Description - MG MG6 Series 2011 Service Manual

Front Suspension

Description

General
The front suspension comprises:
• Two MacPherson struts
• Two 'L' shaped lower arms
• Anti-roll bar
• Two anti-roll bar links
• Front subframe
• Swivel hub, bearing and drive flange
The front suspension design features anti-dive and anti-squat
geometry via the anti-roll bar and 1:1 strut movement ratio.
The layout and design of the struts minimizes camber loss due
to side forces, improving handling and steering response.
Front Subframe
The subframe is fabricated from hydro-formed tubing providing
a light and strong structure. All machining of critical geometric
locations is performed after fabrication to ensure accurate
location of the front suspension and steering components.
The subframe is mounted on six rubber mounts and provides
location for all front suspension components, except the strut
top mounts, engine and gearbox mountings.
brace, fitted between each subframe rear mounting point and
the body, provides additional rigidity to this subframe. The
layout of the mountings ensures that subframe movement
under cornering forces, which cause unwanted steering
effects, is avoided.
MacPherson Strut
Two MacPherson struts control the damping of the front
suspension. Each strut assembly comprises a damper unit,
a coil spring and a top mount assembly. The coil spring is
retained in a compressed condition between the strut spring
seat and the top mount assembly. Isolators at each end of the
spring reduce noise transmitted from the suspension to the
body. A bearing is fitted to the underside of the top mount
assembly and allows the spring to rotate as the steering is
operated. A dust cover is fitted between the bump stop
and the damper and protects the damper rod from dirt and
damage.
The coil spring axis is offset to the axis of the damper. This
arrangement provides side load compensation, which reduces
friction within the damper.
Damper
The front dampers feature 85 mm bump and 95 mm rebound
damping. Each damper is handed.
Each damper is gas charged and oil filled, and is of twin
tube construction. The twin tube construction allows the
damper piston to operate on an inner tube with an oil/gas
Version 2.0
cavity between the inner and outer tubes. This minimises oil
cavitation and eliminates the effect of damage to the outer
tube affecting piston operation.
The damper is attached at its lower end to a location in the
swivel hub and is secured with a pinch bolt. A tang on the
damper locates in the swivel hub and ensures that the damper
is correctly orientated.
The damper rod is located in steel inserts in rubber bushes,
which are integral with the top mounting plate, and are secured
with a washer and nut. A hexagon is provided in the outer end
of the damper rod to restrain the rod from rotating when the
nut is tightened. The damper rod is sealed in the damper with
a low friction seal.
An angled spring seat is integral with the damper body and also
provides the attachment point for the ARB link.
A welded bracket, near the bottom of the damper, allows for
the attachment of the brake hose, the ABS speed sensor cable
and on the RH damper, the brake pad wear sensor harness.
Coil Springs
The coil springs fitted to the strut assembly are manufactured
from silicon chrome vanadium. The top of the spring is located
A subframe in a spring isolator which in turn is located in the top mount
bearing. The base of the spring, which is fitted with an isolator
sleeve, is located in a spring seat that is integral with the
damper body. Both isolators reduce noise transmitted to the
body from the suspension. The front springs differ between
engine type and vehicle specification and each spring can be
identified by a colour code painted on the coils of the spring.
Top Mounting Plate Assembly
The top mounting plate assembly comprises of the top
mounting plate, a double rubber bush and three studs. The
bushes are located into the top mounting plate. Steel inserts
are bonded into the centre of the bush and prevent the
locknut on the damper rod over compressing the bush when
it is tightened. The axis of the bush is not square to the plate,
which allows the bearing to be located with its axis aligned to
the offset coil spring. Three lugs on the underside of the plate
provide for the attachment of the top mount bearing which is
an interference fit in the lugs. The bearing and the bush are
not serviceable and a new top mounting plate assembly must
be fitted if replacement is required.
Lower Arm
The lower arm is an 'L' shaped, high strength alloy forging that
connects the swivel hub to the subframe.
The arm has an outer ball joint that has a parallel shank. The
parallel shank locates in a split location in the bottom of the
swivel hub and is clamped in position by a bolt and locknut.
An inner ball joint is also fitted and is positioned near the road
Suspension System
551