MN-745
13
Q. Is it necessary to keep air in the air springs at all times and how much pressure
will they need?
The minimum air pressure should be maintained at all times. The minimum air pressure
keeps the air spring in shape, ensuring that it will move throughout its travel without
rubbing or wearing on itself.
Q. Is it necessary to add a compressor system to the air springs?
No. Air pressure can be adjusted with any type of compressor as long as it can produce
sufficient pressure to service the springs. Even a bicycle tire pump can be used, but it’s
a lot of work.
Q. How long should air springs last?
If the air springs are properly installed and maintained they can last indefinitely.
Q. Will raising the vehicle on a hoist for service work damage the air springs?
No. The vehicle can be lifted on a hoist for short-term service work such as tire rotation
or oil changes. However, if the vehicle will be on the hoist for a prolonged period of time,
support the axle with jack stands in order to take the tension off of the air springs.
TUNING THE AIR PRESURE
Pressure determination comes down to three things — level vehicle, ride comfort, and
stability.
1. Level vehicle
If the vehicle’s headlights are shining into the trees or the vehicle is leaning to one side,
then it is not level (fig. 13). Raise the air pressure to correct either of these problems
and level the vehicle.
2. Ride comfort
If the vehicle has a rough or harsh ride it may be due to either too much pressure or not
enough (fig. 14). Try different pressures to determine the best ride comfort.
3. Stability
Stability translates into safety and should be the priority, meaning the driver may need
to sacrifice a perfectly level and comfortable ride. Stability issues include roll control,
bounce, dive during braking and sponginess (fig. 15). Tuning out these problems usually
requires an increase in pressure.
GUIDELINES FOR ADDING AIR
1. Start with the vehicle level or slightly above.
2. When in doubt, always add air.
3. For motorhomes, start with 50-100 PSI in the rear because it can be safely assumed
that it is heavily loaded.
4. If the front of the vehicle dives while braking, increase the pressure in the front air bags, if
equipped.
Bad headlight aim
fig. 13
Rough ride
fig. 14
Sway and body roll
fig. 15
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