'73 RS glass question

[BeauneYard]

Hello 1973 RS aficionados.

I have a few question on ’73 RS glass…

…similar to my ’73 RS magnesium to silumin crankcase question a few weeks ago, my glass questions might not have a definitive answer.

Would all first series cars built for homologation have had Glaverbel glass installed? What about second series cars? My understanding is only the front windshield and the side-rear windows used lightweight Glaverbel glass.

Did all 1,580 RS’s manufactured have Glaverbel installed, lightweight Glaverbel for the first series (and second?) homologation cars and normal thickness Glaverbel for non-homologation cars? Or, was there a second glass manufacture for non-homologation cars, and cars converted to M472 trim?

Did first series cars ordered by customers in M472 Touring trim, return to the factory and have the lightweight glass replaced with thicker glass, or would the lightweight Glaverbel have remained on these cars? I believe the M471 models had fixed rear-side windows while the M472 Touring model had pop out rear-side window. Does this mean all glass would have been swapped out for thicker glass on first series cars converted to touring trim, or would the Glaverbel light weight glass have been installed in the pop out rear-side windows?

Thanks again - stay safe and healthy! - Cheers

[928cs]

May I suggest you to read this book first?
https://www.tag-motorbooks.com/carre...nglish-edition

You should find a lot answers, but as usual with Porsche, there is never a rule without expection

After that, spend a lot of time with owners and inspect their cars.

And in about two to three years, you should be ready to buy an RS 2.7, without much help

It is always a gamble to buy an expensive car, but keep in mind that the RS 2.7 is certainly one of the most faked car in the world, and their lifes were complicated.

[911MRP]

There is a thread on this but in short ( some? all?) early Sekurit roll up windows on 911744 were thinner than 73 series TES. Measured examples in thread support information published. Porsche did a cost benefit review reportedly on some window glass options beyond windscreen and fixed rears on some sport.

Windscreen of thin glass proved fragile one or two of the thinner ones are said to survive on M471 and 472. Once again in any such discussion there is need to segment 911744 by series (not generalise across lifecycle of 911744 or just think simplistically M471 vs M472). Some later M471 got opening rear vents when Porsche couldn’t be “RSed” to make the later M472 and M471 RS Sport (sometimes misleadingly called called lightweights) using special limited edition lightweight parts. Yes they ran out but if serious they could’ve ordered more. No need to take time and money to do it to original proper spec as by then they are not weighed or homologated with possible exception of a very few... although without a later example being a vin expressly mentioned in a FIA paper many of these could be debated.

Also agree invest in that well regarded tag reference book if you are thinking of investing in RS —not flawless — does answer a lot, many details examined some despite factory access a bit vague or skimmed over — but very useful for serious buyer.

also search here is your friend on all manner of minutiae on RS

[rower]

The answers are out there.

I believe you are confusing Homologation cars with those that got weighed for certification.
They needed 500 cars to homologate. They pulled some out that were stripped to get them weighed.

The m471 and m472 cars were identical coming down the assembly line. Light steel tubs, lightweight glass etc. The only difference was bolt on parts like the bumper, trim and the interior.

Both had lightweight windshields. My series 1 touring is the only one I am aware of with it’s surviving lightweight windshield (it’s a 35km car). I’m told the museum may have another.

At some point post series 2 the supply of thin metal tubs, glass, etc started running out and the cars became more like a normal S.

(And that’s just dust when this picture was taken)

[BeauneYard]

Thanks guys. I do have the book and found the reference to Sekurit as the door/rear pane glass manufacture and Touring models having “series-production” glass, my oversight. Most questions answered. Posted for reference.
Cheers

[BeauneYard]

The answers are out there.

I believe you are confusing Homologation cars with those that got weighed for certification.
They needed 500 cars to homologate. They pulled some out that were stripped to get them weighed.

Thanks rower, I was under the impression all homologation cars were weighed.

[911MRP]

If you search for the thread I referenced it shows examples of m472 having thinner than series production Sekurit roll-up Door windows as measured by owners in the last few years so evidently some left the factory with thin Sekurit roll down windows of that thinner than normal i.e. had for glass of that unique to RS Sekurit specification in the book extract posted.

Afaik each and every one of the first 500 series initially planned and then the just over 500 more they made to for the other group certification were individually and independently weighed at the Stuttgart town scales — independent weight noted for each chassis number important to provide the proof to FIA that 500 distinct examples had been ordered and made to the homologated weight spec. Then 500 more.

I’d be interested in seeing in period evidence showing which , (if any), later series examples beyond that circa 1000 known to be weighed were also taken to the Stuttgart town scales. While a handful or so ( iirc seven?) of the third series were “0“ so did not leave with M471 or 472 — homologation spec — is there any evidence of a visit to the scale of any of these or indeed any other third series chassis.

A subtle point but.. there is a difference between being built to homologation spec (annotated zero no M471/2 ) and the factory taking the action to independently weigh these later ones at town scale to provide proof of their weight to FIA by that stage. I am not convinced the later cars called “homologation” were ever weighed although eager to see period evidence to contrary.

Simply leaving factory in the cheapest “homologation spec“ may not actually equate to certifiably being recorded as a chassis that was actually weighed to get to homologation approval for 911744. A point that maybe gets confused on the word homologation.

To illustrate one country (Switzerland) price list of March 73 shows a sales price for RS and the m471 and 472


There may be similar three level price cards from other countries where such cars ordered but this price-list is to hand

So ....if a customer ordered a RS at the (lowest) sales price without paying the extra m471 or even more for M472 did the factory build that one from thin panels other limited edition parts then take it to Stuttgart scales and put it through formal FIA homologation steps as a consequence? Doubt it! The trigger to build a car to homologate a modification (like suspension) would be engineering led surely? For that reason I remain sceptical that third series “Homologation-spec ” cars in each case always had formal FIA homologation role (leaving aside the couple of VINS known to have named on fia papers for a modification e.g for rear suspension geometry or silumin)

By way of comparison I believe there is unarguable proof that all the first circa 1000 were built to precise spec weight target being a key factor and used for formal homologation certification purposes — so these ones are by definition all homologation cars — regardless of whether converted or the couple of handfuls among that first thousand that were “0“ so were not converted.

Splitting hairs? Semantics on homologation. A general car board distinction too far, maybe, but maybe not on ESR, When homologation spec third series might command a big price premium over a car from first 500. If folks really understand distinctions and happily pay for the “0” small numbers rarity then fine, but if it is a premium paid thinking it is for that chassis some big deal formal homologation role in series 3? Particularly if many of the limited edition elements for homologation ( like thin glass) no longer always done by that stage for commercial or pragmatic parts supply reasons.

Open as always to see evidence from back in 73 rather than drawing upon later surmising - interested to see hard proof to the contrary.

Steve

[rower]

This gets more complicated.

Yes, From what I understand the 500 were weighed and then sent back to have the weighty options of the 471 and 472 put back in.

However, I am confusing that with the 17 Homologation cars that were sold in the spartan trim. (People refer to this as the Homologation cars, and Porsche apparently considered calling them RSH. Dick Moran, who I bought my RS from, collected many).

Interestingly, not all of the 17 H cars had the lightweight steel, apparently, as they were running out by Series 3. (Apparently the steel saved 21 lbs). Glass ran out, aluminum front cross member, etc.

My touring also has the lightweight side glass too, so not confident that only the “lightweights” had it.