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

[Mike K]

Measure the pistons with a micrometer maybe and the bores ?

[Andrew Rowe]

Hi Big D, can you post a pic of the ammeter you are after, may have something laying about, Cheers Andrew.

[Big D]

Hi Mike

Yes, I have sent the cylinders to the brake guy and he will do that. I don't trust my calipers.

Hi Andrew

It looks like this but it is a special Ammeter designed to work across a shunt. I can give you a part number if that helps.

[Big D]

Hi all,

Amongst other projects this week, I’ve done a bit more tinkering with different things on the M8.

I started up the engine again a week or so ago. It hasn’t run for nearly two months but started up almost immediately. I think the fuel pump on it is working very well. It was the first time I had the engine running since I fitted the exhaust system on it and sitting in the driver seat, I wasn’t sure it was running initially as the engine was very quiet. Here is another video: https://youtu.be/b6F-Bt4FQ_4

I had left the drive shafts off so I did some testing with the clutch and the gearbox. The clutch is definitely working well and while initially I was able to move through some of the gears, I found I was getting some binding and changing back from reverse into neutral was very tight.
I isolated the problem to the remote linkages, not the transmission. I had fabricated the longer of the two shafts that run between the transmission and the transmission control housing. Although I had the length of the long rod correct, the mounting hole spacing for the universal joint was out by a few mm. After drilling some new holes I put it all back together again and the transmission now shifts smoothly. I used some fairly sturdy pipe for this rather than solid rod. It seems sturdy enough so will see how that goes.

I ran the engine again and shifted through all the gears. It does shift very smoothly but the hydraulic clutch will take some getting used to. It just has a completely different feel to what I’m used to. Reverse gear does sound rumbly but I guess that is the cut of the gears?

Since that testing, I’ve fitted all the driveshafts ready for my road test. I was missing the little cap/cover that locks the universal joint bearing caps in place. After a bit of searching, I found some at a local scrap dealers. Interestingly, these are the same size as the covers that go in the hull above the sponsons for access to the tubing and wiring that runs through the channels on the sides of the vehicle. I have a couple of spares if anyone needs these.

I picked up a couple of M8 wheels a while back so I had the old run flat tyres removed and the wheels blasted and painted. I will swap these out with the two Scout Car/Half track wheels I currently have on the M8.

I spoke to my brake guy today. He has been working on the wheel cylinders I sent him. In his testing, he couldn’t fault one of the cylinders (!!) but does believe that the other one is leaking between the sleeve and the cylinder. He is going to press this sleeve out and fit a new one. Hopefully that will fix that one. He agreed with you guys in the US that the kits with the full cup and new pistons (the GMC type kits) are the way to go, so my plan going forward is to fit these new kits to each cylinder, bleed the system and monitor each wheel cylinder. If the cylinder develops a leak, I’ll send it back to the brake guy so he can redo the sleeve. It’s a lot of work, but I can’t see another way to progress things and it should all be for the best with the new pistons. That’s the plan, anyway….

A couple of other jobs I’ve been working on are a bridge weight sign and the turret ring indexing. Anthony from Axeholme Signs came to the party again and supplied me with a paint mask for the bridge weight sign and decals for the turret ring markings. The turret ring markings take some time to do but they do give a very nice result. Having the covers out of the vehicle is the way to do it. I'd say it would be a bit awkward doing it with them fitted around the turret.

That is all for this week…

[Big D]

More photos.

[Big D]

Hi all,

I’ve been tied up working on some other projects so it’s been a while since my last update.

My brake guy has hopefully worked out a solution for me. You might recall in his testing he couldn’t fault one of the wheel cylinders I sent him but believed the other one was leaking between the cylinder and the sleeve. He has changed tack a bit and now believes some different cups will do the job. He supplied me with 12 x English made cups and 12 x Spanish made cups. These are about 1.5mm shorter than the Japanese cups (still good quality he thinks) I was using with the new kits. He fitted these in the two cylinders and had been testing them on the bench at 100psi with no leaks. They are noticeably freer in the cylinder bores than the other cups. I have now replaced all the original pistons and cups with these new pistons, springs and full cups. I’ve made a note that I’ve fitted the English made cups on the driver’s side of the vehicle and the Spanish made ones on the other side. I bled the brakes using the pressure bleeder and I will monitor the wheel cylinders now for leaks. I have my fingers crossed!

After bleeding the brakes, I moved the M8 under its own power in the workshop for the first time today. That was quite a feeling but the elation quickly disappeared when I realised I have some tweaking to do and need to sort a number of things out.

The transfer case linkages are not right as I could only select low range today and got no movement in high range. I also couldn’t engage the front axle using the lever. Hopefully it is not an interlock problem in the transfer case but I’m more inclined to think I have the lengths of both fabricated control rods wrong so I will need to adjust those.

I’m also not sure about the gearshift lever. I mentioned this some time ago that I had two different shaped gearstick levers, and both appeared to be originals. I had fitted the one that seemed to be a better shape but it really limits where you can have your legs without clashing with the gearstick lever and the steering wheel. I am going to try the other one which has a lower profile when in the forward position (reverse/first gear).

I’d have to say to that having never driven one of these vehicles before, they appear best suited to someone smaller than me! I am 184cm and 93kg (6 ½” and 204 pounds) and it feels a real tight fit in that driver’s area. It seems there is little room between the left side of the steering wheel and the side of the hull and the right side of the steering wheel and the gearstick. It also feels like you’ve just about got your knees up around your ears when you have your feet on the pedals. I think the fact that my body is well over 50 years of age doesn’t help either! LOL. What are others’ experiences? A slightly smaller diameter steering wheel would help I feel.

Thanks to Brian for supplying me some working ammeters. I’m not quite sure what I changed with the shunt wiring but after some experimentation, I now have a working ammeter in the instrument panel.

That is all for today…

[Big D]

More photos.