Suspension - Vibration/Shake/Resonance Noise
Article No.00-14-3
Date
7/10/00
Subject
VIBRATION - SHAKE-RESONANCE NOISE - SPEEDS ABOVE 72 KM/H (45 MPH)
FORD:
1999-2001 EXPLORER
ISSUE
A vibration at speeds above 72 km/h (45 mph) may occur on some vehicles. This may be due to an imbalance in one or more of the driveline components which results in a resonance that produces a noticeable vibration usually in the seat or steering column.
ACTION
Refer to the following Drive Diagnostic Procedure and System Balancing Procedures. Follow the initial drive diagnostic and note any changes after each drive.
DRIVE DIAGNOSTIC PROCEDURE
1. Ask questions of the customer and find out when the vibration occurs. Base diagnostic work on customer usage of vehicle (such as gear, speed, load, and towing.) It is also best to ride with the customer and make sure you know exactly what the concern is. Also, use an Electronic Vibration Analyzer (EVA) if available at seat track, rear pinion, and front differential cover to find the source of the concern.
2. Start the vehicle. Does a vibration exist when you perform neutral rpm engine run-ups? If it does, review engine driven components, fan, and transmission torque converter for possible imbalances. Repair these concerns first and retest.
3. Before driving the vehicle, review the tires for signs of wheel misalignment or worn suspension parts such as shock absorbers, ball joints, and bushings. (Reference Section 100-04 in the appropriate model year Workshop Manual.) Repair and/or replace worn parts. Drive vehicle to see if concern is corrected.
4. Document the operating conditions required to duplicate the customer's concern including: Coast/Cruise, AUTO/4H/4L, Acceleration/Deceleration.
5. Document the vehicle speed, engine rpm, and gear at which the concern is duplicated. If an EVA is available, document the frequency (hertz) and amplitude of vibration.
6. On 4.0L 4X4 models while at a stop, place the transmission in Neutral. Switch from 4AUTO to 4L. Place the vehicle in Drive and drive a short distance (6-9 meters/20-30 feet). Put the transmission back in Neutral and switch back to 4AUTO. Re-drive the vehicle at highway speed. If the vibration goes away or gets worse, contact Borg-Warner at 1-765-286-6569.
7. Inspect transmission mount to see if it is twisted or mispositioned. Look for strap grounding out against the mount. If this is occurring, loosen the mount bolts, neutralize the mount position, and allow the strap to straighten out. Tighten the nuts and bolts to 87-110 N.m (64-81 lb-ft) in torque stages. Retest the vehicle.
8. If an EVA is available, isolate the vibration to a probable rotating component. Using the EVA, match the monitored frequency to a possible rotating component using the engine speed or vehicle speed method as described in Section 3-30 of the NVH Student Reference Book supplied with the Ford NVH class or Page 0-9 of the SPX Kent-Moore Instruction Manual that comes with the EVA test equipment.
9. After recording all information, review the following Symptom Chart first to avoid the replacement of good parts.
SYMPTOM CHART
SYSTEM BALANCING USING AN EVA
The following procedure is a basic outline on how to system balance the vehicle using various methods available. For more detailed information, refer to Section 100-04 of the Workshop Manual or the manual provided with your Electronic Vibration Analyzer (EVA).
Before starting, be sure that the runout of the driveline components is within specification. This specification can be found in the Workshop Manual or in this Diagnostic Procedure. If components are found to be good, proceed with strobe balancing using the EVA.
1. Number the ends of the driveshaft by the transmission and the axle pinion 1 through 4, putting a number every 90 degrees. Then place an accelerometer at each end of the driveshaft.
2. Mount the accelerometer on the bottom of the rear axle differential or the transmission extension housing. Be sure to position the sensor as close to the driveshaft as possible, assuring that the UP side of the accelerometer is up and the sensor is horizontal.
3. Have the vehicle positioned on a hoist and set up on jack stands to level the vehicle with the wheels removed.
NOTE
BEFORE STARTING TO STROBE THE VEHICLE, BE SURE ALL LOOSE ARTICLES ARE CLEAR OF MOVING COMPONENTS. NEVER TOUCH MOVING PARTS WITH YOUR HANDS.
4. Turn off all accessories and have an associate start the engine. Place the engine in gear and accelerate the vehicle to speed where the vibration occurs.
5. With an inductive timing light clipped to the trigger wire of the EVA and the accelerometer plugged into input A, be sure both the EVA and timing light have a 12 volt source.
6. Verify that the predominant frequency displayed on the EVA matches the frequency of the original reading taken with the EVA. Press "STROBE" key on the EVA pad. The EVA will display a series of questions in order to select the correct filter. Press "YES" to select the correct filter. Be sure that the frequency is in the middle of the filter range only if these ranges do not give the desired results.
7. The display on the EVA shows the test frequency, the amplitude, and the filter range. The driveline is balanced when the strobe amp is between 0-4, or when the flashing strobe becomes erratic or ceases.
8. Point the timing light at the driveshaft. The strobe will appear to freeze the driveshaft. Note at which of the numbered marks it is on or closest to.
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 303000, 304000, 702000, 702300, 703000, 703200, 703300