DAF CF65, CF75, CF85 Series . Manual - part 1083

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1-1

Shock absorbers

DIAGNOSTICS

ΧΦ65/75/85 series

9

1

1. SHOCK ABSORBERS

1.1 FAULT-FINDING TABLE

SYMPTOM: SHOCK ABSORBER PRODUCES NOISE (CHATTERING, BUMPING ETC.)

Possible cause

Remedy

Shock absorber is loose.

Secure shock absorber.

Attachment rubbers too soft.

Fit new rubbers.

Shock absorber comes into contact with other 

components.

Remove components or fasten them.

Shock absorber cover is loose.

Secure shock absorber cover or replace shock 

absorber.

SYMPTOM: SHOCK ABSORBER DOES NOT FUNCTION

Possible cause

Remedy

Internal shock absorber defect.

Replace shock absorber.

Shock absorber loses oil.

Replace shock absorber.

SYMPTOM: SHOCK ABSORBER LEAKAGE

Possible cause

Remedy

Defective piston rod sealing.

Note: a thin, greasy layer is normal.

Replace shock absorber.

SYMPTOM: SHOCK ABSORBER TOO HARD

Possible cause

Remedy

Incorrect shock absorber type fitted.

Fit correct shock absorber type.

Internal shock absorber defect.

Check shock absorber using a test bench and 

replace, if required.

SYMPTOM: SHOCK ABSORBER TOO SOFT

Possible cause

Remedy

Incorrect shock absorber type fitted.

Fit correct shock absorber type.

Internal shock absorber wear.

Check shock absorber using a test bench and 

replace, if required.

Shock absorber loses oil.

Replace shock absorber.

Vehicle overloaded.

Adjust vehicle loading.

DIAGNOSTICS

1-2

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Shock absorbers

1

ΧΦ65/75/85 series

9

SYMPTOM: POOR DRIVING CHARACTERISTICS/FLAT WEAR SPOTS ON THE TYRES

Possible cause

Remedy

Incorrect damping.

Check shock absorbers using a test bench and 

replace, if required.

Vehicle overloaded.

Adjust vehicle loading.

SYMPTOM: SHOCK ABSORBER HITS END STOP

Possible cause

Remedy

Defective stop rubber.

Replace stop rubber.

Insufficient damping.

See under Shock absorber too soft.

Vehicle overloaded.

Adjust vehicle loading.

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2-1

Leaf suspension

DIAGNOSTICS

ΧΦ65/75/85 series

9

1

2. LEAF SUSPENSION

2.1 FAULT-FINDING TABLE

SYMPTOM: LOOSE U-BOLTS

Possible cause

Remedy

Use of a U-bolt or nut of an incorrect property 

class.

Use U-bolts and nuts of the correct property class.

The tightening torque used for the U-bolt nut was 

too low.

Tighten the U-bolt to the specified torque.

Reuse of a U-bolt with corroded or damaged 

thread.

Fit new U-bolt.

No or inadequate cleaning of the thread 

(which includes removal of paint) before reuse 

of the U-bolt.

Thoroughly clean the thread when reusing it.

No oil or faulty application of oil on the thread and 

the bearing surface of the nut.

Apply the oil as prescribed.

The nut has been tightened using a tool rotating 

too fast. There is a risk of the nut being welded to 

the thread.

Tighten the nut slowly.

Coating (i.e. paint) on the contact faces of the 

connection.

Clean the contact faces before assembly.

Inadequate retorquing of the U-bolt nut or no 

retorquing.

Tighten the U-bolt nut as specified.

SYMPTOM: BROKEN SPRING

Possible cause

Remedy

Regular overloading.

Adjust vehicle loading.

Driving too fast over bad roads.

Adjust speed when the road is bad.

Notching effect due to welding or grinding 

activities.

Cover spring assembly when welding or grinding.

Spring damaged due to impact of a steel hammer. Never hit the springs using a steel hammer or 

some other hard tool.

Incorrect repair of a spring leaf which has broken 

before.

When replacing a broken spring leaf, always 

replace the leaf on top and under the broken leaf; 

better yet, replace the entire spring assembly.

Spring has been heated.

Replace spring assembly. Springs should never be 

heated.

DIAGNOSTICS

2-2

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Leaf suspension

1

ΧΦ65/75/85 series

9

SYMPTOM: SPLAYING OF THE SPRING ASSEMBLY (BROKEN SPRING SHACKLES)

Possible cause

Remedy

Incorrect pre-tension of the U-bolts.

See symptom: Loose U-bolts.

SYMPTOM: SPRING HITS END STOP

Possible cause

Remedy

Vehicle overloaded.

Adjust vehicle loading.

Sagged spring assembly.

Check spring opening of both spring assemblies. 

Replace spring assemblies.

Broken spring.

See symptom: Broken spring. 

SYMPTOM: SHIFTING OR BREAKING OF CENTRE BOLT

Possible cause

Remedy

Incorrect pre-tension of the U-bolts.

See symptom: Loose U-bolts.

SYMPTOM: BUMPING OR CHATTERING OF THE SPRING

Possible cause

Remedy

Shackle pin bearing play at air-sprung front axle.

Replace shackle pin/bearing bush.

Loose U-bolts.

See symptom: Loose U-bolts. 

Loose shackle pin locking at air-sprung front axle. Secure the shackle pin locking.

Spring bracket is loose.

Secure the spring bracket.

Spring comes into contact with other components 

during spring action.

Check freedom of movement of spring.