1. Clutch Basics manual adjust / lube ZF Sachs Twin Extend operation & maintenance
Western Region
Art Herrnberger

2. ON LINE TRAINING

3. Manual adjust clutch

4. CLUTCH OPERATION BASICS
Disconnects / Connects engine from / to transmission
99% of clutch wear occurs at vehicle start. (starting vehicle in low gear = max clutch life)
Double clutching = disconnects mass of engine from trans while shifting gears.

5. Clutch Components

6. Clutch Brake Should be called the “Input Shaft” Brake

7. DISENGAGING AND

8. Diaphragm Spring generates Clamping Force of Clutch
Diaphragm pushes on Retainer,
Retainer pushes on Levers,
Levers push on Pressure Plate
Lever ratio amplifies Diaphragm Force

9. Release fork clearance
Be sure the linkage / peddle full return

11. Release bearing to clutch brake clearance
Release bearing to clutch brake clearance inch /16th inch - ½ inch min

13. Is release fork to brg clearance less than 1/8 inch?
CHECK FORK CLEARANCE AT EACH SERVICE, TAKE A TURN
ON THE ADJUSTING RING….
MAINTAIN 1/8 INCH = MAX CLUTCH LIFE
RECORD before & after adj measurements = MAX CLUTCH LIFE

14. WHAT IS CLUTCH ADJUSTMENT?
Maintaining clamp force

15. Diaphragm Spring generates Clamping Force of Clutch
Diaphragm pushes on Retainer,
Retainer pushes on Levers,
Levers push on Pressure Plate
Lever ratio amplifies Diaphragm Force

16. (Contact point of Diaphragm on Cover Housing is a fixed position)
Diaphragm Force (Compression) Controlled By Position of Retainer
(Contact point of Diaphragm on Cover Housing is a fixed position)

17. Retainer Position is Controlled by Adjusting Ring
Retainer is positioned by Lever
Lever orientation is a consequence of:
Disc + IP/PP thickness (uncontrollable)
Adjusting Ring setting (controllable)
Indirectly, Adjusting Ring setting Controls Diaphragm Force

18. How to Properly Control Diaphragm Force, When You Can’t See inside the Clutch to Position Retainer?
(0.530”)
(1/8”)
Freeplay
Sleeve Length is Known, Therefore Release Bearing Clearance to Clutch Brake and Freeplay is Used to Detect Retainer Position
Freeplay Loss Indicates Retainer Position is Changing (Eventually Requiring Clutch Adjustment)

19. Diaphragm Spring Characteristic
Force
Compression Stroke
Dual Trace Caused By
Friction (Hysteresis)
Return Stroke
Diaphragm Force in Frictionless System
Free State
Deflection

20. Clutch Characteristic – Clamp Load Curve
Loss of Free-play Indicates Adjustment is Required
Set Point Prior
to Adjustment
Set Point at Initial
Installation
Required
Clamp Load
Clutch bolted to the flywheel
.530 clearance bearing to
clutch brake
Free state
Amount of Wear
Which Causes
Free Play to
Become Zero
Free Play = Zero
Bearing at .530”

21. Clutch adjustment is turning the adj ring to move the pressure plate forward to compensate for friction disc wear (Measured by position of release bearing)
The following are also methods of adjusting a clutch
Clutch adjustment is turning the adjusting ring
Not changing height of peddle. Not taking slack out of linkage. Not extending a linkage rod, or reducing. If a turn is not made on the adjusting ring, it is not a clutch adjustment! . The pressure plate load is controlled by the position of the levers to the spring and back of pressure plate. It is maintained by adjusting ring movement. All other changes to the system are not a clutch adjustment.

22. Clutch brake clearance factors
Clutch brake wear
Transmission bearing retainer wear

23. What is condition?

25. Trans input bearing retainer

26. Release Fork Does it pull straight back on Release bearing?
Wear patterns tell a story
Bushings
Shafts
Conditions
Anti rotation surfaces.
Hardened forked needed?

27. Lube interval = 15,000 miles CHASSIS GREASE IN A RELEASE BEARING?
Chassis grease will not stay put at high temp

28. CLEAN OLD GREASE FROM ZERK.

29. Cross shafts & linkage

30. Block or “Cage” clutch at removal
Pressure
Plate
(3 inch ½ inch thick blocks at removal….keeps levers loaded)

31. Clutch basics Summary Maintain 1/8 fork clearance = max life
Clutch brake squeeze is 1/2 inch - 9/16th inch
Make a clutch internal clutch adjustment at each service
Use proper lube
Do not lube the clutch brake friction surface
Block / or “cage” clutch at removal

32. TWIN EXTEND clutch 15 ½ inch two plate Controlled center plate
Self adjusting
Locking adjusting mechanism
Open architecture clears the mechanism of dirt

33. Key Features
Open architecture “free flow” design – adjustment mechanism is not confined to a narrowly clearanced packaging space. If / when dirt ingestion occurs, build–up remains in areas that do not reach adjustment mechanism

34. Key Features
Patented “Controlled Center Plate” mechanism ensures full release of Both Disc Assemblies
XTend locking mechanism prevents misadjustment due to system vibrations or shock loads

35. Shipping (caging ) bolts
Four 7/16 X 1.5 inch bolts

36. Initial check. Set up.
1) VIDEO
2) PDF file

37. Twin Extend Self adjusting. Routine adjustment not needed
Not maintenance free, check the system at PM
Normal lube interval
Cage bolts must be in place to install / remove
A punch and a hammer will not torque the spanner nuts

38. ZF Sachs Twin Extend clutch basics manual adjust / lube
Questions?
Thank you
Western Region
Art Herrnberger