Nov 132014

Time pressures delayed the full electrical shakedown testing until after the engine was up and running. Power is only required to the ignition and fuel pump circuits to start the engine so all the other fuses were removed. Having said that, I did end up fitting the fuse for the instrument voltage regulator in order to obtain oil pressure and temperature readings while the engine was running.

The other fuses were now fitted in turn, stopping to test each of the components they fed, before moving on to the next fuse. The resulting snagging list was encouragingly minor:

  • The main beam can’t be flashed from the indicator stalk
  • The original hazard flashing unit is on the blink!
  • The brake fluid warning light isn’t coming on
  • The wiring to the rear brake and sidelights have been crossed over
  • One of the cooling fans is a little noisy and spins the wrong way!
  • The heater fan is making contact with the housing
  • Neither the washer or wipers work
  • Only one horn worked

Overall I was quite pleased with that for a first test. Especially as it was the first time the cooling fans and wiper motor had been tested since I rebuilt them and the washer, wiper, brake fluid warning light and horn were all simply missing earth connections. So easily solved.

Indicators and hazard lights
There was a fair amount of head scratching when wiring up the hazard warning light switch. The part number identified it as a hazard switch from an XJ6 and its pin connections conflicted with those in the Illustrated Parts Manual!

Hazard wiring diagram Hazard switch wiring

So I attempted to go back to first principles (or my understanding of them!) to work out the correct wiring. The one thing that was puzzling me was why separate indicator and hazard flasher units were used. They are essentially performing the same role – converting a constant DC supply into a square wave, with a suitable duty cycle to provide the correct flash duration and frequency.

The light bulb moment came when reading the requirements to pass an MOT. The hazard lights must be able to operate without a key in the ignition while the indicators are only powered when the ignition switch is on. The other difference is the power rating as the hazard unit needs to draw more current drive both sets of indicator lights at the same time.

The duty cycle of the unit is achieved by a bimetallic strip which expands and contracts depending on whether current is flowing. When the indicators are on, the current generates heat in the two metals, which expand at different rates. This causes the strip to move away from its contact and break the circuit. Without a current, the strip rapidly cools and the circuit is re-established allowing current to flow once more and the process to repeat.

Therefore the flashing frequency or ‘duty cycle’ is directly related to the rate of expansion/contraction of the bimetallic strip, which is a function of the current flowing. This is why modern LED indicator bulbs often do not work on classic cars as they draw far less current and therefore may not generate sufficient heat to switch the traditional units. Modern transistor based units are available to overcome the problem.

Therefore the switch needed to have the following connections:

Hazard switch in OFF position

  • Indicator flashing unit is introduced into the circuit (the two green wires are connected)
  • Hazard flashing unit is cut out of circuit (connections between the LGN, GR & GW wires are broken)
  • The indicators can then be operated via the switches built into the indicator stalk

Hazard switch in ON position

  • Indicator flashing unit is cut out of circuit (by removing power to its green wire)
  • Hazard flashing unit is introduced (by connecting its LGN output to both the GR & GW indicator feeds)

The only problem was the random frequency of the hazard flashing which was easily solved by fitting a new flasher unit.

Cooling Fans
The S2 cars have an otter switch to turn on the cooling fans at its rated temperature and requires a special connector, which has been on back order for ages. A spare dash switch was rigged up in its place so the fans could be switched on and off at will, which would be useful when testing and tuning the engine. The first fan spun up and ran smoothly and quietly, which was very pleasing, as they hadn’t been bench tested after their refurbishment.

However the operation of the second fan was noisier because the blade was not quite square on the armature shaft, causing vibrations. Removing it was a fiddly process with the engine bay completed so I was cursing not having bench tested it!

But more importantly, the motor was rotating the wrong way, pushing air forward towards the radiator rather than drawing air through it. Its effect would be worse than having no fan at all. When travelling at speed there would be a natural flow of air through the radiator. Having a fan blow against this flow would reduce the cooling ability.

It is rather odd because reversing the supply polarity of series wound DC motors (and indeed shunt wound motors) does not reverse the direction of rotation. The only way to rectify this would be to reverse the connections on either the field or the rotor windings (but not both!).

The rotating force (torque) on the armature shaft is the result of the interaction of the magnetic fields of the armature and the field winding – opposite poles attract, like poles repel. The directions of these magnetic fields are dependant on the direction of the current following through them.

Therefore changing the polarity of the power supply does not reverse the direction of rotation because both the field and armature currents will be reversed and therefore both magnetic fields. A double negative if you like, that cancels each other out!

The only practical option for these Lucas motors was to reverse the field winding, which was a very simple job.

Field wires just needed swapping All sorted – an easy soldering job

The fan now rotates in the correct direction to draw air rearward through the radiator. The fan was also re-seated to stop the fan vibrating so much.

I was trying to fathom an explanation as to why the motors were rotating the wrong way and then recalled that I had difficulty dismantling the two motors I’d acquired many moons ago, at the start of 2012. They were of the same design but had the fans mounted the wrong way round.

The person had indicated they were selling them as they had upgraded to modern fan units. However I suspect they had sourced motors from a different vehicle and noticed they were turning the wrong way. They had then mistakenly concluded mounting the fans the wrong way round would rectify the situation, rather than just improve their efficiency in making things worse!!

Wiper motor & Intermittent module

Intermittent control above
brake warning light

I’d decided to fit the Hella intermitted wiper module that other E-Type forum members had advocated. It works independently from the two speed wiper switch on the dash and the modification is reasonably discreet and reversible. The intermittent control uses the hole in the dash for the rear window heater on the FHC, which is blanked off on the OTS cars.

Like the hazard warning switch, the part number on the wiper motor switch also suggested it had originally come from an XJ6. The problem was the connected terminals were different to the correct switch (OFF 5-7, Normal 4-5, Fast 2-4) and so it was another case of trying to work out how it should be wired.

The combination of common sense and trial and error eventually produce the correct operation, which differed from the wiring suggested by the forum post. I’ve wired intermittent module into the ULG feed rather than the suggested YLG wire, which is for operating the motor at high speed.

At the same time, I also decided to add a jumper lead (with an inline diode) from the washer switch to the slow speed supply to the motor. Therefore the wipers now operate automatically while the washer switch is pressed. The diode is needed to stop it working in reverse, with the washer operating when the wipers are switched on!

Heater Motor
A complete new heater unit had to be fitted as the original had largely rusted away. The resistor, providing the dual speed operation, is riveted to the base plate of the heater motor. I’d foolishly assumed the new units would be supplied complete with the resistor already attached – dream on!

The resistor is sold separately and, due to the lack of clearance, requires the base plate to be removed from the motor in order to fix it. The wires are then soldered to the resistor rather than via spade connectors. As a result, the loom has bullet connectors built in, approx 6″ from the end of the wires, to allow the motor to be separated from the loom if it needs to be removed for servicing.

Resistor provides 2-speed operation Loom wires are soldered in place Fitting was tricky due to
the engine frame

However the looms didn’t come with the rather crucial two wires needed from the resistor to the motor terminals! The other issue came trying to re-fit the motor to the heater housing which had already been attached to the bulkhead. Removing it wouldn’t be an easy option as the cooling system had now been filled.

The reason the motor and fan cage couldn’t be fitted onto the housing was the base plate fouled on the engine frame. It was necessary to detach the fan cage from the motor by undoing the clamping grub screw. This allowed the cage to be fed up into the housing and then reconnected to the motor once the motor was clear of the engine frame.

The fan just had to be re-attached ever so slightly nearer the motor to cure the fouling problem found during the initial shakedown tests.

Alternator testing
The electrical component that I’d been putting off testing was the re-wired alternator. The modifications to the alternator were more far reaching than any of the other electrical work and so there was more scope for things to go wrong. Once all the other electrical issues had been resolved, I fitted the alternator belt and prepared to start the engine. Would it work or would it blow any of the other components?

Unfortunately I didn’t have a suitable ammeter to measure the theoretical maximum output of approx 60 Amps and so my testing was limited to measuring the voltage at the battery terminals with a multi-meter:

  • With the engine off, the terminal voltage should be approx 12.7v
  • When running at idle, the alternator should raise the terminal voltage to around 13.9v-14.3v
  • The terminal voltage should reach between 14.3-14.6v running at 2500 rpm

In theory if the alternator output drops from the last two levels then it points to the failure of one or more of the rectifying diodes. If it rises above 14.8v, then the 4TR voltage regulator unit is not limiting the maximum voltage and needs to be replaced to avoid overcharging the battery. However I also have to consider that any lack of output could also be due to the additional diodes introduced to self-energise the field winding.

It was a welcome anti-climax that the initial test appeared to be successful. Although I’ll need to do further checks to ensure it’s charging when the car is run for a longer period.

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


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