Suspension Systems- Checking Shock Absorbers

To identify a problem with any steering or suspension components the first thing you do is drive the vehicle find out where the problem is coming from front, rear etc. If its a knocking or constant sqeek, make sure you check the shock absorbers fully and every other source!

FLUID LEAKS

Loss of oil from the shock absorbers result in 'poor functioning' and hence loss of damping. ALWAYS consider the effects that leakage will have on damping.

The leakage and therefor damping will not get better but more worse.

MOT FAILURE ITEMS

• A shock absorber which has negligible damping effect.

• External damage or corrosion to the shock absorber so that the unit does no function.
• An insecure or detached shock absorber.

A fluid leak serious enough to indicate that the fluid seal of the shock absorber has failed.

NOTE:slight seepage causing a thin fluid film on a shock absorber is not a reason for rejection!

MOUNTINGS

If these are broken or weakened, either by metal fatigue or by excessive corrosion there is a danger of breakage and shock failure.

MOUTNTING BUSHES

A cracked or abnormally deformed mounting bush may cause noises in the suspension when accelerating, braking or going over obstacles.

CORROSION

Check for corroded , broken and missing weather(dust or dirt) shield / gaiters. These allow dirt onto the piston rod, which can cause the chrome finish to become pitted and in turn cause failure of the seals allowing a loss of oil.

DAMAGE

Check for damaged, dented or bent working cylinders or piston rods. deformation of the body of the shock absorber may slow down or stop the piston as it moves back and forth.

SEIZURE

the vehicle experiences all shock directly. this will damage some or all of the mountings and render the vehicle unsafe.

MISMATCHED

Check for unmatched shock absorbers. This indicates an incorrect fitment, shock absorbers must always be recommended to be fitted in matched pairs (if not then the feel and handling of the vehicle can still be very much uncomfortable, the feel would be like wearing a brand new Nike air max trainer on one foot and wearing a flat k Swiss trainer on the other foot and the feel between the two when running is completely different).

RELATED SUSPENSION COMPONENTS

Always look for further evidence to establish the condition/performance of the shock absorber.

Other suspension components should be included in the shock absorber inspection check?

TYRES

It is very important to check tyres for signs of shock absorber wear. Remember a tyre that is up in the air, when it should be in contact with the road surface, is of no use to the driver.

ROAD SPRINGS

If the road springs are weak or snapped, this will indicate that the springs have been overworked, possibly because of lack if damping. Look for signs of coil clash.

BUMP STOPS

Bump stops are for limiting suspension vertical movement. Check weather or not any bump stops are missing, damaged or shiny, this may indicate that the shock absorbers are bottoming out.

REMEMBER: Worn shock absorbers also increase the wear on other mechanical components of the vehicle.

 When examining semi - strut, inserts and strut legs units pay particular attention to the following;

• Top mounting (wear and condition)
• Road spring (weak or broken)
• Spring seat (corrosion)
• Pistion rod gaiter (missing or damaged)
• Brake bleed nipples (brakes may not bled)
• Metal brake pipes and flexible brake hoses (condition)
• Inner wing (condition and strength)
• Steering and suspension ball joints (play or knocking)
• Rubber bushes (splits or heavy perishing)
• Wheel bearings (hold road wheel 3 and 9 ,12 and 6 and feel for play)