Driveline System-General Information: NVH Ford Econoline E150

Noise Acceptability

Note. A gear-driven unit will produce a certain amount of noise. Some noise is acceptable and audible at certain speeds or under various driving conditions such as a newly paved blacktop road. Slight noise is not detrimental to the operation of the axle and is considered normal.

With the Traction-Lok® differential axle, slight chatter or groaning noise on slow turns after extended highway driving is considered acceptable and has no detrimental effect on the locking axle function.

Analysis of Vibration

Few vibration conditions are caused by the rear axle. On a vibration concern, follow the diagnosis procedure in NOISE, VIBRATION & HARSHNESS unless there is a good reason to suspect the axle.

Axle Noise

Note. Before disassembling the axle to diagnose and correct gear noise, eliminate the tires, exhaust, trim items, roof racks, axle shafts (4234) and wheel bearings as possible causes. Follow the diagnostic procedures in NOISE, VIBRATION & HARSHNESS .

The noises described as follows usually have specific causes that can be diagnosed by observation as the unit is disassembled. The initial clues are the type of noise heard during the road test.

Axle Shaft Bearing Noise

Axle shaft bearing noise is similar to gear noise and differential pinion bearing whine. Axle shaft bearing noise will usually distinguish itself from gear noise by occurring in all driving modes (drive, coast, and float), and will persist with the transmission in NEUTRAL while the vehicle is moving at the speed in which the concern is occurring. If the vehicle makes this noise, remove the suspect axle shaft, install a new bearing and a new axle seal. Re-evaluate the vehicle for noise before removing any internal components.

Clunk

Clunk is a metallic noise heard when the automatic transmission is engaged in REVERSE or DRIVE. The noise can also occur when throttle is applied or released. It is caused by backlash somewhere in the driveline or loose suspension components; it is felt or heard in the axle. Refer to TOTAL BACKLASH CHECK .

Additionally, clunk may be heard upon initial drive-away. This occurs as engine torque shifts vehicle weight, forcing changes in driveline angles, preventing the driveshaft slip-yoke from sliding on the output shaft. To correct for this condition, lubricate the slip-yoke splines. For additional information, refer to DRIVESHAFT .

Scheme 20

1. Raise and support the vehicle. For additional information, refer to «JACKING & LIFTING»(ref-210109) .
2. Remove the driveshaft. For additional information, refer to «DRIVESHAFT»(ref-210112) .
3. Install the Drive Pinion Flange Holding Fixture. Clamp a rigid bar or pipe to the tool. Clamp the other end of the bar or pipe to the frame or a body member in order to prevent movement of the rear axle pinion flange.
4. Lower the vehicle so that one rear wheel is resting on a wheel chock to prevent it from turning. The other rear wheel will be used to measure total rear axle backlash.
5. Rotate the free wheel slowly, by hand, until the feeling of driving the rear axle is encountered. Place a mark on the side of the tire, 305 mm (12 inches) from the center of the wheel, with a crayon or chalk.
6. While holding the crayon or chalk against the tire, rotate the wheel slowly in the opposite direction until the feeling of driving the rear axle is encountered again.
7. Measure the length of the crayon or chalk mark on the tire. If the length of the mark is 25.4 mm (1 inch) or less, the rear axle backlash is within allowable limits. If the chalk mark is greater than 25.4 mm (1 inch), check for these conditions: Elongation of the differential pinion shaft and holes in the differential case (4204). Missing differential pinion thrust washer (4230) or differential side gear thrust washer (4228). Galling of the differential pinion shaft (4211) and bore. Excessive ring gear and pinion backlash. Follow the procedure for the type of rear axle to check backlash.

Scheme 21

Driveline Vibration

Note. An analysis of vibration can also be conducted using the Vibration Analyzer and following the manufacturer's directions.

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 various speed ranges. Driveline vibration can be perceived as a tremor in the floorpan 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. Check the driveline angles if the vibration is particularly noticeable during acceleration or deceleration, especially at lower speeds. Driveline vibration can be duplicated by supporting the axle upon a hoist or upon jack stands, though the brakes may need to be applied lightly in order to simulate road resistance.

Scheme 22

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

1. Raise the vehicle promptly after road testing. Use a twin-post hoist or jack stands to prevent tire flat-spotting. Engage the drivetrain and accelerate to the observed road test speed to verify the presence of the vibration. If the vibration is not evident, check the non-driving wheels with a wheel balancer to rule out imbalance as a possible cause. If required, balance the non-driving wheels and repeat the road test. If the vibration is still evident, proceed to Step 2.
2. Mark the relative position of the drive wheels to the wheel lugs. Remove the wheels. Install all the lug nuts in the reversed position and repeat the road speed acceleration. If the vibration is gone, refer to the tire and wheel runout procedure. If the vibration persists, proceed to Step 3.
3. Inspect the driveshaft(s) for signs of physical damage, missing balance weight, undercoating, incorrect seating, wear and binding universal joints. Clean the driveshaft and install new universal joints or install a new driveshaft if damaged. Check the index -marks (paint spots) on the rear of the driveshaft and axle pinion flange. If these marks are more than one-quarter turn apart, disconnect the driveshaft and re-index to align the marks as closely as possible. Check the alignment of the index marks on the driveshaft to transmission tailshaft. For E150 and E250 vehicles, if a yellow dot is visible on the front of the driveshaft, it can be aligned with a yellow dot on the transmission output shaft. For additional information, refer to «DRIVESHAFT»(ref-210112) . After any corrections are made, recheck for vibration at the speed where the symptom occurred. If the vibration is gone, reinstall the wheels and road test. If the vibration persists, proceed to Step 4.
4. Raise the vehicle on a hoist and remove the wheels. Rotate the driveshaft by turning the axle and measure the runout at the front, the center, and the rear of the driveshaft with the indicator. If the runout exceeds 0.89 mm (0.035 inch) at the front or center, the driveshaft must be installed new. If the front and center are within this limit, but the rear runout is not, mark the rear runout high point and proceed to Step 5. If the runout is within the limits at all points, proceed to Step 7 .
5. Scribe alignment marks on the driveshaft and the axle pinion flange. Disconnect the driveshaft, rotate it one-half turn, and reconnect it. Circular axle pinion flanges can be turned in one-quarter increments to fine tune the runout condition; half-round axle pinion flanges are limited to two positions. Check the runout at the rear of the driveshaft. If it is still over 0.89 mm (0.035 inch), mark the high point and proceed to Step 6. If the runout is no longer excessive, check for vibration at the road test speed. If vibration is still present, re-index the driveshaft slip yoke on the transmission output shaft one-half turn and road test the vehicle. If the vibration persists, proceed to Step 7 .
6. Excessive driveshaft runout may originate in the driveshaft itself or in the axle pinion flange. To determine which, compare the two high points marked in Steps 4 and 5. If the marks are close together, within about 25 mm (1 inch), the shaft must be installed new and the vehicle road tested. If the marks are on opposite sides of the driveshaft, the yoke or axle pinion flange is responsible for the vibration. When replacing an axle pinion flange, the driveshaft runout must not exceed 0.89 mm (0.035 inch). When runout is within limits, recheck for vibration at road speed. If vibration persists, balance the driveshaft.
7. To balance the driveshaft, install one or two hose clamps on the driveshaft, near the rear. Position of the hose clamp head(s) can be determined by trial-and-error.
8. Mark 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 that shows minimum vibration. If two adjacent positions show equal improvement, position the clamp head between them.
9. If the vibration persists, add a second clamp at the same position and recheck for vibration. If no improvement is noted, rotate the clamps in opposite directions, equal distances from the best position determined in Step 8 . Separate the clamp heads about 13 mm (1/2 inch) and recheck for vibration at the road speed. Repeat the process with increasing separation until the best combination is found or the vibration is reduced to an acceptable level.
10. Install the wheels and road test (vibration noticeable on the hoist may not be evident during the road test). If the vibration is still not acceptable, install a new axle drive line vibration damper first, if so equipped. If the vibration is still not acceptable, refer to «REAR DRIVE AXLE/DIFFERENTIAL-DANA 60 & 70»(ref-210113) , «REAR DRIVE AXLE/DIFFERENTIAL-FORD 8.8" RING GEAR»(ref-210116) or «REAR DRIVE AXLE/DIFFERENTIAL-FORD 9.75" RING GEAR»(ref-210117) for differential case and ring gear runout checks.