So if any of you were to pit a flathead into a model A would you box the frame or keep it stock and why
First of all, can't keep it stock if you box it, but I don't think you meant it to be a trick question?? Anyhow, if it's going to go much faster than a stock Model A, the frame needs to be boxed for strength/rigidity. Flexing frame is a major contributor to unstable handling characteristics.
Depends on engine power and intend use to me. Hot motor and or track time yes. Daily/Sunday driver no.
Done a partial box on mine. Kicked the rear crossmember up 5" and lengthened 4" to acommodate the 59AB, so that area is boxed. My centre crossmember is a K, so that area is not boxed, but the forward area will be, mostly because the steering box makes the rails twist.
From what I've read in other posts, you can get away without boxing it up to 100 HP or so, especially if you keep the stock drivetrain in it.
I will give you an example. I have a stock A model frame with a banger in it. When you go around some corners the frame flex's and a door pops open. I have fixed that problem now, and no i didnt weld the doors shut
Put in an x-member and box it then you will be done with the frame no matter what you do to it in the future..... A stock model A frame is 80 years old do you really want that under your car without doing anything to it.......
Frame flex is inherent in any frame where the parts are riveted. Welding out these factory joints stiffens one up nicely, but leaves enough give that they retain much of the original comfort and manners. Mild flatheads won't make enough torque to warrant fully boxing the frame. Most any car will benefit from boxing forward of the firewall, but a stock flatty wouldn't even justify that. Anything making real torque with decent traction will twist up a stock frame severely.
Hey, are you talking about me again!!! Ok just so you guys know whats going, if he is talking about me, I'm building another ch***is for my 28 coupe, model A rails, new 32 crossmember in the front, 39 ford X member and a model A crossmember in the back. I am putting a mild mild 8ba flathead in it, basicaly stock with the exception of two carbs and headers. 39 Ford ******, 39 front axle and a 39 rear end (i bought a 39 fordor as a donor car. I wasnt planning on boxing the ch***is as it is a mild mild flathead and it is not going to be driven hard (i cant afford to fix it when it breaks). So thats my plan!
I was thinking the same thing... ....but I still have no desire to paint any car like an easter egg and put tan leather interior in it. So I think I am safe.
It also depends on the suspension set-up, how much differential weight-transfer loading there is likely to be. That can result in torques many times the driveshaft torque in first gear. The stock suspension doesn't generate much in the way of weight-transfer-related torsions, but just about everything that is usually done to improve the suspension does. This is especially true of non-traditional suspensions that were developed with much more rigid vehicle stuctures in mind. I'm very much interested in warp-flexible suspension designs that eliminate weight-transfer-related torsions entirely. The simplest example is the Citroën 2CV interconnected-coil system: http://www.ukcar.com/features/tech/suspension/interlinked.htm So, in a nutshell: Stock suspension: don't box Upgraded suspension: box Warp-flexible suspension: don't box
Engine power notwithstanding, even with stock banger motor; Fact; The Model A frame is too flexible for ANY SINCERE hot rod application. On our Grandpa’s, during the period 1953-56, my brother and I put it through the paces, just about any abuse two kids could put a car through. Over sagebrush, down cow trails, chasing rabbits and I don’t know what=all. When it was restored in 1995 the front cross member was discovered to be all busted up, and the frame was cracked in several places, from flexing would be my ****ysis. Certinly not from horsepower. When we drove it across a deep rut in the pasture, depending on what direction we came from, invariably one of the doors would pop open, and one time that flexing caused the rear window to crack. That inherent flexing of the frame can lead to disaster on a high speed run when steering input is countered by inertial forces, causing that flimsey structure to vibrate like fiddle string.
Since you really don't have a strong opinion either way, box it now before it's a complete car and you have to take it apart completely to box it 3 years from now if you change your mind.
That's funny because I know what your talking about also.... I know I won't paint one like an easter egg and I can't AFFORD tan leather interior....
I am doing the same thing with a '29 rpu: stock A-bone frame, basically stock 8BA flathead welded up crossmembers. We'll see how that works. I've heard and read that partially boxed frames tend to crack behind where the boxing ends. Anyone out there have real-life experience with this? And that Bluebear thing came to mind immediately. I freakin hate TV.
The first time we took a body off and found how little torsional stiffness there is in a stock frame scared me enough, I have voted for boxing the frame, but I got to be honest it's a lot of work, and I only ever did it a couple of times, before deciding I could make a whole new frame quicker and take care of a whole load of issues ( lower/longer/shorter/diffrent axles/suspention/etc ) at the same time. I did a pair of rails for a friend a few weeks back, he not being a welder or machinist, he had all the pieces cut, and did a drawing of where everything had to go, I bored all the holes on my mill, and then jigged it up on tressles and welded it for him, did not take that long, he was happy to pay me to cover the cost of the gas and electric. Yeah, not boxing the frame is definately to shouts of 'BLUEBEAR', forever more guys.
Dropping a stock 331 caddy (160 hp) which is probably heavier than your flatty in an original a frame.Boxing may not be neccesary but I'll feel a little safer knowing I'm heading off potentail problems down the road.It's getting boxed for sure.
I boxed my Model A frame to put an stock 8BA in it. The frame was pretty abused when i got it so i had to replace a few spots on it and decided it box it in to avoid any other problems that could occur in the future.
In the series of "American Hot Rod", Boyd Coddington ended up firing Bluebear because Boyd insisted an A frame had to be boxed, and Bluebear refused because he said it spoiled the look on trad rods.
Boxed for me, I just had a naked A frame on the workshop floor and they ain't strong anywhere, so it got boxed
Had no idea who ya'll were talking about.Figured it was a hamb member.I spend about 300+ days a year on the road and tv time is a rarity.
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