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

[Big D]

More photos.

[Big D]

Hi all,

The rear axle is now complete with hub, internal axles and drums and is ready to roll under the hull. I do need a breather for the axle so will have to see if I can find one of those.

The intermediate axle is awaiting the brake Tee connections which are on the way (thanks Mathijs). Apart from that it is also ready to roll under the hull.

I’ve now completed the hydraulic plumbing for the brakes, throttle and most of the clutch. The clutch is complete up to the engine bay area and I’ll finalise that once I get the engine and gearbox in. So far I’ve worked my way through about 45 metres (nearly 50 yards) of steel tube for the brakes, throttle, clutch and fuel lines. I’ll still need another couple of metres of ¼” tube to finish the fuel lines.

I was having a few issues finding a suitable connector for the 3/8” tubing to go to the throttle slave cylinder. The parts manual lists the fitting as: 11/16-20NF-2 x 5/8-18NPT which I’d never seen before. I thought I might have been stuck finding that but it sounds like I have located one and it is hopefully on the way. I also have the correct adaptors for the hydrovac ordered and on the way.

I fabricated a couple of mounts for the hydrovac. This allowed me to get that in place and finalise the lengths of all the remaining brake lines. I fabricated a couple of small brackets for the flexible hose connections for the front and rear axles. Both of these brackets were missing off the hull. Hopefully where I routed the front line won't interfere with the protective cover that goes over the transfer case.

On the subject of hydrovacs, I have only just realised my hydrovac is a single input and single output unit. I’m not sure how I formed the impression that it had two inputs and two outputs and what I thought was an input port on one side was actually a plug! The hydrovac does appear to be a second series Bendix but looks like it is for one of the models of halftrack.

As a result, I won’t actually need the second (¼”) line I made up to go from the master cylinder to the hydrovac. That was waste of a couple of hours of my life making that. Haha. This actually simplifies things a lot for me though. What I’ve done is to adjust the plumbing a little for the lines to the axles. I have put an extra Tee connection on the hydrovac output so that all axles are connected to that one output. The 5/16” line running from the master cylinder is now to routed to the input on the hydrovac. My plan is to temporarily connect the 5/16” line direct to the ¼” line going to the axles so I can bleed and test the brake system. That will at least tell me that aspect of it is working alright before I get the hydrovac completed and connected.

I may do some painting with some of the paint stencils next week before I get the hull up on its wheels. The hull is at a nice height to work with as it is.

I am still looking for a nut for the steering gear sector shaft if anyone can help. This is 1 1/8-16NF-3. The wheel nuts are 1 1/8-16NF-2 and the thread is very close, but not quite right. What are the differences between NF-2 and NF-3?

That is all for this week.

[Big D]

More photos.

[Big D]

Hi all,

I have the M8 on its axles now. Once I completed the final touches on the rear and intermediate axles, I positioned them behind the hull and got one of the guys in the engineering workshop to bring the crane truck through. We opted to lift the rear of the hull first and get the rear and intermediate axles in place first, before lifting the front of the hull off its blocks and putting the front wheels on. It all went pretty smoothly but it was still about 2 hours work by the time I dealt with positioning the axles and fitting the torque rods to hold them in place. Thanks to Willy and Reg, I found that I could use two of the tie rod ends for the adjustable torque rods that were already on the rear axle. There was enough movement everywhere to allow me to fit the adjustable rods to those ends and secure the other end on its pin.

I feel like I’ve reached another milestone with the restoration in getting it to this stage, and it is a good feeling to see it on wheels. I still have some work to do though in setting up the torque rods. One of the fixed torque rods I had (not an original) seems to have a slightly bigger diameter pin on the ends and it won't seat properly in the hole on the trunnion or in the axle, so I think I will need to find an original. I also ran out of time to tidy up the threads on the torque rod mounting pins before the truck arrived, so I still need to find a 1 1/4-12 die nut and tidy the threads up.

Out of interest, what type and capacity of jack do the M8 and M20 owners use to lift an axle and remove a wheel?

I need to get some more of the 7/16” axle stud adaptors as shown in the photo. These align the internal axle in the hub and are described as adaptors in the manual. I would have called them collets, but can anyone point me to a supplier for these? I see they are on EBay as part of modern commercial wheel stud kits but I haven’t found them sold seperately yet.

Before putting the M8 on its axles, I took the opportunity to put some of the paint stencils on. It was a good height to work from without the wheels on. I used water based flat white paint and applied it with a roller. The markings came out really well and I’m very pleased with them. The only issue I had was trying to keep the star decal on the front straight as it went over the two raised strips of steel that go across the front of the hull. I found the best way to deal with that was to cut the decal in a couple of places to get it to go evenly over those steel strips, and then cover the cut with some bits of masking tape. I got the odd bit of paint bleeding through in those areas, but that scraped off nice and easy. These were good paint stencils and I had good support from Tony, the supplier.

That is all for this week.

[Big D]

More photos.

[John Mackie]

Hi Darryl, I would call the parts you require split cones, p presume they are the same as Ford trucks 1934==1953 , part # BB 1142 B. they are for 7/16 studs . Later , heavier axles use a similar but larger cone. I think I have seen them in Mac's catologue. If you ars stuck I may be able to source some in Wagga -Wagga, let me know.

[motto (RIP)]

Hi Darryl
In post 308 you asked if anybody knew the difference between -2 and -3 UN threads.
I only noticed the question today and had a look in a copy of Machinery's Handbook 1971
To put it simply the differences are to do with production and not maintenance. The numbers designate the class of thread in relation to manufacturing tolerances and should be compatible.
In relation to the axle flange collets, I can't guarantee that they are the same but the Studebaker US6 used those which probably means they were also used on the split diff GMC 6x6. Ross Prince may have them.

Dave

According to the GMC SNL, collets are used on the rear axle drive flanges. They are referred to as dowels and the Timken Detroit part number is TD-1246-X-232 General Motors part Number is GM-2124231

[Big D]

Hi John

Thanks for that. I will check them out and let you know if I get stuck.

[Big D]

Hi Dave

Thanks for that. That is interesting. The wheel nuts should theoretically fit then, with them being the same thread and pitch. Why they won’t, is a mystery!

I will keep searching....