Holiday 2002 NEPTUNE, Owner'S Manual

Page: 289 / 344

Three height control valves (HCV) inflate or deflate the air springs maintaining
the proper suspension height throughout the load range. Two valves are used at
the rear drive axle. These valves control rear suspension height and left or right
tilt of the motorhome. Only one valve controls front suspension height. The
height control valves mount to the main frame of the motorhome above the
axles with a linkage rod connecting the valve to the axle.
The actuating components inside the valves are oil dampened to reduce valve
reaction to momentary suspension bounce and rebound. When a constant
suspension change occurs, such as a load change or weight transfer through a
sustained corner, the valve reacts adding or purging air from the air springs as
needed.
The air springs mount between the axles' H-frame assembly and the two
main frame rails. Air spring support plates mount to the main frame and the
H-frame. There is a specified distance the air spring must maintain between
the mounting plates. Other than specified distance between the plates not only
compromises ride quality and handling, it adversely affects shock absorber
travel, drive shaft angle and various other running gear components.
Should it become necessary to check the suspension ride height, start with
the motorhome on a flat level surface. The air system must be fully charged
with the suspension normalized at ride height. Specified distances may vary
plus or minus ¼". Small offset adjustments to the rear valves may be necessary to
compensate for slight tilt. Example: Adjusting the curbside rear height control
valve up will pivot the roadside front corner down.
NOTE: Drive shaft angle is affected by the suspension ride
height. Improper drive shaft angle can damage suspension
or shorten the life of universal joints. Shock absorbers and
air springs are in travel centers at proper ride height.
To adjust the suspension ride height begin with:
• The motorhome on flat level surface.
• Air system fully charged.
• Suspension at normal ride height.
Start by checking the distance in the front.
1. Measure the distance between the mounting
plates of the air springs.
2. If the measurement is off, loosen the adjusting
lock nut at the eccentric slot on the valve.
3. Move the plastic arm up to raise suspension
height, this will inflate all the front air springs.
Move the plastic arm down to lower suspension
height, this will deflate the air springs. Make
adjustments in small increments.
Chassis Information
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2 0 0 2 N E P T U N E
10 • 289
HEIGHT CONTROL
VALVES
Measurements for the Neptune:
(A) Front - 9½ in., Rear - 11½ in.
OM090348C
Adjusting