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

ON LINE TRAINING

Manual adjust clutch

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.

Clutch Components

Clutch Brake Should be called the “Input Shaft” Brake

DISENGAGING AND

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

Release fork clearance Be sure the linkage / peddle is @ full return

Release bearing to clutch brake clearance Release bearing to clutch brake clearance .530 inch - 9/16th inch - ½ inch min

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

WHAT IS CLUTCH ADJUSTMENT? Maintaining clamp force

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

(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)

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

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)

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

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”

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.

Clutch brake clearance factors Clutch brake wear Transmission bearing retainer wear

What is condition?

Trans input bearing retainer

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

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

CLEAN OLD GREASE FROM ZERK.

Cross shafts & linkage

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

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

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

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

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

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

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

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

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