Posted by Malcolm [Boardmaster] on Monday, December 06, 2004 at 7:43PM :
In Reply to: Re: Look at these spider gears posted by cgrey8 from vpn.automatedlogic.com (68.208.14.2) on Monday, December 06, 2004 at 5:28PM :
Moderator
Driveline Angle
An incorrect driveline (pinion) angle can often be detected by the driving
condition when vibration occurs.
A vibration during coasting from 56 to 72 km/h (35 to 45 mph) is often caused
by a high pinion angle.
A vibration during acceleration, again around 56 to 72 km/h (35 to 45 mph),
may indicate a lower than specified pinion angle. Refer to Section 00-04 for
pinion angle procedure.
When it is certain that the tires and driveline angle are not the cause,
inspect the axle. Refer to Section 00-04.
Driveline Vibration
Driveline vibration exhibits a higher frequency and lower amplitude than does
high-speed shake. Driveline vibration is directly related to the speed of the
vehicle and is usually noticed at speeds of 72 km/h (45 mph) or higher.
Driveline vibration can be perceived as a tremor in the floor pan or is heard as a
rumble, hum or boom. Driveline vibration can exist in all drive modes, but may
exhibit different symptoms depending upon whether the vehicle is
accelerating, decelerating, floating or coasting. If the vibration is particularly
noticeable during acceleration or deceleration, especially at lower speeds, then
driveline angle should be checked. Driveline vibration can be duplicated by
supporting the axle upon a hoist or upon jackstands, though the brakes may need to
be applied lightly in order to simulate road resistance.
Raise vehicle promptly after road-testing, on twin-post hoist or jackstands,
to prevent tire flat-spotting. Engage drivetrain and run-up to observed road
test speed to verify presence of vibration. If not evident, check non-driving
wheels with wheel-balancer spinner to rule out imbalance as a possible cause.
On 4x4's, unlock front hubs or remove hub covers before spinning wheels. If
required, balance non-driving wheels and repeat road test. If vibration is still
evident, proceed to Step 3.
If vibration appeared in road-speed hoist test, mark relative position of
drive wheels on rear axle assembly (4006) or hub lugs to permit reinstallation in
original position, and remove wheels. Secure brake drums, if present, by
installing all lugnuts in reversed position and repeat road-speed run-up. If
vibration is gone, see drive wheel runout and balance procedures in Section 04-04.
If vibration persists, proceed to Step 3.
Inspect driveshaft (4602) for signs of physical damage, missing balance
weight, undercoating, or improperly seated, worn, or binding universal joints.
Check the index marks (paint spots) on rear of driveshaft and rear axle companion
flange. If these marks are more than 90 degrees apart, disconnect driveshaft
and reindex to align marks as close as possible. Clean driveshaft and replace
universal joints as necessary, or replace driveshaft if damaged. After any
corrections are made, recheck vibration at road test speed. If gone, reinstall
wheels and road test. If vibration persists, proceed to Step 4.
With vehicle on hoist and wheels off, measure runout at front, center, and
rear of driveshaft with indicator, rotating driveshaft by turning a brake drum
or rotor. On a one-piece driveshaft, if runout exceeds .89mm (.035 inch) at
front or center, the driveshaft must be replaced. If front and center are within
this limit, but rear runout is not, mark the rear runout high point and
proceed to Step 5. If runout is within limits at all points, proceed to Step 7 or
Adjustments, Driveshaft Balancing.
NOTE: Move universal joints in each direction of rotation during reindexing.
If a universal joint feels stiff or has a gritty feel in any direction,
replace the rear axle shaft universal joint (4249).
Circular rear axle companion flanges can be indexed in 45-degree increments
to fine tune the runout condition. Check runout at rear of driveshaft, and if
still over .89mm (.035 inch), mark high point and see Step 6. If runout is no
longer excessive, check for vibration at road test speed, and, if still
present, reindex the driveshaft slip yoke (4841) on the transmission output shaft 180
degrees and road test the vehicle. If the vibration persists, proceed to Step
7 or Adjustments, Driveshaft Balancing.
Excessive driveshaft runout may originate in the driveshaft itself or in the
rear axle companion flange. To determine which, compare the two high points
marked in Steps 4 and 5. If the marks are close together, within about 25mm or 1
inch, the shaft is eccentric, and should be replaced and checked for
vibration. If the marks are on opposite sides of the driveshaft, about 180 degrees
apart, the yoke or rear axle companion flange is responsible. After replacing,
check for runout. When replacing a rear axle companion flange, driveshaft runout
should not exceed .89mm (.035 inch). When runout is within limits, recheck
for vibration at road speed. If vibration persists, balance the driveshaft.
Driveshaft balancing involves installing one or two hose clamps on the
driveshaft, near the rear end of a one-piece driveshaft. Best positioning of the
hose clamp head(s) can be determined by trial-and-error, if special balancing
equipment is not available. If transducer-and-strobe equipment is available, see
Adjustments in this section for balancing procedure.
Mark off the rear of the driveshaft into four approximately equal sectors,
and number the marks 1 through 4. Install a hose clamp on the driveshaft with
its head at position No. 1. Check for vibration at road speed. Recheck with the
clamp at each of the other positions, to find the position for minimum
vibration. If two adjacent positions show equal improvement, position the clamp head
between them.
If condition is still not acceptable, add a second clamp at the same position
and recheck vibration. If no improvement is noted, rotate the clamps in
opposite directions, equal distances from the best position determined in Step 8.
Initially, separate the clamp heads about 12mm (1/2 inch), and recheck
vibration at road speed.
Repeat the process with increasing separation until the best combination is
found, or vibration is reduced to an acceptable level.
Install wheels and road test, since vibration noticeable on the hoist may not
be evident during the road test. If vibration is still not acceptable,
replace the rear axle drive line vibration damper, if so equipped. If road test is
not acceptable, replace ring gear and pinion.
Driveline Angularity
Driveline angularity is the angular relationship between the engine
crankshaft (6303), the driveshaft and the rear axle pinion. Factors determining
driveline angularity include ride height (rear spring (5560)), and engine mounts. Low
speed vibration, less than 72 km/h (45 mph), especially when the vehicle is
subjected to heavy acceleration or deceleration, is an indication of improper
driveline angles. When these conditions exist, check the universal joints for
proper seating, mounting and operation.
Driveline Angularity
Driveshaft Vibrates
Road test vehicle to determine critical vibration points. Note road speed,
engine rpm and shift lever positions at which vibration occurs.
Stop vehicle and run engine with clutch depressed (automatic transmission in
neutral) through critical speed ranges determined in Step 1.
With clutch depressed, all potential engine and clutch concerns are
eliminated. If vibration persists, the driveline must be balanced as described in this
section.
I HAVE NEVER GOT THE HOSE CLAMP BALANCE METHOD TO WORK, SEND IT TO A
DRIVESHAFT SHOP. IF YOU HAD A SHAFT MADE MAKE SURE THE U-JOINTS ARE PHASED CORRECTLY
A16 CHECK (REAR) WHEEL HUB RUNOUT
With rear disc brake rotors removed, check axle hub face runout and rotor
pilot radial runout.
Hub face runout should be less than 0.05mm (0.002 inch).
Rotor pilot radial runout should be less than 0.05mm (0.002 inch).Is
measurement within specification?
Pilot (Radial)
Flange Face (Lateral)
Bolt Circle (Radial)
Ring Gear Runout Check
If the ring gear runout check (before disassembly) exceeds specification, the
condition may be caused by a warped ring gear, a damaged rear axle housing,
loss of differential bearing preload or debris between the ring gear back face
and the case flange. Perform the following steps to determine the cause of
excessive runout.
With the pinion removed, place differential case/gear subassembly with
differential bearings (4221) and differential bearing cups (4222) in rear axle
housing.
Install a 6.75 mm (0.265-inch) differential bearing shim (4067) on the LH
side of subassembly.
Install the LH bearing cap finger-tight.
Install progressively larger differential bearing shims on the RH side until
the largest differential bearing shim selected can be assembled with a slight
drag feel.
Install the RH side bearing cap. Install bearing cap bolts. Tighten to 95-115
Nm (70-85 lb-ft).
Rotate the assembly to ensure free rotation.
Install Dial Indicator with Bracketry TOOL-4201-C or equivalent. Check and
note ring gear runout.
If the runout is within specification, the original out-of-specification
runout was caused by insufficient differential bearing preload. If the runout
exceeds specification, go to Step 9.
Remove differential case from the rear axle housing.
Remove ring gear using a drift that will bottom in ring gear bolt holes.
Strike at alternate holes around gear.
Install differential case assembly in rear axle housing without ring gear.
NOTE: The differential ring gear and pinion are matched and must be replaced
as a set.
Check differential case runout again. If the runout is now within limits, the
ring gear was out of specification and the differential ring gear and pinion
should be replaced. If the runout is still excessive, the differential case is
damaged and should be replaced.
wheel hub face runout is less than 0.06 mm (0.002 inch)
Front Hub Runout
Rear Hub Runout
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