IDIOT GUIDE TO F1 STOCKCAR SPECIFICATIONS & TERMINOLOGY The weight of the car & the 52 & 56 rule Total weight min.1350 kg, max. 1550 kg. Max inside = 740.6 kg. Max front = 616 kg Front Inside = 325.9 kg - Max front = 44%. Front Outside = 290.1 kg, Max. inside = 52.9% Cross weight from back inside to front outside = 704.8kg/50.34%- Min outside = 47.1% Back inside = 414.7 kg Min rear = 56%- Back outside= 369.3 kg Suspension and Steering Coil Over Spring rates: optimum = 325lb inside front, 375 inside rear, 350 outside rear, 350-375 outside front. Tyre pressures - Hoosiers on tarmac = inside both 15psi, outside front 22psi, outside rear 18psi (gain during race of up to 8psi) * Inside radials used on shale need more pressure, as much as 5psi Shockers. Shale cars: various including AVO, GAZ units at 5/8" diameter shaft. Tarmac cars: again various, the favourite is Leda and the same 5/8" shaft Rear suspension brackets - are mounted directly above the axle on tarmac and slightly below for shale. Most drivers have their own ideas as to what is best for their own cars handling. Leaf springs were once the norm but were by and large replaced in the 1990’s by coil overs. Front Toe in/Out - wheels ideally should not be parallel, a bit of toe in or out will have the effect of stabilizing the wheels once the car is moving at speed. Camber – there must be a measure of outside negative camber to ensure the tyre covers the maximum track surface; adjustments are made after taking the tyre temperature, finding the cold spots where there has been less contact. Castor – The amount of distance the stub axle pivots. Basically it’s the Tea-Trolley effect, but negated adequately by power steering. KPI (King Pin Incline) The movement of the swivel point has the effect of lengthening (inside) or shortening (outside) of the wheelbase when cornering. Thought to be a plus factor on oval circuits. Squat/Dive - the effect of the front end of the car pushing down during braking; addressed by choice of coil spring rate, adjustment of damper settings and pivot points of radius arms Bump Steer - an effect of minimal axle movement under compression and lift: basically, as the car moves forward, the axle stays behind slightly. Ackermann - the tyre scrub encountered on cornering because of the different arcs the wheels follow. Compensated by the positioning of the track rod ends. Rear Radius Arms - long and strong axle mountings, fixed to the “birdcage”, 4 - link rear end. Torque Arm - a "fifth link" fixed to bottom of rear axle centre attached to gearbox bell housing Panhard Bar - a transverse link across multi link suspension creating beneficial weight transfer at both ends of the car. Axles Traditionally F1 stockcars used FG/LD axles. They are quite heavy and as a result, most drivers are leaning towards Transit axles, especially on shale. They are lighter and have a lower linear drive. The more competitive tarmac drivers are fitting race prepared half shafts imported from America. Engines The 454ci big block Chevrolet power units as well as the 510 and 540 models are the standard F1 stockcar engines. These MklV engines were fine but the gradual technical development of the factory engines has rendered newer versions unsuitable for racing. The smaller 350 and 400 small block engines are more expensive, but much favoured by many top drivers today, however; the 400 is becoming more and more rare. Both big and small block engines generate approx. 500bhp, some as much as 600bhp, but rarely can all that power be optimised to the full benefit of the cars traction. Although Chevrolet are the favoured power unit’s, Dan Squire racing No.291 uses a Buick and Iain Stirk racing No. 65 uses a Dodge. ~ The detail here is extracted from various sources and is in no way definitive ~ ALTERNATIVE VIEWS OF RON KROONDER'S SHALE CAR - click on image to enlarge (fotos © Jörg Nöske)