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Wiring diagrams Section: Differentials & Drive Axles

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Front Axle - 9 1/4 Aa: Other RAM Pickup 2500

Differentials & Drive Axles 14 illustrations ~1033 words

LOW SPEED KNOCK

Low speed knock is generally caused by

Worn U-joint(s).
Worn side-gear thrust washers.
Worn pinion shaft bore.

DRIVELINE SNAP

A snap or clunk noise when the vehicle is shifted into gear (or the clutch engaged) can be caused by

High engine idle speed.
Transmission shift operation.
Loose engine/transmission/transfer case mounts.
Worn U-joints.
Loose spring mounts.
Loose pinion gear nut and yoke.
Excessive ring gear backlash.
Excessive side gear to case clearance.

The source of a snap or a clunk noise can be determined with the assistance of a helper. Raise the vehicle on a hoist with the wheels free to rotate. Instruct the helper to shift the transmission into gear and listen for the noise. A mechanics stethoscope is helpful in isolating the source of a noise.

Condition	Possible Causes	Correction
Wheel Noise	1. Wheel loose.	1. Tighten loose nuts.
Wheel Noise	2. Worn wheel bearing.	2. Replace bearing.
Axle Shaft Noise	1. Misaligned axle tube.	1. Inspect axle tube alignment. Correct as necessary.
	2. Bent or sprung axle shaft.	2. Inspect and correct as necessary.
	3. End play in pinion bearings.	3. Refer to pinion preload information and correct as necessary.
	4. Excessive gear backlash between the ring gear and pinion.	4. Check adjustment of the ring gear and pinion backlash. Correct as necessary.
	5. Improper adjustment of pinion gear bearings.	5. Adjust the pinion bearings preload.
	6. Loose pinion yoke nut.	6. Tighten the pinion yoke nut.
	7. Scuffed gear tooth contact surfaces.	7. Inspect and replace as necessary.
Axle Shaft Broke	1. Misaligned axle tube.	1. Replace the broken shaft after correcting tube mis-alignment.
	2 Vehicle overloaded.	2. Replace broken shaft and avoid excessive weight on vehicle.
	3. Erratic clutch operation.	3. Replace broken shaft and avoid or correct erratic clutch operation.
	4. Grabbing clutch.	4. Replace broken shaft and inspect and repair clutch as necessary.
Differential Cracked	1. Improper adjustment of the differential bearings.	1. Replace case and inspect gears and bearings for further damage. Set differential bearing preload properly.
	2. Excessive ring gear backlash.	2. Replace case and inspect gears and bearings for further damage. Set ring gear backlash properly.
	3. Vehicle overloaded.	3. Replace case and inspect gears and bearings for further damage. Avoid excessive vehicle weight.
	4. Erratic clutch operation.	4. Replace case and inspect gears and bearings for further damage. Avoid erratic use of clutch.
Differential Gears Scored	1. Insufficient lubrication.	1. Replace scored gears. Fill differential with the correct fluid type and quantity.
	2. Improper grade of lubricant.	2. Replace scored gears. Fill differential with the correct fluid type and quantity.
	3. Excessive spinning of one wheel/tire.	3. Replace scored gears. Inspect all gears, pinion bores, and shaft for damage. Service as necessary.
Loss Of Lubricant	1. Lubricant level too high.	1. Drain lubricant to the correct level.
	2. Worn axle shaft seals.	2. Replace seals.
	3. Cracked differential housing.	3. Repair as necessary.
	4. Worn pinion seal.	4. Replace seal.
	5. Worn/scored yoke.	5. Replace yoke and seal.
	6. Axle cover not properly sealed.	6. Remove, clean and seal cover.
Axle Overheating	1. Lubricant level low.	1. Fill differential to correct level.
	2. Improper grade of lubricant.	2. Fill differential with the correct fluid type and quantity.
	3. Bearing preloads too high.	3. Adjust bearing preloads.
	4. Insufficient ring gear backlash.	4. Adjust ring gear backlash.
Gear Teeth Broke	1. Overloading.	1. Replace gears. Examine other gears and bearings for possible damage.
	2. Erratic clutch operation.	2. Replace gears and examine the remaining parts for damage. Avoid erratic clutch operation.
	3. Ice-spotted pavement.	3. Replace gears and examine remaining parts for damage.
	4. Improper adjustments.	4. Replace gears and examine remaining parts for damage. Ensure ring gear backlash is correct.
Axle Noise	1. Insufficient lubricant.	1. Fill differential with the correct fluid type and quantity.
	2. Improper ring gear and pinion adjustment.	2. Check ring gear and pinion contact pattern.
	3. Unmatched ring gear and pinion.	3. Replace gears with a matched ring gear and pinion.
	4. Worn teeth on ring gear and pinion.	4. Replace ring gear and pinion.
	5. Loose pinion bearings.	5. Adjust pinion bearing preload.
	6. Loose differential bearings.	6. Adjust differential bearing preload.
	7. Ring gear run-out.	7. Measure ring gear run-out. Replace components as necessary.
	8. Loose differential bearing cap bolts.	8. Inspect differential components and replace as necessary. Ensure that the bearing caps are torqued to the proper specification.
	9. Housing not machined properly.	9. Replace housing.

DIAGNOSTIC CHART

Scheme 82

Scheme 82: PINION DEPTH MEASUREMENT

Ring and pinion gears are supplied as matched sets. Compensation for pinion depth variance is achieved with a select shim. located between the rear pinion bearing and pinion gear head.

Measurements are taken with pinion bearing cups and pinion bearings installed in the housing. Take measurements with Pinion Gauge Set and Dial Indicator (special tool #C-3339A, Set, Dial Indicator).

Scheme 83

Scheme 84

Scheme 85

Scheme 86

Assemble Pinion Height Block (special tool #6739, Block, Height) (3), Pinion Block (special tool #8878, Gauge, Pinion Height) (6) and rear pinion bearing onto Screw (special tool #6741, Screw) (5).
Insert assembled pinion height block (1), pinion block (2), rear bearing and screw into the housing through pinion bearing cups.
Install front pinion bearing and Cone-Nut (special tool #6740, Cone) onto the screw. Tighten cone-nut until Torque To Rotate the screw is 1.7 - 2.26 N.m (15 - 20 in. lbs.).
Place Arbor Disc (special tool #8289, Set, Arbor Disc) (4) on Arbor (special tool #D-115-3, Arbor) (3) in position in the housing side bearing cradles.
Install differential bearing caps on arbor discs and snug the bearing cap bolts. Then cross tighten cap bolts to 85 N.m (63 ft. lbs.). NOTE: Arbor (3) should rotate freely in the arbor disc (4).
Assemble Dial Indicator (special tool #C-3339A, Set, Dial Indicator) (1) into Scooter Block (special tool #D-115-2A, Block, Scooter) (3) and secure set screw.
Position Scooter Block/Dial Indicator flush on the pinion height block. Hold scooter block and zero the dial indicator (1).
Slowly slide the scooter block across the pinion height block over to the arbor. Move scooter block till dial indicator crests the arbor (2), then record the highest reading.
Select a shim equal to the dial indicator reading.
Install select shim between rear pinion bearing and the pinion gear head.
Install pinion gear and establish Pinion Torque To Rotate (PTTR) with and inch pound torque wrench (2).

Scheme 87

Scheme 87: DIFFERENTIAL BEARING PRELOAD AND GEAR BACKLASH

Backlash is adjusted by moving the adjusters in and out or both. By moving the adjusters the case/ring gear will move closer or further away from the pinion. In most cases this adjustment can be used to achieve the correct gear tooth pattern and set the case bearing preload.

Scheme 88

Remove adjuster lock bolts (3) and adjuster locks (2).
Loosen the differential bearing caps.
Slide differential case (1) toward the pinion gear until the gears make contact/zero backlash. If zero backlash cannot be obtained, turn the pinion side adjuster until zero backlash is obtained.
Holding the differential case toward the pinion gear, turn bearing adjusters with Wrench (special tool #8883A, Wrench, Differential Adjusting) until they make contact with the differential bearings/cups.
Back off the ring gear side adjuster 4 holes, to obtain initial ring gear backlash.
Install ring gear side adjuster lock and bolt. Do not tighten adjuster lock bolt at this time.
Tighten pinion gear side adjuster firmly against the differential case bearing cup.
Rotate the pinion several times to seat the differential bearings.
Loosen pinion gear side adjuster until it is no longer in contact with the bearing cup, then tighten it until it makes contact.
Tighten pinion gear side adjuster an additional: New Bearings: 6 Adjuster Holes Original Bearings: 4 Adjuster Holes
Install pinion gear side adjuster lock and bolt.
Tighten bearing cap bolts to 85 N.m (63 ft. lbs.).
Tighten adjuster lock bolts to 25 N.m (18 ft. lbs.).
Measure ring gear backlash with a Dial Indicator (special tool #C-3339A, Set, Dial Indicator) (1) and Dial Indicator Stud (special tool #L-4438, Dial Indicator Post) at eight points around the drive side of the ring gear (2). The backlash should be 0.08 - 0.25 mm (0.003 - 0.010 in) with a preferred backlash of 0.13 - 0.18 mm (0.005 - 0.007 in).

Note. Backlash measurement should not vary more than 0.05 mm (0.002 in) between measuring points. If measurement does vary inspect the gears for burrs, the differential case flange and ring gear mounting.

Scheme 89

Scheme 89: GEAR TOOTH CONTACT PATTERN

Wipe clean each tooth of the ring gear.
Apply gear marking compound to all of the ring gear teeth.
Verify bearing cap bolts are torque to specification.
Apply the brakes lightly to create a 14 N.m (10 ft. lbs.) pinion rotating torque.
Rotate the pinion/pinion yoke 4 full revolutions in each directions.
Read gear tooth contact pattern.

Gear contact pattern is correct. Backlash and pinion depth is correct.

Scheme 90

Ring gear too far away from pinion gear, coast side toe (1) and drive side heel (2). Decrease backlash, by moving the ring closer to the pinion gear using the adjusters.

Scheme 91

Ring gear too close to pinion gear, drive side toe (1) and coast side heel (2). Increase backlash, by moving the ring away from the pinion gear using the adjusters.

Scheme 92

Ring gear too far away from pinion gear, drive side heel (1) and coast side heel (2). Decrease backlash, by moving the ring closer to the pinion gear using the adjusters.

Scheme 93

Ring gear too close to pinion gear, drive side toe (1) and coast side toe (2). Increase backlash, by moving the ring away from the pinion gear using the adjusters.

Scheme 94

Pinion gear set too low. Increase pinion gear height, by increasing the pinion depth shim thickness.

Scheme 95

Pinion gear set too high. Decrease pinion depth, by decreasing the pinion depth shim thickness.