Lucas 11 AC alternator guides
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) the 'Lucar' field terminal spades are of different design.
Lucas Part No.54215076 Suits earlier brush holder, shown below :
Lucas Part No.54218506Suits later brush holder, shown below :
Removal - Brush Holder
Remove the nuts, washers and insulating pieces from the output terminal at the rear of the alternator. (See sketch left.) Remove the two brush holder retaining screws and withdraw the brush holder assembly from the rear end bracket. Take care not to lose the two washers fitted between the brush holder moulding and the end bracket, as these must be refitted in their original locations on reassembly.
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 vehicle.)
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 photos above) are supplied complete with their spring and 'Lucar' field terminal blade.
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 (oil, 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 blade.
Later brush holder: Place each brush into the holder, (ensure 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.
Drive End : 6202 Z or 2Z Deep Groove Ball Bearing (As there is no regreasing facility, 6202 2RS would give better life.)
Non-Drive End INA or Lucas Needle Roller Bearing