Anti drive/anti squat system
Discussion
Im knocking up my own car, im lucky as in my usual job im an inventor so i have a 4 axis VMc cnc turning etc etc, so i'm trying to keep accuracy high in the areas i can control, chiefly suspension geometry. Being a bit lazy i designed my uprights and associated geometry without any anti dive, or anti squat, and i've been wondering about whether i should look back at the geometry to add in some anti dive at least, the car is mid engined, alfa v6 transverse. I was wondering about using a third damper/spring to generate anti dive/squat, I understand high aero cars use them to control ride height under high aero loads, they run a high spring rate, i was wondering about doing the opposite, using a light spring, mainly to return the damper, and using a slow speed damping circuit to control the dive.
In usual anti dive geometry(in my limited experience) you align the wishbone inboard pickups in line with the CoG so longitudinal forces under braking are through the wishbone pickups and so you dont get the downward force, if i put a 3rd spring and damper it should slow the dive but you'll still get the downward force. I was wondering if anyone has any experience of such a setup, or advice on it.
Thanks
In usual anti dive geometry(in my limited experience) you align the wishbone inboard pickups in line with the CoG so longitudinal forces under braking are through the wishbone pickups and so you dont get the downward force, if i put a 3rd spring and damper it should slow the dive but you'll still get the downward force. I was wondering if anyone has any experience of such a setup, or advice on it.
Thanks
on a race car its common for anti dive to be added to the front end by inclining the upper or lower wishbone points (rearward higher than forward mountings).
same goes for rear anti squat, but forward points raised. Normally you don't need as much anti squat as dive though, 2-5 deg max on rear.
some weight transfer is required of course as a function of handling and to be honest without knowing helluva lot more of the car, design and prospective usage, youre gonna get nothing other than vagaries as above.
If the cars relatively small and light (think single seater or bike engine car) it may need neither engineered in.
its common on hillclimb single seaters to see a 3rd spring setup, sometimes with a damper too, but as a specific design element. These cars use uber sticky tyres and much wider wings than a normal formula car, with much more aggressive aero, and can produce DF figures a good number of times the cars own weight, hence the 3rd spring usage. I cant see the need on a similarly light car without the huge aero loadings though
same goes for rear anti squat, but forward points raised. Normally you don't need as much anti squat as dive though, 2-5 deg max on rear.
some weight transfer is required of course as a function of handling and to be honest without knowing helluva lot more of the car, design and prospective usage, youre gonna get nothing other than vagaries as above.
If the cars relatively small and light (think single seater or bike engine car) it may need neither engineered in.
its common on hillclimb single seaters to see a 3rd spring setup, sometimes with a damper too, but as a specific design element. These cars use uber sticky tyres and much wider wings than a normal formula car, with much more aggressive aero, and can produce DF figures a good number of times the cars own weight, hence the 3rd spring usage. I cant see the need on a similarly light car without the huge aero loadings though
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