Ford Blitz Restoration/Rebuild

[Tony Wheeler]

Originally Posted by Private_collector

This little crack will need repair regardless. It has seen some dreadful treatment in the past?

Quite possibly, but I suspect the principal cause of blitz chassis failure is removal of the original body. The loss of rigidity leads to enormous flexion in the rear chassis, which is really quite spindly, esp. the Ford rear chassis. Also the loss of weight over the rear axle means the springs are virtually rigid, so the rear chassis simply twists back and forth over uneven ground, eventually causing fatigue cracks. We rarely see a bent chassis from overloading, but it's common to see fatigue cracks from constant torsion. Of course, with a dodgy crane fitted, the torsion forces can be massive.

Another area subject to repetitive torsion is the front chassis under the steering box. The chassis rail is only single skin at this point, and it has to support the engine mount on one side, and the spring hanger on the other side, plus the back and forth steering wheel force multiplied 20+ times through the steering box. Pics below show a fatigue crack in this area on a F60L chassis I scrapped recently. As you can see it has progressed almost half way through the chassis rail....imagine the consequences of sudden total failure at speed!

[Keith Webb]

I like the way you think things through, Tony.

Another common fatigue spot (at least on Fords) is the top of the dash panel and where it bolts onto the steering shaft bracket, due to flexing of these parts over the years. You sometimes see either cracks stretching from the bolt holes, sometimes even a half-moon shape separates when you undo one of these bolts.

[Tony Wheeler]

Here's another fatigue crack on the same F60L chassis. This one has cracked through the double skin section amidships. It's located precisely above the dodgy front crane mount which has focussed the bending/twisting forces at that point. I think you can see why I scrapped this chassis!

[Private_collector]

Thankfully no cracking found in front part of chassis. I'm bloody glad too, after all the horrors you have told me

I had been rethinking about removing the rear little bit of chassis rail. In fact I thought about having that piece cut off but replaced by the engineers. The pintle brackets will obviously be on this area, and I have reservations about loading forces on replaced sections, in eventuality that I do use to tow something. What do you think? I won't attempt repair, but would direct replacement of last foot or so be sufficiently solid to tow anything?

When I removed the very front cross member, I noted that the radiator support plate was welded to the chassis rail on driver side, and both sides of the cross member were welded to rails in two places each side. Is this normal? It was actually quite neat work, and not in fitting with the other very sub-standard work displayed. Of course there may have been more than one 'welder' over the trucks history. The reason I wish to know this is so I know whether to re-weld these areas again (not literally me).

One final point, regarding rear springs. I had previously disasembled both rear spring sets for blasting, but am now thinking about using the springs off my other vehicle. My chassis does not have the spring over-rider holes in the rails since it had been shortened. The springs off other truck DO have the over-rider leaves on spring sets. In light of what you had said, Tony, regarding the lack of weight in rear = very hard springs, is there any point in including these overrider springs on the finished product???? It may be more of a correct look, but is there any purpose to having these retained? I won't be adding anywhere near the weight the vehicle was designed for, even if I go ahead with the 40mm BOFORS idea. Remembering my version will be a much lighter replica.

What do you fellows think? All comments welcomed!

[Tony Wheeler]

Originally Posted by Private_collector

Thankfully no cracking found in front part of chassis. I'm bloody glad too, after all the horrors you have told me

I figured that photo might send you scurrying up front to have a look! I found that crack rather frightening myself, I'll definitely be checking there in future. Glad to hear yours is sound there.

[Tony Wheeler]

Originally Posted by Private_collector

I have reservations about loading forces on replaced sections, in eventuality that I do use to tow something. What do you think?

Naturally it's preferable to avoid any joins in the chassis rails if possible, however if it's done properly I'm sure it can be just as strong, if not stronger, than original.

Sometimes it's unavoidable, for example one of my FGT chassis has been chopped just behind the rear crossmember, so I'll have to butt weld the chopped sections back on, and weld some reinforcement plates inside the rail. The replaced section has to carry the rear fairleads as well as the pintle hook, so the join will have to bear winch cable forces as well as towing forces. For cosmetic reasons I don't want to plate the outside of the chassis rail, but even without external plates I'm confident it can be made at least as strong as original. Naturally I'll keep an eye on it but even if it does fail I'm sure it won't suddenly fall off completely.

If you're worried about weakening the rear chassis by extending it, you may be encouraged to know it was standard RAAF practice on F60Ls. It so happens I have one of these. The chassis has been extended about 22" by inserting a section of channel inside the chassis rail, overlapping about 6", and welding "band aid" patches on the top, bottom, and outside. A second rear crossmember has been fabricated, and riveted in place about 22" aft of the original one. The pintle hook is mounted as usual, so they obviously had no concerns about towing. In fact I've been told the whole purpose of the exercise was to improve trailing when towing (although I suspect on mine it was also to accommodate a lengthened tray).

The Ford manual also recommends: "Whenever it is necessary to cut or remove any portion of the frame, the rail should be cut at an angle of 45 degrees, in other words, make the cut longer than the width of the rail." It also talks about reinforcement plates (page J-4).

Based on RAAF practice and the Ford manual I would conclude that it's quite acceptable to chop and rejoin the chassis, provided it's done properly.

[Tony Wheeler]

Originally Posted by Private_collector

I noted that the radiator support plate was welded to the chassis rail on driver side, and both sides of the cross member were welded to rails in two places each side. Is this normal?

It's "normal" but it's not "original"! Most working blitzes seem to accumulate various chassis welds over the years, but originally everything was only riveted or bolted. As far as I've been able to discover myself, the entire chassis was completely untouched by a welding rod when it left the factory. Even the factory fitted chassis reinforcement plates (see pics) were only riveted.

[Tony Wheeler]

Originally Posted by Private_collector

is there any point in including these overrider springs on the finished product???? It may be more of a correct look, but is there any purpose to having these retained?

They were only ever fitted to 60cwt CMPs so unless you're putting that kind of load on the back I can't imagine they'd ever come into play. They weren't fitted to SWB CMPs which were very conservatively rated at 15cwt. The FGT had all the 60cwt features but even it didn't have auxiliary springs (although it did have 2 extra leaves in the main springs).

Based on those specs I'd say they'd be superfluous for your application. As for the correct look, they'd only be appropriate if you wanted to replicate the F60T (ie. the 110" wheelbase prime mover mentioned previously).

Unless you particularly like the look of them there's probably not much point. You can always stick them on later if you change your mind, or if you happen to acquire that real Bofors from the roundabout!

[Phil Waterman]

Hi Tony

As always you are bring up and interesting issue, this time frame repair, lengthening and strengthening.

On my 1942 Pattern 13 C60S I needed to add 24" to the rear of the frame so that I could put the radio box on and have it fully supported. What I did as the tails of the frame are not tapered was to have the extensions pieces bent up out of 1/4 steel at a local steel fabrication shop to match the existing frame along with them I had two rails bent up which are a drive fit to go inside the truck frame and the extensions. Then I drilled the extensions to take the trailer hitch etc. to match original frame then I drilled the other end of the new inner rails to match all the old holes in the end of the frame. When bolted in place and painted the extension is hard to detect. No welding so the frame can be restored to original length easily.

On my 1941 Patter 12 C60L I was faced with a different problem rust had caused the inner frame to buckle plus rust damage. Though I supplied the fabrication with detailed drawings of what I wanted them to bend up out of 1/4 steel they didn't understand that the bends were all outside of bend to outside of bend hence the new rails end up being 1/4 inch off. (Yes if they really bent them inside of bend to inside of bend the frame should have 1/2 off.) Any way the solution actually turned out even better the put the frame rails back in the sheer and cut them lengthwise at a slight angle. This allowed two halfs to put inside the truck frame each a little off set then with the portapower drove one of the new pieces so that it was wedged very tightly inside the main frame. After line boring all of the old rivet holes sized for a drive fit of new grade 8 bolts bolted the entire frame back together. Then turned up the heat on the mig welder and welded the joint seam on the new inside frame. Frame seems to be staying tight in straight after several years of hard use.

My point is that it is some time easier and results in a stronger frame repair to have new metal bent to the required sizes as it is to try to find replacement parts. There seem to be more willing donor vehicles out your way. For me I must rely on the kindness of friends up in Canada to find me bits of CMP which are needed.

Of course sometimes I wonder what will the lads 60 years from now who are working on our trucks think, will they be able to figure out what is a 60 year old repair vs. 120 year old original design. But hopefully thanks to things like MLU the knowledge base of CMPs will be stronger. Just as it stronger now than it was 30 years ago.

Cheers Phil

[Tony Wheeler]

Originally Posted by Phil Waterman

There seem to be more willing donor vehicles out your way. For me I must rely on the kindness of friends up in Canada to find me bits of CMP which are needed.

Yes, you're definitely CMP deprived in the US Phil! I'm not sure how many were shipped down under but it must have been in the tens of thousands I would guess. Fortunately a good percentage have survived in one form or another, thanks mainly to their durability in various civilian roles over the decades. It's only in quite recent times they've attracted interest amongst MV collectors.

The chassis repairs you describe are good examples to follow I think. As you suggest, there's no need for welding if the components are securely bolted together. After all, the pintle hook itself is entirely bolted on.

I enjoyed the serendipity in your misunderstood channel specs! The resulting "expandable channel" solution was rather clever I thought. I may even pinch the idea for my FGT chassis repair! Alternatively, I may leave a gap between the two pieces so I can run welds along the edges, directly onto the inside face of the chassis rail. I'm also considering replacing the spring hanger rivets with longer ones and running them through the reinforcement piece. Whatever I finish up doing it needs to be strong enough to withstand lateral forces generated by the winch cable. I like your 1/4" channel - very beefy!

Just for fun I've included some pics of a nearby CMP boneyard with some of the "willing donor vehicles" you mention. I daresay this pile would have come in handy for your chassis extension. I'll leave you to identify the eclectic mix of parts!

Cheers,
Tony

[Private_collector]

Battery Box old 1.jpg Battery Box old 2.jpg
Started on making a new battery box this weekend. Original frame is in extremely poor condition and cannot be used for anything more than a template.
Battery Box template 1.jpg Battery Box template 2.jpg
Template made and checked for accuracy.
Battery Hold Down Bolts 1.jpg
The battery hold down bolts are in good condition, and can be reused. I will need to find one more of the brass wing-nuts shown in this photo.