At the time, I claimed that changing one wire led me down the path of completely removing the dash, but that's not quite right. I did indeed decide to change from an ammeter gauge to a voltmeter along with the alternator installation, but I had long wanted to emulate several other modified TD's I had seen on the web, which changed the stock setup to have four gauges along the top of the central instrument panel.
The real decision point came when I realized that the combination switch for the ignition key and the headlights was no longer working. I investigated, and found that after only 67 years, the body of the ignition switch had irrevocably perished. There are missing bits at the top that had held it together previously.
I believe it was made of Bakelite, one of the earliest plastics. It lasted 67 years. All I could do was thank it for its service, and decide what to do next. A reproduction replacement was $100, and I wanted that space for a gauge anyway. THAT is what led me down this rabbit hole... and that led me to many hours in this enviable position:
The state of Beck TD's current wiring was also a factor. Even in 1952, the TD's wiring scheme was antiquated. Only two fuses, and somehow those only protected the horn and wipers. All the important stuff was unfused. In addition, Beck had been rewired in its past, to a very high standard of work, but with only a couple of wire colors, and every wire was 12 gauge. That made it almost impossible to trace what was going on under the dash for repairs or improvements.
In addition, I've added halogen headlights and a pair of high-intensity driving lights, both of which pull much more current through the ignition switch than the MG engineers ever intended. The modern way is to pass all high-current loads through a relay. I designed a system and described it to Jake Roulstone, who played such a pivotal role in Part 45. He informed me that what I was doing is very common in the world of commercial trucks, so common that it has a name: "cab relay system."
Basically, my plan was to have a large (80 amp) relay attached to the battery, and the ignition key would turn that on. That would then feed a set of fused relays for the various functions that make a car run. Space is so tight in a TD, I split those functions into two connected boards. Here's the primary board. The bullet-shaped thing to the left is an 80-amp fuse, and it connects directly to the battery. Just after I bought it, Jake showed me a reset-able circuit breaker for only a dollar more. I guess if I ever blow that fuse, I'll buy the circuit breaker at that point. From the fuse, there's a big red terminal block to supply unswitched (always "on") power to those thing that need it, like the clock. The square thing is the 80-amp relay.
The other board has six relays with fuses built in, for the various high-current loads in the system. There's low beams, high beams, driving lights, horn, starter solenoid, and one labelled "spare" but will eventually be the fuel pump relay, probably.
The red terminal block on this board is switched power ("on" when the key is on), and the other two allow attachment of the input triggers to turn the relays on, and the outputs to the lights and other loads. In the car, they live "around the corner" from each other, with a heavy-gauge wire connecting the output of the 80-amp relay to the switched terminal block on the big board.
The other part of the puzzle was how to arrange the instrument panel. I even incurred the expense of a second, already-modified, instrument panel to use for experimentation. Here it is with a set of Bosch gauges installed as proof of concept:
Sadly, I quickly realized that the stock holes just wouldn't do, and there wasn't enough "meat" in the panel to move them. A very skilled welder could cut that part of the panel away, and weld in a blank field, but I'm not that guy. However, I do have a very large milling machine with a very precise digital readout. I used that with an electronic edge finder to map out the mounting holes and large gauge holes of the stock panel:
Once that was documented, I could create a few trial designs (this one is the one finally installed):
Having the precise measurements was helpful in another way, when I realized that the thin mahogany was not quite strong enough to mount those Bosch gauges in the center because the indicator lights created a weak spot. No problem, I just milled up a 1/8" thick aluminum stiffener, and whittled it freehand until it fit around all the obstructions.
Thankfully, I was able to wire all that up on the workbench. It looks chaotic, but it is much easier to trace than the old harness. Load wires are big, and "informational" wires are little.
All the functions that remain on the panel (dial lights, for instance, or signals that go from one place to another) are wired right on the panel. That contrasts with the old harness, which could have a 12-gauge wire taking ground for a light bulb all the way to the engine compartment. I also used a scheme using colored tape (also suggested by Jake R.) to tag certain wires so that I know what they do. I had come up with a custom scheme, but then Charlie Baldwin urged me to use the standard MG color codes. I decided to do so, even though it was more work. For example, this tape tag says the original wire color was green, with a red stripe. You just have to ignore the fact that the actual wire is white!
I installed the dash, and I'm happy with the way it turned out after final wiring. Everything works, and it looks nice, and echoes the shape of the original panel.
Let's take a closer look at this decidedly non-stock panel:
The new gauges do what they do. Sadly, Bosch didn't make a clock and I wanted one, so I had to find a close match from VDO. Looking down the centerline of the dash, the three indicators are high beams (blue), alternator charge (red) and low fuel (green). Right below that is the horn button. It didn't show in the photo, but it has a little horn icon that even lights up with the dash lights. Below that to left and right are buttons for the turn signals, and I'll talk more about that in a second.
On the bottom row, from left to right we find the ignition key (which has "twist to start" instead of the separate pull on a stock TD, or separate button on Beck previously), driving light switch (wired to only work with the high beam headlights), the aforementioned turn signal buttons, the low/high beam switch and the headlight switch. Because of the tight space behind the panel, that's all that would fit!
Jake R. also told me about the turn signal solution that the two switches control. It's unusual to have buttons instead of a lever for turn signals, but the great advantage is that pressing both simultaneously turns on hazard flashers, a feature that wasn't dreamed up until decades after Beck was made. They also self-cancel after one of three preset times, chosen by the length of button press. The center of these buttons are LEDs that flash along with the lights.
Here's a photo from the seller of the module that makes it all possible. I'm including it because when I got mine, they had changed the label and it no longer shows the connections. If I hadn't had this photo, I wouldn't have known how to wire it!
Well, this was a huge project, but a really successful one. I don't log my shop time, but this must have consumed 40-50 hours. I must say, I enjoyed every minute! This kind of project that combines creativity, craft and attention to detail really floats my boat. Just one more task... document it all for myself and for the next owner! I already have plenty of notes and charts, so it won't be too hard...
Continue on to Part 47...
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