The Un­fair Ad­van­tage

Australian Muscle Car - - Modern Muscle -

So, you and your mate have bought your­self some slot cars to have some fun with over a few beers. He’s a Ford man and you like the idea of rac­ing his Brut 33 Fal­con with your HDT To­rana, and kick­ing his butt like it’s 1974 again. But wait. That Scalex­tric To­rana is no match for the Fal­con. Why can’t you keep up? When your To­rana hits a curve, it trips and rolls over like a Las Ve­gas hooker. Un­like the hey­day of the real L34, the Scalex­tric Fal­con is a bet­ter racer, and the rea­sons for it are plain and sim­ple. The dy­nam­ics that help your Scalex­tric hang in the slot mean that the wider and longer chas­sis of the Fal­con is more pre­dictable in a slide and less likely to jump out of the slot.

The late Mark Dono­hue was a great racer and car de­vel­oper. The ti­tle of his bi­og­ra­phy The Un­fair Ad­van­tage, was in­dica­tive of his rac­ing phi­los­o­phy – get the car set up so that beat­ing the other guy isn’t hard work. In the same way, set­ting up your slot car can re­duce the num­ber of spec­tac­u­lar, car­wreck­ing crashes, and hope­fully level the play­ing field. Set out in this month’s col­umn are some lowkey im­prove­ments for the To­rana that could make you look like the Harry Firth of slot cars.

The first step is to take off the bod­ies, and it re­veals the essence of the prob­lem for To­rana rac­ers. The Fal­con has a much big­ger foot­print on the track and uses a sidewinder mo­tor. The To­rana is the same height as the Fal­con but much shorter and slightly nar­rower. It also runs an in­line FF mo­tor, which is no­to­ri­ous for its all-ornoth­ing power de­liv­ery.

At this point it is a good idea to ro­tate the rear axle by hand. Check for any notchy or click­ing feel­ing be­tween the gear on the axle and the mo­tor pin­ion. It could mean mould flash­ing from the cast­ing, or as com­monly seen in older cars by Span­ish maker Flyslot, a cracked pin­ion. In this case the Scalex­tric ones felt good, how­ever I did de­tect a sig­nif­i­cant amount of slop be­tween the axle and the ny­lon bear­ings. This al­lows any im­bal­ance in the wheels and tyres to show up as wheel hop.

Re­mov­ing the tyres re­vealed that the outer rim of the plas­tic wheels has been made with a larger di­am­e­ter (13.3mm) than the in­ner rim (12.7mm). It’s only a small amount, but this dif­fer­ence makes the tyre sit up on the out­side. This is handy for re­duc­ing rolling re­sis­tance up front, but at the back it stops the tyre from sit­ting flat on the track and re­duces avail­able grip. The tyres that came with my To­rana also had a very square edge. When the car starts to slide at the back, this makes the tyre prone to catch­ing on the track sur­face. Putting a bit of a ra­dius on the edge makes the slides more pre­dictable.

To smooth things out I de­cided to re­place the en­tire rear axle set-up. I used Slot­ing Plus alu­minium wheels which are wider, a 28 tooth gear, a pre­ci­sion rear axle and me­tal bear­ings with lu­bri­ca­tion holes. The gear has a big­ger di­am­e­ter, so I had to grind a re­lief in the bot­tom of the chas­sis to make room for it. It did leave two small pin­holes, which I filled with glue and painted black. I found that the pre­cise fit of the new bear­ings high­lighted a mis­align­ment in the bear­ing mounts, so I ran a small round file across the mounts to straighten things up. The wider rear wheels al­low fit­ting of wider and lower race rub­ber.

To hide the changes, I turned down the old Scalex­tric rear wheels to fit as in­serts in the new alu­minium wheels. This was done by putting the Scalex­tric axle in a drill chuck and run­ning a Dremel against the plas­tic wheel. Some pa­tience is re­quired, as it’s easy to take off too much or over­heat the plas­tic. While you are at it, the new rear rub­ber is sig­nif­i­cantly wider than the orig­i­nals and might at­tract some at­ten­tion. I ground a lit­tle off so it is not so con­spic­u­ous.

An­other way to im­prove cor­ner­ing speed is to get the blade of the guide to sit fur­ther into the slot. The re­place­ment tyres I used on the rear have a lower pro­file so I used the same ones on the orig­i­nal front wheels. That left the front tyres clear of the ground, be­ing held up by the

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