CHAPTER 5. REPAIR AND OVERHAUL (REBUILD)

CHAPTER 5

REPAIR

AND

OVERHAUL

(REBUILD)

Section I. PRELIMINARY INSTRUCTIONS FOR TRANSMISSION

OVERHAUL (REBUILD)

5-1. General

(2) The utmost care should be used in han-

dling of parts during cleaning and overhaul

a. Equipment Needed. Proper equipment must

be available before disassembly is started. This

(rebuild ) operation. Nicks, scratches, dents, or burs

equipment includes a suitable hoist of at least 1/2

can prevent proper assembly or cause malfunction

after assembly. This is especially true of valves and

ton capacity. proper hand tools and special tools,

valve body parts.

improvised tools. receptacles for small parts, wood

(3) Abrasives, files, scrapers, wire brushes,

blocks. wiping cloths, and an arbor press. Refer to

and sharp tools should never be used on surfaces

paragraphs 3-4 and 3-5 for lists of special and

where finish is important to the operation or sealing

improvised tools.

of parts, except where specifically recommended.

b. Parts to Discard. Cotter pins, lock wires, lock

(4) Gum or varnish may be removed by

strips, and gaskets should be discarded at trans-

soaking in dry cleaning solvent or mineral spirits

mission disassembly. New parts should always be

paint thinner and by the use of a soft bristle brush.

supplied in such cases.

Crocus cloth may be used to remove minor surface

c. Avoiding Component Damage. Care must be

irregularities. Lapping compound may be used, if

used to avoid damage to transmission components

required, in valve body bores to prevent valves from

during disassembly, cleaning, inspection, repair,

sticking. Clean thoroughly to remove compound

and reassembly. Scratches. nicks, and dents caused

after use.

by careless handling may cause oil leakage or

(5) A soft wire (brass or copper) may be used

improper functioning and could result in trans-

to clean oil passages. Always flush such passages

mission failure. All defective parts must be

thoroughly after cleaning.

replaced.

(6) If steam cleaning is used, dry the cleaned

d. Torque Requirements. All standard torquing

parts immediately with compressed air, and apply a

requirements for bolts, screws, and nuts are

film of oil to prevent rusting. Never use lye or

tabulated in table 6-1. Where special torque

caustics which will corrode or etch metal surfaces.

requirements apply. they will be found in the

(7) Do not clean the lubricant from new

applicable text.

bearings. Keep new bearings wrapped until they

5-2. Cleaning Recommendations

are to be installed. Soak bearings which have been

a. Importance of Cleanliness. Cleanliness is of

in service in dry cleaning solvent or mineral spirits

paramount importance in servicing the trans-

paint thinner to loosen deposits of dirt. Do not spin

mission. All components must be thoroughly

bearings during cleaning or drying. After cleaning,

cleaned and kept clean throughout the rebuild

turn bearings by hand and note any evidence of

process. The presence of dirt can cause malfunction

grit. Reclean them if grit is present. Refer to TM 9-

and possible failure of the transmission. Refer to

214 for further information on cleaning bearings.

TM 9-208-1 and TM 9-208-2.

5-3. Inspection and Repair Recommendations

WARNING

a. Castings. Forgings. and Machined Surfaces.

Forewarn personnel in the immediate area

(1) Inspect all castings and forgings for

when using compressed air for cleaning.

breaks, cracks, and wear or scoring that would

Compressed air. coming into contact with

impair serviceability. Remove nicks and small

the human skin or causing flying metal

surface irregularities with crocus cloth or a soft

chips. can cause serious injury.

stone.

b. Cleaning Parts.

(2) Inspect all oil passages for obstructions

(1) Every component should be thoroughly

and dirt. Reclean passages if necessary.

cleaned after the transmission is disassembled.

(3) Inspect mounting faces for nicks, scratch-

Cleaning is necessary to insure effective inspection

es, and scores. Remove minor defects with crocus

for wear, damage, and serviceability of com-

cloth or a soft honing stone. Replace any parts in

ponents.

5-1