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

[Big D]

Hi Doug

I was saying it more in jest. My steering wheel comes off nice and easy to.

[Potteque]

Hello Darryl,
About your brake issue... As you may know we are still under RE construction (facebook page: Barbaras Restoration, M.20), both rear axles are reassemble and my father and I've the same question !
How can the air leave when the wheel cylinders are vertical ? Most of the people said we need to bleed them... with a vacuum bleeder.
Begin next year we will start the all brake system... keep you for sure posted !
Br,
B.

[SURPDLR]

All,
For bleeding the brakes I have taken to using a pressure pot on the master cylinder AND pumping the pedal at the same time. I have even added a vacuum bleeder on the cylinders at that point, as needed. All 2 or 3 at the SAME time. It goes against everything I have ever been taught or told, BUT it works!
The M20 I did that with has brakes that LOCK up with a firm pedal. If you are not ready for it, it is easy to end up with injuries when stopping (The dreaded armor mouth). - That is a feature of the Type 3 hydrovac I think.

Speaking of Hydrovac's, are you sure your soft pedal problem is not in the hydrovac? You bled all 3 bleeders on it in the right order?

Good luck, you will win this eventually.

[Big D]

Hi Jeff,

Yes, sure did. See my update below.

[Big D]

Hi all,

The last few weeks have involved more time spent on the brakes. If I had a dollar for every hour I have spent on the brakes, I would have quite a pile of cash built up now. This is a bit of a long story but it does show the various things I have tried to get these brakes working. I’m not there yet but I’m sure there will be some out there that can benefit from my experiences so far below.

You will recall the problem I was having was that when applying the brakes, the pedal basically went to the floor. It had a spongey feel to it and it just didn’t seem to want to ‘pump up’ to give anything like a firm pedal. From what I could see it appeared to be due to air being trapped in the wheel cylinders since the change to the Raybestos type pistons and full cups, which was something I had seen others having problems with.

My retired mechanic friend Brian spent a fair bit of time with me helping with different ideas about how to solve the problem. We spent a day trying different things and came away completely convinced there was nothing else wrong with the brake system, aside from the wheel cylinders. When clamping off the rubber hoses going to each of the axles, a firm pedal is suddenly restored. Releasing the clamp on each axle produces a proportionate amount of ‘softness’ to the pedal.

We tried a number of tricks to get the air out of the wheel cylinders, including using a pressure bleeder, a vacuum pump, a combination of both pressure bleeder and vacuum pump, bleeding both wheel cylinders at the same time, a combination of pressure bleeder and someone working the brake pedal, all without success.

I read a lot about the problems others had found. I saw what they had tried and it seemed to be everything that I had already done. I even removed the check valve in the master cylinder as I’d read that with my type of Hydrovac with its own built in check valve, you didn’t need one in master cylinder as well. Not that I really expected any improvement, but that made no difference. It was suggested to me that the hydrovac might have been creating some sort of vacuum effect with the wheel cylinders, so I built a small line to bypass the hydrovac. Again, I wasn’t expecting it to be that based on my fault finding and I wasn’t surprised when that also had no effect. That darned air just didn’t seem to want to come out of the wheel cylinders.

I started some ‘blue sky thinking’ trying to come up with novel ideas on how to attack the problem, including:

• Reversing or driving the vehicle up a steep slope like a steep ramp, blocking the wheels and bleeding on the angle
• Driving one side of the vehicle up a ramp and then bleeding one side of the vehicle
• Installing the brake backing plates rotated 90 degrees, so that the wheel cylinders were positioned horizontally (why wasn’t the M8/M20 designed like that?)
• Removing the wheel cylinder caps and compressing the pistons just a little with welders finger type vise-grips while bleeding
• Bench bleeding the wheel cylinders prior to installing them on the backing plate (how?)

It occurred to me that Tee connections on the brake backing plate should have been designed with a bleed screw built into it. The Tee connection is the high point on the wheel and it made sense, but I had never heard of anyone trying this. The Tee connection is used on all wheels but when it is fitted to the rear and intermediate axles, there is a spare 7/16-20 port which would normally be plugged. When the Tees are used on the front axle the flexible hoses go into that 7/16-20 port and so the 7/16-24 port below is plugged.

I got my hands on some brake bleeder repair kits which have a straight 7/16-20 thread. I could get some with a 1/8 NPT but these did not fit well enough and I couldn’t source any with a 7/16-24 thread.

I fitted the 7/16-20 bleeders to the Tees on the intermediate and rear axles with some good thread sealant in the port that would normally take the flexible hose if the Tee was mounted on the front wheels. Although you are bleeding at the input to the wheel cylinders, I did get some air out when I bled the system again, but not enough to make any appreciable difference to the brake pedal.

I had read about reverse bleeding the system and after talking to a couple of other people, I figured that if I could get some fluid pressure fed into the wheel cylinders then I might be able to extract that trapped air out through the bleeders I had fitted to the Tee connections on the rear and intermediate axles.

I left the pressure bleeder cap fitted with a length of plastic tubing on the master cylinder. I ran this tubing to a jar thinking this would catch any overflow from the master cylinder that was pushed through the system by the reverse bleeding.

I started on the rear axle and clamped off the rubber brake pipe to the intermediate and front axles so as to isolate them. I connected a smaller piece of plastic tubing to the pressure bleeder and connected it to the wheel cylinder bleeder screw. I connected my bleeding jar to the bleeder nipple I had fitted to the Tee connection. I only used a couple of pounds pressure, but it was a messy job as the fluid tends to want to come out of the threads on the bleeder screw. It appeared to work though and was pushing fluid and a bit of air up to the Tee connection and out into my bleeding jar. I periodically checked the jar connected to the master cylinder but this didn’t show any signs of fluid coming through that far. It looked like the fluid and air went straight to the bleeder nipple on the Tee connection which was what I was after.

I did both rear and intermediate axles in this way. The bleeder screw I installed on the Tee connections really does make this possible. The front axle wasn’t so straight forward and with it not having a bleeder I fed the fluid through the bleeder screws on the wheel cylinders and cracked the line connections to the Tee while I bled. I wasn’t sure this was that successful.

After all this reverse bleeding, I tested the pedal and found some improvement. I still had a pedal that went to the floor but after about three pushes it started to firm up and it got to the point where I had a spongey pedal for about half of its travel before it felt nice and hard.
I decided to try another plan that I came up with and which I hadn’t heard of anyone else trying. As I said before, I’m not sure why these wheel cylinders were vertically mounted. It seems they would do the same job being horizontally mounted and be a darned sight easier to bleed Anyway, I guess the designers had their reasons…

I removed the wheels and hubs from the two rear wheels. I also removed the guards over the lines on the axle and unbolted the Y connection on the axle. I then unbolted the brake backing plate from the axle and punched all the studs out. With some careful jiggling you can actually rotate the backing plates a fair bit to get the wheel cylinders in a better position to bleed.

I rotated the backing plates on both sides to get the first wheel cylinder I was going to bleed into the 11 o’clock position. The flexible rubber hose to the axle Y connection allows this movement and with the bleeder on the outside, this then becomes the high point on the wheel cylinder.
I pumped up the pressure bleeder to about 5 pounds and released the bleeder screw on that cylinder. It was literally a ‘holy Crimp One Off’ moment as air spewed out into the jar like a bullet out of a gun. Once I’d done that cylinder I rotated the backing plate to get the other wheel cylinder into the 1 o’clock position. Again, heaps of air came out into the bleeding jar.

I repeated the process on the wheel on the other side of the axle and had exactly the same result. Air literally flew out of the bleeder into the bleeding jar. I never thought I would be so happy to see air in a brake system. It just goes to show how much air is trapped under those full cups when the wheel cylinders are in that vertical position.

Encouraged, I went and tried the brake pedal and I could feel an immediate difference. The pedal did not immediately go to the floor so I knew I was on the right track.

I repeated the process on the intermediate axle and again had good results with lots of air coming out of the wheel cylinders.

The front axle was even easier with having the flexible hoses and they allowed me to rotate the backing plates a fair distance around, almost to the 12 o’clock position. Again, lots of air came out of these cylinders.

After I finished bleeding them, I tested the brake pedal again. I now have some semblance of a brake pedal. It is a bit spongey on the first couple of applications but firms up after that. I still need to adjust the brake shoes after having the wheels apart and I believe this will make a difference to the feel of the pedal.

For the first time, I can hear the master cylinder operating as it should. However, when I apply the brakes I can hear a ‘whooshing’ sound in the line on the right side of the hull, where the joiners in the three lines are under the metal cover. I can’t see any reason why there would be noise at that point. Perhaps there is an airlock in the line there somewhere but that is what I am thinking. I am also finding the pedal is still 'following the foot' a bit still so that might suggest there is still air somewhere and contributing to the softish pedal so there is still more fine-tuning required. I will pressure bleed again using the bleeder block at the high point at the back and I’ll give that line a bit of a rattle/tap as I do it.

For anyone else making the change to these Raybestos piston setups I recommend you add in these bleeders. If the input lines to the axles are broken then you will need a way to get the air out before it gets to the wheel cylinders. You do not want the air going down into those cylinders and these bleeders on the Tees seem like the ideal way to do that. If you are careful in bleeding you should be able to get the air out of the bleeder before it gets pushed down into the cylinders.

I have been thinking about a way of adding bleeder screws to the Tees on the front axles and have attached a photo of what I have come up with. It simply involves adding a second Tee connection, fed by a fixed line from the lower one, with a bleeder screw in the end. I might use a bit of epoxy glue just to hold the second Tee to the first one. Someone else might have a better idea but this doesn’t involve any machining or making up of new parts.

As I say, someone may get some ideas for their setups from my experiences. If I was doing it all over again, I would fit the bleeders, carefully bleed at the bleeder screws on the Tee connections. Then rotate the backing plate to get the air cylinders as high as possible, and bleed them from there. That should allow them to full with fluid and get all the air out of them. Then I’d return the backing plate to the correct position and put the rest of the hub assembly together.

Anyway, that is quite enough for this post. Until next time…..

[Big D]

Hi all,

I have finally got some brakes on the M8. In my last update I mentioned that after rotating the brake backing plates and bleeding all wheel cylinders I still had a slightly soft pedal. I clamped off all the axles again and individually checked them. I found that when I released the front and intermediate axles, the pedal was still firm but when I released the rear axle, I had a spongey pedal. Bugger! This axle was the first one I did with my new method so maybe my technique was not that good.

I was initially a bit reluctant to remove everything from that axle again and so I pumped up the pressure bleeder and bled off the bleeders I had fitted into the Tee connections. I then bled off the wheel cylinders. The fluid was clear with no signs of air. It was bugging me and I wasn’t happy so I decided to strip the hubs again. I rotated the backing plates and bled again and sure enough I got more air out of two of the cylinders. Not a lot like before, but it was there. A test of the pedal showed that it was firm like the others. If anyone is thinking about bleeding their brakes in this way, I can tell you while the process looks a bit daunting when you think about it, it is only about two hours to do a complete axle including bleeding.

This process confirmed for me with the Raybestos modification to the wheel cylinders, bleeding off the wheel cylinders when they are in the standard position is a complete waste of time. It has also shown that bleeding off the bleeders I put in the Tee connections is only useful to prevent air going into the wheel cylinders. It won’t remove air from the cylinders themselves. That air will remain stuck under the cups until you put the wheel cylinder in a rotated position where air can come out from under the cup. I think if I had to do a complete brake set up again, I might even replace the solid brake lines on the axles with flexible lines. This would make the bleeding process even easier.

Anyway, I feel like I can move forward again now after the last few months of frustrations with the wheel cylinders. I still have a little tweaking to do though. I fired up the engine today and tested the brake pedal to see if the Hydrovac is working. There was no discernible drop in the pedal on start up so I will check the vacuum connections. Maybe I haven't got something quite right there.

Next up, I started preparing the rear floor and engine covers for fitting. I left some bullet holes in the engine covers. That may not be to everyone’s taste but I figure they are all part of the vehicle’s history and they will be a good talking point. I’ll fit the engine covers once the guys are back working next door and I can use the fork hoist.

The floor is made from sheet metal that I cut, folded and welded. I also bolted a bit of box section to it to strengthen it a bit. I made the rear section so that it slides under the intermediate section. It is a slightly awkward thing to fit but I figure that if I have to remove any floor section it is more likely to be the intermediate section.

The floor section seems to fit nicely but I should have made the rear holes slightly bigger in diameter as with a couple of coats of paint on them, the bolts are a bit of a snug fit when trying to line the holes up with the nuts I welded onto the back panel.

That’s it for this year. Merry Xmas and a happy New Year to you.

Cheers
Darryl

[Big D]

Hi all,

Happy New Year. Just a quick update to show the latest progress.

I have completed the floor now. Everything seemed to line up with the exception of one hole. Not sure what I did there but that is now corrected. I had considered fabricating small profiled strips to go across the joins in the floor like the original floor, but in the end didn’t think it was necessary. I guess these ridges were there to provide grip as well as strengthening the floor but I don’t see that as an issue with what this will be doing.

The grenade and flare boxes are now fitted. The inner part of the hull is certainly taking shape now.

I have fitted the front fenders. They certainly change the look of the vehicle. In keeping with the look of the rest of the vehicle, I just tidied these up rather than completely restoring them to ‘factory finish’. I guess the purists might prefer that everything was straight and dent free but I still want the vehicle to look like it has been used. It has been in a war…

Out of interest, how have other M8/M20 owners fitted their front fenders? Does the folded edge at the rear of the fender sit under the sponson edge or over it? The holes on mine do not line up at all well if I fit them with the folded edge sitting over the top of the sponson. The holes do line up a lot better but not perfect if I have them as per my photo. I have seen photos of them fitted both ways so was curious what everyone else’s was like.

Now that I have the tool lockers fitted, I am not happy about the placement of the latches on one of the repro lids. I will need to reposition the latch so I figured I would put some latches on that looked more like the originals. Does anyone have a source for a latch that looks correct, or have originals by chance?

That is all.

[Big D]

Hi all,

I fitted the turret and the engine covers yesterday. I hadn’t actually planned for the turret to go on just yet but I have a new project coming in and I need the space so I thought I would just get it done. It certainly creates another ‘wow’ moment seeing the turret go on.

The turret was all ready to fit so there wasn’t a lot of preparation required. I did have to fit the last turret support bearing into the hull. I had left that off until now to avoid smacking my head on it each time I got into the hull. One of the guys from Action Engineering next door came through with the truck and Hiab crane to give me a lift. These Hiab cranes are much better for fine movement adjustments than mucking around with a forkhoist.

The main problem we had was slinging the turret so that it lifted evenly. We decided to sling it around the three gun ring mounts along with a stabilising strap around the barrel. I mulled over stropping through the opening where the rear plate on the turret is fitted along with the barrel but we decided this way was going to make it more stable during lifting. As you’d expect, there is some weight in that gun at the front of the turret. After a little bit of mucking around with the lifting strops we got it up and lowered onto the hull. It sat there nicely and we were immediately able to rotate it on the three support bearings just with one finger pushing on the barrel. We tried rotating it right around but I must have the placement of the fire extinguisher bracket not quite right as the base of the seat towers comes into contact with the back of the extinguisher bracket. I will get that moved.

The movement of the turret on the bearings is quite good but there are a couple of points where the rotation isn’t as smooth, so I will look at that. I have the turret hold down rollers sitting in place now and I will need to set all of these up. Several look like they will need shimming so I’ll get all those fitted next week.

I have the quadrant covers ready to fit over the turret roller lock bearings. I have seen some period photos of the arrow marking the zero point that is painted on the inside of the turret. Can anyone give me some dimensions of this arrow and perhaps a close up photo?

I also fitted the engine covers. Thanks to Reg who warned me about being careful with fitting the cover over the carburettor so I monitored that closely. Sure enough, there was a bit of grinding required in that spot for it to properly clear the carburettor. Grinding is not the sort of thing you want to do over the fuel tank but I covered the engine bay with pieces of timber and then some leather blankets and that worked out fine.

The hinge mounting plate for the engine covers is one I made up. I had ‘test fitted’ the engine covers on the hull after that but it’s amazing what a few coats of paint does as the engine cover on the carburettor side is sitting a little high at the fuel tank end. I think I will have to lift that engine cover and tidy up the face of the hinge mounting plate where it meets the engine cover. Those covers are certainly unwieldy and not easy to lift unless you are actually above the engine cover….

I also did some work on the rear sand skirts. I had a mix up with these with the sandblaster/painter a year or so ago. The sand skirts were very rough with both having some wicked bends in them. I had only done a very rough straightening job on them and just wanted them sandblasted but he painted them anyway! As a result I’ve had to remove a lot of the paint and dolly out some of the bigger dents before applying some fibreglass. I may actually ‘revisit’ the front guards later on as now that they are on and I am looking at them all the time, I’m not sure I’m happy that they are straight enough.

I had to move the M8 yesterday as I had parked it where there is a leak in the roof of the workshop right above the M8, which was annoying me. I hadn’t started the engine for 5-6 weeks but it started up first time and ran nicely. I have also figured out that having the steering wheel easily removable is the way to go for being able to easily squeeze into and out of the driver’s seat. Once you are in there it is not too bad. It is getting the legs around the steering wheel that is the problem for me, especially climbing in and out.

That is all for this time…

[Tapper02]

Tremendous milestone Darryl! It looks great fitted together.

-Tom

[Big D]

Hi Tom,

Thanks for that. Yes, as you say another little milestone. It is certainly satisfying seeing it get to this point.

[armoured_smiler]

it's looking so good

[Big D]

Hello armored_smiler,

Yes, looking good now. It is quite a buzz seeing how it has progressed.

[Big D]

Hi all,

I have spent the last couple of days setting up the turret. When I initially got the turret on it didn’t seem to completely rotate well and felt like it was sticking or binding. I got the impression that maybe the turret was just a little off centre in sitting on the turret support rollers. I thought I might have had to give the turret a little sideways nudge but in the end, that wasn’t required.

I first made sure all the tyre pressures were correct and used a sprit level across the top of the turret to check that the turret was level. It was good so there was no need to adjust the support rollers.

I followed the instructions in the TM 9-1743 manual for setting up the turret roller blocks. I fitted all the turret roller blocks around the ring and tightened them all down. I only had to use a shim under two of the roller blocks. I think I could have probably got away without these but they helped with the installation of those blocks and the later adjustment of the vertical roller sorted everything out.

I loosened off the castellated nut on the eccentric spindle for the vertical roller and rotated the shaft with a screwdriver until I had 0.010 gap between the roller and the turret bearing surface. The manual says 0.005-0.010 but I just set everything up to 0.010 and it worked out fine.

I fitted the turret traverse. I used a grease oil slurry in it rather than just gear oil. I gave the turret a test run then and it traversed nicely. I noticed a couple of slightly tight spots and after checking around the base of the turret I can see where there has been some contact between the repaired turret skirt and the ring on the top of the hull. It looks like a bit of paint has come off so hopefully it is just the thickness of paint that is causing that.

I have noticed the turret traverse is smoother on the first speed of the traverse and it can be easily rotated with one hand on this speed. When switching to the second speed on the traverse, it certainly traverses faster but at times requires more effort. It is almost requires two hands to operate it like that. Is that normal or should it be just as easy as the first speed but at a faster rotation?

I was happy with the state of the turret so I decided to fit the roller block covers. I couldn’t find the required dome slot head screws in 5/16-18 so I have fitted some hex head screws for the moment until I find the correct screws.

These roller block covers are a neat fit. I’d have to say that once they are in there the turret looks real good and I’m very pleased with the result. The other 37mm ammo rack is now fitted and I just need to rejig the dummy rounds I have.

I fixed up the problem I had with the engine covers and the mounting plate. I have also made some handles up for the engine covers. I worked out that my engine crane can safely lift the engine covers so that is handy to know for future reference. I also had to move the fire extinguisher bracket by about 10mm. My placement of this wasn’t spot on and the seat tower was contacting it during its rotation.

That’s all for today.

[Big D]

Hi all,

I’ve been busy doing a few small tidying up jobs on the M8. My master ‘to do’ list is gradually getting smaller so I guess that is a good sign.

I had saved a trace of the star decal I used on the front of the hull and used the outline to paint the part circles on the inside of the front hatches. They came out pretty good.

A Zero arrow in the turret for the sighting quadrant was next. Thanks to Jonathan for the dimensions which I used to make a small paint mask.

I’ve done some more work on both sand skirts. I spent probably a day and a half dollying out the dents and creases in the second sand skirt. Even after that, I think I could have spent more time on it. The sand skirts were both pretty beaten up and when I got them they looked like a Sherman tank had driven over them, but I think what I have done so far will have to do. It still needs to look like it has been in a war. I used the last of the star paint masks I had to paint the US stars on the sides of the sand skirts and they look pretty good now. I will look to do something about the front guards at some point. I am not happy about those but they will do for the moment.

I knocked up a very rough compass mount which will do until I can find (and afford) the real thing.

I made up some exterior decals for the hull and tool locker covers. I am not convinced on the use of decals especially with some of the rougher steel surfaces and if (when) these come off I think I will make some paint masks instead.

I had a long pin .50 cal pintle arrive for the trolley on the gun ring and I’ve been busy cleaning that up. The pintle came with a trolley stuck to it, with the pin from the pintle completely seized in the trolley socket, so I had to spend some time trying to get that out.

I’ve also been doing a bit more work on the turret. I wasn’t happy with the movement of the turret and it seemed tight in places in its rotation. I removed the traverse gear and sure enough the problem appears to be the skirt on the turret binding with the ring on the hull. I had repaired a section of the skirt on this and it looks like it might have a few high spots on the inside which are rubbing on the paint on the outside of the raised ring on the hull. I’ll persevere with that.

That’s all for this week.

[Big D]

Hi all,

I seem to have been really busy lately but in between time I have completed a few things on the M8. I picked up a couple of NOS BG-96 radio covers, one of which I’ll use in the SCR-508 radio in the M8. They are very nice and give the radio setup a nice clean look.

I got my hands on an original Kidde fire extinguisher so I stripped that and restored it including putting a new decal on it. It does look nice now. I also picked up a couple of headlight locking pins which I have cleaned up and fitted, along with the remaining recoil oil can holder which I’ve also repainted and fitted into the crew area.

I wasn’t happy about how the handbrake was working so I have pulled that out and reassembled it.

I’ve taken the M8 for another couple of road tests. It is not road legal, and I have to be careful where I drive it around here, so I didn’t get it into top gear but I drove it around the block a couple of times and it did go well. My impressions from being a first time M8 driver are that first gear is quite low and once you get into second gear it feels like it really wants to accelerate. It seems to handle well enough and you don’t notice the size or weight of it. Here are a couple of videos:

https://www.youtube.com/watch?v=Q3skUfbKPKI

https://www.youtube.com/watch?v=S0wuoETkehk

I found I was having a problem with the return of the throttle. When I took my foot off the gas pedal, the throttle would hang for a bit instead of returning quickly. The return spring I fitted on the arm on the slave cylinder was one I picked up and was a guess on strength, so I figured I needed to find another that would return that throttle arm a whole lot quicker. In the meantime I saw a post on the M8/M20 page on Facebook which talked about a return spring on the arm on the throttle master cylinder at the foot-pedal. I was not aware of this and it seems like not everyone has it fitted. I’m told it was a later modification but I am not sure about that. I fabbed up a tab and found a spring of the right size and fitted it. I have yet to test it but I think this will make a big difference.

I finished the engine cover locking handles I fabricated. In five years of searching, I had never seen any original engine cover handles for sale so I fabricated these. The originals have a tab with a square hole punched in it and a matching milled square on the threaded rod of the handle, held on by a nut. I didn’t have access to a square punch and the milling on the handle itself was another complicating factor so I made up a simple handle out of bent rod with a thread on the end. I welded a nut onto the tabs (at the correct angle) I made and put a pin through the nut so it can’t turn once its on there. It seems to work.

Apart from that, I’ve just been adding a few accessories to the vehicle like the 37mm Spare Parts Box and .30 cal spare parts box, ammo cans etc. I need to fab the strap for the front of the fire extinguisher holder but don’t have too many more things to do on the vehicle now. I am still tweaking the turret skirt as that is still binding a bit but I am getting close now to the vehicle being done.

That’s all for this week.