NOTE: A hard, crystal-like substance sometimes forms a ring in cylinder bore near
where piston stops when brake is released.
3. Inspect pistons, cups, and cylinder bores for scratches, scoring, pitting and
corrosion.
4. Use crocus cloth or a hone to remove deposits or minor surface irregularities. If
bore does not clean up readily, replace cylinder.
5. Inspect tapped holes of cylinder for thread damage. Use a tap to clean up minor
damage. Replace cylinder if threads are damaged due to cross-threading of
capscrew or fittings.
6. Check passage in bleeder screw. Use a piece of fine wire to open passage if
blocked. Also check threads for damage. Replace bleeder screw if threads
cannot be cleaned up.
7. Piston movement should be smooth.
1.6.4 Assembly
1. Lubricate cylinder bore, spring, cups, and pistons with clean brake fluid. Install
into cylinder. Open side of cups and flat side of piston must be toward inside of
cylinder.
2. Install rubber boots making sure they engage grooves on cylinder.
3. Install bleeder screw into cylinder but do not tighten.
1.6.5 Installation
1. Position wheel cylinder, install capscrews and lock washers, and tighten to 15-20
ft-lbs torque.
2. Spread brake shoes apart enough to allow projections of brake shoes to engage
cylinder properly.
3. Connect brake line to wheel cylinder. Tighten tube fitting firmly. Do not
overtighten.
4. Bleed brake system as described in chapter 2, section1. Check for leaks when
bleeding system.
5. Install brake drum as described in paragraph 1.5.4.
After initially mounting wheel and tire assembly, recheck lug nut
torque after the first hour of operation and after the first 8 hours of operation. After
this, check monthly or every 250 hours, whichever comes first. Do not lube wheel
studs as it will result in inaccurate tightening torque. Failure to follow these
procedures could result in wheel mounting failure and loss of vehicle control.
CHAPTER 3 OVERHAUL AUGUST 31, 2008
1 GENERAL REPAIR PAGE 11
M100 Tow Tractor Manual No. 46052
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