Apr 242012
 

As with all the other electrical units, the alloy parts were was ultrasonically cleaned and then sprayed with Gtechniq S1 SmartMetal while the other steel parts were zinc-nickel plated. The next two tasks were to sort out the gearbox lid which had been distorted and also to strip and paint the yoke.

The offending motor gearbox lid after several attempts at heat shrinkingThe centre area of the gearbox lid has been stretched at some point. Therefore its outer perimeter no longer made a continuous seal and so would allow water into the gearbox housing.

The suggested solution was to heat shrink the centre section of the lid to reverse the deformation – heating the centre of the lid to near red heat and then rapidly cooling. After several attempts of heating the lid with a gas blow torch and cooling using a can of compressed CO2, all I succeeded in doing was to work harden it in exactly the same shape as before. Aaaaaaargh!

It probably needs to be heated to a much higher temperature using oxy acetylene. In the end I cheated to avoid holding up the rebuild and obtained a replacement lid. When I get time I’ll give it a proper go at flattening the lid, as I would like to keep the original with the correct stampings.

The wiper motor yoke painted in silver hammerite .... at some point I'll repaint in the correct colourNext up was the yoke which contains the two permanent magnets. The magnets can be removed by lifting the retaining clips so the yoke could then be shot blasted before being painted in silver hammerite. I was quite pleased with the finished article even though the silver hammerite was not quite the correct colour.

During the refurbishing of the cooling fan motors I had found a dark silver hammered paint from Rust-oleum, which is very similar to the orginal colour. At some stage I will re-paint the round bodied yoke but decided to put it off for now. Mainly because of the difficulty I’d had getting a good finish with the Rust-oleum product.

Fortunately the armature wasn’t in such a bad state as those in the cooling fan motors and so all that was required was some light wire brushing and polishing before the S1 SmartMetal coating. I had investigated the availability of new brushes and parking switch units but these seemed to be rather difficult to get hold of. Therefore when I spotted a ‘new, old stock’ brush unit for sale I thought I’d get it as a spare for the future. However I’ve not yet found anyone who can supply the parking switch units.

Cleaned armature Triple Brushes Wiper Motor Parts

The armature was wired brushed to remove the worse of the rust. It was then polished and finally sprayed with Gtechniq S1

The armature brushes and parking switch unit

The wiper motor compentent ready for the rebuild, including the spare armature brushes unit

The rebuild starts with installing the armature brushes and parking switch unit, as these are wired together. The brushes are secured by three small setscrews and the connecting wiring passes through a notch in the motor gearbox housing.

The parking switch is secured by two setscrews from the inside of the gearbox compartment, as shown in the middle photo below. This also shows the protruding parking switch plunger which is activated by a cam on the underside of the gear wheel. The cam positioning is such that it operates the switch when the wiper blades return to their normal rest position.

First fit the brushes Parking switch attachment ACF50 applied to Yoke

The brushes and the parking switch unit are the first to be fitted

The parking switch is attached by two setscrews from inside the gearbox housing. Note the switch plunge which operates when the wipers return to their normal rest position

The interior of the yoke was sprayed with ACF50 which provides a good protection from moisture

After several attempts at fitting the armature and yoke, I found it easier to first fit the armature into the brushes and motor gearbox and then fit the yoke. With this approach its was necessary to hold the armature’s worm drive from within the gearbox so that, when fitting the yoke, the yoke’s magnets didn’t pull the armature out of the brushes. Also don’t do what I did and forget to fit the plain washer between the armature and motor gearbox housing!

Care was also needed in making sure that the thrust and fibre washers were correctly seated in the yoke bearing housing. The easiest way to do this was to join the two with yoke positioned so the ‘bearing’ housing was facing downwards.

Initially I tried to put the armature into the yoke and then attach them both to the motor gearbox. However the problem was it was then difficult to withdraw the three sprung brushes at the same time as inserting the armature, because the yoke restricted access to the brushes.

The middle photo below shows the arrow head marking on the motor gearbox and a corresponding line on the yoke. These need to be aligned when refitting. Also shown is the threaded armature stop. This was then screwed into the gearbox housing until it touched the nylon cap on the armature shaft, before being backed off a 1/4 of a turn.

Next fit the armature Alignment markings Belleville washer goes here

The brushes were then withdrawn to allow the armature to be inserted

The markings on the motor gearbox housing and the yoke must be aligned when re-fitting

The Belleville washer provides pre-load for the armature shaft

The Belleville washers is then positioned within the gearbox before inserting the geared output shaft. The rest of the gearbox was then filled with grease before the output rotatry link and gearbox lid were refitted. The rubber moulding sealing the output shaft area had hardened and split.

At the time I dismantled the motor, it was one of the few parts that wasn’t being remanufactured. Probably because it was only used on the Series 2. However by the time I has started the rebuild, one of the suppliers had made a small batch so I decided to grab one while still available.

Re-packed with grease Output rotary link Motor rebuild completed!

The geared output shaft (just about visible) was inserted and then the remaining space packed with grease

The output rotry link was refitted which also secures the geared output shaft. Although I'd forgotten to insert the rubber seal first .... so I'll have to refit it

The completed wiper motor

The only thing that remains is to adjust the various wiper motor & rack linkages which can only be done once they’re installed in the car. People usually leave the installation of the windscreen until the latter stages of a rebuild. I guess this is because it would restrict access to dash area. However I’m tempted to install the windscreen as soon as the dash wiring looms and dash panels are in place. Therefore I’ll be able to adjust the linkages before the bulkhead access become restricted.

Feb 232012
 

A rather grubby wiper motorThe wiper motor in the S2 is a Lucas Type 15W motor, the output of which drives a connecting rod to the triple wiper rack. From what I can tell the 15W motor essentially works in the same manner as the DL3 wiper motors used in the earlier cars, except that the parking switch is now internal within the 15W.

There are two main sections of the wiper motor; a round bodied section (which acts as the yoke, completing the magnetic circuit) and the motor gearbox. The round bodied section has two permanent field magnets attached to its inner wall and houses the motor’s armature. At the end of the armature shaft is a worm drive that drives the geared output shaft in the motor gearbox.

Worm drive at the end of the armature shaftThe two long yoke retaining bolts were removed which enabled the round bodied section and armature to be carefully withdrawn until the worm drive is free. Unchecked, the action of the worm drive would pull the armature shaft further into the motor gearbox. A threaded stop screw limits the permitted travel of the armature shaft and there’s also flat thrust washer between the armature and motor gearbox.

The internals were quite badly corroded ... like everything else!The armature can then be withdrawn from the yoke. Although a reasonable amount of force is required to overcome the magnetic attraction between the permanent magnets and the armature.

The interior of the yoke was fairly heavily rusted and all the tiny, loose rust particles were now annoyingly attached to the permanent magnets.

The thrust plate and fibre washer in the 'bearing housing'The end of the armature rotates in, what the manual describes as, a bearing housing in the cap of the yoke. However there isn’t a bearing as such. Only a small thrust plate and fibrous washer. I didn’t realise they were there at the time of dismantling so I was lucky not to lose them.

A cover on the main motor housing provides access to the geared output drive. Sometime in the past this cover had become deformed and so it no longer provided a tight seal around its full perimeter (just about visible in the lower photo to the right).

The main housing cover had been deformed creating a gap which would allow water inThe cover can be pressed back into shape but it immediately pops back, in a similar manner to the lid of an opened jar. I think it’s referred as oil canning and is a result of the centre area of the lid having been stretched.

It should be possible to reverse the stretching by heat shrinking the centre of the plate but that will have to wait until the rebuild.

Removing the cover revealed copious amounts of thick brown grease. I think the grease had dried out long ago and it was surprising the motor was able to turn at all! The rest of the dismantling was very straight forward.

Hardened grease within Worm drive engaged Triple armature brushes

Over time the grease had dried out and hardened. It was surprising the gear could actually turn

Armature worm drive re-engaged for photo. Armature free play is set by tightening a screw, just visible on the left

The

As the wiring between the armature brushes and the parking switch unit is fixed, they had to be removed together. This required the removal of the geared output shaft to gain access to the screws securing the parking switch unit. The output rotary link is removed which enabled the geared output shaft to be withdrawn.

Output rotary link Geared output shaft Parking switch screws

Removal of the output rotary link

Withdrawing the geared output shaft

The removal of the gear wheel provides access to the screws securing the parking switch unit

The geared output shaft has a Belleville washer (conical spring washer) inside the motor gearbox to provide pre-loading and a flat washer between the motor gearbox and the rotary link.

Parking switch wiring Belleville washer Rear rubber seal

The motor has three brushes to provide dual speed operation, which are connected the parking unit

Conical spring washer between the geared output shaft and the motor gearbox

Motor gearbox and the rubber moulding sealing the output shaft had hardened over time

Feb 182012
 

Unscrewing the two long bolts provides access to the internal componentsOne of the great things I’ve found about the restoration of the various electrical components is that they were designed in an era before our ‘throw away’ society. Therefore overhauling the units is well within the capability of most enthusiasts. As with the fuel pump, the stripping down of the fan motors was very simple.

Having said that, the fans had been attached the wrong way round and no matter what I tried they would not come free. I tried using a small, hub puller type tool on the first fan. However all this achieved was to shear the nylon fan from its central metal fixing, which then had to be carefully cut off using a Dremel tool. So two new fans were added to the ever growing shopping list of parts required!

The fan motor casing consists of a square steel body clamped between two alloy end plates. After the two long screws have been withdrawn, the end plates can be prised from the body with a screw driver. These Lucas motors weren’t designed to be watertight as the rear end plates have openings for the electrical connections. So, over time, water ingress had taken its toll on the interior components.

Rear end plate

Corrosion within!

A rusted armature

A little persuasion was all that was needed to remove the end plate

The internals were fairly rusty ... probably not helped by the openings for the electrical connections in the end plate allowing water in

The armature had suffered worst

As the fan was still attached, the rotor (or armature), the front end plate and fan had to be removed as one. The only other parts within the motor are a wound stator and the armature brushes mounted in a plastic holder. The holder can be withdrawn by removing the two screws on the underside of the motor body.

Wound stator removal

Wound stator & brushes

Stator is just a push fit

Two central screws secure the stator housing

Stator housing can then be removed

The stator removed from the plastic housing

The stator can then be pushed out of the plastic holder. The brushes are loose fitting and can simply be pulled apart and lifted away from the holder. In the end neither fan blade could be removed intact. A Dremel with a cutting disc was needed to remove the metal fixing that remained stubbornly attached to the armature shaft. Once it had been removed the armature and front end plate could be separated.

A thrust washer sits between the front end plate and the armature. A similar washer isn’t necessary between the armature and the rear end plate. When the fan is operating, the fan blade produces a forward force on the armature pushing it towards the front end plate and away from the rear end plate. Therefore there is no load on against the rear end plate.

Thrust washer between the front end plate and the armature