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    • #7002

      Gentlemen,

      I’ve prepared and attached an update in draft format of the current Scratch32 Rules & Guidelines (v3.0) that addresses the following:

      • Eliminates the confusing reference to 15″ wheels and sets all of the basic wheel sizes in metric (millimeters);
      • Offers a basis from which to calculate wheel diameter and width to avoid confusion and make compliance intuitive;
      • These updates to wheel dimensions are not substantive – they do not change anything – but clarify the rules as they were;
      • In hot rods wheel size is no longer restricted to 14mm wheels – hot rod wheels may be smaller in diameter since this does not offer any performance advantage;
      • In hot rods the previously mandatory SC0120 DArt tire is now no longer mandatory but still highly recommended;
      • In sportscars since we have the relatively new SP+ subclass the ‘target’ motor reference allowing any motor to be used especially for heavier models is no longer necessary and so the SP class is once again restricted to only ‘Slow’ motors listed in G7. All models using any other motor will be classed as SP+;

      The draft version reflects all of these changes. For convenience I’ve marked all of the changes as follows:

      • deletions are crossed out; and
      • additions are in red.

      Please feel free to print/review your own copy (attached below) and comment by replying to this thread or in person at our next scratch32 event. You must be logged in to review the attached draft and comment below.

      Attachments:
      You must be logged in to view attached files.

      The Happy Canadian Scale Modeler!

    • #7022

      Note: Because some reputable aftermarket 1970’s Grand Prix era replacement rear wheels measure 12.4mm in diameter and therefore although slightly beyond scale the 12mm maximum which was believed would cover all possibilities for this class should be increased to 12.4mm… this is merely a maximum allowance and everyone is still encouraged to make or obtain wheels that are as close to scale as possible – the problem with 1970’s era wheels is that to the best of my knowledge most of the readily available replacements are well beyond scale…  :wacko:

      The Happy Canadian Scale Modeler!

    • #7059
      Avatar photoMiA

        A very welcome clarification for those of us who always had difficulty doing the 15″=14mm. dance. Thanks Art. :rose:

      • #7060

        A Pre-War Grand Prix Class Proposal:

        After discussions last night it appears that we are making considerable headway towards a pre-war class and the rules that would govern. For the benefit of those who had to leave early or who could not attend here are the suggestions so far:

        1. Model Eligibility – Any model that competed in a Grand Prix before 1939;
        2. Motor – BWMS050 ‘low’ power motor in an inline configuration (any gearing);
        3. Tires – Front & rear tires must be DArt DA0210;
        4. Wheels – 16.2mm x 5.5mm maximum;
        5. Minimum Clearance – But for the guide, wheels/tires & crown gear no part of the chassis, any of its components or body may be less than 5mm above the surface of the track;
        6. Maximum Width – The width of front and rear rolling assemblies may not exceed ??mm in width, excluding inserts, nuts or knock offs which may extend beyond – within reason;
        7. Maximum Overall Tire Diameter – Front and rear tires must not exceed 23mm in diameter.

        Subject to further clarification from several who have built or are working on pre-war models we will try to incorporate this class into our next version of the scratch32 rules & guidelines. For the time being any pre-war class will be treated as a separate event. Because I know how important deadlines are we will schedule a first pre-war event sometime in the early fall – there should be enough rainy days between now and then for some of us to cobble something together… Thanks to those who have contributed to this discussion and especially F1nutz for being the first one to succeed in building a gem of a model for this challenging era… :yahoo:

        The Happy Canadian Scale Modeler!

      • #7167

        For Item #6 above we have a measurement of 54mm overall width of rolling assemblies/track (excluding insert/nut/wheel detail) which I’ve taken from Felix’s topic so far… any others to consider?

        The Happy Canadian Scale Modeler!

      • #7168
        Avatar photoMiA

          A Pre-War Grand Prix Class Proposal: A few thoughts:

          I don’t know whether any of this is particularly relevant to establishing a class basis, but:

          1. The track widths of the vintage cars with bicycle fenders depends basically on where the fenders end up after they are attached to the car. This fixture is at the end of two long, thin, fragile pieces of plastic. Being old, some of the fender fitment is not necessarily precise due to variations in tooling and the affects of old age and treachery on the plastic (warping). On one side of the front of the Bentley this was quite pronounced with little to be easily done about it. I put the fenders on as well as possible and put the wheels under them. Front track is: 53.94 mm., (remarkably close to Felix’s) rear is 50.20, both with DArt wheels and tires. A possible situation Art noticed on the Aston Ulster. On the original  Blower Bentley the track was about 56″ (I haven’t found a difference between front and rear, this scales to 44.5 mm. for 1/32.) So apparently the model manufactures are not totally accurate and this will probably vary from manufacturer to manufacturer and from model to model. On the real Ulster they were the same at 52″.

          2. On the Bentley the wheels and tires look small, although they measure very closely to the actual wheels/tires that came with the kit.(~23.00mm for the DArts vs. 24.66mm for the kit plastic wheels.) If I were able to find bigger (taller) wheels/tires the model would look better IMHO.

          3. Current ground clearance on the Bentley is ~4mm. Which will be increased with a small change to the next chassis build (although I don’t think I’ll try to change this one), or with the addition of taller wheels/tires should they ever be forthcoming??

          Apart from these discrepancies and a few small touch ups, Mr. Birkin is ready for an on track trial??

        • #7170

          Thanks MiA.

          1. Instead of just a minimum clearance we could adopt a ratio (say 10:1) to determine minimum clearance based on width (track). I’m not a fan of this methodology but it could work; and
          2. With gearing ‘open’ technically we do not need a maximum overall tire diameter but given that 11t (or 12t) pinions for a 1.5mm motor shaft are both harder to find and do not mesh as well with the go to slot.it crown gears I’m not yet convinced that we can do without a maximum overall tire diameter – in which case that would leave us with needing to define a maximum. 23mm appears to work with 2 of the 3 models canvassed so far. I can make a slightly taller tire if necessary.

          In any event, I’ve tweaked the above class proposal for further discussion:

          1. Model Eligibility – Any model that competed in a state or club sanctioned road, rally or endurance race or Grand Prix anywhere in the world before 1939;
          2. Motor – BWMS050 ‘low’ power motor in an inline configuration (any gearing);
          3. Tires – Front & rear tires must be DArt DA0210;
          4. Wheels – 16.2mm x 5.5mm maximum;
          5. Minimum Clearance – But for the guide, wheels/tires, bushings/bearings & crown gear no part of the chassis, chassis components or body may be less than 5mm above the surface of the track;
          6. Maximum Width/Track – The width of front and rear rolling assemblies may not exceed 54mm in width, excluding fenders, inserts, nuts or knock offs which may extend beyond – within reason; and
          7. Maximum Overall Tire Diameter – Front and rear tires must not exceed 23mm in diameter.

          The Happy Canadian Scale Modeler!

        • #7172

          I will incorporate the points from my post on May 26 & June 4 (above) into a revised draft unless anyone has any other comment/suggestion… :mail:

          The Happy Canadian Scale Modeler!

        • #7174
          Avatar photoMiA

            For comparison of wheel and tire combinations I have measured  some of the offerings used  in some of the plastic 1930’s kits I have. This may be of some use, or may serve only to add valuable confusion.

            Model                                                                  Wheel Diam (mm)                              Tire Diam (mm)

            Airfix 1930 Blower Bentley                                           16.65                                             24.66

            Pyro 1930 Blower Bentley                                             16.9                                               25.13

            Pyro 1934 Bugatti Type 59                                            17.09                                              23.38

            Pyro 1931 Alfa Romeo 1750 Grand Sport                   14.86                                             22.77

            Pyro 1931 Aston Martin International LeMans         16.00                                             25.37

            MPC 1933 MG K3 Magnette                                          16.45                                              22.09

            Original wheel/Tire sizes during this era seem to have been a bit of a mish-mash from the manufacrurer’s. For our practical purposes, except in rare cases where you are able to make your own wheel/tire sets, we will be pretty much be limited to the tall/tin wheel/tire combinations that are available to us.

            Currently that’s:

            1.  (and so long as he is willing to make them)  a DArt Custom with a wheel Diam. of ~16.34mm and a tire diam. of ~23mm untrued.  Based on the above chart these might look a bit small on some cars and a bit large on others but in all cases are certainly within reason. If they look tall just true them a bit.

            2. Another source is RS Slots in the UK. They offer 3 vintage wheel tire sets. All three of their wheels are 16mm dia x 3.25mm wide with 2.5mm boss for grub screw. That’s pretty much the DArt size. Their inserts vary by spokes, 36,48 and 60. Tyre choice is small sport (21.4mmx 2.8mm wide), medium road  (20mm dia x 3.15mm) or large road (22.15mm dia x 4.4mm wide). There is no mention as to whether the tires are urethane or rubber.

            So as far as standardizing, wheel sizes in the 16-17mm. diameter range with a max. tire diameter of 23mm. should seem to be appropriate for a start. These are right in line with Art’s current thoughts and current DArt or RS Slots vintage wheel/tires and will probably be what we can get our hands on for most practical purposes. You will probably want DArt tires unless the RS Slots ones are urethane.

            … Mr. Birkin is running the Blower on the test stand as I write this.

          • #7175

            Please also note:

            Fantasy period liveries are permitted in any scratch32 class, which would apply to our pre-war class as well. This has always been the case with the exception of La Carrera Panamericana or Targa Florio events for which an actual livery (number may be changed provided the font is the same) must be used. I bring this up only as a reminder for some… I think it best to include a line regarding this in our general rules section which I will also add to our draft…

            The Happy Canadian Scale Modeler!

          • #7176

            Thanks for the additional info MiA. I think we have enough of a direction now to allow everyone to start building with confidence. :good:

            The Happy Canadian Scale Modeler!

          • #7178

            Just another reminder that as F1Nutz has done make sure your guide is not exposed when you look at your model from above. This may mean choice of guide is important not to mention placement behind the front axle may be necessary…

            The Happy Canadian Scale Modeler!

          • #7183
            Avatar photoMiA

              Perhaps I’m jumping the gun here a bit, but since it is a scratch built model I sent in a Scratch32 form for the Bentley. As there is not really an official class on the form it will will need to be changed from 1950’s F1 to Show/Parade/Miscellaneous/Vintage, whenever an appropriate class is added to the data base. I’m attaching a picture to go with it as there is no place on the form to do so.

              It is done in the livery of the #8 car as raced at LeMans in 1930 by Sir Timothy Birkin.

              Based on an Airfix kit, it runs on a set of DArt custom Vintage wheels and tires. Thanks Art.

            • #7193

              Hi MiA,

              I admire your eagerness using the form even though there is no official class nor event yet…

              Your model looks great!

              But I think the fenders are letting down the overall look of your model – they seem to suggest an exaggerated circumference for the tires beyond what the photos suggest – which in turn draws attention to the fact that the diameter of your tires are smaller by 1-2mm…  it is all about optics with models…

              BTW – will you be painting your DArt wheels green/black too (like the original)? I hope so…

              The Happy Canadian Scale Modeler!

            • #7218

              Trying to combine models right up to 1939 is somewhat of a problem. It was pointed out to me that some are lower and don’t look right sitting up so high to meet the minimum clearance – so we’ll need to bring the year of eligibility forward perhaps to 1936 or 1937 to exclude those models… or leave the rule as is and just enforce the clearance…

              The Happy Canadian Scale Modeler!

            • #7219

              In order to avoid any confusion the updated draft rules will explicitly exclude using sandpaper to polish/clean braid even though they already only permit one ‘thing’ to use with braid – Ronsonol…

              The Happy Canadian Scale Modeler!

              • #7225

                This braid sanding (polishing) binge by those not in our group requires cleaning immediately afterwards – and that compounds the problem. Sanding must be a spillover from 1/24…

                Why if racing on clean copper tape anyone needs to resort to this is beyond my understanding… Worn braid should simply be replaced – it costs next to nothing.

                Those that are compelled to resort to these things to save a few cents or to gain some perceived advantage should re-visit their reasons for racing with friends…

                The Happy Canadian Scale Modeler!

            • #7220
              Avatar photoMiA

                The 30’s were such a glorious time for race car design. It started out with manufacturers using re-purposed touring cars with riding mechanics and perching the frame somewhere close to the centre line of the axles like old Bentley’s and the 6C1750 Alfa. (You knew I was going to find a way to talk about Alfa’s :wacko: ).

                By the mid 30’s more purpose built cars like the P3 Alfa of 1934 had done away with the riding mechanic and Auto Union and the Silver Arrows Mercedes were just coming over the horizon.

                  

                There were some epic races between the older designs as they were driving off into the sunset and the newer lower cars as they were coming screaming over the hill. Nuvolari’s victory at the 1935 German GP at the Nurburgring in an old P3 Alfa when he defeated the early Auto Unions and Mercedes Silver Arrows teams comes to mind.

                And by the late 30’s automotive technology had advanced such that manufacturers like Auto Union, Mercedes and Bugatti were building race bred cars with frame and axle geometry that allowed ground clearance of only about the section height of the tire. Even Alfa was getting in on the act with it’s type 512. (Lovely isn’t it?? :yahoo: )

                Should we exclude some of these wonderful race cars from the late 30’s simply because they are too low? And they certainly wouldn’t look ‘right’ if perched up on the centre line of the axle which would be necessary to get 5mm clearance. Seems a shame to not have a way to run these cars if someone might wish to build them. Perhaps so long as the car is built so that the axles come out from under the body as much as possible in the same place as they originally did and they look ‘right’, lets try to include them.

                Of course this would obviously result in a plethora of running heights, some  models probably having a clearance of somewhere around 3mm. in our 1/32 case, and intuitively these cars will probably make faster vintage racers than say the 1930 4 1/2L blower Bentley :unsure: . They’ll probably run at about the same rates as our 50’s GP cars given the proposed motors and open gearing.

                Not to suggest it, but perhaps 2 or 3 or more vintage groups (but just 1 vintage class to cover the 30’s) as is currently being done for some classes, split either by type of derivation (touring derived or purpose race) or maybe year or even ride height might be appropriate. Hopefully anyone building one of these vintage cars will want it to look right! We could run them all together at first  and as time goes by if there is sufficient interest run them in their own groups  as the fields grow.

                What a great way to learn more about this era of early automotive history.

                Any thoughts?

              • #7221

                Well put MiA!

                I would be happy to make models to run in two sub-classes for pre-war – one with a minimum ride height of 5mm (I think the years would sort themselves automatically) and another with none…

                Unfortunately many read our topics and replies but never log in to respond – so we can only guess what they think – why is that? I don’t care what they think. On the one hand we’ve had those who have harped until death to make changes (like Chuck and the Ernie gear) while others never chime in (like those who monkeyed Chris’ choice to eliminate NASCAR)… and now finally we’ve got a website forum dedicated only to our group for free membership… I guess the cost is still too much for some… when people don’t show up to race and discuss nor participate in these forums they shouldn’t be surprised when rules are made without their input. So be it.

                The Happy Canadian Scale Modeler!

              • #7223
                Avatar photoMiA

                  I suspect we’re playing to a very limited interest group here regardless…. B-)

                  And yes I suspect cars would sort themselves into appropriate groups quite quickly. :scratch:

                  Simple test:

                  Does it look like this:                                                or this :

                            

                  Or this                                                                                              Or this

                    

                  And for those pesky transitional years cars, maybe it looks more like this. :yahoo:

                  And there you go, three groups no waiting!! My dream garage as well!!

                  Can you image cars changed that much in 10 years (less if you consider the early Mercedes/Auto Union cars which came around ’34 I think)!! :scratch:

                   

                • #7224

                  Some great looking cars you’ve pointed out – we will see an Alfa like that racing sometime soon…. love it!!!!

                  The Happy Canadian Scale Modeler!

                  • #7230
                    Avatar photoMiA

                      The two seat Alfa (1750) is going to be my next vintage attempt, apparently there are several nice resin versions of the P3,  and for the 512, take 1 part Type C Auto Union, gently stir in 1 part type D Auto union, shake well,  and voila a Type 512!! :yahoo:

                  • #7226

                    Interesting to note that the frame of the car is visible on the ‘higher’ ones – and on the lowered ones it is wrapped over / covered by the body panels…

                    The Happy Canadian Scale Modeler!

                    • #7231
                      Avatar photoMiA

                        Staying with more or less the same cars, it’s interesting to look at the drawings of them to see where things were placed relative to the frame that allowed the cars to become lower, and how much lower they became.

                        For the Bentley, one can see that although accommodations were made in the rear  for the drive axle, and that bits do hang down, the frame is basically perched just above the centre line of the wheel hubs, the body above that, making for a very tall car (somewhere around 6 feet!!)

                         

                        By the 1938 Alfa Romeo Type 158 Voiturette the front suspension was placed well above the frame, the engine was tucked down in the frame but was still vertical and somewhat tallish, the rear differential was offset upwards so the car sat much lower, but the driver still sat quite upright and combined with the tall front placed motor made for a taller car than it’s intended successor the type 512.

                         

                        It’s intended replacement the Type 512 turned the whole thing around. It put the lower bits in the front,  dropped the driver lower between the rails, developed a flat 12 motor to reduce engine height, and used ideas developed earlier to get the rest of the bits as low as possible.

                         

                        All this effort resulted in a ground clearance slightly less than the section height of the tire.

                        And just for fun!! :yahoo:

                         

                    • #7235
                      Avatar photoMiA

                        Stumbled across this site dedicated to Grand Prix race cars of the 1930’s. A plethora of information with race grids, results, discussions, cars, variants, races and even livery by race!! Thoughts on tires, fuel and even mechanics duties.

                        http://www.kolumbus.fi/leif.snellman/main.htm

                        If you’re interested in this era you’ll find a lot of it here, including the wonderful 1935 Monaco-Trossi with a radial 16 cylinder, twin supercharged two stroke engine!!

                         

                        And apparently someone has made a slot car model of it! Spectacular!! :rose:

                            

                        http://www.slotforum.com/forums/index.php?showtopic=53032&page=2

                         

                      • #7464

                        Here is what I hope to be the final draft of v4 of the Scratch32 rules. I’ve done my best to incorporate all of the changes/considerations noted above, including the addition of a new PGP/PGP+ class. If I’ve missed anything please let me know.

                        Attachments:
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                        The Happy Canadian Scale Modeler!

                      • #7525

                        There appear to be no comments, concerns or further suggestions so we’ll update our Scratch32 rules to v4 online – and they will take effect immediately. Cheers! :wacko:

                        The Happy Canadian Scale Modeler!

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