Jaguar XJ (X350). Manual — part 277

Shudder (Judder)

Shudder is a low frequency oscillation of the entire steering system (tire, wheels, steering gear and

linkage, etc.) when the vehicle is steered during static-park or at low speeds. Shudder is very

dependent on road surface.

Torque Ripple

Torque ripple is a concern with Electric Power Steering (EPS) systems. Torque ripple is most evident

at static-park steering the wheel very slowly from lock to lock. Torque ripple is primarily caused by

motor commutation.

Torque/Velocity Variation (Phasing/Effort Cycling)

Steering wheel torque variation occurring twice in one revolution is normally as a result of problems

with the lower steering column (intermediate shaft), but foul conditions generally result in either

constant stiffness or single point stiffness. Depending upon the orientation of the joints, the steering

can feel asymmetric (torque falling off in one direction and rising in the other) or else it can simply

have pronounced peaks and troughs as the steering moves from lock to lock.

Wheel Fight (Kick Back)

Wheel fight is excess feedback of sudden road forces through the steering system and back to the

driver. It is evaluated at all vehicle speeds over cobblestones, rough roads, and potholes. The tires,

wheels, and suspension generate forces into the steering systems. Steering friction, hydraulic

damping, hydraulic compliance, mechanical compliance, steering ratio, and assist gain all affect how

much is transmitted to the driver.

Steering Linkage

CAUTION: Steering gear boots must be handled carefully to avoid damage. Use new clamps

when installing steering gear boots.

Inspect the boots for cuts, deterioration, twisting or distortion. Check the steering gear boots to

make sure they are tight. Install new boots or clamps as necessary.

NOTE:

The following steps must be carried out with assistance.

1 . With the wheels in the straight ahead position, gently turn the steering wheel to the left and the

right to check for free play.

2 . Free play should be between 0 and 6 mm (0 and 0.24 in) at the steering wheel rim. If the free play

exceeds this limit, either the ball joints are worn, the lower steering column joints are worn or the

backlash of the steering gear is excessive.

CAUTION: DO NOT attempt to adjust the steering gear yoke. Failure to follow this

instruction will result in the steering gear warranty to become invalid.

The backlash of the steering gear cannot be adjusted, install a new steering gear. For additional

information,

<<211-02>>

4 . Grasp the steering wheel firmly and move it up and down and to the left and right without turning

the wheel to check for column bearing wear, steering wheel or steering column. For additional

information,

<<211-04>>

3 .

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211-02 : Power Steering

Specifications

Specifications

Torque Specifications

Description

Nm lb-ft lb-in

Power steering fluid cooler retaining bolts

7

-

62

Power steering pump retaining bolts

25 18 -

Lower steering column slider pinch bolt

30 22 -

Lower steering column to steering gear pinch bolt

30 22 -

Steering gear retaining bolts

100 74 -

Power steering pump supply line - vehicles with petrol engines

15 11 -

Power steering pump supply line - vehicles with 2.7L diesel engine 22 16 -

Power steering control valve actuator retaining bolt

2

-

18

Steering gear supply and return lines retaining bolt

10 7

-

Power steering fluid reservoir retaining bolts

10 7

-

Description and operation

Power Steering

Item Part Number

Description

1

—

Lower steering column

2

—

Power steering fluid reservoir

3

—

Power steering pump

4

—

Power steering fluid cooler

5

—

Power steering lines

6

—

Steering gear

The vehicle uses a rack and pinion type, variable ratio steering gear with speed proportional
servotronic. The power steering pump is belt driven on all model variants and the power
steering oil cooler is of a tube and fin type and is mounted to the front of the cooling pack.

A variable steering rack ratio reduces the amount of turns from lock to lock to improve
parking maneuvers without loosing any steering feel at higher speeds.

The steering assistance decreases smoothly at a calibrated rate to increase the steering efforts
required as vehicle speed increases. The steering efforts are controlled by the actuator
position, which in turn is controlled electronically by the speed proportional servotronic curve
which is incorporated within the Generic Electronic Module (GEM).

Absolute cleanliness must be observed when replenishing the fluid or dismantling any part of
the system. New fluid from a sealed container must be used.

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