Restoration of Ford M8 armoured car U.S Ordnance number 7373

[sawbuck]

Correct yellow? That seems to be but a trifle amongst the grand scheme of things.

[Big D]

Hi Sawbuck,

Yes, I guess I have bigger things to worry about. Haha.

[willwagner]

BigD, you wouldn't happen to have a wiring diagram for the M8 would you? We have one here that the wiring is horribly deteriorated in and I am in need of some help tracing the circuits from front to the engine compartment.

[Big D]

Hi Willwagner,

I used the one out of the manual. I could email a bigger image to you if it will help.

[Big D]

Hi all,

In between odd jobs on the M8, over the last couple of weeks a friend and I have been working on the Hercules engines for my scout car and the M8. It was a good chance to look at the differences between the scout car and M8 clutches which might assist other rebuilders.

I’ve attached a picture of an M8 pressure plate on the left and a Scout Car pressure plate on the right. The M8 pressure plate assembly is 355mm in outer diameter and the scout car clutch pressure plate assembly is 370mm in outer diameter to match the bigger flywheel. Of interest is that the face plates within the two pressure plates are the same dimensions.

The other point of interest is the two clutch plates pictured in photo 2. The one on the left is for an M8 and the one on the right is from a Scout Car. The overall diameter of these clutch plates are the same. The spline configuration and sizing appears to be the same and in fact, I think the hubs are exactly the same. However, the splined sleeve is fitted in opposite ways on the hubs between the scout car clutch plate and the M8 clutch plate. Photos 3 and 4 show the Scout car pressure plate and clutch disc on the left and the M8 pressure plate (the one in primer paint) and clutch disc on the right, so you can see the differences.

This could be of interest if you are after new fibre facings for your M8 or scout car. I’ve seen some dealers advertising M8 fibre linings and some advertising Scout car linings and from what I can see, the fibre facings will interchange. In addition, a complete M8/M20 clutch disc should work on a scout car and vice versa, providing the splined sleeve is positioned in the right way in the hub when the fibre linings are fitted.

Not sure how widely all this was known but hopefully a bit of handy information for M8/M20 and scout car engine rebuilders.

We have halfway built a fuel tank for the M8. In the end, I went for alloy construction, based on the advice I got from my fuel tank guru. It is 800mm wide, 460 mm high and 200mm wide, giving a volume of about 73 litres, which will be plenty for the use this M8 will get. The alloy construction is strong. I have a new fuel sender (thanks Kenet) and matching fuel gauge (thanks Charles) coming to set it all up. I anticipate strapping the tank to the cross section steel at the front of the engine bay, but will post photos once I’ve done this.

I’ve been putting off making up the hydraulic bleed junction I had been talking about. Not sure why, but it just went into the too hard basket for a while. I’d seen someone else make up one of these and I thought it was a great idea for improved access to all bleed points. Anyway, I thrashed out version 1 over the last couple of days. It is a block of alloy, drilled for the three hydraulic lines. I tapped all the holes for 1/8” NPT fittings. On the input side, I have NPT fittings coming which are female threaded at the inputs for standard tube nuts. On the other side, I have fitted NPT female adaptors for the bleed nipples. Finding the right fittings was a big part of the battle and I figured NPT threads were the best way to go. A bit of thread sealant on all the threads should do the trick. As I say, I don’t have the female adaptors for the tube nuts here yet, but you should get an idea of how it will work. I will mount the block on a sticky paid for starters and providing it all works, I’ll glue it in place.

Can anyone suggest a modern equivalent for the spring clips for the .30 cal spare barrel? I have drilled out the old broken bolts but now need to replace the clips.

Other things I’ve been working on are fitting some WW2 stamped jerry can mounts to the rear of the vehicle, gluing some felt strips on the radiator, and overhauling the carburettor.

By the way, the Hardy/Spicer FK35GB83 universal joint is a perfect match for the smaller propeller shafts on this. I’ll post on the M8/M20 crossover list as well.

That’s all for this week.

[Big D]

Hi all,

Most of my time these last couple of weeks has been in tidying up odd jobs like rebuilding the carburettor and water pump. Both are ready to fit now but I will need to give the water pump a coat of the correct grey paint. I ran out so I’ve used some other grey paint in the meantime. There are some differences between the water pumps for the scout car and the M8 as you scout car guys can probably see.

I have also made a start on the gearbox rebuild. I had been putting off stripping it until I knew parts were on the way, but they should be here in a few weeks time. The gearbox seemed to come apart reasonably easily but as soon as I started stripping it I noticed that there were a couple of very small needle rollers in the bottom of the case. I figured one of the shafts was going to have some problems but it appears now that I have everything out, these needle rollers are not from this gearbox. Phew!

The countershaft assembly looks like it will clean up nicely. There is a little bit of pitting on the gears here and there, but overall, not bad. I will replace the bearings at either end.

The mainshaft has some problems. As you can see, one of the synchro rings is broken and there is a fair bit of wear on both sets of rings. The synchro face area on third gear is also badly worn so the gear needs replacing. As I say, I have new parts coming to so while I’m waiting on those, I’ll be cleaning up the housing and making up some gaskets ready for re-assembly. I'll also fit new mainshaft bearings.

I finished off the bleeder block for the hydraulics in the engine bay. Let’s see if it leaks when I get the fluid in there!

That is all….

[Dawgman]

those gears look beautiful overall. Im doing a complete teardown and rebuild on my M3a1 Scout Car transmission right now also and am cleaning and painting my case right now also, and waiting on bearings. Nice job Darryl!

[Big D]

Hi Dawgman,

Thanks for the reply. I never thanked you for the information on the Scout Car clutch release bearing, so thanks!

Yes, it doesn't look too bad so far. I will disassemble the mainshaft today. Hopefully there are no more surprises in there.

I didn't strip my scoutcar gearbox. It all looked good and seemed to function okay, at least from what I could see. I guess time will tell. The engine is done now so we will fit it soon.

All the best with your gearbox rebuild. Some photos would be great....just in case...

[Dawgman]

You're welcome Darryl!
I was thinking of starting a White Scout Car transmission rebuild thread. I've discovered some useful tips and techniques not discussed in the military TMs in the course of tearing down and reassembling mine.

[Big D]

Hi Dawgman,

Great idea. I have a spare gearbox that I should rebuild. I’d be keen to see your thread and photos and am sure others would be.

[Big D]

Hi all,

I don’t have a lot to report this week as I’m still waiting on gearbox parts, so progress on that has ground to a halt. I’ve attached a few more pictures of the components now that I have everything stripped. You can see the damage on third gear and to the synchro hub for 1st and 2nd gears.

As Willy pointed out to me, cleaning out the oil galleries in the front of the gearbox housing are very important. This is the feed for the front bearings from the oil pump. My housing had a broken plug in the front and at first glance it looked like a Welch plug to me, but it is a NT 1/8” brass plug which I had to remove with an extractor. New bearings and the replacement third gear and synchro rings should hopefully not be far away.

I managed to get hold of a set of the elusive engine bay panels. Many thanks to R for coming up with them. I'm told these are quite important for the cooling on these engines. I’ve cleaned a couple of the panels up already and painted them. The metalwork on the two bigger panels is quite thin in places so I didn’t blast them and instead have been removing the paint using paint stripping discs and a wire wheel. I’ll do some patching of the holes and then get them painted. These panels are a great score.

That's it for this week.

[Dawgman]

I might be wrong but I do believe there are less restorable M8 projects wth more NOS spare parts available, and more restorable M3a1 Scout Car projects with less NOS spare parts available!! It sure seems that way in my parts searching.
Good work Darryl! I hope my project is half as nice as yours!

[Big D]

Hi Matt,

Yes, I think you could be right on that assessment.

Not a lot to report this week as I’ve been busy getting the rebuilt Hercules engine back into the scout car, which has taken up a bit of my time. It is looking good though.

As far as the M8 goes, here are a few photos of the lower engine panels temporarily fitted into place so you can see how they are arranged. I think I will leave the small panel under the fuel tank in there prior to the fitting of the engine. It is not the easiest of things to fit into place. The other panels can go in once the engine is fitted and everything is looking good.

With the help of a friend, we’ve started assembling the engine for the M8. The machining has been done on the head and bores have been taken out to 0.060” oversize. Don’t you just love cleaning all the cosmoline off those NOS parts! I’ve fitted the plumbing to the new oil pump so that it is ready to fit.

I was going to remove the crankshaft pulley wheel from one of the old crankshafts I had and reuse that, but it is a little rough and the locking nut is quite badly rusted. I figure it will take some time to remove that so I will search out a NOS pulley wheel instead. If anyone has a spare one, I’d be interested.

For the information of the Scout Car engine rebuilders, I’ve attached a photo showing the difference in diameters of the M8/M20 pulley wheel and the Scout Car pulley wheel; 6 ½” on the M8/M20 versus 7” for the Scout Car.

The new ring gear for the flywheel has arrived, as has the third gear and synchro hub for the gearbox. I’m just waiting on the synchro rings now to be able to reassemble the gearbox.

The other protectoscope box I was looking for has also arrived.

Does anyone have any of these adjuster screws for the timing covers for the JXD engines?

That is all for this week.

[sawbuck]

Wow, nice.

I suggest you test fit the new blocking rings to make sure they do not hang up on the synchros.
Crisp edges on new parts can cause a no-shift condition which would require the gearbox to be torn apart again.

[armoured_smiler]

Hi,

Just a question about the Scout car's Hercules JXD front 'cross member'. Mine is exactly like yours, in the respect of the 'cut out' is facing the engine, but on my friends Scout car it is the other way round, which seems to give more gap between the pulley wheel and cross member, because I have noticed on mine the back of the pully it has 'rubbed' on the cross member. Is it possible to get this the wrong way round? or is it slightly angled at the ends IE not 90degs?

Regards
Paul