That will catch and hold crap and moisture in the bottom of the frame rail. The perfect condition for starting the corrosion process. The design put up by @anthony myrick at least has openings at the bottom edge so this muck can be easily and regularly flushed out.
We here dont drive our cars in the wet ??? LOL. I am only the caretaker of my cars ,I dont really care , who ever gets them next can restore or fix em .. Not trying to be rude , just the way it is ..
Great info! This is everything I was looking for, and then some. Thanks very much for all of your helpful replies.
You mentioned sitting the frame on jackstands and getting each end level (with a level ?). My question is, if someone does that and gets any warpage, how would they know which part(s) of the frame moved? They can bow up down and even sideways as well as any combination of those things. Remember also that the track of the vehicle down the road also requires that the suspension components you attach must be in alignment with each other. There have been a lot of frames done exactly as you recommend and have turned out satisfactorily. I'm reasonably sure there are others who have not turned out well, or this subject would never come up. It doesn't take much movement at a midpoint of a frame to cause the ends of the frame to move a decent amount. As for 1-800 Tig.............proud to be a member of that group. I cut my teeth on an old Lincoln Tombstone welder and it gave me a lot of good service. The thing about building old cars is they aren't very versatile. Good for most thicker stuff, but lots of PITA slag to deal with. Step up to a modern Mig machine and you can do a lot more things a whole lot easier. I respect people who are craftsmen and can use old technology (usually very labor intensive) tools to make things. As for the old stick welders, I don't think many craftsmen use them as they recognize the difference between respect for something like a brake,bead roll,louver press which seldom have any modern technological improvement...............and a having a more modern and more versatile type of welder. Mig welding was first used in 1948, and Tig was first used in 1942. The whole point here is trying to help someone with no experience understand how to do something the correct way and why its important. Then tell them about other ways but also point out the possible major problems they can have doing it that way. If they want to take a chance , thats their choice..........they just need to know that there are concerns about doing things the way you have suggested.
I wouldn't do a full length weld. Add the strength where needed, weld just enough to hold it in place. If it's a showpiece frame slated to be ground and all pretty-pretty that's another move, but how much is too much, or enough? And to that end, warping, moving around, stop it before it happens. Weld all the X-members 1st so the main rails can't pull up as easy vs just counting on the OEM rivets, might stop the "booiinggg!" when it's released. Again, the welds, the bigger and hotter the more they can shrink, more forces you don't want. Doesn't have to be rocket science and a fully boxed frame could be an advantage but I'd still be selective as I go about it. Maybe if it was inside the rail a little and selectively stitched the metal would do the work and less welding is needed, and to some level might look better too. How necessary? Well, 60s perimeter frame convertibles and some hardtops had full boxed frames. Postwars too, and if not boxed had heavy reinforcement welded to the bottoms and other strategic areas. Once again it boils down to "pick your poison" and the end uses.
And judging by some of the crap that I have delt with I agree. The rails under the 32 Coupe I just did were so far off that when I cut the homemade center crossmember out they literally sprang back to closer to their original state.
I agree, and most people don't have them today either. Most people also didn't have todays income levels even if adjusted for inflation. I'm also sure that many things that were done in the 50s would not survive todays higher HP engines, higher speeds, and sticky tires. How many people back then knew how to correct bump steer and speed wobble.........but they drove them anyway. People made do with what they had..........but it doesn't make it the right thing to do today. Drove many miles on Recap Big O tires back in "the day"............any size for $9.99 When is the last time you saw anyone running recapped tires today? Things change.
Torch and stick welders did enough; just glad they didn't have cut off grinders and "hot metal pumps".
Irrespective of the intent to allow flex in a T or A frame, unboxed, they both do. I have demonstrated it to skeptical customers on several occasions. If I can constrain one end of the frame, and then use only my light to moderate physical strength to twist it, it has no business at freeway speed unless it has been strengthened.
Any open channel frame can twist, doesn't matter if it's a T or A, or the frame on a big truck....what might be important, is if that twisting is detrimental to how the car works. The early Fords had the suspension load at the center of the crossmembers (where the springs attach), and they lasted forever. When you move the loads around, then you might need to change the frame's characteristics to match it's new job.
Proper suspension movement is controlled by shock absorbers, spring rates, and suspension geometry. When the frame is allowed / designed to flex and becomes part of suspension travel, it is uncontrolled. That is not ideal for ride, handling, or planting the tires.
I noticed and kinda dived into looking at that as well, many years ago. I was going to do an IFS and IRS in a car. The more I dug, I found that the use of a rigid frame was best and to let the suspension do the work in order to tune different aspects of it and eliminate frame movements. I never moved on with the project so have no practical experience, but seemed to make sense at the time.
Modern frames are designed to twist. Not as much as early frames, but are designed to collapse during a collision of Blume early frames. unibodies twist. Building and bridges move Airplanes do all kinds of goofy stuff. Ships move under stress. Watch a drag car in slow motion. Even cranks and rods exhibit twists and bends. A head can even lift up from forced induction. Rigidity is relative.
All of those things would work better if they were rigid. But a plane would need so much reinforcement it would probably be to heavy to fly. And for everything cost, weight, production methods, etc. limit the amount of rigidity. it is a compromise. If flexible was better, everything would be made of hinges. For our purposes, improving the performance of ancient designs, there is a lot we can do that was not seen as necessary by the manufacturer decades ago.
I wonder about twist vs move. I recall many talking about how 35-40 frames were made to twist/etc. then someone posted a pic of a 35-40 car in a 4wd kinda stance, one wheel high, etc corner to corner. Makes you think a bit. If the frame is in a “twist” seems body parts won’t line up, or could you open/close a door? Regarding uni-bodies, other than VWs the F-bodies were uni-body as well, and quite common to have stress cracks behind the window at the roof. That’s what aftermarket offered subframe connectors to make them rigid. But just to box a frame just to do it…seems like a lotta work unless there’s an intent involved.
The questing here is how much reinforcement. My opinion is there is no performance improvement for boxing the entire frame. Unless you roundtrack or demo derby. Thickness? 1/8th, 3/16th. I’ve seen 1/4. Seems overkill unless it’s something like my school bus. it flexes. I’m glad. Helps that low slung behemoth make it over stuff. Fully welded looks visually good. Any added performance? Probably not.
The bolted on body adds some rigidity, but not a whole lot on an early car, especially a roadster. And that's why some roadster doors pop open. So if you don't want your doors to pop open... If I had to choose between boxing the frame and adding a well-built X-member, I think I would pick the X-member. But I think both is bedda.
I’ve added unseen structure to old rides that keep the doors from unexpectedly opening. Kinda like a belt line high “cage”. Connects to the b-posts. Curves around under the hat rack area/behind the seat. Then a brace up from the sub rails. The deck lid rain gutter structure was tied into it. Doors shut better. Gaps were more consistent.
I was gonna go there but didn't. Both tangible values, body-added strength and doors popping open. A well restored/constructed/reinforced body adds a ton of strength to the platform. Stabilized subrails and an extra iron support where wood was used is worth it's weight in gold in that regard. Doors popping open, well how bad does a body have to be to move over 3/8" and come off that latch? Countless miles with the OEM latches, never had one pop open. Maybe I'm just an anal type that uses new springs and the like all the time. Strength; even on a restored car if one were to weld at the top (where it can't be seen) each area that used rivets, how much twist did we fix right away? Ok, revealing secrets that made a few cars feel tight and new again. The same can be done with steel body crossmembers. Now the body has renewed resistance to twist and adds that overall stiffness. This isn't just at you Ricky, all of us playing along. And yes, boxing is good when we want a (can't help myself) "knockout punch" from our hot rods. Still, just like booze, religion and politics moderation is best. Last thing, a Packard main rail is 3/16" thick. A Duesy is a full 1/4". I can raise a naked Packard frame somewhat, I grabbed a naked Duesy frame 3 yrs ago and said "no fuckin way!" Needed help. No twist. Go figure...
Here is an original 1919 ford model T frame . 100 inches long , 23 inches wide , 3/16 thick There are 2 running board braces missing from the frame . I am restoring this one for a 1919 I have
Early Ford frames are part of the suspension and designed to flex. To box, tack things together a foot apart to start and go from top to bottom, side to side, then follow with 1 in welds using the same random welding til you are happy with it. then check the only important thing, that the front and rear crossmember are in the same plane and square with each other "X" measure and you'll see. Portapower if needed to square it up. Twist as needed to get crossmembers in same plane. The best plan is to use a 32 cross member and a couple of square or round tubes from the trans area back to just before the kickups in the rear frame to make a"K". I ran a channeled 29 Ford roadster on stock "A" frame and springs with a 364 Buick in it for 50 + years with no problems. This isn't JPL labs, it's old cars.
I prefer to tack a frame together on a jig. I start releasing portions as I finish welding. In the end the jig is a guide for warpage, but not holding anything. You can get a lot of residual stress in a frame by constraining the final welds. It will come out eventually. Learning how to "lead the weld" is critical to getting a square, stress free frame. This is dated, but entertaining:
I just read every entry on this thread and now have zero clue on how to proceed with my problem. I have a 39 Pontiac frame. It appears to be pretty solid except a PO cut out the X member from the middle. I was planning on boxing the frame and building a new X member similar to the attached pic. After reading this, I’m concerned I’ll end up trashing the frame due to warpage. I’m an amateur welder and do not have any type of jig, large ass table of any other way to tie the frame down. This car will not see a tremendous amount of HP. Should be around 250 HP SBC. Can I skip boxing this frame, build my cross member basically off the frame and weld it in? Would this alleviate the warpage concern? Maybe add in a few strategic box areas? Thoughts?
For 250 hp I’d rebuild a X-brace set up that works with the engine/trans being used. But that’s just me. Friends 33 Plymouth only reworked the x members to fit the trans he used behind a 354 hemi. No issues. He had metal bent to resemble the OE center X brace. Even with similar holes to help with exhaust.
My friend when we were 16, (1958) had a newly restored '31 Plymouth PA coupe, 3 window w/rumble seat. I built up the engine, bored .125" w/Silvolite pistons, used Wakeshaw guides from Air compressor. LOL Fast & reliable, ran great for 2 years, 'til graduation. Blew the engine (broke crankshaft) so in 1961 I installed a 354 Chrysler hemi, w/ adapter to '50 Merc overdrive trans. Made a plate crossmember, with a welded 90* flange on top, pair of round tube legs ('K' style) We took our wives on a shake down run from San Jose to Sacramento, then across Bay bridge to San Francisco. Shattered the ring gear on a S.F. hill, (the 'Rice-a-Roni' ad hill!) Stayed over, had a bud chain-tow us back to San Jose, with his hopped-up Ranchero... 1961.
He did something like this set up. had a friend with a press brake. Made pieces that resembled the OE X- brace that allowed the trans to fit. Very sturdy chassis.
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