My Martini RSR build project

[gled49]

Patrick, these original flares are not rolled, I asked my body guy not to roll them when installing. Flat lip is about 1/2” wide

[patrick911]

Thanks. I get that, the flares I ordered from Aase in the US were also not rolled when I received them,
but the question is more, how were they used?, as I can imagine the tires hitting these sharp pieces of metal would not do them any good.
I've seen RSR pics where they seem completely rolled, others, like the one above where only the top bit is (which makes sense in light of the earlier comment re: hitting tires).

I really like to see a few detailed (preferably period) pictures that show what the state was when they raced (rolled/not rolled/partially rolled).

[patrick911]

Just got reminded how all details matter.
I was checking the 'flares' thread in the 'other Porsche passions' directory, where I saw the discussion on the flares being either lap-welded or butt-welded.
I had no idea and just assumed that they were butt-welded originally, which is what we did.
However, checking the Maxted-Page site for the pictures of the recently restored R6, it seems to indicate they may have lap-welded them... too late now to change.


^ Picture taken from Maxted-Page site - seems to show the flares are lap-welded.


Finally, a question: I see this extra ring on the rev counter on R6.
We obviously need to replicate this but does anyone know what it was for?


^ Picture from maxted-Page website. What's the ring for?

[911MRP]

Hi Patrick

If using the MP site for reference on your bid which seems to be a theme how are you validating what they did on their workshop is to original spec? Not knocking them as not used their services but many things get done thought to be as original factory spec by restorers anad shops?

I leave aside the whole it's a limited edition homologated 911744 that was hand converted to M491 and then used as racecar so lord knows what has changed ...my question is more on seeking to do a replica wat is the reference point for minute details?

Enjoying your project and certainly not criticising just the whole faithful attention to original detail but ultimately a replica choices that get made intrigue me

Cheers

Steve

[patrick911]

Hi Steve,

The recently restored original R6 martini car (and the pictures on the maxted-page website) is obviously one of the sources we refer to, but Jason's (my metalworker) knowledge on these cars, the Carrera RS book, heaps of period pictures, the R-to-RSR book, other projects, and the pbase site, discussions here, etc are all adding to the knowledge base.
And when in doubt, I will use period pictures obviously over any current restoration.
And yes, I've noticed that Maxted-Page has made a few 'mistakes' with their real build (like the position of the front rubber tie-downs), and that's OK, as mine obviously will have a few things too; it'll be near impossible to get it 100% right, not least because as you say, they were limited edition, raced (hard) & modified through the season, etc.

In the case of the ring around the rev counter, I've seen this on [period pictures of] the sister car (911.360.0020/museum car) as well so I do believe that M-P have researched that correctly.
Just don't know what it is for?

[patrick911]

I think I worked it out; it is a VDO tacho out of a Porsche 908. (!)

When looking for pictures I noticed that the R6 (0588) and (R7) 0020 cars both had this ring, and looking a bit more into it, it shows that the tacho those cars have, is same size as the two dials flanking it, so it's smaller than the standard tacho.
I also noticed that the layout differs. the standard 10,000rpm / 30,000imp RSR tacho (item 911.641.304.00) has the "1" (1,000rpm) at about 7 O'clock position and the "10" at 4:30 position, with the info on the bottom centre and the left/ right indicator lights flanking the "5".
The works RSRs however seem to have the '1' at 4:30 position and the '10' at 1 o'clock. with "VDO" at the 3 O'clock position and a different text on the bottom centered.

The below pictures are those of the restored R6 and a 908 and to me the tacho's seem to have identical faces, so it would make sense, if the 908 tacho weight even slightly less, they would have fitted it.


Now who's got a spare Porsche 908 tacho they want to measure and part with?

[geneulm]

This is a mechanical tach, not electronic. Significantly smaller diameter than the electronic versions -- I have a later GR4 version, which was used up through the GRB era. Will see if I can dig through my stash and find it.

[Mr9146]

This is a mechanical tach, not electronic. Significantly smaller diameter than the electronic versions -- I have a later GR4 version, which was used up through the GRB era. Will see if I can dig through my stash and find it.

Do you have the all the parts? That would be cool!

[geneulm]

Yes. The factory made a pto off the right cam bank for most. Later version had an adapted oil scavenge pump (935, 956, 962). Originals and replicas can be had. One could probably be fairly easily be made using Lucas tach drive bits.

FYI. The internals of the mechanical vdo tach look SHOCKINGLY like the insides of a much cheaper Lucas racing tach.

[patrick911]

thanks guys,
yes I'll figure something out with a 'cheap' or broken 100mm diameter VDO dial and some VDO or Lucas internals with a custom made face as this 10K racing tacho.
I'll report back when I've got something made up.

Darren scared me a bit yesterday in his 'flares' topic (other Porsche passions), where he indicated that the shock towers on RS/RSRs had to be bigger (Carrera RS book states that the FIA application for this asks for the size of these domes to be increased from 85mm diameter to 100mm.), so that coilover springs could be fitted without them rubbing against the metal, which made me check if this was a thing for 2.8RSRs as well or not...

The thing is, if you look at pbase or some restoration pictures in magazines or in books, there's 2.8 RSRs that do have these bigger shock tower turrets.
I think that's probably because they took the option to fix these springs onto their cars as soon as it got approved, to stay competitive in the subsequent seasons, because the use was not yet approved in 1973.

The FIA/CSI homologation application (update 15/4e on application 3053) is active for chassis 911.460.9001 and later, and was approved on the 1st of August 1975, so not for 2.8RSRs. I'm sure they may have experimented with these in group 5 (as these requests were all lodged for group 4) earlier, but not likely in May 1973.

The real R6 that Maxted-Page restored doesn't have them, and although that doesn't mean a whole lot, the sister car (the museum car 911.360.0020) doesn't either.
It would make sense that the car in the spring of 1973 would not have them, but then again, they were prototypes, so who knows when they did start using them in protos?

Whilst we're on the topic of FIA/CSI homologation, I listed somewhere in the introduction that the car would be as it was at the Targa Florio, and below is the overview of changes/allowed modifications that Porsche requested after it's initial homologation of the Carrera RS for group 3 (application 3053) in October 1972, for chassis 911.360.0001+
The question though remains, which options were on the factory RSRs that raced as prototypes in group 5 before this was approved for group 4?

1/1: group4 from 10/1972 onward: 917 brakes, front strut brace, clutch disc modification
2/2: group4 from 10/1972 onward: rocker arm, high butterfly stacks, 4 bearing camshaft, twinplug cilinder heads, 92mm cilinders (=2.8L)
3/3: group4 from 10/1972 onward: wider flares front & rear, central oil cooler
4/4: group4 from 10/1972 onward: different fuel tanks (85L, 110L, 120L FIA FT3 fuel cell), fuel filler through hood
5/5: group4 from 10/1972 onward: option to replace the 2 batteries left and right and have one in the smuggler box
6/6: group4 from 12/02/73 on: raised spindle in front shock from 108 to 126mm
7/7: from 01/04/73 onward: 7J front and 8J rear (which allowed them to use the 9J front & 11J rear)
8/1E: from 15/03/73 on (from 911.360.0901): shortened trailing arms and extended moved pickup points
9/8V: group4 from 01/07/1973: cover over spring plate, other cover over front A-arm mount
10/9V: group4 from 01/08/1973: central lock wheels
11/2E: from 05/05/1973: case changed from magnesium to silinum (aluminum?)
11/3E: from 01/10/1973: correction, reinstating 2 batteries

We know that the Group 5 (prototypes) ran the Le Mans race in June 1973 with centre lock wheels (approved for group4 only later in August that year), we also know that R6 drove the Targa with the initial 3.0 engine that was still magnesium (aluminum cases were approved the week before the Targa), so when did the 1973 RSR start to experiment with coilover springs, approved generally for 1974 cars in 1975 only?