ANGLE-SPRING CLUTCH ADJUSTMENT PROCEDURE
STEP # THIS PROCEDURE COVERS BOTH 14” AND 15 1/2” CLUTCHES
1 After clutch installation, check the clearance between the yoke tips and wear pads on bearing housing for 1/16” clearance. This determines pedal free play. (See Illustration)
Adjust the clutch linkage to increase or decrease the yoke-to-bearing clearance. NEVER USE THE INTERNAL CLUTCH ADJUSTMENT FOR THIS PURPOSE.
2 Check for proper clutch brake and bearing gap of 1/2” to 9/16”. If the gap is not within these tolerances, the clutch needs adjusting. If the clutch does need adjusting, remove the lock strap and set the clearance between the bearing and clutch brake at 1/2” to 9/16”. THIS DIMENSION IS CRITICAL. DO NOT VARY - EITHER OVER OR UNDER THESE DIMENSIONS - UNDER ANY CIRCUMSTANCES.
Use the internal adjustment on the clutch to move the bearing. Turn adjuster clockwise to move bearing towards transmission (to decrease clearance) or counter clockwise to move the bearing towards the engine (to increase clearance). If internal adjustment exceeds 4 notches either way the clutch may not release or may slip.
Put tension on the linkage to be sure bearing is stretched and no movement towards the engine is noticed. Measure clutch brake and bearing gap with 1/2” - 9/16” gauge. (See Illustration) Once the adjustment is set, re-install lock strap.
REMINDER: The bearing must move a minimum of 1/2” or clutch will not release. Eliminate lost motion before checking for 1/2” movement. Lost motion is generally caused by loose or worn linkage, or worn yoke or cross shaft bushings.
3 If internal clutch adjustment was made re-verify the 1/16” clearance between the yoke tips and wear pads on bearing housing shown in Step #1 above. If necessary, re-align linkage to obtain proper clearance. (See Illustration)
4 Re-verify the clutch brake squeeze by inserting .010 feeler gauge between bearing and clutch brake, then depressing the pedal to end of stroke. The feeler gauge must be tightly clamped between the bearing and the clutch brake. (See Illustration) This verifies the contact of the bearing to the clutch brake.
The clutch brake will be squeezed if the total pedal stroke slightly exceeds the movement required to move the yoke/fork 5/8” to 11/16” (the combined total of the 1/8” clearance between yoke tips and wear pads and the 1/2” - 9/16” brake squeeze gap.
IN THE EVENT THE BRAKE IS NOT BEING SQUEEZED, DO NOT CHANGE THE 1/2” - 9/16” GAP FOR THE CLUTCH BRAKE, OR THE 1/16” CLEARANCE FOR THE BEARING HOUSING, CONSULT THE VEHICLE MANUFACTERER SERVICE MANUAL.
In analyzing the reasons for the brake not being squeezed, other things to check for are:
A. Worn linkage components or yoke and cross shaft bushings. If necessary, replace those components.
B. Improper linkage assembly. Verify that linkage is assembled in the correct hole locations.
C. Pedal stroke. To adjust, raise the upper and/or lower the lower pedal stops.
NOTE: MAXIMUM BRAKE SQUEEZE (IN CAB OF TRUCK) SHOULD NOT EXCEED 1” FROM THE END OF PEDAL STROKE. IF IT DOES, IT CAN BE ADJUSTED BY:
A. Changing pedal stops in cab to reduce total pedal stroke.
B. Increasing 1/8” yoke-to-bearing setting to lower squeeze. (This will increase free-pedal travel)
5 Once the external parts are in tune with the clutch, record the measured amount of free-pedal movement in the vehicle log. This is the normal (standard) pedal travel for this vehicle. Then, if and when the clutch again needs adjustment, it should be adjusted back to this standard.
Example: If pedal travel standard is 2”, the clutch may need adjustment when wear has reduced it to about 1” of travel.
NOTE: Clutches are adjusted at the factory to original equipment specifications, and should require very little internal adjustment to achieve proper release and engagement. The clutch must not be adjusted to accommodate thin or worn flywheels, or worn linkage, yoke and/or cross shaft bushings, or to accommodate other drive train deficiencies. Adjustment for such purposes will either cause the clutch to not function properly or will cause early clutch failure, and will be apparent on factory inspection of warranty claims... and therefore will void the manufacturer warranty.