Lotus Evora, Service Notes

Page: 50 / 370

Page 5
Lotus Service Notes Section CK
Camber Adjustment
Camber is the angle from vertical of the wheel when viewed from the front, and is said to be negative when
the wheel leans inwards at the top (positive when leaning outwards). The primary purpose of camber is to
achieve the maximum efficiency of the tyre under cornering loads and body roll, with the specification closely
allied to a particular wheel/tyre combination. The camber angle changes with suspension travel, becoming
more negative on bump, and should be measured only at the specified ride height. Incorrect camber can result
in handling deficiencies and excessive tyre wear.
Eccentric cams at the inboard pivots of the lower wishbone provide a means of camber adjustment. The
front pivot bolt is inserted from the rear, and the rear pivot bolt from the front, with each bolt head featuring an
integral eccentric cam. A corresponding eccentric camplate is clamped beneath the nut, and is keyed to the
bolt via a tongue and groove feature to ensure alignment between the two cams. Each cam is constrained
by vertical guides integral with the subframe structure, whereas the pivot bolt hole in the subframe is slotted
horizontally. Thus by turning the bolt (and eccentric cams) the wishbone pivot point may be moved inboard or
outboard.
When adjusting camber, the front and rear pivot bolts should be moved by a similar horizontal distance to
minimise the effect on castor (see below) but be aware that the horizontal movement produced by turning the
cambolts accords with simple harmonic motion, and is not linear. After adjustment, ensure that the nuts are
tightened to 86 Nm (only at ride height).
Cambolt Effects
From a midpoint position (i.e. centres of bolt and eccentric on common vertical axis, stamped arrow pointing
vertically upwards or downwards);
Foreward cambolt; 90° cambolt rotation moves pivot horizontally by 5mm, and
- changes camber angle by 0.25°
- changes castor angle by 1°
Rearward cambolt; 90° cambolt rotation moves pivot horizontally by 5mm, and
- changes camber angle by 0.7°
- changes castor angle by 1°
Note:
Forward cambolt; Moving pivot axis INboard;
- reduces negative camber
- increases castor
Rearward cambolt; Moving pivot axis INboard;
- reduces negative camber
- reduces castor
Total adjustment range - camber 4°
- castor 0.8°
Camber angle
c29
Vertical Wheel centreline