wheel torque JAGUAR XJ6 1994 2.G User Guide

may include:
0
0
Loose or worn wheel bearings.
Loose or worn suspensions or steering components.
0 Worn or damaged drive shaft slip yoke joint.
0 Front disc rotor runout.
o Loose engine or transmission supports.
0 Driveline alignment.
0 Engine driven accessories.
Suspension Systems
11.4 DIAGNOSIS AND TESTING
' 11.4.1 Tire Wear
Tires should be inspected as abnormal or excessive wear may becaused by incorrect wheel alignment, wheelbire im- balance, or incorrect tire pressure.
1 1.4.2 vibration and Roughness
Vibration, roughness, and shimmy conditions may be caused by excessive tire or wheel runout, worn or cupped tires,
or wheel and tire unbalance.
Most of these conditions are due to irregularities in the road surface, hence driving the vehicle on different types of
road surface will often indicate the cause of the condition.
Do not automatically suspect the tires when attempting to diagnose a vibration concern as other sources of vibration
Before investigating any other vibration concerns,
a roaG &est and a customer inter\,.dw (if possible) should be carried
out. This can provide much of the information needed to find the source of vibration.
Drive the vehicle on a road that is preferably smooth and free of undulation and
if vibration is apparent note, the speed at which thevibration occurs, whattype of vibration occurs in each speed range (mechanical or audible), howthevibra- tion is affected by changes in vehicle speed , engine speed and engine torque, and the type of vibration sensitivity
(torque sensitive, vehicle speed sensitive, or speed sensitive).
Some of the condition terms used when describing sources of vibration are explained as follows:
0 Torque Sensitive
This condition can be improved or worsened by accelerating, decelerating, coasting, maintaining
a steady
vehicle speed and application of engine torque.
0 Vehicle Speed Sensitive
This means that the vibration always occurs at the same vehicle speed and is not affected by engine torque,
engine rpm, or transmission gear selection.
B
0 Engine Speed Sensitive
This means that the vibration occurs
at varying vehicle speeds when a different transmission gear is selected.
It can sometimes be isolated by increasing or decreasing engine speed with the transmission in 'NEUTRAL', or
by stall testing with the engine in gear. If the condition is enginesensitive, the condition is not related to tires.
If the road tests indicates that the vibration is related to the tires or wheels,use a 'lire Wear Diagnosis Chart' to
investigate the cause of concern. Should the road test indicate that there is tire whine, but noshake or vibration,
the noise originates from the contact between the tire and the road surface.
X300 VSM 3 Issue 1 August 1994

12.2 (continued)
rrouble
Excessive pedal travel (Cont'd)
Brakes grab
Brakes drag
Hard brake pedal when pressed
Excessive brake noise
Cause
Worn tandem master cylinder piston
seals or scored cylinder bore
'knock back'. Excessive brake rotor
run
-out or loose wheel bearings
Brake pads contaminated by grease
or brake fluid
Brake pads distorted, cracked or
loose
Loose caliper mounting bolts or
guide pins
Seized or incorrectly adjusted parking
brake or cable
Broken or weak parking brake return
springs
Caliper pistons seized
Brake pedal binding
at pivot points
Vacuum booster binding
Tandem master cylinder faulty
Lack of vacuum
at the vacuum
booster
Tandem master cylinder
pushrod
binding
Frozen tandem master cylinder pis
-
ton
Brake caliper piston or caliper guide
pins seized
Worn brake pads
Bent or cracked parking brake shoes
Foreign objects in brake pads or
park- ing brake shoes
Broken
/ loose parking brake hold
down springs or return springs
Loose caliper mounting bolts
Remedy
Renew tandem master cylinder
Check brake rotor run
-out and renew
as necessary. Adjust wheel bearing
Renew brake pads. Check
pipework for leaks
Renew brake pads
Check caliper and repair
/ renew as
necessary
Examine parking brake and repair
/
renew as necessary
Renew parking brake return springs
Examine calipers and repair
/ renew
as necessary
Examine brake pedal bushings and
repair
/ renew as necessary
Renew vacuum booster
Examine tandem master cylinder and
repair
/ renew as necessary
Check vacuum hose. Repair or renew
as necessary
Renew tandem master cylinder
Renew tandem master cylinder
Examine caliper and renew/ repair as
necessary
Renew brake pads
Renew parking brake shoes
Examine brake pads and and parking
brake shoes. Clean or renew as
necessary
Examine parking brake assembly.
Re- pair or renew as necessary
Re
-torque caliper mounting bolts

Brakes
12.8
SRO 70.60.21
PRESSURE CONSCIOUS REDUCING VALVES - RENEW
Refer to Section 12.4, Brake System Bleeding before carrying out this procedure. Pay particular attention to the warn- ings and cautions relating to brake fluid, cleanliness and cleaning materials.
Note: The illustration shows the hydraulic control module of a 6 cyl. vehicle with traction control. Hydraulic control
modules on non-traction control vehicles have only three outlet ports. Apart from this, the removal procedure
is the same for all vehicles.
. Raise the vehicle.
Displace the bleeder screw dust cap of the front LH caliper.
The dust cap will remain captive on the bleed screw.
rn Connect a bleeder tube and bottle to the bleeder screw (1 Fig. 1) and open the bleeder screw.
Fit a brake pedal hold-down tool (JDS-9013) between the
brake pedal and the steering wheel. Adjust the tool to op- erate the brake pedal 60mm down. This operation is
necessary to prevent fluid
loss from the reservoir through
disconnected brake pipes.
. Re-tighten the front LH caliper bleeder screw. Disconnect
the bleeder tube from the bleeder screw and remove the
tube and bottle. Refit the bleeder screw dust cap.
rn Place absorbent material underneath the hydraulic con- trol module to absorb any spillages.
. Undo the rear brake pipe gland nuts (1 Fig. 2) at the pres- sure conscious reducing valves (PCRVs) (2 Fig. 2). Remove
the rear brake pipes.
m: Take necessary steps to prevent rotation of the
PCRVs when removing the rear brake pipes.
Fit plugs immediately to the brake pipes and the PCRVs to
Undo and remove the PCRVs. Fit plugs immediately to the
. Clean the surrounding area.
. Fit new PCRVs to the hydraulic control module, removing
plugs immediately priorto connection. Tighten the PCRVs.
. Connect the rear hydraulic brake pipes to the PCRVs, re- moving the plugs immediately prior to connection.
Tighten the gland nuts.
prevent
fluid loss.
PCRVs
and the hydraulic control module.
0
Note: Take necessary steps to prevent rotation of the
PCRVs when fitting the rear brake pipes.
. Removethe absorbent material and clean the surrounding
. Ensure that all fixings are torque tightened to specified tol-
Release the brake pedal hold-down tool and remove.
. Bleed the brake system (refer to sub-section 12.4.4).
. Examine the hydraulic control module for leaks.
area.
erances. Fia.
1
Fia. 2
X300 VSM 25 Issue 1 August 1994