Roadmaster V8-305 5.0L (1992)
Fig. 11 Power Head Assembly Exploded View. Delco-Moraine Tandem Diaphragm Booster
Disassembly
1.
Remove pedal pushrod boot, silencer, check valve, vacuum switch and grommets, as equipped, then the front housing seal.
2.
Scribe matching marks between front and rear housing sections, then mount booster assembly in suitable holding fixture with rear housing facing
up.
3.
Apply pressure to housing with holding fixture forcing screw and rotate rear housing counterclockwise to unlock housing halves.
4.
Slowly release spring tension, then remove booster assembly from holding fixture. Do not allow spring tension to release suddenly, as damage
or personal injury may result.
5.
Lift off rear housing, then remove primary power piston bearing from housing.
6.
Remove power piston group and return spring from front housing, Fig. 10.
7.
Remove master cylinder piston rod and reaction retainer from front of piston, then the silencer from the rear of the assembly, Fig. 11.
8.
Hold piston assembly at edges of divider and strike pedal pushrod against work surface to dislodge diaphragm retainer.
9.
Remove primary diaphragm and support plate, secondary power piston bearing and housing divider, then the secondary diaphragm and support
plate from piston, noting installation position of components.
10.
Clean and inspect components, then replace as needed. Do not disassemble power piston. If service is required, power piston must be
replaced as an assembly.
Assembly
1.
Position power piston assembly on work surface with pedal pushrod facing up.
2.
Lubricate inner lip of secondary diaphragm, fit diaphragm over support plate, then install assembly onto power piston.
3.
Install secondary power piston bearing into divider with flat surface of bearing on side of divider with 6 lugs, Fig. 11.
4.
Install guide sleeve J-28458 or equivalent over power piston, lubricate inner diameter of secondary bearing, then install divider assembly with
lugged side facing up.
5.
Lubricate inner lip of primary diaphragm. Fit diaphragm over support plate, then install diaphragm assembly on power piston.
6.
Ensure diaphragms and support plates are properly positioned, install new diaphragm retainer, then seat retainer on power piston using guide
sleeve J-28458 or equivalent and hammer.
