Shock absorbers are often overlooked when evaluating the safety or roadworthiness of a vehicle because they cannot be easily seen, and are therefore difficult to check for signs of damage or wear.
And because they wear out gradually, motorists often adjust unconsciously to the change in their vehicles handling, unaware that the efficiency of vital components is compromised. It is therefore essential that you check your customer’s shocks for them and remind them how dangerous worn shocks can be. Although worn shock absorbers seriously affect a vehicles handling and safety – not all problems related to suspension are necessarily caused by worn shock absorbers.
Monroe South Africa offers the following technical tips for fitment centres:
Steering wheel vibrations
This may not necessarily be from worn or poorly fitted shock absorbers. Other causes include: Poor wheel alignment, poor wheel balancing, worn mountings, worn suspension bushings, worn steering dampers, unevenly worn brakes and even problem tyres.
Shock rubber/bushing not lasting
This could be caused by loose nuts, paint not cleaned off threads before tightening, incorrect sequence or position of rubbers during installation, incorrect position or omission of washers, over-tightening of mountings (not using correct manufacturers torque spec) or just that the rubbers have worn out due to extreme terrain. In some cases this may also lead to the damage of the actual shock or vehicle suspension mountings.
Although there is always the possibility that the shock may have worn/faulty seals, leakage is often caused by piston rod damage during installation (not using the correct tools); damaged or missing dirt shields (particularly if the vehicle is driven in a dusty environment) accident or stone damage, rod corrosion and faulty damaged or missing protection kits. Always replace the rubber boot and bump rubber protection if it is showing any sign of wear such as splitting or moving on the piston rod. This will extend the life of the shock.
Preventing the seal from failing
Don’t forget to lower a vehicle back onto its suspension before finally tightening up. If a telescopic shock is left hanging while the vehicle is in the air on a lift and it is then tightened up at this point (particularly if it is over-tightened) it can cause the piston rod to operate at the incorrect angle putting a side force on the seal that can cause it to fail.
Irregular and increased tyre wear
This may not necessarily be from worn shocks but can also be caused by incorrect tyre pressure, incorrect wheel alignment, faulty brakes or personal driving style. If the tyre wear is in the centre of the tyre the pressure is too high; if is on both outer sides the pressure is too low; if it is only on one side or feathered, the alignment or balance may be out. If the wear is uneven and patchy then the shocks may be worn.
Steering not centering
If the steering will not centre by itself this could be caused by worn or damaged shock mountings which can also be caused by overtightening or using an airgun or not tightening to the manufacturers torque spec. This may also be accompanied by poor handling and faulty suspension tester readings often mistaken for worn shocks.
Monroe shocks have a special “bleed valve setting” built in to make it easier for the installer to prime the shock before fitting. If it is felt by hand it could lead to the incorrect assumption that they are soft or softer than other makes of shock.
Priming the shocks is essential to get the oil flowing and valves working correctly before the vehicle is driving, bearing in mind that standard twin-tube shocks cannot work effectively at angles greater than 45 degrees, and that the shock has been in a box on its side for months before being sold.