Jan 162014

There’s been a dramatic drop off in progress with the restoration in the last month or so. Partly due to the horrible winter weather, resulting in an apathy to venture out into a cold, dark garage!

In the meantime, attention has turned to sorting out bits and pieces that could be worked on indoors, although it gives an excuse for the gratuitous inclusion of some photos of the main reason for the lack of headway … a diving trip in warmer climes!

Progress is delayed due to a spot of diving …. with some immature 6m Whale Sharks

Back to the plot …..

Several years ago I’d come across an owner’s restoration of a ’63 OTS where they had redesigned the looms to their own specification, incorporating relays for the headlight circuits. The addition of relays made good sense, as they remove the main current bearing wires from behind the dash area, but I wasn’t convinced about having bespoke wiring looms made.

Deviating too far from the original wiring looms would mean that, if I subsequently encountered electrical problems, I’d be on my own as it would be hard seeking accurate advice from fellow owners. There was also the fear of overlooking a critical wire when the looms were made up or getting the length of one of the wires slightly wrong. It would be an expensive mistake to fix!

So the idea of adding relays was shelved and a new set of standard looms purchased. Fortunately this proved to be the right course of action. At the time, I hadn’t spotted the wiring diagrams I was using weren’t correct for my car. They didn’t have the changes in circuitry covering the introduction of the ballast resistor into the ignition circuit.

Rather timely, as I was starting to look at the lighting and bonnet electrics, an excellent write up of a headlamp relay modification was covered on the E-Type forum. The installation is very discreet with the relays being mounted out of sight behind the LHS ‘sugar scoop’. The only visible sign of the modification is the main power feed, taken from the alternator B+ terminal.

The downside of tucking the modifications within the bonnet is that it will be much trickier to maintain if something fails. The headlight bowls and possibly the indicators would need to be removed to gain access.

I had some spare repro 6RA relays so all I needed to purchase were some suitable coloured & rated wires and two in-line fuses. I also decided to install Halogen headlights at the same time.

The circuit diagram shows the planned wiring modifications, with the additional components labelled in red.

There are two spare terminals in the 8-pin bonnet plug, which were originally for the bonnet mounted horns found in the earlier cars and, I believe, the provision for optional extra spot/driving lights.

One of these spare terminals was used for the single high load wire running from the alternator B+ terminal to the 10-way connector in the bonnet. (It’s much easier to take a supply from the B+ post rather than travelling all the way back to the battery.)

I managed to feed the wire into the PVC sleeving to the bonnet plug so the only visible sign of the installation in the engine bay is a single sheathed wire running from the alternator to the bottom left of the picture frame, which has been cable tied to the existing loom.

From the bonnet connector, this feed splits in two to provide the 12v supplies to the dipped and the main beam relays. The relays have a double spaded terminal for the switched output, so the wires to the left and right hand lamps were connected directly to the relay.

Wire and fuse ratings
The Halogen dual filament bulbs are rated as 55W/65W at 12v so the dipped and main beams for each bulb will draw around 5.5 amps and 6.5 amps respectively (assuming a charging battery voltage of 14.3V).

Normally only one set of the filaments are on at any one time. However the worst case is when the main beam is ‘flashed’ while the dipped beams are on. Even though this should only be for short periods of time, I thought it prudent to assume the maximum current required for both headlamps would be 24 amps (2 dipped @ 5.5A each and 2 main beam @ 6.5A each).

Therefore 44/0.30 cable, rated at 25 amps, has been used for the supply from the alternator rather than the 28/0.30 cable suggested in the forum write up. Inline fuses have been used for the connections to the two relays. Their wiring is rated at 30 amps which is more than enough, although they have both been fitted with 15 amp fuses as the expected loads are 11 amps dipped and 13 amps main beam.

Using two fuses should ensure that a blown fuse won’t result in the complete loss of lighting!

The original wiring for the dipped beam (Blue/Red) and main beam (Blue/White) will now just be used to switch the relays. The coil resistance for the 6RA relays was measured at approximately 83 ohms so the switching wires will now only need to carry around 0.17 amps. Therefore the dash mounted fuses 1 & 2 have also been replaced, by 0.25 amp fuses.

As the whole bonnet area had been coated in copious amounts of Waxoyl, I also fitted some PVC sheathing to the bonnet loom in an attempt to keep it clean. I just need to tidy up the cabling when the headlamps are fitted.

Apr 122013

The separate wiring loom for the starter solenoid relay was sent off to Autosparks so they could have a look and use it as a pattern to make up a new loom.

In the meantime, I’d posted my wiring dilemma on the E-Type forum to see if others could shed light on the relay wiring. A fellow S2 owner kindly pointed out that there was a change to this area of the wiring during the S2 production run. As it happens, at exactly the same time my car was passing through the factory. I guess that it hadn’t been reflected in the service manuals because the modification had been made mid-production run.

Around the end of ’69, a ballast resistor was introduced into the ignition circuit with the aim of improving cold starting. The original 3 ohm coil was replaced by a ballast resistor and coil wired in series, both being around 1.5 ohms. When the ignition switch is turned to start the engine, the starter relay activates, delivering power to the starter solenoid but also bypassing the ballast resistor.

Therefore when starting, the full 12 volts is applied to the coil. The spark energy is increased over the original setup as the current flowing into the coil is greater due to the lower coil resistance.

Once running, the ballast resistor is introduced back into the circuit. As the coil and ballast resistor have a similar impedance of around 1.5 ohms, the voltage drop across each is roughly the same. Therefore a voltage of 6v is applied to the coil during normal running.

I found the wiring diagram above on one of the American Jaguar sites which shows the wiring connections for ballasted cars. Autosparks also confirmed that they stock this ‘ballast resistor’ loom. Although I think I’ll get the car running before I cut and tape the unused wires in the main loom!

It was a good opportunity to get Autosparks to make up the additional wiring, using the correct colour coding, that I needed for the few upgrades I’d planned – the mechanical brake light switch to supplement the hydraulic switch and the boot light.

There was also a number of wires that I believe are missing from the sundries wiring pack, such as earthing wires for the rear light clusters and a beefier jumper wire between the two brown fuses. Touch wood, I’ve now got everything to complete the wiring.

Alas, it was again a case of one step forward and two back. Very early on in the work on the bodyshell, the LH outer pedal side panel had been replaced where the main loom comes out behind the voltage regulator bracket. The panel was from one of the main suppliers of panels so I foolishly assumed it would be spot on.

It was only once I came to fit the voltage regulator bracket that I found out that its mounting holes had been punched in the wrong place. They were about 5-6mm too close to the sill closing panel so that the bracket doesn’t fit. The bracket did change for the S2 cars so it might be that the panel also changed and I was supplied the wrong part.

Either way – not happy! I should have checked it well before it had reached the paint shop. It’s not the end of the world but it will always niggle me as I’ll know it’s not correct on the car. The annoying thing was I’d spent ages sourcing and refurbishing a replacement bracket, as the studs on the original had all sheared trying to remove it.

The first replacement was purchased from SNG but the fitting was incorrect, using bolts rather than attached studs. Some time later, I managed to get a rather tatty one on eBay which was covered in a mixture of black and green paint. It took several applications of Nitromors and wire brushing before it was good enough to be re-plated.

The problem I find with zinc plating is it’s too blingy (although I’m sure the brightness would dull slightly once exposed to the elements). I decided to experiment and sprayed it with a two-pack clear satin lacquer. The results were even better than I had hoped/expected. The satin finish obviously tones down the brightness but it also has a softer, smoother to the touch feel and a more uniform metallic finish.

After all that effort I didn’t really want to start butchering a perfectly good original part to fit. instead I planned to trim the original bracket to fit and then repair the welded studs but SNG Barratt now supply the brackets with the correct studs relatively cheaply. So I’ll adapt one of their repro parts rather than an original part.

I think I’ll also spray most of the plated parts in the engine bay with the clear satin lacquer. Hopefully it will also provide a more durable finish.

Jan 152013

Unfortunately the number and quality of the photos taken of the routing of the wiring looms during the dismantling was woefully inadequate! The three photos below were the only ones of any use but at least they gave a starting point for the main and dash looms.

The main, dash and alternator looms route behind the glovebox. The dash loom joing the LHS body harness in this corner The fuse boxes and wiring looms behind the centre console The dash loom behind the steering column mount

Dash Loom
The dash harness was first to be fitted and it’s fairly obvious how it is routed as it is just held in place by the protruding tabs along the dash length. The tabs were covered with heatshrink to avoid chafing. Its lateral positioning was determine by referring back to the dismantling photos and the group of mainly green and purple wires needs to be directly below the right hand fuse boxes.

Main Engine Loom
The engine and front lighting loom was next to be added. The length running in the cabin also runs behind the same protruding tabs. The loom then passes through into the engine compartment via a hole in the left hand footwell and along the upper tube of the left sub-frame. The alternator spur is fixed to the sub-frame with a P-clip. The remainder of the loom passes down, across and then up the picture frame and finally back along the upper tube of the right sub-frame. Two more P clips, on the bottom bolt of each of the upper front wishbone brackets, are used to secure the loom to the picture frame.

Alternator Loom
The alternator loom follows a similar route as the main engine loom using the same hole in the footwell. Obviously only going as far as the alternator.

Fan Looms
The fitting of the fan looms will have to wait until the fan relays and fans have been installed.

Re-wiring starts with the dash loom

Left & Right Hand Body Looms
The routes of the two body looms are a mirror image. They start just below the windscreen pillar where they are connected to the dash looms. From here they drop down and travel forward running behind a protruding tab which can be bent back to secure it in place. They then run within a indented channel on the inner sill until they reach the rear bulkhead.

They pass up the bulkhead/wheel arch join, entering the boot space via holes in the vertical section of the rear bulkhead. Inside the boot space, they run directly upwards and then rearwards behind more tabs before passing into the wheel arches via holes just behind the bootlid hinges.

EDIS Megajolt Looms
As I had opted to install EDIS Megajolt electronic ignition system this will need to be installed before the other dash components are put in but I’ll cover this installation in another entry.

A problem solved ….
One issue has now been resolved. During the labelling of the looms I found that they were missing the green & brown wire for the reverse light switch. There’s a sundries wiring pack that is needed in addition to the six main looms and it contains the separate wires such as the reverse wire, dash illumination and a few switches/gauges wires.

Feb 212012

The intention had always been to replace the existing wiring loom, which had had its fair share of modifications in the past. Much of the braided covering had either been caked in oil over the years or had disintegrated. As it was to be replaced and to speed up its removal, I had cut the loom where it passes through the bulkhead and removed it in two sections.

Fortunately, at the time of removal, I wasn’t aware that the loom was in fact made up of a number of looms. So the two sections were boxed and not separated into the individual looms. I was thankful of that when I came to deciphering the wiring diagram against the new looms, as I was able to refer back to a complete loom.

I was fairly confident that I wouldn’t have too many problems doing the re-wiring (pride before a fall?). Just in case, I purchased a copy of a wiring diagram produced by Coventry Auto Components which was to supplement the Jaguar service manual diagram. You can never have too much information ….. unless it’s conflicting or incorrect!

Somehow the old loom had turned itself into a right old bird’s nest while in storage. It took quite a while to untangle it so that it could be laid out, mimicking how it is routed within the car. Armed with a multi-meter and the wiring diagrams, I set about the simple task of labelling the new looms …

… four days later the finishing line was in sight. I had printed a large copy of the wiring diagram which was used to track the progress. Wires that had been identified were labelled at both ends indicating what they should be connect to and then highlighted on the diagram as ‘accounted for’.

The wiring convention used by Jaguar employs colour codes to signify the type or purpose of the wire, eg green for a regulated, fused source. Therefore a loom would often have a number of wires of the same colour. Once a wire disappeared beneath the loom’s braided sleeving, it wasn’t always obvious which of the similarly colour wires reappearing was it’s other end! So a multi-meter, set in continuity mode, was extremely handy and took out the guess work.

Other issues that, for now, remain unresolved are i) a missing green & brown wire for the reverse light switch and ii) a spare purple & white wire at the centre of the dash. The E-Type forum is very helpful in cases like this as there’s a wealth of knowledge available from the forum members. I was not alone with both the missing and extra wires as one member had decided to use the spare purple & white wire for the reverse light switch. Perhaps I’ll need to do the same.