Davz said:
buzyg said:
Z4 is supposedly 50:50 weight distribution
if that is true, how did they manage this with the 2.0, 2.2, n52 and the heaviest of all 3.0 m54?
50/50 weight balance is for a static load but with acceleration and braking, this weight distribution will constantly change. So brake hard before a bend and the mass moves forward with the car diving down at the front lessening traction at the rear, chuck it into a bend and the mass moves to the side, combine the two + the mass of the engine, weight balance, I am assuming, will not be 50/50. With increased damping at the front will this lessen the effect of a dynamic load?
Anyone on here with experience of setting up race cars?
One can assume they managed it by placing different engines either more forward or rearwards in the engine bay. I doubt the distribution is exactly 50:50, but should be similar across the range.
I don't see how damping would significantly affect load transfer during braking, cornering, etc. From what I remember, all the body roll (longitudinal or lateral) is caused by moments about the centre of mass/roll centre of the car, and what counter-interacts those moments is the spring stiffness, k (and the geometry of the suspension arms in some cases, i.e anti-dive & anti-squat geometry). The load that the tyre experience has more to do with the distance from the Cg, so mostly affected by weight distribution of the car.
The harder the spring, the more it can counter-interact those moments, therefore, the less the ride height changes, so less change in camber, etc., thus handling would be improved. However, there must be a balance for everything, too hard a spring and the suspension won't move to conform to the shape of the road and instead will cause the whole corner of the car to kick up thus reducing grip at that corner of the car; too soft a spring a spring and it won't react quickly enough. And damping is set up to complement the spring, to dampen its reaction. One may want to increase damping in scenarios where the suspension needs to react more quickly due to a rough surface for example.
I've just realised I was just waffling on without thinking too much as I love this subject, but here's my disclaimer:
I don't remember much of this stuff, and I probably don't know enough about it to be discussing it with anyone. I'm a Mechanical Engineering student who designed the steering system for a 4WD FS car, as well as its space frame. So I wrote a script that calculated the loads on all wheels due to acceleration, braking and cornering (so longitudinal and lateral weight transfer), so at some point I did derive the equations from FBDs and knew my stuff. I'll probably wake up tomorrow, read what I wrote here and cringe.
