TM 5-3810-289-34
(b) Press camshaft from gear.
counterclockwise against indicator point and set indicator
Note.
Care must be taken to prevent gear
at "O".
breakage due to improper use of press and support bars.
(c) Move gear clockwise against indicator
(4) Note type of key used. See figure 3-189
"B"-straight, as viewed from gear case of engine.
equidistant points on gear.
(d) Normal gear backlash for J six-cylinder
engines with new gears is 0.004/0.007 in. between
mating gears.
Figure 3-189. Camshaft gear key from gear case end.
e. Installation of Gear
Figure 3-190. Securing camshaft bearing retainer to
(1) Coat gear hub area of camshaft with
block.
lubricant.
(2)
Install camshaft thrust bushing on
camshaft with grooves in bushing toward gear.
(3) Heat gear evenly to 4000F. (204.400 C)
with heating torch (not a cutting torch).
(4) Press on new camshaft gear, aligning
gear keyway with camshaft key.
(5)
Check between thrust bearing and
camshaft gear for 0.007 to 0.011 in. clearance for new
thrust bearing.
f. Installation of Camshaft.
(1) Lubricate all camshaft bushings (in
block) with high pressure grease.
(2) Rotate camshaft during installation to
allow lobes to pass through bushings easily.
(3) Index "O" on camshaft gear with 'O' on
crankshaft gear; this is Number One topcenter firing
position.
Figure 3-191. Checking camshaft gear backlash.
(4) Slide camshaft completely into block;
align bearing retainer mounting holes with those in block
(e) Worn gears will naturally have more
and secure with lockwashers and capscrews through
backlash than new gears and will rattle if backlash
openings in camshaft gear. Refer to figure 3-190.
exceeds 0.012/0.020 in. If noise is not objectionable, do
(5) Tighten capscrews to 30/35 ft. lb.
not replace gear(s) unless backlash exceeds 0.020 in. or
g. Camshaft Checks After Installation.
unless gear(s) is/are visibly worn.
(1) Gear backlash. Bear backlash is the
Caution: Insufficient gear lash or improperly
amount of play between intermeshed gears. Excessive
back lash is a good indication that gear (s) is/are worn
mated gears cause quick gear failure.
and should be replaced.
(2) Camshaft end play.
(a) Backlash of all gears in gear train may
(a) Secure dial indicator gage clamp to gear
be checked with a dial indicator gage or narrow feeler
cover plate.
gage.
(b) When dial indicator gage is used, locate
gage so contact point contacts gear tooth; move gear
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