MG TF Series User Manual

E THE FLYWH8EI. AND tJLUT£H_------ -- ------ - ----
The actual cause of the trouble must be ascertained
and rectified.
The free pedal movement, measured at the pedal pad,
should be fin. (19 rnrn.), and the clearance between
the stop on the dutch withdrawal lever and the stop
on the flywheel housing should not be more than! in.
(13
mm.). (See" G," Fig. E;2, page EA.)
To obtain a dean release, the release lever plate
should move a distance of -iIr in. (7·9 mm.) towards the
flywheel.
Spring pressure
A
tolerance of not more than 10 to IS lb. (4·5 to
6·8 kg.) pressure Is allowable on the compression
load of the operating springs when at their assembled
height, and all clutch springs are tested for this before
assembly.
The cI utch 0 peration spri ngs are not affected by
high
dutch temperatures, as the pressure plate
absorbs heat rapidly, the springs have only line
contact, and a draught is continually passing under
them when the engine is running.
Tolerances
Wear on the working faces of the driven plate is
about ·001 in. (·02 mm.) per 1,000 miles (1600 km.)
under normal running conditions. The accuracy of
the alignment of the face of the driven plate must be
within ·015 In. (,38 rnrn.),
Driven plates
It Is important that the clutch facings are not
touched with greasy hands, nor any 011 or grease
allowed to come into contact with them.
Lubrication of the splines of the driven plate Is
provlded at assembly only, when eS881 graphite
grease or zinc-based" Keenol .. is used.
It Is essential
to install a complete driven plate
assembly when renewal of the friction surfaces is
requlred, If the facings have worn to such an extent
as to warrant renewal, then slight wear will have
taken place on the splines, and also on the torque
reaction springs and their seatings. The question of
balance and
concentricity is also involved. Under no
circumstances is it satisfactory to repair or rectify
faults in
dutch driven plate centres, and we do not
countenance this as manufacturers.
Condition of clutch facings in service
It Is natural to assume that a rough surface will give
a
higher frictional value against slipping than a polished
one, but this Is not necessarily correct. A roughened
su rface consists of small hills and dales, only the" high
spots" of which make contact. As the amount of
useful friction for the purpose of taking up the drive
E.8
Is dependent upon the area In actual contact, It is
obvious that a perfectly smooth face is required to
transmit the maximum amount of power for a given
surface area.
Since modern facing materials of the asbestos
type have been I ntroduced in service the polished
surface is
common, but it must not be confused with
the glazed surface which is sometimes encountered
due to conditions to be discussed subsequently. The
ideally smooth or polished condition will therefore
provlde proper surface contact, but a glazed surface
entirely alters the frictional value of the facing, and
will
result in excessive dutch slip. These two
conditions might be simply Illustrated by comparison-
between a piece of smoothly finished wood and one
with a varnished surface; in the former the contact is
made
directly by the original material, whereas In the
latter instance a film of dry varnish Is interposed
between the contact surfaces, and actual contact is
made by
the varnish.
If
the clutch has been in use for some little time
under satisfactory conditions, the surface of the facings
assu mes a high polish
th rough which the nature of the
material can be seen dearly. This polished faclng is
of light colour when in perfect condition.
Should oil in small quantities gain access to the
clutch and find its way onto the facings, it will be burnt
off as a result of the heat generated by the slipping
occurring under normal starting conditions. The
burning of this small quantity of lubricant has the
effect of gradually darkening the facings, but provtded
the polish of the facing remains such that the nature
of the material can be distinguished clearly it has little
effect on clutch performance.
Should increased quantltles of oil obtain access to the
fact ngs, the n one of two cond Itio ns, or a com blnation of
these, may arlsa, depending upon the nature of the oil.
1.
The 011 may burn off and leave a carbon deposit
on the surface of the facings, which assume a
high
glaze, producing further slip. This isa
very definite, though very thin, deposit, and In
general It hides the grain of the material.
2. The oil may partially burn and leave a resinous
deposit on the facings. This has a tendency
to produce a fierce clutch, and may also cause
excessive .. spinning" due to the tendency of
the face of the linings to ad here to the su rface
of the flywheel or pressure plate.
3.
There may be a combination of conditions (1)
and
(2)wh lch prod uces ate ndency to " judde r "
on clutch engagement.
Still greater quantities of all produce a dark and
soaked appearance of the facings, and the result will be
further slip, accompanied by fierceness or " [udderlng "
Wishvilles Classic
Automobile Library

MG TF Series Specifications

General

Brand	MG
Model	TF Series
Category	Automobile
Language	English