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Thread: Aluminium front cross member. First year?1973?

  1. #1

    Aluminium front cross member. First year?1973?

    I would like to know if the aluminium front cross member was used also in the late 1973 production.Many thanks .Gaspare

  2. #2
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    Calendar 73 ? Yes but in some post impact bumper
    Model year 73 - Yes, but selectively as "SW" special equipments for RS model only.

    iirc the aluminium front cross member was in model year 1973 routinely fitted to that year Carrera RS model for homologation reasons.

    Don't believe aluminium crossmember part was used on 73 S examples -- maybe they were used very selectively for sports purposes or factory racers etc before that RS application?

    Others here might remember / know better, so I'm open to be corrected.

    The various paper editions of my 72/3 spare parts manuals has a minor inconsistency between three edition printings regarding this part. (The two later editions were actually printed sometime after the 73 model and contain updated pages dated from 74 onwards; they show part up-issue information), the earliest edition was around while that model years cars being produced.

    Two front crossmember parts ( suffix .03 and .04) are listed in all three of my 72/3 parts book editions; only one, the standard crossmember, version is drawn. Standard part marked #1 and a "SW" special equipment part (#1) is listed in relevant text list section however

    In early edition of spare parts binder dated late 1972 it shows: "SW" then "blanks" meaning special equipment alternative part but somewhat confusingly the cheaper paperback book format (not ring binder) and the a different later printing of the 72/3 maroon ring binder shows "SW" ....and for some reason ....a dash appears (-) in the RS column in these two editions?

    Suspect what various books are conveying in this inconsistent / confusing way is the alternative to steel, the aluminium part (marked SW meaning special equipment) is actually the normal specification for the Carrera RS. Doesn't quite say that however if I'm correctly following the legend (SW and -). I would have expected (#2) to show "SW" and quantity "1" but just in RS column?

    (Earlier parts book also shows suffix .03 and .04 for those parts but that is not era of your question)

    Wasn't the special equipment crossmember used more widely in impact bumper models for model year 1974 cars onwards ie after the annual model changes during Porsche factory summer break but still in calendar 1973?

    If this understanding/ interpretation is correct then to your question it would have been available late 1972 > 73 but technically only applicable among the " longhood models" to a Carrera RS for Model Year 1973. Possibly more widely in late calendar 1973 for face lift impact bumper cars -- but I don't follow those models very closely.

    Also often is the case in old Porsche parts, I'm sure the odd exceptions....pre impact bumper cars thought to have one as an original fittment from new in longhood might surface
    Last edited by 911MRP; 09-19-2016 at 07:20 AM.

  3. #3
    Righteous Indignation 70SATMan's Avatar
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    The 73RS unit was forged aluminum while the 74-on regular units were cast aluminum. Never heard of a MY 73 regular 911 having the cast aluminum cross member but, a very late model 73?? Transition year as well but, I'd be really surprised if they had run out of the steel cross members.
    Michael
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    Quote Originally Posted by 70SATMan View Post
    The 73RS unit was forged aluminum while the 74-on regular units were cast aluminum. Never heard of a MY 73 regular 911 having the cast aluminum cross member but, a very late model 73?? Transition year as well but, I'd be really surprised if they had run out of the steel cross members.

    I have an early build (1st sept 73) impact bumper Row Carrera 2.7 with welded Rs flares and rs tunnel reinforcements, it also has aluminium cross member that I am not sure is original as have seen most with steel,also in Ryan's Carrera 2.7 book he states the factory changed back to steel 9th April 73. How would you tell the difference between forged and cast cross member, would it be the date stamp?
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    Hadn't appreciated there were cast vs forged versions either.

    Thanks for that detail Michael. Is there a source for that? Presumably that makes the one-year-only unique to RS forged examples quite rare.

    I'll have a much closer look next time under my car vs other late 73 and 74 cars with aluminium crossmember.

    Update: Carrera RS book edition 2 says: April 9 73 steel front axle support 911341013.00 used instead of .03....between chassis 1035 and 1114 installed versions alternating until stocks depleted. The crossmember was part required for homologation -- another of those differentiating things like thin panels that once the 1000 (or so) homologation cars were built and certified could let the RS revert to more regular series-production parts due to supply and or simplification.

    (No mention of cast vs forged that I can see from quick skim of the Book.)
    S
    Last edited by 911MRP; 09-19-2016 at 08:27 AM. Reason: Update from Carrera RS Book

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    Member #226 R Gruppe Life Member #147
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    The original RS version used 2 8mm bolts with nuts, at the crossmember, to mount the fore/aft ALU support bar. The later ALU crossmember, used a steel support bar with single 10mm stud welded to it. The stud was also used to locate and mount the tray at the front. The early crossbar used the early tray mount system. G.Led

  7. #7
    Righteous Indignation 70SATMan's Avatar
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    Quote Originally Posted by 911MRP View Post
    Hadn't appreciated there were cast vs forged versions either.

    Thanks for that detail Michael. Is there a source for that? Presumably that makes the one-year-only unique to RS forged examples quite rare.

    I'll have a much closer look next time under my car vs other late 73 and 74 cars with aluminium crossmember.

    Update: Carrera RS book edition 2 says: April 9 73 steel front axle support 911341013.00 used instead of .03....between chassis 1035 and 1114 installed versions alternating until stocks depleted. The crossmember was part required for homologation -- another of those differentiating things like thin panels that once the 1000 (or so) homologation cars were built and certified could let the RS revert to more regular series-production parts due to supply and or simplification.

    (No mention of cast vs forged that I can see from quick skim of the Book.)
    S
    There used to be a couple of threads devoted to the forged part which incidentally does not have date codes or part numbers as the cast units have. Also, even though forged and tougher than the cast part, it's visually much beefier with more rounded radii. Also used on the RSR, I would imagine the forged weighs more than the cast though I don't think I've ever seen posted weights on the forged bar.
    Michael
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    Did the Iroc series cars run with the aluminium cross member?
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  9. #9
    In case a pic or 2 help. Here is an original early RS forged version.







    HTH

    Alan

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    Thanks for posting image Alan

    Would have taken a look at the real thing at your very enjoyable Canford Classics open morning last month if I'd known. This post reminds me to say a belated thanks to you and your team for an interesting day, chance to catch up with some old Porsche friends and the very tasty bacon buttie.

    Cheers

    Steve

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