Improved highways permit sustained high speeds.
The fact that engines and entire power trains can now
cruise at higher R.P.M. can introduce vibration
(g) Capscrews loose, omitted or missing from
frequencies, that were not critical in the past. At slower
remote control, shifter housing, bearing caps,
speeds these items would get by or only pass through
P.T.O. or covers, etc.
critical periods while accelerating or decelerating through
(h) Welch "seal" plugs loose or missing entirely from
machined openings in shifter housing or case.
In the past, drive line vibrations such as bent tubes,
(i) Oil drain-back openings in bearing caps or case
joints out of phase or alignment, bad angles due to short
plugged with varnish, dirt, covered with gasket
couples, clutches out of balance, gears and shafts in
auxiliaries out of balance, were fairly obvious. These
(j) Broken gaskets, gaskets shifted or squeezed out
items will become more critical in vehicles running at
of position, pieces still under bearing caps, clutch
sustained high speeds.
housing, P.T.O. and covers, etc.
Critical vibrations associated with higher speeds are
(k) Cracks or holes in castings.
not the old thumping or bumping type, but are high
(L) Drain plug loose.
frequency vibrations which sting or tingle the soles of
(m) Also possibility that oil leakage could be from
your feet, tickle the end of your fingers, etc. This type of
vibration will cause gear seizures, bearing failure due to
retainer rivet failures, promote brinelling, fretting,
Walking or Jumping Out of Gear:
For clarification we would like to separate walking out
(h) Gear whine is usually caused by lack of backlash
of gear and jumping out of gear into two distinct groups.
between mating gears-improper shimming of P.T.O. units
Walking out of gear is usually associated with power
is the big offender here.
applications or coasting on long smooth grades, i.e.,
Noise in Neutral
when power is applied the shift lever moves into the
neutral position. Occasionally it may be impossible to
hold the shift lever in gear by hand.
Sometimes this condition may also be noted when
coasting down a long relatively smooth grade or power is
(b) Worn, or scored countershaft bearings.
being applied on the coast side of the gear.
Dana/Spicer transmissions and auxiliaries are
(d) Sprung, or worn countershaft.
provided with "hopping guards" for most gear positions.
(e) Excessive backlash in gears.
Therefore, if the units are walking out of gear it could be
(f) Worn mainshaft pocket bearing.
(g) Scuffed gear tooth contact surface.
(h) Insufficient lubrication.
(i) Use of incorrect grade of lubricant.
preventing full engagement of the sliding clutch gear or
(b) If the gear has been shifted completely into position
Noise in Gear
some other malfunction which could move the gear or
the shaft itself out of its proper location.
(a) Worn, or rough mainshaft rear bearing.
(b) Rough, chipped, or tapered sliding gear teeth.
(c) On new or rebuilt units the wrong parts or old
(c) Noisy speedometer gears.
defective parts may have been used; thereby rendering
(d) Excessive end play of mainshaft gears.
the hopping-guard feature useless. High mileage units
(e) Refer to conditions listed under Noise in Neutral.
may start walking out of gear due to the general
slip-outs or partial engagements due to conditions listed
(a) Oil level too high.
(d) Walkout on coast side could be caused by lack
(b) Wrong lubricant in unit.
of hopping guard feature for this particular gear position.
(c) Non-shielded bearing used at front or rear
If remote controls are used, the mechanic must satisfy
bearing cap. (Where applicable.)
himself that the remote units are satisfactory and that
(d) Seals (if used) defective or omitted from bearing
auxiliary is actually at fault. A number of items that would
cap, wrong type seal used, etc.
prevent full engagement of gears are: