Xray XB8R Instruction Manual - page 37
37
Rear roll center
Characteristics
Higher
· increases on-power traction
· decreases traction under braking
· use to avoid traction rolling at corner entry
· use under low-traction conditions
· reduces rear tire wear
Lower
· decreases rear traction
· use to avoid traction rolling mid-corner and corner exit
Rear Roll Center
You can raise or lower the rear roll center by adjusting the following components:
· Rear upright lower mounting position.
The rear lower arm attaches to the rear upright in one of two mounting holes.
· Rear upper camber link mounting position.
The inner end of the rear upper camber link can be attached to the rear shock tower in
one of 7 positions. The outer end of the rear upper camber link can be attached to the
rear upright in one of 3 positions.
SHOCK ABSORBERS
Adjust the shock absorbers and their mounting positions to suit track conditions.
Piston Hole Type
There are two different types of shock pistons that can be used in the XB8.
Piston hole type
Characteristics
Conical up
(with dot on the piston)
· less dampening when shock is compressed
· more dampening on rebound
Conical down
(with dot on the piston)
· more dampening when shock is compressed
· less dampening on rebound
Straight
· equal damping all the time (compressing and rebounding)
Piston Hole Size
For each type of shock piston (conical or straight holes), there are three pistons with holes
of different sizes.
Piston hole size Characteristics
Smaller
· harder damping
· slower chassis weight transfer
· slower response
· decreases chance of bottoming out when landing if used with “thicker” oil
· decreases chassis roll if used with “thicker” oil
· use with thinner oil if track is rough
Larger
· softer damping
· increases traction
· quicker chassis weight transfer
· quicker response
· increases chance of bottoming out when landing if used with “thinner” oil
· increases chassis roll if used with “thinner” oils
· use with thicker oil if track is smooth
Shock Oil
You can use shock oils of different weights in a shock absorber.
Shock Oil
Characteristics
Thinner
· same characteristics as larger pistons holes
Thicker
· same characteristics as smaller pistons holes
1.5
1.4
1.3
1.5
1.4
1.3
Silicone Shock Oil
Rear upper camber link
- length
Characteristics
Shorter link = outer hole on tower
and/or inner hole on hub
· increases rear camber gain
· increases traction slightly
· decreases steering and stability
Longer link = inner hole on tower
and/or outer hole on hub
· decreases rear camber gain
· increases stability
· slows down the car‘s responsiveness
XB8R SET-UP
STRAIGHT HOLES
CONICAL UP HOLES
CONICAL DOWN HOLES
Rear upright - lower pin
Effect on Rear Roll Center
Upper hole
· lower rear roll center
Lower hole
· higher rear roll center
Rear upper camber link
- shocktower
Effect on Rear Roll Center
Upper holes
· lower rear roll center
Lower holes
· higher rear roll center
IMPORTANT!
Make equal adjustments on both left and right sides of the car.
Note that typically you should use piston hole sizes to suit the track conditions
rather than alter the oil viscosity.
Part
Viscosity
Part
Viscosity
359515
“150”
359545
“450”
359520
“200”
359550
“500”
359525
“250”
359560
“600”
359530
“300”
359570
“700”
359535
“350”
359580
“800”
359540
“400”
359590
“900”
Use only the genuine premium quality
Xray silicone shock oils.
The shock oils are availabe
in 50ml size in these
viscosities: