Technical Model A Frame Straightening and Metallurgy

So my sort of build thread is here.
https://www.jalopyjournal.com/forum...etc-build-thread.1341093/page-5#post-15775046

I had an issue with the frame at the rear motor mount area. Egged out bolt holes and a crack in the bottom and up the side of the frame. In addition, the bottom part of the frame was worn thin from loose motor mounts. I repaired those issues, on one side by welding in a new section of metal on the bottom.

As the motor mount area seems to be problem in general and I've read it's not a good idea to box only a portion of the frame, I made some "tapered" [so to speak] fish plates to go inside the frame.

So far so good, but on the side of the frame where I didn't replace the bottom section there was also wear from the motor mount, [thinning the lower portion of the frame] and here's where I screwed up.
I filled that with weld and put too much localized heat in to the frame.

The result was the frame warped and now the left frame horn is maybe 1/2" higher than the right.


The right side of the frame is flat, front to back. The left side is flat to the rear motor mount area then curves upward.
Right side;


Left side;

The 1/2" gap is pretty much the 1/2" the left frame horn is high.

The straightening issue is compounded by the fish plates I added. [making the metal thicker.]


I mean it seemed like a good idea at the time and if I hadn't added the excess heat by filling the bottom rail/plate with weld I probably would have been ok.

The metallurgy part.
So I was wondering, if I heated the inside, outside and top on the area of the motor mount holes, avoiding the bottom rail, would those areas expand enough to lower the front rail by 1/2". And if by the grace of God that does happen, do I let it air cool, or squelch, and if I squelch, by what method? Wet rag, air gun?

Or, do I use a piece of I-beam, chain the front, rear and the area to the rear of the motor mount to the I-beam and use a bottle jack. [If I went that way I think I would weld a piece between the two open areas of the frame to keep them from bending].
Or, do I heat the bottom of the frame and the lower portions of the fish plates and shrink them, drawing the front of the frame down? And if I do that, dull red and wet rag squelch or air?

Keep in mind on that side the frame is straight from the rear to the area of the rear motor mount then rises.
Those dang fish plates really seemed like a great idea until now.
I know I could probably find a frame but I would really like to fix this one. [all matching numbers for whatever that's worth.
P.S. it's no big block, it's going to be a banger.
Any suggestions would be appreciated!

robj
Learning as I go...

 

I'm going to offer you some advice, a blind guy won't see it and a dumb one will think it has to be like that.
But that said, others will surely say straighten it. I'm too tired to argue it or enlighten you on the procedure you mentioned but will offer this advice, metal expands when heated, then contracts on cooling. You get more contraction then expansion, use that to your advantage.

 

I would first check with a straight edge on top of the rail to see where the shrink/bend begins, it looks like in front of the group of three holes. Check with a straight edge on both sides of the bend and mark the start and stop with a sharpie. The principle is if the steel have shrunk, it could go back again, the shrink builds in tension in the steel and heating and getting it back relieves the stress which is good. I'd clamp a large I-beam heat it up and straighten it out.

 

We straighten heavy tube like this at work all the time. I would heat a silver dollar sized area on the outside bottom of where the left rail starts to curve up and a area across the bottom web of the frame.
you can clamp a beam or whatever heavy iron you have to lead it, but just letting it go on its own will work too.
Let it cool on its own and it should move easy. If you dont get it on the first try, you have to pick another spot forward of the first.
One thing I found with straightening this kind of stuff is to set up a surveyors transit and 'shoot' the frame in level on the part that is good. Then as you straighten you can follow your progress with just looking through the transit.

 

just let some air out of the left front tire.....

....or some chain and a jack....

.....and one *** always seems to hang lower than the other....
I guess that is what I get for not being a restorer....my end objective is to drive it during the day and look at it at night

 

That side of the Model A frame has always been a weak area. Remember there was a lot going on in that area, Battery box and battery, clutch and brake pedals and even the weight of the driver. Combine that with poor roads in the '30s and '40s when the car got most of its use and you can see why most Model A frames sag in that area. I have restored several Model A's since my first one in 1968 and every frame had a "sag". in this area. I have the luxury of using a friends body shop and chain the frame down and use a combination of bottle jacks, floor jacks, string lines and an 8' level to true the frame, it's not rocket science. I always tell people, when Ford put the body on the frame he did not use shims, so if someone needs shims to get his body true, the frame is most likely the cause. If you have access to an "I" beam that should work just fine.

 

Yeah you screwed yourself by welding the doubler plate in before you checked for straightness. But I bet if you work twice as hard with a big I beam and torch, you could heat and jack it back to level. Put the I beam below, with chains hanging it from the rail, and the jack under the bend. Heat the bottom flange and the sides, both inside and outside, and push from below. Sneak up on it. Probably should let it cool to make sure it’s perfect, because the heat alone might shrink it a little.

 

When you heat metal it expands, and when it cools it shrinks to a smaller size than where it started. Cooling quickly exaggerates this effect. So, if you heat the bottom flange dull red a few inches, then cool with ice it should shrink the bottom flange and push the side up. your fish plate may or may not have an effect.

 

always thought that shims were used on ***y line--learned something new

 

I’ve never seen shims on any original old Ford I’ve taken apart.

 

Pressure down on front
Warm it up
Whack it
M***age the repaired with 2 BFHs.
One to wack. The other is a dolly
You reverse any possible shrinkage from welding by wacking it
Works for sheet metal
Works for thicker metal

 

For the sake of argument, how bent and twisted do you think it has to be to make it undriveable? Unsafe. Noticeable to the average guy looking?
Leaving it alone, how will it affect driveability. Ask that question. You planning on breaking speed records with it?
Will doing more fix the problem or exasperate things further?
You have options, I agree. Stopping and reexamining what got you here is a start. I'm going to suggest you start by opening a good book to read.


One book covers it all. Ideas to straighten, metallurgy...all there.

 

My father saw a good demonstration when he went to Blackhawk Frame Straighting school.

The instructor asked “How many of you have been taught/told not to heat a frame when straightening it?”

Many put their hands up, the instructor quickly pointed out that when metal is bent it produces heat!

Knowing he would have one in the cl*** who would argue that fact, the instructor proceeded to pull out a coat hanger, cut the ends off it repeatedly bend in and touch it to the skin of the student who was arguing and asked “So do you still believe that bending metal doesn’t produce heat?”

 

Do as you wish with it, but ask yourself this question first: "How many things am I going to do half-***ed on this car?"

 

patsurf, I have been playing with Model A's since I purchased my first one in 1968 (yes, I'm that old) and have restored several and taken apart several more and never seen a shim in an original car. As I originally stated, if you need a shim, your frame needs to be addressed. The body dropped onto the frame and it was bolted down, they had no time for shims.

 

Pressure down in front with the frame mounted to a sturdy level surface

stress relieve with hammers
Heat if needed

old car frames move easy
Edit. Your would probably be the reverse.
Hold and push up.

 

I straightened a ‘37 plymouth frame by placing it under my wife’s SUV’s front tires, essentially holding it on my driveway and proceeded to floor jack up the “low side”. No heat, no hammers. I slightly exceeded “plumb” to have it end up good. I also made a giant “pickle fork” out of a long piece of 1.5x6 rectangle tube that I could slip over the frame rail (from above) and tweak the rail while my wife’s SUV was parked on the frame. It may have been a little crude, but it held the frame securely while I made adjustments.

 

It was straight before the plates. Where I screwed up was getting too much heat in the lower rail when I filled the thin spot in the metal with weld instead of cutting it out and welding a new piece in like I did on the other side.

 

So your thinking is heat the bottom area of the frame, [and the lower portion of the fishplates] for contraction to pull the front down?
I'm also think if I tried this, air, [natural] cooling would be best as squelching sort of "freezes" the metal where it is? Or does squelching shrink it further?

 

Thanks. That's pretty helpful..

 

What surprises me in all this conversation, is no one said, did you see that hot mess of a fish plate? Or, holy **** that was a lot of welding. Nope...none of it. So with acknowledgement I'd like to point that out. Say that should be a conversation in itself.
That said, sure, while you could attempt to cold work it back to straight, the ends past the stiffness of the plate being weaker would likely bend there instead. That's my guess anyways. But it would bring it up in a ***** flat spot kind of way.
Instructors... did you ever wonder how some of us got jobs? Held them? I don't suggest you flex it back and forth in an attempt to generate heat. It will alright... I just imagine that little grid of atomic cubic structure getting it's neck wrung from all that Indian burn flexing.
And with out offense intended, beating the **** out of it with big hammers. Not that it doesn't work, because it does, I just can't stand the noise. It reminds me of a pork chop being hammered into a schnitzel. That hammering force pushing the metal somewhere. And it's hard labor. Straight out of the dirty 30's. Grrrr. manly. And I doubt those kids have a stiffener on the inside do they?
Long chain, jack all, a torch. Little tension, little red hot heat, let it cool, recheck. Repeat as required.
I wanted to say you should gouge grind all that out... restraighten the frame , and then do it again right this time with some thought and understanding. Could have would have should have but no. Not me. I said, maybe leave it. Damage is done. Sure...(insert Homer voice) it's not perfect Ned, but will your attempts to do so improve it to perfect, or a smaller flaw?
In pipeline codes they now might leave defects depending on location because the repair risk is greater than the defects harm.
Letting that sink in... will you trying to fix it actually make it better? That's the point isn't it? Can we make it worse, yes. Make it better, possibly. Make it 100%...? Perfect is a pretty high bar.
How being the question, I'm going to suggest the answer will be revealed based on your personality and character...So, under pressure of being half***, reviewing your options... I see you're likely to try beating it cold, heat and beat hot, heat and pump jack with chains, or cut it out and do it all again?
Not that you don't have enough to think about, but contraction actually occurs quickly with the loss of heat and after that its mostly just hot. you might try heating a s**** plate similar to your fish plate to see how it reacts. That is if your not cutting it out to do again?

 

I agree with NoelC, perfection is a tough thing to chase, and often gets lost in the real world.
Your efforts to correct a 1/2' dip over 3' of frame length stand a better chance of making it worse, then it does making it better. When you have to run a string line to be able point out the defect, your going towards the extreme.
Once the car is ***embled and sitting on the tires, you would never see it (leave the string line at home). The frame doesn't sit on jack stands on a level floor outside of the garage, it is supported on springs and sits on tires on usually imperfect ground. Unless you are preparing to enter the car for the Rydler style compe***ions, move on and build it. If someone should see it (which they never will) and point it out, tell them you built it that way in preparation of the long term effect the motor's high torque will have on that frame rail.

 

You will see it, because the hood won’t fit right. It’s very common and Model A guys have been fighting it for decades. But there’s no space to just shim stuff up front when fenders, radiator, and braces are all supposed to bolt directly to the frame. If the rail was low, you could fake it with shims.

 

Got that motors book 20+ years ago when I was doing my apprenticeship, every now and then I’ll grab it. As you stated pretty much everything is there in it.

 

Quite the interesting dilemma. Curious to see how you manage to fix it ***uming you do. If it were me, I’d to try to get it straight somehow.

 

I would have had it straightene by now

 

I-beam running the length of the bent rail. Chain down front and rear tips, jack under the bend. Apply heat to the top corner of the rail above the bend, then a slight feather V shape heat pattern down on the outside of the rail. So you'll have a heated corner that runs down the side of the rail to basically a point at the bottom corner.

As you heat apply pressure, you'll hear the metal talk to you, heat first then jack, more heat then more jack, repeat.... you want the rail to relax as you heat not be forced. Might take 20 to 30 minutes of this, don't rush it or you'll collapse the rail. You want a little at time.

Put a straight edge across the front and rear and go a little, check straight edges as you go.

You'll probably want it 1/4" to 3/8" past to start with. Once your there, kill the torch, let it sit overnight. Next day let it off and see where you sit. Repeat if necessary and just go a little further each time.

Been doing frame work everyday for the past 44 yrs and still doing it...

...

 

Had one similar years ago.

set the frame on blocks except the end we were moving.
Set that block where we believed the bend started.
Got some friends to stand on the ends of the frame where the blocks were.
Stood on the end not supported by the block.bounced it some.
It moved.
Banged on it with a hammer
Old car frames are EZ to move

 

Done that a few times.

basic swag repair

trucks like to swag at the bed and cab
Super EZ repair

 

Anthony,
Peter Paul and Mary sang a song about you
I think it goes something like “if I had a hammer”