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Steve Betney's Work Bench


Now, this little car wasnít even part of my projectsí WIP pile or even a glint in my eye before the Old Warden Mayfly event a couple of months ago, but it has somehow jumped to the head of my production schedule and been finished already, and is back to my F1 type of subject, albeit a rail car rather than tethered this time.

Having stopped for my customary chat with Bill and Pat Langley by Billís portable oval rail racing track near the old compass circle at Old Warden, and seeing a variety of his diesel rail cars rotating as usual at various speeds, up to 3 at a time, I decided that I really had to have something to run at future OW events to keep Bill company. He informed me that he has constructed an even larger, 4-rail figure of 8 track layout which he plans to use in future, so there will be room for more cars presenting an even more impressive spectacle, so I decided to make a car to join in, hopefully at OW Scale Weekend.

After a long root through my car partsí stock, I came up with an old, used MRRC aluminium chassis casting for 1.0 to 1.5cc engines as a basis, procured a while ago on eBay. This had the cast-in engine mounting blocks already drilled, and an AM 15 fitted these exactly. An AM 10 would be better suited to the track, but I only had a 15 to hand so will start with that whilst I look out for a decent 10. The position of the engine, and most particularly its cylinder head, which was just about exactly half way between the front & rear axles, dictated the choice of full size subject to model, so that the head would be in the open cockpit area. This excludes many vintage front engine F1 cars which have the cockpit and driver closer to the back axle, and even many more modern rear engine cars, which also have the problem of not suiting the MRRC chassis shape.

A long web search came up with the 1960s Cooper Climax car as a suitable and quite attractive candidate, and in particular the 1962 T60 1.5 litre model driven by Bruce McLaren, which has an interesting looking cowl over the cylinder heads and carbs just behind the driverís head, and also an unusually shaped open rear end. A 3-view drawing was located and then scaled to suit the 7.75" wheelbase of the chassis, so the plan and side elevation outlines of the body were defined. Repro Raylite 2.25" tyres are a suitable scale for the rear, drive wheels, and similar diameter repro Peri & Rice tyres were selected for the front for their narrower tread and scale appearance. I found some nice pressed metal hubcaps which fit both of these tyre types at toydecals.com in the USA, ERTL type ETP-001 at $13 plus postage for a set of 4, and these add a nice touch to the appearance of the finished wheels and model, though they are not strictly the correct spoke pattern. A further root around my partsí stock came up with a suitable modern RC flywheel and clutch assembly, a set of 2:1 bevel gears, 3 MRA 5mm bearing housings, an old c/l team race fuel tank and a 13" long block of hard balsa wood, so a kit was to hand.

The images show the layout of the model, which has a swivelling front axle simply because the base MRRC chassis had used one, so the front mounting block on the casting was already drilled and slotted for this configuration, and I just cleaned it up and used a pair of flanged ball bearings to mount the swivelling pillar for the 5mm axle.

The aluminium wheels turned up for the Peri & Rice front tyres have deep groove 5mm ball bearings inboard and thin, sintered bronze sleeves to the outside. The 5mm rear, driven axle is mounted in two MRA bearing blocks, and the 5mm pinion bevel gear drive shaft supported in a 3rd MRA housing, as can be seen from the image of the finished chassis. I wanted to have a fuel cut out on the AM engine rather than rely on running out the tank each time on the track, so I modified a small RC throttle I had spare (I donít remember its origin) with a wire "sneaker" arm added. This is Araldited into the venturi, and a couple of small blanking plugs similarly fixed into the spraybar mounting holes to seal them off.

It took a surprisingly long time to make up the 4 rotating rail guides or zonkers, using information from Jim Elsegoodís published article in an old old Retro Racing Club Newsletter, as these have to be made to quite close tolerances and be free to rotate easily on their internal bearing surfaces (see the image of the underneath of the chassis).

Bill Langley and Jim have found from experience that a pair of zonkers located just in front of both the front & rear axle at the centre line of the car work very well, and are much simpler to make than the vintage MRRC pivoting plate designs. If you want a copy of these instructions, please email me at stevebetney(at)aol.com and Iíll send you the info.

The balsa body was designed to use internal 1/16" by ĺ" aluminium strip side rails epoxy glued into its inside bottom edges, so that it could be fixed with four 6BA screws through the sides of the body into the tapped holes on the 4 lugs cast on the edges of the MRRC chassis for this purpose. After ensuring that the bare chassis plate snugly fitted in this way into a carefully excavated recess in the hard balsa wood body blank, the body plan and side profiles were drawn and the block band-sawed to shape.

Then the part I like the most, carving and sanding the body to final external shape, followed by the less favoured internal excavation, and my least favourite final finishing stage. I used flexible weave 2oz glass cloth applied both externally and internally using Z Poxy resin, then multiple coats of cellulose sanding sealer and Imperial Blue cellulose spray paint and some final coats of fuel proofer (horrible job, it went badly yet again and took 4 rubbed down brushed layers Iím sad to report).

I gave the car the racing number 35, as a nod to our SAM 35 society, which has just voted at the recent AGM to include vintage and sports style tethered (and rail) cars in our scope of modelling activities. Come and join us (go to sam35.org.uk), the monthly SAM 35 Speaks magazine with some colour content is worth much more than the membership fee, and it will include at least the occasional tethered car content