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Thread: My Martini RSR build project

  1. #31
    Senior Member uai's Avatar
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    Hi I'm not sure if you want to use the car in FIA (or in Germany DMSB) events, but if yes you'll need different cut off switches the old 2 pole are not allowed for usage anymore.

  2. #32
    Senior Member patrick911's Avatar
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    Thanks Uli, is it?
    Good points, and it's not just the cut-off switches, the newer regulations also require to have rollover bars welded in, whereas the RS/RSRs had the feet welded, but the actual rollover bar structure bolted to those feet.
    So I'm not going to be compliant at all. Now I'm not much of a racer anyway, and apart from the odd track day maybe, I just plan to take it on Sunday morning drives, roadtrips and clubruns.

    Btw, love your BMW 2002!

  3. #33
    Senior Member patrick911's Avatar
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    Question:
    I've read that the RS and RSR's had forged aluminium front cross members, ('Konradsheim', 'from R to RSR'), backed up by this topic here on earlyS, but when looking at the restoration pictures of R6, I'm confused.
    My understanding was that the aluminium cross member was exactly the same dimensions, just made from a lighter material, but this picture seems to indicate they're using something completely different on the original Martini RSR.

    I've seen forged aluminium cross members for sale and would like to buy one, but only if it's the correct one for this car.
    Anyone know what this is?

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    RSR aluminium cross member

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    Underside of R6 - cross member seems different - picture from the Maxted Page website

  4. #34
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    Earliest 911744 had forged but iirc later when weight was no longer an issue for homologatIon and looking
    make more profit I suppose later ones got series steel. Can't recall the cutoff offhand but pretty sure it is a known. Like other special RS parts the limited edition things ran out and things became much closer to series TES in a number of parts and processes .
    Don't know about R6 spec originally and who knows if through its life repairs replacements and restorations are authentically to spec?

    Later on aluminium reintroduced but cast with part number in G series. Comparison pictures are on this site somewhere

    More general question: I get the drive to fastidious authenticity and exacting detail on a genuine original Porsche Rennsport or such (and shame on restorers if that failed in that on R6) but have to say the concept of correctness to spec and authenticity is quite baffling on a declared replica -- when the car is by design a replica where to draw the line on details and authenticity? Whatever is done to replica is never the car it is aping? At weekend a friend and I saw a car that from a distance aped the Sebring 12h winning RSR cosmetically but had what looked like a 3.2 or similar very obvious on cursory glance through the rear grille. Disappointing and seemed to pull the rug out but on reflection if a replica maybe saved a shed load and was sensible/ok? Not criticising I don't know as I'd never do a replica homage so maybe don't get the whole homage concept?

    I've chipped in to thread to be helpful several times so hopefully not being rude but genuinely interested as I see projects like this from time to time and intrigued by the approach on such fastidious replica homage projects.
    Last edited by 911MRP; 07-22-2019 at 05:53 PM.

  5. #35
    Senior Member patrick911's Avatar
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    Quote Originally Posted by 911MRP View Post
    (...) where to draw the line as whatever is done is never the car It is aping?
    True, it's a slippery slope for sure.

    Steve, you're not being rude at all; Things like your contribution a few weeks back just make my day so thanks again for that!
    it's a very good question. As I stated in the very first post I'm obsessed with these cars but will never be able to own one, but I'd love to drive in and own something that is as close as possible to the real deal.
    Partly to compare how the almost same basis (my 1973 911 2.4T) could be modified by the factory so much that it won most of the races that year, but also because to me it's the best version of my favorite car.
    I guess part of the fun for me is the research and to try and find out exactly where I (have to) deviate from the original, learn and share on the journey.
    Then there's also like you say, there's so many Martini lookalikes out there, and when you get closer there's always something that bothers me. Turbo flares, wrong decals, right hand drive, etc.
    Maybe I'm a bit of a perfectionist?
    Last edited by patrick911; 07-22-2019 at 07:11 PM. Reason: added explanation

  6. #36
    Senior Member Darren65's Avatar
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    Quote Originally Posted by 911MRP View Post
    More general question: I get the drive to fastidious authenticity and exacting detail on a genuine original Porsche Rennsport or such (and shame on restorers if that failed in that on R6) but have to say the concept of correctness to spec and authenticity is quite baffling on a declared replica.......
    .....each to their own but I think the whole point on a project like this is about the detail and being as close as you can be.

    I'm never likely to own an original but I'm in the process of building a 3.0RS and want it to be more than a looky-likey; if you're going to do it, at least do it well.....I doubt I'll be as detailed as Patrick but the thrill for me will be the knowledgeable wondering if it's the real deal or not if they stumble across it. More importantly I want my car to feel and drive like a real RS and that's certainly achievable.

    Btw Patrick, I've never seen a photo of an early race that clearly shows a small mirror fitted and am a little sceptical in that respect. Even so I fitted one to my sports modified T because they're pretty cool and 'could' have been fitted in period so why not!

    Enjoying the thread, cheers

  7. #37
    Senior Member patrick911's Avatar
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    The chassis is almost ready for blasting and priming, so in preparation for the build up phase, which is a few months away, Iím trying to establish what suspension, wheels and brakes need to go on, and then search and purchase those required parts.
    Again, the intention here is to share the information that I collected over the last couple of years from various sources, and keep it in a single RSR related topic.

    Wheels
    The RSRs in 1973 had the extended flares front and back and were fitted with one piece forged aluminium 9x15Ē Fuchs wheels in the front and 11x15Ē Fuchs wheels at the rear. Nowadays these are very hard to find and very expensive due to their rarity.
    I had no choice but to go with replica wheels (for now). The biggest problem with them is the outside extra lip that the original doesnít have and the fact theyíre not one piece forged.
    It bothers me, and it identifies the car as a replica right away, so eventually I will buy something better.

    But before I could buy a set of wheels, I needed to understand what offsets the originals had, as the whole suspension, brake, (shortened) trailing arms and wheel setup for my project should be matching that of the original í73 RSR.

    The factory RSR had 9Ē et+3 on the front (911 361 020 03), where the +3 refers to a 3mm offset (et = einpress tiefe) toward the inboard (chassis) side from the centre of the wheel. For the rear the RSRs were fitted with 11Ē et -27 wheels, where the centre of the wheel is 27mm to the outboard (curb) side compared to the centre.

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    The Braid replica Fuchs wheels that I wanted have almost the same offset, the only difference is that the offset for the 9Ē front wheels is -3 instead of +3, so in effect these are six millimetres closer to the guard.
    Reading through a lot of various RSR replica build projects, this is what I found regarding safe clearances (elsewhere here on the forum):

    - For the tightest inner clearance in front on a 9", you could run a 9" et+18 with no spacer.
    - For the tightest outer clearance in front on a 9", run a 9" et-5.
    - For the tightest inner clearance rear on 11", you could run a 11" et+10 with no spacer.
    - For the tightest outer clearance in rear on 11", run a 11" et-32.

    Iím sure the poster would have tested this, but I havenít yet for my car, so in case I find this incorrect, Iíll update this post to keep the data correct.

    I would say that when in doubt, take a wheel with a more positive offset because you can always use spacers whereas with a too negative value you will hit the guards and there no easy fix for that.

    But for building a true RSR replica the solution is clear; 9x15 +3 up front and 11x15 -27 in the rear with Michelin TB tires all around and shortened trailing arms.

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  8. #38
    Senior Member patrick911's Avatar
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    Tires:

    Tires for the racing cars were – contrary to popular belief that they were Michelin TB15s – Dunlop Racing tires 230/600 – 15 CR88 in front and 260/600 – 15CR88 in the back. (road test document from 1973). I do however love the look of the Michelin TB15s, so there’s no doubt that those will go on my car. Other than that, I don’t believe Dunlop racing tires are road legal and are no longer made.

    Norbert Singer’s notes on R6 at the Targa Florio however show R6 being shod with 245/575-15 Dunlop slicks on the front and 290/575-15 on the rear.

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    Question then is, what size rubber needs to go on if those Dunlops are not an option?

    For the front I’ve seen various sizes being mentioned.
    The Michelin website indicates 23/62 – 15TB15s, but various forums indicate those don’t fit and should be used for the rear of an ST only. They seem to be rubbing the guards when steering, which is something you don’t want obviously.
    Harvey Weidman, Mike Moore and others here on the forum indicated in related topics that the 18/60-15 (215/55) tires are the way to go on a 9” front wheel for the RSR, which is what I will do too.

    For the rear wheels, most people specify the 26/61 -15 TB15 (295/40) tires, but there’s also mention of the 23/62-15 (270/45) as well.
    Comparing the rolling distance of the two tires, is looks as if the larger rear wheel is the better match with the front.
    (source: https://classic.michelin.com/en/Comp...-range/TB-15):

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    I'll hold off buying these until the car is closer to completion, but it feels good to have this already prepared.
    Last edited by patrick911; 07-25-2019 at 05:20 PM. Reason: spelling

  9. #39
    Senior Member patrick911's Avatar
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    related to the other topic in general info on 'belly pan dimples'.
    Without shutz/tar on both sides, they are open which obviously can't remain that way. My metal worker has welded them shut, and will leave the welds visible.

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    I love the unfinished look and it sort of makes sense to me that they wouldn't have cared back in '73 to clean/wirebrush the welds,
    but does anyone know what it really looks like on a real RSR?

  10. #40
    Pirelli makes a nice tire (P7 Corsa Classic) that will fit your car.
    They are used by tarmac rally cars nowadays.

    https://www.pirelli.com/tyres/en-ww/...-corsa-classic

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    Last edited by skinnerd; 07-31-2019 at 10:44 PM.
    -Doug
    1973 911E
    1971 914

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