BMW M4 GT4 User Manual page 17

BMW M4 GT4 // CHASSIS
SPRING PERCH OFF S E T
Used to adjust the ride height at this corner of the car by changing the installed position of the spring. Increasing the spring perch
offset will result in lowering this corner of the car while reducing the spring perch offset will raise this corner of the car. These
changes should be kept symmetrical across the axle (left to right) to ensure the same corner ride heights and no change in cross
weight. The spring perch offsets can also be used in diagonal pairs (LF to RR and RF to LR) to change the static cross weight
in the car.
BUMP S T I FFNES S
The bump stiffness setting is a paired adjustment controlling both the low and high speed compression damping characteristics of
the damper. In this case 0 is minimum damping (least resistance to compression) while 25 is maximum damping (most resistance
to compression). Increasing the bump stiffness will result in a faster transfer of weight to this corner of the car during transient
movements such as braking and direction change with increased damping usually providing an increase in turn-in response
but a reduction in overall grip in the context of front dampers. High speed compression damping will increase proportionally to
the increase in low speed compression damping which will also result in harsher response to kerb strikes. At smoother tracks
more bump stiffness will typically increase performance while at rougher tracks or ones with aggressive kerbs less compression
damping can result in an increase in mechanical grip at the expense of platform control.
REBOUND S T IFFNES S
The Rebound Stiffness setting is a paired adjustment to both low and high speed rebound damping characteristics. Increasing
rebound damping will slow down the rate at which the damper extends in both low and high speed situations. A typical low damper
speed situation would be as the car rolls back to level on a corner exit while a high speed situation would be where the suspension
is extending after large kerb contact. 0 is minimum damping (least resistance to extension) while 18 is maximum damping (most
resistance to extension). While high rebound stiffness will result in improved platform control for aerodynamic performance and
overall chassis response it is important to avoid situations where the shock is too slow in rebounding as this will result in the tire
losing complete contact with the track surface which can induce or exacerbate severe oscillations.
C AMBER
Camber is the vertical angle of the wheel relative to the center of the chassis. Negative camber is when the top of the wheel is
closer to the chassis centerline than the bottom of the wheel, positive camber is when the top of the tire is farther out than the
bottom. Due to suspension geometry and corner loads, negative camber is desired on all four wheels. Higher negative camber
values will increase the cornering force generated by the tire, but will reduce the amount of longitudinal grip the tire will have
under braking. Excessive camber values can produce very high cornering forces but will also significantly reduce tire life, so it is
important to find a balance between life and performance. Increasing front camber values will typically result in increased front
axle grip during mid to high speed cornering but will result in a loss of braking performance and necessitate a rearward shift in
brake bias to compensate.
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BM W M4 G T4 // US ER M A N UA L