in my source appears to be published after the 1971 annual shutdown based on other material on the source and appearing in a winter 71/2 quarterly.

It caveats that the production figures are estimated

I'll leave the percentage maths on 911S and coupe Vs Targa etc to folks interested in such things. Figures reported to press on a factory press release may help triangulate to numbers quoted elsewhere.

Noted the comment about selling down existing stocks short work weeks from labour disputes and loss of sale 1.8 percent over previous year.


Steve

[davep]

I believe the 2 week strike was in November 1971, so in the 1972 model year; thus not a factor.
It is probable that the production reduction began in February (or very late January) 1971. Production was reduced from mid seventies to sub sixty daily; about 20%. Further it was said that an additional 3 or 4 days a month were cut from the work week.

I do have a theory that involves the assigning of the Fahrgestell-Nummer (Chassis number or VIN). The Fahrzeug Auftrag (vehicle order/production order) would have the Produktions nummer (production number) on it and the build particulars attached. Then the labels with VIN, engine # and transmission # are attached to the production order as the engine & transmission are installed and the VIN is assigned, the number stamped, and the tags attached. So, I suspect that if the printed label with the VIN or the tags are missing, then the VIN would not be used. Exactly where in the production process the VIN was assigned and stamped into the chassis sheet metal I do not know. I just think that they were forced by circumstances to skip all those VIN's.

[JackMan]

Subscribed

[HughH]

Dave

If your theory of a roll of vin stickers (or similar) going missing meant that they had to skip those ones I would have thought that a check would be to find the production numbers of the last produced (or nearest to last) T, E and S coupe to see how close that comes to the theoretical highest production number for Porsche built 911 coupes in the 1971 MY

My numbers (sourced from Aichele and taking of 10 for each of the T, E, and S numbers allowing the vin series to start at 0011 in each - but not the Karmann ones) suggest the highest coupe production number for Porsche built cars should be about 1015071. ie 4507 T's 1078 E's and 1420 S's. But 1934 T's were built by Karmann and thus have a different production number sequence so that should be deducted from the total..

But if there were 236 less S's the highest production number would be about 1014835, possibly a big enough gap to spot if the very last cars built can be identified. It cannot be done IMO by just looking at S's as I have seen evidence that they sometimes did a whole run of one engine variant together with them having similar but not completely consecutive production numbers (I think there was a run of T's at the end of the 73 run. My 73E was 60 from last of the E's but more than 1000 production numbers before the end of the 1973 Coupes)

So if there is a 1971 production number higher than 1014835 those "missing" cars would have had to be made. Likewise if we can find a very late build T E and S all with production numbers suitably lower than 1014835 that it is possible that those S vins were never used and instead of there being 1420 71S's there would only have been about 1184.

I already know of a very late build S (less than 10 vins from last) that has production number 1014834 - so there only needs to be a few small changes in assumptions like the vins did not all start at 0011, or the Karmann ones also started at 0011, or indeed for it to be made slightly out of sequence, for that to line up with the theory that those "missing S vins" were never made.

[brookedale091462]

"128 technical high school students were employed" the key to the continuation of craftsmanship and apprenticeship. The major failure of the US system of industrial stewardship.

If they couldn't count to just above tens thousand no wonder they soon brought in external management and changed from a KG

No doubt historians will have minuteae details behind the attached but this is how Porsche reported the " business year" in a press release. Without a date range pertaining to that in the text unsure of the exact period covered although suggests accounting year. The release is undated in my source appears to be published after the 1971 annual shutdown based on other material on the source and appearing in a winter 71/2 quarterly.

It caveats that the production figures are estimated

I'll leave the percentage maths on 911S and coupe Vs Targa etc to folks interested in such things. Figures reported to press on a factory press release may help triangulate to numbers quoted elsewhere.

Noted the comment about selling down existing stocks short work weeks from labour disputes and loss of sale 1.8 percent over previous year.


Steve

[davep]

Hugh, indeed we need to closely look at the production numbers of the late Porsche bodied coupes. Production number 1014834 Is currently the highest that I know of. I am attempting to find other late production #'s to confirm what we have been told. Getting people to provide VIN and production # combinations is difficult but critically important.