Repair - TM-9-2815-200-350333

Table 6-9. Connecting Rods, Crankshaft and Associated Parts Overhaul Standards - Continued

Sizes and fits

Fig.

Ref.

Wear limits

Point of measurement

of new parts

No.

letter

Component

Outside diameter of split sleeve bearing must

B-4

be press fit in bore. Burnish to seat sleeve

bearing prior to finish diameter

B-4

Inside diameter of bushing-type sleeve bearing

2.0027

2.0040

2.0025

Outside diameter of piston pin

2.0002

B-4

2.0000

1.9998

Fit of pin in bearing

0.0042L

B-4

0.0023L 0.0027L

SS-H

Note. Refer to paragraph 6-3b for explanation of symbols.

6-17. Repair

sions and install new pins. Whenever oversize

Crankshafts.

pins are used, it will be necessary to ream the

(1) Replace crankshafts that are deeply

flywheel and transmission drive gearshaft ac-

scratched, nicked, burred, scuffed or galled.

cordingly.

Minor

imperfections

the

journals

may

(5) Replace a cracked crankshaft or a

repaired by polishing with a crocus cloth dipped

crankshaft showing evidence of wear due to bent

in dry-cleaning solvent or mineral spirits paint

or twisted connecting rods.

thinner.

b. Connecting Rods and Bearings.

(2) Crankshafts that are worn beyond

(1) Connecting rod bolts.

standard wear limits specified in the overhaul

(a) Replace bolts that do not fit snugly in

standards (table 6-9) or with journal or crank-

rod and cap.

case damage may be ground undersize to the

(b) Replace bolts that have damaged

limits established for crankshaft rework (table 6-

threads, galled pilot diameters, or diameters that

9).

are not

within

limits

specified

overhaul

standards

(table

6-9).

(3) In the event any of the crankpins or

journals are found unserviceable, it will be

necessary to polish or grind all crankpins or

evidence of

that

any

show

scratched, or

stretching.

journals uniformly undersize to maintain the

balance of the crankshaft. Extreme care must be

(2) Connecting rod bearings. R e p l a c e a l l

taken when regrinding, to maintain the con-

bearings that do not check within limits specified

centricity of the entire crankshaft and not to

in overhaul standards (table 6-9) or when

exceed a surface roughness of 12 micro inches.

bearings do not show 75 percent contact by

All radii on the crankpins and journals, effected

Prussian blue transfer after bore check.

by grinding undersize, must be re-established to

(3) Connecting rod assembly. Discard con-

original configuration. The crankshaft nitride

necting

rods

that are bent or distorted.

finish of crankpins and journals must be in-

Straightening of connecting rods is not per-

spected by magnaflux or similar method for

mitted. Break and polish sharp edges at con-

fractures and surface cracks after finishing.

necting rod counterbore and rod contour (fig. 6-

(4) Replace dowel pins (18 fig. B-3) and

35). Replace connecting rod assemblies which

straight pins (25) in crankshaft flange if pins do

are not within limits specified in overhaul

not fit securely in flange, are out-of-round or if

standards (table 6-9). Connecting rods with

pins do not conform to limits specified in the

worn or damaged piston pin bearing may be

overhaul standards (table 6-9).

repaired. Replace worn or damaged piston pin

Note. The headless grooved dowel pins in the

bushing-type

bearing

using

arbor

press.

flywheel end flanges are available in 0.005 and

Bearing split line must be 90 degrees from

0.010 in. oversize. Ream crankshaft flywheel

longitudinal center line. Line-ream new bearing

mounting

flange

necessary

oversize

dimen-

to size shown in overhaul standards (table 6-9).

6-39