Driveline - Vibration/Noise at Low or High Speeds: Overview
11/08/9547/01/95/US
SUBJECT
Driveline Vibration Diagnosis and Remedy
MODEL
Range Rover Classic
Discovery
AFFECTED VEHICLES
LP
LH All
LJ All
LD
DETAIL
Vibration complaints can be difficult to diagnose accurately. The following procedure, if followed precisely, will help diagnose such complaints in as little time as possible.
FOOTNOTES
*1 When test driving choose a route where the road is as smooth and flat as possible. Where possible, use roads with the least traffic flow. To maintain consistency and allow for valid assessments of vibration levels, the same route must always be used.
*2 In cases where the vehicle has a vibration at more than one speed, attempt to repair only one vibration at a time. For instance. if a vehicle exhibits vibration at 35 mph and 65 mph, try to repair the vibration at 65 mph first.
*3 WARNING: When test driving the vehicle with one driveshaft removed, use EXTREME caution as the vehicle will handle differently during abrupt maneuvers. Avoid using wide throttle openings.
DISCOVERY: Differential lock must be engaged to drive the vehicle with a driveshaft removed.
RANGE ROVER: To avoid damaging the viscous coupling unit, avoid heavy acceleration and keep the road tests as short as possible.
*4 When determining if the vibration is improved, focus on the specific vibration being diagnosed. For instance, if the vehicle is driven with the rear driveshaft removed to reassess a 65 mph vibration, focus on the 65 mph vibration only. It is not unusual for a vibration to introduced at a different speed when operating with one shaft only. These other vibrations can be disregarded.
*5 Measure drive flange runout using a dial indicator at the points indicated in figure 1.
*6 A decoupled driveshaft can be identified by having a rubber flex joint at the differential end.
*7 To fit the cross joint type driveshaft, the differential drive flange must be replaced. Before fitting the new flange, slip the spacer over the pinion. Failure to fit the spacer will result in bearing damage.
*8 The differential nose angle is the relationship of the differential to the frame. Measure the nose angle with a Craftsman protractor (part# 939840) or equivalent as follows:
a. Place EAS in standard ride height. Road wheels must be on ground.
b. Measure the angle at the bottom of the frame, mid way between the axles.
c. Measure the angle across the face of the differential drive flange (driveshaft removed).
d. Subtract the frame angle from the flange angle to arrive at the nose angle.
The flowchart is a step by step process of how to accurately diagnose and fix the vibration issue. Included are some notes and comments to aid in the diagnosis and repair.
This procedure compliments bulletin 76/15/95/US "Body Noise, Vibration, and Harshness."
ACTION REQUIRED
Upon customer complaint of vibration noise at low or high speeds follow diagnosis and procedure below.
PARTS INFORMATION
FRC 8641 Front Discovery Driveshaft
FRC 8387 Rear Discovery Driveshaft
FRC 9542 Front Range Rover Classic Driveshaft
FRC 8389 Rear Range Rover Classic Driveshaft
FRC 3002 Driveshaft Flange, Discovery and Classic
539745 Pinion Spacer, Discovery and Classic