chassis to its best advantage
Balancing Act
Or how to weight-jack your
chassis to its best advantage
By Philippe de Lespinay & Greg Gilbert
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Our subject was this Tamiya Porsche 962 body
mounted on a
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When racing your
car on a wood track and without the help of a traction magnet, a change of tires
is necessary. The stock rubber tires will not provide the same kind of traction
as neoprene foam tires will, and it will be time to switch to the High
Performance part #
THP2402 or
THP3202
depending on the scale of your car. Matching aluminum front
wheels THP2403
or
THP3203
fitted with the stock rubber tires can also be fitted.
Our subjects for this are a
24
chassis fitted with the beautiful Tamiya Porsche 962 body with molded-in windows
and headlight covers, and a
32
chassis fitted with a vacuum-formed Audi R8 body.
The test tracks chosen were a 160' Hill-climb and a 120' modified figure-8 with banking. With no weight added, the cars reach maximum top speed but have too much grip, and plain refuse to slide while cornering. This results in eventually cornering on two wheels, while the car lifts itself out of the slot. Not a case of under-steer, more a case of being too "tight" in racing terms. In both cases, self adhesive lead weights were added under the nose of the steel pan, and we ran side weights in various positions on the sides of the steel pan, searching for the right direction, helped by the electronic timer. By the time when ended the testing, over 2 seconds were gained on a 6.5-second lap time, showing how responsive the cars are to changes. While we could not quite make the cars slide as much as we would like to, they were much more responsive and manageable. They are proving themselves to be a driver's car, and they will certainly reward the talented drivers from the rest.
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Numerous test crashes, some incredibly violent, resulted in a bent axle during an accident with a Group-10 wing-car, in which the wing car...lost, and lots of impacts on the chassis, but no other damage than shown on the front weights. As the front tires actually ride on the track and space the braided contacts from the track, very little wear has shown on these contacts but the tires pick up a lot of the debris left from current racing involving traction compounds. It is wise to clean up the front tires often with a rag wetted with solvent such as lighter fluid or mineral spirits. |
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Amazingly, the Tamiya body showed absolutely no damage other than friction marks which were easily polished. Apparently, the body flexes enough during impacts, to allow the steel pan to take the bulk of the impact, and spring back into position, about 1/8" ahead of the bumper... Nice body indeed... Just make sure that no decals are applied exactly in the corner, because they will not last. |
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Final weight after testing was a hefty but sweet-handling 5,4oz or 151.2 grams. Another 25 grams worth of driver's compartment, driver, various details and under-tray can be added and a slight balancing act may be needed for fine tuning. |
The
32
car responded immediately to the weight addition and is now a real
sweetheart, cornering nicely and running identical lap times with the larger car
in spite of its smaller size. The weight was added in a similar manner but it
did not seem to need any on front of the rear wheels. of course the tires are
the determinant factor here, and we used some older Parma blue rubber for this
test, as well as a pre-production
High-Performance
THPR45
aluminum spur gear.
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The LMP vacuum formed body is made of 30-thou PETG plastic, and would normally be fitted with an injected wing and driver. Setup this way, the car is a real pleasure to drive, and multi-US 1/32 scale national champion Greg Gilbert really enjoyed himself. |
