Lucas 11AC Alternator
Brushes & Bearings - For Sale
Lucas 11AC alternators were supplied with two types of brush
holder, and although the brush itself is the same, (17.9 x 7.9 x 4.6mm)
'Lucar' field terminal spades are of different design. I have
both types available at £3.50 per pair + p&p (50p mainland
|Lucas Part No.54215076
||Lucas Part No.54218506
Suits earlier brush holder, shown below :
||Suits later brush holder, shown below :
The drive end (pulley end) bearing as fitted to the Lucas 11AC
alternators were pre-greased and fitted with a single metal shield - as
indicated by the 'Z' suffix at the end of the bearing designation.
An improvement on this is the rubber shielded ('RS' suffix) type, which
I can now supply at £1.50 each + p&p (75p mainland UK).
Note: Although the rubber shields
improve resistance to dirt and moisture, they reduce maximum allowable
continuous speed of the bearing to 14,000 rpm. The alternator will
typically run at two to three times the engine speed, and under normal
driving conditions will probably run at below 10,000 rpm (check your handbook),
so unless you've a race tuned engine regularly used for race & rally,
this is unlikely to be an issue !
Please use the on-line form
or alternatively e-mail me with
Will ship outside the UK, not a problem - please enquire for postage
|Removal - Brushes
Earlier brush holder: Using a small terminal screwdriver,
close up the retaining tongue at the base of each field terminal blade
and withdraw the brush, spring and terminal assembly from the brush holder.
Later brush holder: Remove the small cover, which is retained
with a single self tapping screw, the brushes can then be gently eased
out of the holder. (Note: This can be done with the brush holder
still on the alternator, which itself doesn't need to be removed from the
Inspection - Brushes
Check the brushes for wear. The brush length when new
is 5/8 in (16 mm), if worn to the wear limit of
5/16 in (8 mm),
the brush assemblies should be renewed. New brush assemblies (see
are supplied complete with their spring and 'Lucar' field
If the original brushes are to be re-used, clean them with a
cloth moistened in methylated spirits, then dry thoroughly. Check
the brushes for freedom of movement in their holders. If necessary,
lightly polish the brush sides on very very fine 'wet and dry' paper, then
clean them and refit.
Inspection - Slip Rings
Before refitting the brush holder assembly, inspect the slip
rings, the surface of which should be smooth, for any signs of contamination
dirt etc.) or damage (pitting, grooving etc.).
Surface dirt from the slip rings can be easily removed by inserting
a cloth moistened in methylated spirits through the hole in the end bracket,
holding it in contact with the slip ring surface while rotating the pulley.
If more serious contamination or damage is evident on the ring
surface, the alternator must be partially dismantled to gain access.
In this case the drive pulley and fan must first be removed to allow the
three through-bolts to be unscrewed. The alignment of the end brackets
and stator should be marked so that they may be reassembled in the correct
angular relation to each other. The drive end bracket and rotor can
then be separated from the stator and slip ring end bracket to allow inspection
of the slip rings.
The surface of the slip rings can be cleaned using Brasso or
'T-Cut', if necessary first use 'Scotchbright', a non-metallic wire wool.
Use of emery cloth or similar abrasive, will leave the slip rings unduly
rough and is best not used. If badly scored, pitted or burned, the
slip rings will need to be skimmed in a lathe.
Refitting - Brushes
Earlier brush holder: Push each brush, complete with
its spring and terminal blade, into its holder until the tongue on the
terminal blade registers in the brush holder. To ensure the terminal
blades are properly retained, the tongue should be levered up with a small
terminal screwdriver to make an angle of about 30deg with the terminal
Later brush holder: Place each brush into the holder,
correct orientation - see photos above), and replace the small cover.
Refitting - Brush Holder
Refit the brush holder assembly on to the slip ring end bracket
and secure with the two retaining screws. Assemble the insulating pieces,
washers and nuts on the output terminal.
Reconnecting the Alternator
Note : The brush which bears on the inner slip
ring should always be connected to the positive side
of the electrical system, (marked on the later brush holder), since
the lower linear speed of the inner slip ring results in reduced mechanical
wear and helps to offset the higher rate of electrical wear peculiar to
the positive brush.