How To: Restoration of Ford M8 armoured car US Ordnance number 7373

[Big D]

Hi all,

I am at the stage where I am fitting and wiring the BC606 interphone boxes and the wiring to the FT237 radio tray and I’m hoping to get some advice from the M8 gurus out there.

I have the TM 11-2702 manual for installation of the radio and interphone equipment. I also have all the other drawings and plans for the wiring of the interphone and radios, as per the photos.

What isn’t clear to me is how the BC606s for the commander and loader are connected.

The plans would suggest that the BC606s for the commander and loader each terminate at the terminal boxes in the sponsons, which I have fitted. It is not clear though how those two terminal boxes are connected. The BC606 for the commander is not the problem, as it has a direct connection to the FT237 through the terminal box in the sponson on that side. How does the BC606 for the loader connect to the commander's side though?

I’ve seen many photos of M8s (like the photo attached) that have the BC606 for the commander and loader connected by way of CO213 cable that is strung along the back wall of the interior of the hull. There is no indication of that method of connecting them in the manuals that I have found. I can see the ease in doing it that way, but is it correct?

I know there is conduit that runs along the side of the hull for each terminal box through into the engine bay. I figured this conduit just carried the 12 volt supply from the engine bay to each of the terminal boxes, for the power supply to radios on each sponson. Does that conduit also carry the CO213 cordage that connects these BC606s?

I don’t have the original conduit that goes through the channel from the engine bay along the side of the engine hull to the terminal boxes (as pictured). I also don’t have the conduit/pipe that runs behind the hull interior back wall in front of the fuel tank, so I am running a little blind on both fronts.

If you have any ideas, I’d be keen to hear them please.

[Big D]

Hi all,

I have now learnt (thanks to Willy) that the conduit that runs around the hull actually carries the 12 volt power supply for the terminal box on each sponson, as well as the CO213 cordage that links the BC606's for the commander and the loader. The conduit terminates at the terminal boxes and then there is a short length of cordage to each BC606. This fits with what I was seeing in the plans.

What I was confused about were photos of some restored M8’s that had the cordage on the firewall inside the hull connecting the commander’s and loaders BC606’s. I understand now that this is a post-war change. I’m going the wartime route with the conduit around the hull, providing I can get my hands on enough of the conduit!

I’ve now connected up the four BC606’s and the FT237 radio tray using the CO213 cordage. Preparing the cordage was a bit of a tedious job. Seperating the shield on the outside is time-consuming as it is very tightly wound around the internal wires.

I wired in the cordage for the driver and co-driver BC606’s in situ, only because I wanted to be sure of the lengths of the cable required. I wired the BC606’s for the commander and loader out of the vehicle and that was a darned sight easier. I’d have to say, that despite all the drawings and plans, without knowing exactly how it was all laid out, I still needed to do lots of research and have a good think about the layout and how it was connected both before and during the installation.

I was (and still am) a bit confused by the layout of the BC606’s. The plans show that the BC606’s for the driver, co-driver and commander should be positioned with the INT/RADIO switch and Volume Control side of the unit down. I setup the BC606’s for the driver and co-driver in this way as per the drawings.

I placed the loader’s BC606 as per the drawings with the INT/RADIO switch and Volume Control up. As I say, the drawings say that the Commander’s BC606 should be positioned with the INT/RADIO switch and Volume Control side down though, which didn’t make much sense to me.

What was the logic to how these BC606’s were fitted? I have seen numerous variations in the setups in restored M8’s, and a number of pictures of M8’s during wartime also showed variations. Why not keep them all in the same layout with the INT/RADIO switch and Volume Control upwards where the crewman can see it and change it if required?

In the end, I positioned the Commander’s unit with the INT/RADIO switch and Volume Control up, as per the Loader’s unit. I guess someone will correct me if it is wrong.

Along with the radio stuff, I’ve been trying to progress the gun. We haven’t been able to remove the two screws holding the recoil system in place. These screws have an allen type head on them but they were pretty knackered and corroded. I had been soaking the screws with penetrating oil for several months but the heads weren’t good enough to get a decent bite on them with the allen screw bit. We tried welding a bolt onto one screw but even then we couldn’t get the thing to budge. As a result, I will be taking it into a metal specialist next week to get the screws removed by spark erosion.

I got the boys in the engineering shop to profile cut a tool for removing the big nut on the barrel. This will allow me to remove the sleigh. Again, this nut is stuck and I’m better off having a tool that fits it properly before trying to lever it much more. l will give this tool a try next week and see if that will shift the nut.

[Big D]

More photos.

[Big D]

Hi all,

Here are a few more progress photos from the last couple of days.

All the radio wiring and conduit is in now, some albeit temporarily. I didn't have any pictures of this cabling before I started so these photos might be handy for anyone else doing this sort of restoration.

I haven’t connected the cordage to the BC606’s for the commander and loader yet. Once I have the radios and a battery in, I will check that the system is working with the BC606’s for the driver and co-driver before connecting the other two BC606’s. I don’t see any point in complicating things until I know I have wired it right.

The mounting of the conduit and piping holding the CO213 cordage is not finalised yet as you can see by the cable ties. You probably get the idea though. I could use some of the correct conduit clamps if anyone has any. My homemade ones just aren’t quite the right shape. I am still finalising the layout and there is a possibility I will have to move the cabling/conduit in the hull to get the firewall in, as that is a tight fit, and not something I am looking forward to fitting. I still have some routing of the wiring to tidy up but I think it is pretty close to how I want it.

The steering box and clutch and brake pedal assembly are next so that I can sort out the hydraulics and instrument panel wiring. I managed to make one pushrod that I needed for the master cylinders and I have the other one coming (thanks John).

[Big D]

More photos.

[James P]

And that my friend big D is one hell of a great job you are doing, I see you got the gun off. When is the big green box getting mounted on axles and tires ?

[Big D]

Hi James P,

Thanks for that. I have the front springs ready to bolt to the hull but I am awaiting the availability of a crane in the workshop to position the hull a bit better so that I can mount the springs and axles. We didn't really have the workshop set up properly when the hull was dropped off after painting so we'll organise this first.

The front axle just needs the hubs reassembled and the brake lines on it done before it can be bolted to the springs. The intermediate and rear axles still need some work before I can fit them.

So, timewise.....perhaps the next couple of months? Fingers crossed.