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'67 BRM P83 proxy build

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  • '67 BRM P83 proxy build

    Here's a car I've been building for the '67 GP of Canada proxy this fall. I've incorporated some ideas borrowed from Chris Walker and Dennis Samson. I started building brass chassis about a year ago when I rejoined Luf's group after a 10 year absence. I built a few that were bad and a few that were OK, but driving Chris and Dennis' cars in the GVSCC Targa proxy was a revelation. Since seeing how those guys do it I've managed to build a few decent chassis.

    The Pre-Wing body mounts on a central plate suspended on pins front and rear, allowing the chassis rails to flex freely.






  • #2
    Beautiful work.

    Tom

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    • #3
      Body work and chassis look great...It is always good to see a Pre-Wing body being built up.

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      • #4
        Very nice!

        How is the rear end of the center pan supported?

        Dennis

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        • #5
          Hello Duke, Very well engineered and built, it should go well!!

          On your next build, you may want to consider using some 3/32 id sintered bronze bushings on the rear axle......they are considerably more precise and smoother (less friction) than straight tubing.

          Again, well done Sir

          Cheers
          Chris Walker

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          • #6
            The work you "best in class" guys do with brass chassis never ceases to amaze me. I take a look at the 849 solder joints (give or take a few...) on the suspension and I just KNOW if I were to ever try something like that the result would be something along the lines of: solder one joint, OK. Solder the second joint, the first one falls apart. Get the first two to stick, they both fall apart when I do the third. And so forth and so on in perpetuity.

            Which leads me to the next feature of the work you guys do. What the photographs cannot convey is how smooth, quiet and quick this little car is, a treat to see it running around the track. We all work to our strengths and avoid our weaknesses, so I will remain on the sidelines and continue to admire and enjoy the work you guys do.

            I know that there are many more great builders out there but specifically to Duke, Dennis and Chris: you guys rock!

            Alwyn

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            • #7
              Originally posted by chrisguyw View Post
              you may want to consider using some 3/32 id sintered bronze bushings on the rear axle......they are considerably more precise and smoother (less friction) than straight tubing.
              There is another approach to this problem. I modified an old K&S tubing cutter by rounding off the profile of the circular blade. Then I used that to swage a groove into the tubing at each end and run a reamer through the tube until it is an exact fit on the axle. The axle then runs on just a line contact at each end that is the exact size. It lasts a long time too, I have frames that have this design that are still slop-free after some years.

              You can see the grooves in this photo, in between the ends of the rails where they solder to the tubes:

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              • #8
                Lovely work, Duke.
                I look forward to racing it this fall.

                Old23

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                • #9
                  Originally posted by gascarnut View Post
                  There is another approach to this problem. I modified an old K&S tubing cutter by rounding off the profile of the circular blade. Then I used that to swage a groove into the tubing at each end and run a reamer through the tube until it is an exact fit on the axle. The axle then runs on just a line contact at each end that is the exact size. It lasts a long time too, I have frames that have this design that are still slop-free after some years.

                  You can see the grooves in this photo, in between the ends of the rails where they solder to the tubes:

                  Similarly, I use sintered bushings and chuck them in my lathe then, with an end mill (typically 1/8") in the tail stock, counter-bore the bush until the actual bearing surface is about 1 mm.

                  EM

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                  • #10
                    Chris - I thought of using bushings for the rear axle, but I wanted the tubing to be as slim as possible - partly for aesthetics, but also because the axle, shocks and intake manifolds are all tight together. I also wondered whether the axle tubes would be more likely to get knocked out of alignment in a crash if there were outboard bushings. The swaged groove is a neat idea though.

                    Dennis - The rear of the centre pan is soldered to a transverse pin that sits in slightly over-size holes in each side of the axle bracket.

                    I really have to thank you two guys (and proxy racing) for helping me learn what makes a fast car. When I first drove Chris' Chevron, I could hardly believe what it was doing. I could see it had something to do with chassis flex, but found it difficult to find any detailed discussion of this online.

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                    • #11
                      beautiful chassis!!

                      great work Duke - and a really helpful thread!!

                      thanks to all

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                      • #12
                        Good mother of 1/32 slot car racing incredible!!!! Can't wait to follow the proxy

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                        • #13
                          Very nice work, my brass work goes a lot like Alwyn's description.

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                          • #14
                            Finished

                            I finally finished this car. It was a ridiculous amount of work - good thing I'm retired! I made the Goodyear, Shell and Spence decals on my inkjet printer. My paint and detail work is still a bit amateurish, but overall I'm reasonably happy with how the car turned out. The final weight is 76g. The metal bits from the Pre-Wing kit raise the centre of gravity slightly (intake stacks, tail pipes and steering wheel), but I thought this might be a good thing. I tested the final car for the first time Friday on Luf's new track and quickly set my personal best lap time, so that seems promising. 6.95s is not quite in Alwyn territory, but pretty good for the rest of us.





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                            • #15
                              Oh my, that is just a beautiful thing. How did you do the driver?

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