Info 911s homologation 71' + info option M471 for my71'

[Andry911]

Good morning,
i am happy to share any information possible, you are experts and i am an attentive enthusiast.

I am certain about the originality of the car and its linear history.

I found the car standing still in a garage for 15 years, 3/4 of the first paint... its last owner had it for 40 (of which 15 were standing still) and he told me he had only done 3 oil changes in 40 years, but only for the age of the oil and not for use. The car has a service in the maintenance book, from the previous owner, with 72,000 km and the car today shows about 84,000.

In addition to the "classic parts for a 71' homologation", so sports seats, rear seat extensions (which i'm looking for because they are missing...the past owner, considering them useless, threw them away), rear backrests seats adjustment on two positions, Koni Sport (still the original ones, think that the car has tires marked 72'... same year as the first 5,000km service in its maintenance book), 3-point seat belts (with label reporting the coeval year of manufacture), rear bonnet and central bumper in aluminum. The only note not in line, the front bumper of the 72' series (shame, who knows what front bumper it mounted...).

One thing i need to figure out instead is the black rear grille and black letters; whether it was possible to have them or simply a change of the previous owner.

I am doing a slow and very conservative restoration (the car has all the original anti-noise, internal glues and under the window seals, etc.), so in these days we moved on, for a personal worry of mine, to the measurements of the sheet metal and we obtained a figure that still made us doubt...and ask questions:

the body panels such as sheet metal doors, front hood, all the fenders, the cross member under the rear window, the roof pillars (we will measure the interiors in the next few days), the rear hood, are between 0.8mm and 0.7mm.

Consider that the car has a low chassis number, date invoice 1 October 1970, so i deduce construction date September 1970; in the midst of the "FIA tourism group 2 approval" issue and the checks in the dealerships on the cars on display, by FIA agents, for the measurements.

You are much more expert than me, so what do you think ?

[70SATMan]

So, the car still has factory undercoating, factory sound deadening, bonnet and engine lid latches, full LWB interior trim, full bumper and rocker S trim??

If so, sounds like what the parts books state for ‘71S but, doesn’t sound like a ‘lightweight’ to me though as everyone has mentioned, ‘71 ended up an interesting year otherwise for the S.

There was only the standard front bumper in ‘71 MY. The ‘spoiler’ bumper arrived in ‘72. No black grill or letters in ‘72.

[Andry911]

I confirm that the car has all the original components, except as mentioned the front bumper (unfortunately), these black letters and rear grille (painted i deduce) which i assume are the result of an update by the previous owner, i add that it also has the prototype momo steering wheel, it is certainly another customization.

But the car has its integrity and originality overall and in detail (original windows, original gaskets on the couplings, original tank gasket, etc etc), the finishes are also all contemporary (at least to my knowledge) for the 71' S model, while the 3-point seat belts were an accessory.

On the bodywork and sheet metal thickness issue what do you think ?

[70SATMan]

Well, I let more knowledgable others answer that. I’ve not really dived into that pool before other than offhand reading about the STs supposedly having some lightweight panels as well as the RS first series cars.

[Andry911]

Thank you very much for your contribution Michael !

[HughH]

I think there is some confusion as to what is a "lightweight" in 1971. In fact there were 2 levels of lightweight 911S's in that year with only a couple of cars (less than you can count on one hand I think) that had thin shells and they were left over lightweight parts from a small run of all the relevant lightweight parts that were initially specially made in 1969 but were not all used up by the end of the 1970 MY.

In the 1970MY, for homologation purposes, ALL 911S's were constructed as "lightweights" - ie stripped down with less trim, thin carpets etc like a T BUT with standard weight steel panels. So they were like the 1968 TR's a 911S in a stripped out car that was trimmed like a 911T inside and a few other things like external trim replaced by tape etc

A small number of these were sold as road cars, or the basis of a competition car for clients to use, and some were used as a basis for factory built ST' s. However MOST of them were then equipped with "option M470" which put back the more luxurious trim found on the E model (as S model in other years). However as it was an OPTION that was not counted for homologation purposes .

In addition there was a very small number of proper lightweight shells with thin panels and other parts of the bodyshell that had been constructed in 1969 in one special run. They were used, along with the stripped out interiors etc for the factory use ST's as well as some track cars for special clients. Various estimates have concluded that probably no more than 44 of these special shells were ever made.

These are usually called "rallye 930kg" shells and are notated as this when used in the build book.

In 1971 MY the homologation number of cars did not matter as that had been achieved in 1970MY. So the standard S now had the full trim and weight built into it and they reversed the option - now to get a trim delete (like the T inside, probably lightweight door panels and trim delete for the exterior) - and that was option M471 (just lik it became in 1973 for the RS). So in effect the 1971 M471 car is the same as the 1970 911S without option M470 - ie the 911S homologation version BUT not the super special 930Kg "rallye" shell one

However in almost every case they were standard shells and in only the couple of cases where left over rallye 930 shells were used (and noted in the build book) were they ever "proper" lightweight lightweights

I hope that helps

[Andry911]

Many thanks Hugh!

I read your content with pleasure and i find myself as a logical thread in your timely clarification between M470 1970 and 1971.

I feel like doing a little more in-depth analysis regarding the M471 option for 1971, since i have not found evidence up to now that it excluded the M470; therefore considering what happened with the failed homologation group 2 tourism and the checks that FIA inspectors did in the dealerships already on the very first cars delivered, one could think that the M471 is something different than the M471 of my 73'.
In fact it is true that for the Carrera RS with M471 it was assimilated a bit to the "Whitout M470" of my 70'.
It should also be considered that for my 72' instead the M471 was completely different... So it makes me think that the M471 for my 71' was not what we believe, unless there is some evidence that i would like to see.

Another topic where i fully agree with your line is on lightweight body:
it seems to me that a lot of light is being shed on the fact that M471 does not always mean lightweight body.
The latter are probably the prerogative and exclusive use between 1969 and 1972 of special cars, as you write, for competition use in official teams or selected customers, always for sporting purposes for important races.


Now i come to this car of mine:
today i went again and with much more attention to measure the thickness of the bodywork sheet metal with professionals (where possible).

We took measurements with a professional ultrasound instrument and repeated the tests several times on various points...the car has variable sheet metal: between 0.6/0.7 (doors, rear bonnet, front and rear fenders, horizontal sheet metal between front hood and glass, roof, front bonnet, internal sheet metal of dashboard instruments and internal sheet metal of doors) 0.8 (rear internal central tunnel, front cross member behind bumper, sheet metal between rear glass and rear bonnet, rear central bumper, sheet metal of side sills, upper shock absorber attachment sheet metal).

I would like to point out the originality of the car, i am absolutely certain of it, all the sheet metal is original and the car was 3/4 first paint.

I do not have the adequate knowledge to ask for a copy of the construction register, but if someone has them...i would be very happy to draw on this possibility.

From a certain point of view however, i am writing it just as a pure reflection, i am not sure that on that register we would find written "Rally 930kg"... perhaps it was written when the chassis were officially intended for competition setup ?!
My car has lived a completely road-going life.
I wouldn't want that in the midst of the brawl over group 2 homologation, the first cars - series - that were delivered to dealers (see FIA ​​inspection), were delivered "sample" (and with special features) to respect the weight of 960kg declared in the request form and with the complete 71' homologation setup...
I assume this, i have no evidence, but rereading in detail the troubled history of 71' homologation...i would expect almost anything!

Hugh, what do you think of this car ?

Regardless of the M471 package or not, is it in your opinion a lightweight body ?

[HughH]

In answer to your last question - no i dont think it was a lightweight body . In 1971 there were hardly any of them and they were reserved, as far as i know, for a small number of German based privateer racers

What market was your car delivered into? My understanding that option M471 was not available for USA market vehicles in 1971
This is a copy of an options list for 1971 and it clearly says option M471 is "Sport equipment (only 911 S coupe) not with US equipment"
what it actually consisted of was the opposite of M470 the year before - ie taking back out all the things that were put into the 1970 car to make it "acceptable" for the general public - ie the trim levels of the 911E (which were standard on the S as well in all years but 1970), and exterior trim, badges bumper over riders, etc that had been deleted and replaced with either tape or nothing



M470 normally was used to upgrade T's to S comfort level apart from in the 1970 year where was also used to add back the options to the stripped out 911S

it was M 470 : Comfort group for T-model:

• Velouren carpeting
• Gold ”Porsche” nameplate and model number
• Aluminium door sills
• 911S rubber mouldings on bumpers and below doors
• Chrome rocker panels
• 911S instruments
• Rubber bumperettes
• Leather covered steering wheel

Somewhere I have a list of M471 changes for 1971 but I cant find it at present However this is the 1972 one and should be very similar - ie slightly more deletes compared to the "add ons" in 1970



here is a photo of a 1970 Homologation car for comparison




and a known 1971 M471

[Andry911]

Many thanks Hugh,
yes everything corresponds for 1970 and 1972 (in this year it absorbed some parts from the "old" sport purpose catalog, which i'm not sure it did for the previous year).
If you find it, it would be very interesting and useful to read the parts list of the M471 package for the 71' homologation, it closed a rim.

Back to my car:
it was delivered new by the dealer in Turin in Italy, it is not among the US models.

Regarding the lightweight body, in your opinion those thicknesses are normal ?

So it is just a note in the construction register that makes a car lightweight or standard ?!
I say this with the utmost respect, it seems very reductive to me.
If the standard bodies are from 1mm to 1.25mm and my car has all parts from 0.6/0.7 to 0.8... how can we say that it is not a factory lightweight body ?!
I am also restoring a S/T with a wonderful sporting past in Italy, i know the cars and the chassis, for this reason i allow myself to have more certainties in what i write.

[HughH]

It is not really the note in the build Book, but that is the best way to actually prove it
If your Car has .6 to .8 mm parts on it especially the external panels and the panels around the floor at the back and across underneath the dash it is quite possible that it is a lightweight construction car
it is just that given there are so few 1971 model Year cars that had genuine lightweight construction the best way to be confident that that’s how it was built would be to see that recorded in the build book
I don’t think you have shared what the Vin number of your car is and the fact that by 1971 there were no kardex Available and all the information was on the computers at Porsche makes it harder to ascertain exactly what it is
Have you got any documentation from Porsche on the car?
Also, are you willing to share the Vin number of it?

The other thing is you have to look at whether it is a M471 and then if it is a special lightweight shell completely separately to the other issue of Porsche trying to homologate the 911 as a 4 seat touring car (the rear seat issue) - they are not related in any way

The other compelling piece of evidence would be something like this if your car was German delivered and lucky enough to still have the original Kfg

However as an Italian delivered car it would not have one of these