Dismantling the Alternator
Once the alt is on the bench the first thing is to remove the insulation from the main +ve output post. This is held by a 10mm headed nut which once removed allows the plastic to be lifted off.
The next step is removal of the rear cover which is held by 4 x 8mm headed nuts/screws as circled.
The rear cover might be Ďstuckí by dirt and corrosion but at this stage should come off with a little persuasion. This will reveal a bright red/orange rubber cover over the brushes and then the brushes themselves can be removed by undoing the 3 x Ph#2 screws (do not be tempted to use pozi driver bits! Phillips are the best fit)
With the brushes out of the way you can now remove the component the 2 pin plug connects to which is circled in blue and secured with the 2 remaining Ph#2 screws circled in red.
Then undo the 4 screws that secure the windings to the diode plate.
And then lift out the rubber insulators from the winding terminals.
At this point I decided to split the alt casing so started by removing the 4 nuts holding the two halves together. 3 of the 4 nuts are circled in this picture with the 4th hiding by the +ve terminal post.
I had to forcibly separate the two halves even though once cleaned up they just slid firmly back together so you may be luckier than me when splitting the casing. To split the halves I used a threaded rod between the peices to open up a small gap then released the pressure and put a wedge into the opposite side which had opened up slightly before reapplying some pressure to further open the gap.
This left the slip ring end bearing stuck in the casing and this is just tapped out with a suitable drift being careful not to damage the washers that fit between the bearing and casing. Next job is to remove the front pulley so the armature can be removed from the main casing. This is a tricky job because try as I might I couldnít secure the pulley tightly enough to undo the 22mm pulley nut without risking damage to the pulley. Fortunately the armature spindle has a 10mm hexagon on the end and by creating a special tool using a 22mm socket and some old steel I had lying around I made a tool that allowed me to fit a socket onto the 10mm hex while undoing the 22mm nut.
Once the pulley is off the armature slides easily out of the front bearing. The front bearing is covered by a securing plate and once this plate is removed (4 x 7mm headed bolts) the bearing can be tapped out by resting the casing on a suitable piece of pipe. Be careful not to damage the winding wires during this stage!
Now once you have got this far the difficult part is over. The only possible complication would be if the slip ring end bearing stayed on the armature spindle rather than in the casing. Removing it from the spindle could be tricky without some kind of puller.
You should now have 2 bearings and a brush cartridge that need to be replaced. I went to an alternator specialist locally and from the TN121000-xxxx number he could supply the bearings and brushes to order at a good price. As I was a bit tight I opted to service the existing brushes and just bought the bearings from him and loose brushes with copper flex tails (cost £1 instead of £12).
I worried about the quality of the new bearings but when they arrived they were an American made product and my regular bearing supplier couldnít get hold of any equivalent so I suspect they might actually be OEM?
PFI part numbers for the large front bearing is 949100-3330 and the smaller one is 949100-2790