A quick gain, can lead to maximum pain

Monday, 23 January 2017

Changing the ride height on your truck or trailer air suspension, maybe a quick fix for a drive line angle issue or reaching a certain king pin height on a trailer. Unfortunately these quick fix changes will eventually lead to some expensive headaches in the future.

Over the past 30 years Powerdown have had many calls about suspension related issues. One of the most common is related to the ride height of rear air or trailer suspensions that have been adjusted above the OEM (Original Equipment Manufacturers) recommendations. This change in ride height can cause damage to your suspension equipment.

SHOCKING WEAR

A shock absorber is primarily designed to operate in the midpoint of the extended and compressed length of the unit.

inside of shock absorber

SHOCK ABSORBER AT THE MID- POINT OF THE STROKE: 

By increasing the ride height of the suspension, the suspension droop is reduced which limits the downwards travel available in the shock absorber. This dramatically increases the likelihood of the damper topping out when the suspension articulates. The piston will effectively hit the top guide of the shock absorber causing fatigue issues in the design. A re-coil cut off or rebound stop will limit some of the damage in the short term, but this feature is not designed for continual topping out of the unit. This will also lead to premature bush failure and other related end fitting damage.

SHOCK ABSORBER ABOVE RIDE HEIGHT  & SHOCK ABSORBER BELOW RIDE HEIGHT

Eventually over time the shock absorber will most likely leak oil due to internal damage from the constant impact. In extreme cases the life of the shock absorber can be reduced by 80% of its normal service life.

Short stroke shock absorbers on trailers and some rear drive air suspensions are more susceptible than others.

ON VEHICLE RIDE HEIGHT GAUGE

In an industry first Powerdown has released a select range of shock absorbers with a recommended ride height sticker. This sticker is designed to indicate where the shock absorber is operating in terms of stroke when the shock absorber is fitted to the vehicle.

The sticker is strategically placed on the body of the shock absorber to indicate shock absorber stroke relative to vehicle ride height.

Ride Height sticker WholeRide Height sticker Close upGREENIf the dust shield edge is in the GREEN zone then the vehicle ride height is correct. This is where optimum performance of the shock absorber is achieved.

 

 

 

Ride Height sticker Close upAMBER If the dust shield edge is in the AMBER/YELLOW zone (on either the top or bottom end) the ride height should be checked. In this position the stroke of the shock absorber is starting to stray outside of the optimal performance zone.

 

 

 

Ride Height sticker Close upRED If the dust shield edge is in the RED zone (on either the top or bottom end) the ride height is way off. This indicates that the likelihood of the shock absorber topping out or bottoming out is highly increased over time. This may also mean that the wrong shock for the application has been fitted.

 

 

If the shock absorber falls into the AMBER/YELLOW or RED zones it is highly recommended that the ride height of the suspension is checked in accordance with the OEM recommendations. This will help avoid premature wear and tear, not only to the shock absorbers, but to the entire suspension of your vehicle.

Please note when referencing the height indicator on each shock absorber, the vehicle must have the engine running and had adequate time to reach normal air operating pressure (approximately 10 minutes). If referenced after the truck has been inoperable for any length of time, the reading may be inaccurate due to loss of pressure in the air springs.

For further information please call Powerdown head office on (02) 4949 0000.