Hot Rods To box or not to box...

Im building an AV8 sedan, flathead, 3 speed, banjo... Should I box the frame or would the 2 extra crossmembers (F1 and T rear crossmember to mount rear radius rods) add enough strength that boxing it would be rendered unnecessary?

 

With that running gear you don't need to box it. But why not do it now, you'll never say I wish I would have......

 

I think its a torsional twisting that you're trying to avoid, and I'm not sure that extra crossmembers would stop that. Plenty of flathead powered rods have run an unboxed A frame without issue, but it seems like it'd be worth the effort, to me. They get flexy as they get old, and you're already there working on it, like chopped51 said.

 

Others have done what you're doing without boxing and are fine. But if it was me I would totally do it. You can recess the plates inside the frame and leave room to run lines etc..

 

Yeah you guys are right. I have boxing plates on their way. Might as well do it. Make the car as solid as possible

 

That's what I plan to do on my 31 Vic, It's getting a flathead too but who knows what might happen five years or more after it is built. And with that Vicky body I can use every bit of extra strength and stiffness that a boxed frame with an x member would give.

 

Box it now and you'll never regret not doing it later.

 

What would Bluebear do? HRP

<iframe width="640" height="480" src="http://www.youtube.com/embed/FewMvAP5LwM?rel=0" frameborder="0" allowfullscreen></iframe>

 

I'd box the front rails for cosmetic purposes. Easier to keep clean. As far as the rest of the frame I wouldn't get too excited about that. I'm assuming you won't be doing high RPM burn outs.

 

First thing that came to me

 

Boxing frames was started by dirt circle track car builders. If you are not going to race on a circle track on Friday night boxing will not be required. The car is supported in the vertical direction only. The forces on the frame can only be vertical. Boxing strengthen the frame for horizontal forces and does little for vertical forces.

 

I just really like the look of an unboxed frame... But i see the benifits.of boxing it and welding the crossmembers in too. I wasnt even considering it till I saw that Elrod boxed the frame on The Question mark coupe. The flatty isnt stock either... Cam, stroked, ported, relieved... And with the shitty Missouri roads... Might be my best bet.

 

Un-boxed, make a K or X member if you want to stiffen the frame up.

 

I think he may want to go around some corners. Boxing will improve torsional rigidity which improves handling.Extra crossmembers help prevent the chassis from twisting which also helps with the cornering ability. Box or not? It's a matter of personal choice.


David

 

It's got nothing to do with how much power you're putting out, it's all to do with one thing..... do you you want to go round corners without the doors popping open? Because even a dead stock Model A with new door latches can do that. I boxed mine, and I can rip around corners now with no problem. Also I'm convinced the stiff frame allows me to use soft springs with reasonably stiff shocks to get a nice, comfortable ride and handles well. I only have four leaves in the rear of my tudor, and it works great.

 

Yep what he said ^^^, there is another reason to box now. Someday you may decide to put a rocket between the rails.

 

Yeah I've had the doors pop open just rocking the car on its springs. I'm going to go ahead a box it. The boxing plated arrived today. And maybe some day a yblock or SBF but never no GM parts on my Ford!

 

non-tubular crossmembers don't do very much for increasing torsional stiffness (or bending stiffness for that matter)
http://weldingdesign.com/archive/no-twisters-or-swingers-allowed

"....in an initial attempt to make the frame resist such twisting, might add a series of transverse stiffeners, as shown in Figure 2. Unfortunately, installing these stiffeners is a nearly worthless exercise: The frame will be almost as flexible with the stiffeners as without."

 

X2, Plus boxing makes your suspension do the work and protects your body sheetmetal from those annoying little rips, tears and cracks...

 

~4:30 here presents Chevy's opinion ca 1938

http://www.youtube.com/watch?v=a137aMMGnVc&list=PLB979C9B290D9E9B4

 

I didn't box mine and wish I had. Limits types of engine you can use. I running a flattie so ok for now.
Butch

 

J ust box the dang frame. Boyd was right , much safer and you will never regret doing it. Not much work to do. Just my 2 cents, besides, I never cared much for Blue Bear.

 

If you were putting something comparable to the original engine, then you shouldn't have to box it...But, V8...box it...

 

Do it now while its apart, if you want to change the drivetran later you won't have any concerns

 

Some of the rectangular tube frames on new pickups are rusting from the inside to the outside. They did not have weep holes and the insides of the tubes were not coated.

 

IH Scout frames were similar. A nice deep dip in the middle, with rodent sized openings in the high up horns on the end so they fill up with acorns and fluffy nests to hold the water even if there are drain holes.

http://img193.imageshack.us/img193/4368/scoutframe.jpg

The rust rate is just a little slower than the body

 

Box and k or X member, you won't regret it.

Scotty