CHAPTER 5. PRELIMINARY INSTRUCTIONS FOR TRANSMISSION REPAIR

TM 9-2520-249-34&P

CHAPTER 5

PRELIMINARY INSTRUCTIONS FOR TRANSMISSION REPAIR

d. Avoid Abrasives.

Abrasives, files,

5-1.

Preparing for Repair

scrapers, wire brushes and sharp tools should never be

a. Get Proper Equipment.

used on surfaces where finish is important to the

(1) Proper equipment must be available

operation or sealing of parts, except where specifically

before disassembly is started. This equipment includes

recommended.

a suitable hoist of at least 2-ton capacity, proper hand

e. Removal Agents. Gum or varnish may be

tools and special tools, improvised tools, receptacles for

removed by soaking in dry cleaning solvent or mineral

small parts, work table, wood blocks, oil-soluble grease,

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

wiping cloths, and a press.

Crocus cloth may be used to remove minor surface

(2) Refer to paragraphs 3-4 and 3-5 for

irregularities. Lapping compound may be used, if

lists of special and improvised tools and equipment.

required, in valve body bores to prevent valves from

b. What to Discard. Lockwires, lockstrips, and

sticking. Clean thoroughly to remove compound after

gaskets should be discarded at transmission

use.

disassembly. New parts should always be supplied in

Cleaning Oil Passages. A soft wire (brass

such cases.

or copper) may be used to clean oil passages. Always

c. Penalty for Careless Handling. Care must

flush such passages thoroughly after cleaning.

be used to avoid damage to transmission components

g. Steam Cleaning. If steam cleaning is used,

during disassembly, cleaning, inspection, repair, and

dry the cleaned parts immediately with compressed air

reassembly. Nicks, scratches, and dents caused by

and apply a film of clean oil to prevent rusting. Cover or

careless handling may cause oil leakage or improper

wrap parts to protect them from dust of dirt after

functioning and could result in transmission failure. All

cleaning. Never use lye or caustics which will corrode

defective parts must be replaced.

or etch metal surfaces.

5-2.

Cleaning Recommendations

h. Lubricant in New Bearings.

a. Importance of Cleanliness. Cleanliness is

(1) Do not clean the lubricant from new

of utmost importance in servicing the power train. All

bearings. Keep new bearings wrapped until they are to

components must be thoroughly cleaned and kept clean

be installed. Soak bearings, which have been in

throughout the repair process. The presence of foreign

service, in dry-cleaning colvent or mineral spirits paint

matter can cause malfunction, and possible failure, of

thinner to loosen deposit of dirt. Do not spin the

the power train.

bearings during cleaning or drying.

WARNING

(2) After cleaning, turn the bearings by

Forewarn personnel in the immediate area

hand and note any evidence of grit. Reclean them if grit

when using compressed air for cleaning.

is present. Refer to TM 9-214 for further information on

Compressed air, coming into contact with

cleaning bearings.

the human skin, or causing flying metal

5-3.

Inspection and Repair Recommendations

chips, can cause serious injury.

a. Castings, Forgings, Machined Surfaces.

b. Clean

Every

Component.

Every

(1) Inspect all castings and forgings for

component should be thoroughly cleaned after the

breaks, cracks, and wear or scoring that would impair

transmission is disassembled. Cleaning is necessary to

serviceability.

Remove

nicks and small surface

insure effective inspection for wear, damage and

irregularities with crocus cloth or a soft stone.

serviceability of components. Oil lines and the oil cooler

(2) Inspect

all

oil

passages

for

must be thoroughly flushed to remove sludge, or debris

obstructions and dirt. Reclean the passage if necessary.

resulting from mechanical failure.

(3) Inspect mounting faces for nicks,

c. Handle With Care. The utmost care should

scratches and scores. Remove minor defects with

be used in handling of parts during cleaning and

crocus cloth or a soft honing stone. Replace any parts

overhaul operation. Nicks, scratches, dents, or burs can

in which defects which cannot be corrected will impair

prevent proper assembly or cause malfunction after

the operation of the transmission.

assembly. This is especially true of valves and valve

(4) Inspect

threaded

openings

for

body parts.

damaged threads. Chase damaged threads with the

correct size tap.

5-1