For more information, refer to the Reference Section on Brakes (Fluid):
brake_system

• A safety defect was issued by the MoCo on certain 1978-1979 FLH, FLH-80, FX, FXE, FXS and 1979 XLH, XLCH models. Motor­cycles were produced and shipped with deficient front brake master cylinders during from June 7, to June 14, 1978. ¹⁾
  • Within the front brake master cylinders, the plunger piston bore diameter was honed up to .015“ over the maximum limit. The oversized bore resulted in a reduced interference fit between the piston seals and the cylinder bore which could allow hydraulic fluid to leak, causing eventual fluid depletion and ineffective braking.
  • Normally, during operation, there would be a prior warning of insufficient brake fluid in the system indicated by fluid leakage around the master cylinder and an increase in the hand lever free movement before braking. However, if this condition were to be left unchecked or ignored, complete loss of the front brake would eventually occur with the increase of fluid loss.
  • Dealers were to replace the defective master cylinders at a reimbursed rate of 0.6 hours before selling any more of the affected models and owners were contacted to bring in their bikes for replacement front master cylinders (43306-78 on XLH/XLCH/FX/FXE/FXS).
  • Affected Sportster models were:
    • 3A17392H9-3A17737H9
    • 4A17404H9-4A17621H9

• A total of 635 XLH and XLS models were produced and shipped between March 30 and April 19, 1979 with a possible defect in the assembly of the brake pedal stop bolt jam­ nut not being securely tightened at the time of assembly. This could allow the bolt to unscrew from the pedal shaft arm & the bolt head to contact the lower inside edge of the sprocket cover, possibly locking or hindering the rear brakes. Each dealer was reimbursed 0.2 hours for each motorcycle serviced to cover costs for labor and pro­cessing. ²⁾
  • Suspect engine VINs were:

XLH ³⁾

XLS ⁴⁾

• The brake pedal stop bolt is located underneath the right side of the engine just below the rear. ⁵⁾
• Always check the jam nut for tightness and check the brake linkage for proper adjustment as follows: ⁶⁾
  • Work the rear brake pedal by hand to determine free play (movement before the plunger contacts the piston in the master cylinder).
  • Free play of the plunger should be app. 1/16” (to be sure the rear brake pressure is relieved when the brake pedal is released.
  • To adjust the free play, loosen the jam nut and turn the stop bolt inward (clock­ wise) to decrease or outward (counterclockwise) to increase the free play. When 1/16“ free play is obtained, tighten the jam nut against the shaft lever while holding the stop bolt in position.
  • Recheck free play.