Check out early fifties Hot Rod mags;the Chrisman coupe used large diameter round tubing and Dick Kraft's Royale roadster was kind of a space frame idea, I think probably chrome moly. You won't find two better examples of early fifties craftmanship.
David - Thanks for the comps bud - always nice to here....! Chili Phil - thanks too....! I lurk here & pipe type were I think it will help...... Rich Pauza
Zach - the debate over 4130N & Mild steel will go on for ever. My stuff use's 1020 DOM for all the long sweeping bends & 4130N for all the die bends & straight runs. The horror story's about 4130N mostly ( in my opinion ) come from guy's using very thin wall material - or incorrect welding - bad suspension geometry - or over all bad design. 4130 N correctly fabricated hold air planes & choppers up in the sky - they are tested to loads a auto would only see in a head on crash. You will have ZERO problems building with 4130N if your design is sound - your welding is up to par - ( TIG or O&A ONLY ) & if you keep your material in the .083 wall + range. 4130N is harder to cope - harder to bend - costs more. If your limited to a ( metal sprayer ) ( MIG ) then your best bet is to stick with 1020 - DOM is best - easy to machine - easyer to bend & very weldable ( any kind of welding ). Just rebember if you go with mild steel - pick up your dia. & wall thickness. A real cool example of the differance between 4130 & 1020 steel tube. - same dia - same wall - take a 20 ft long stick of each & clamp 4 feet of each lenght to your favorite shop bench - watch what happins with the 16 feet left hangin over the bench - you will be surprized....!
did you guys know that helicopters are chromolly? did you also know they are mig welded? mig.not tig? did you also know that 4130 has to be stress relieved or it will crack near a weld? i would use .120 wall tube if i was building a single tube frame. do your research before you kill yourself.
Zach,thought of these two when I saw your thread.Belmont Sanchez's '31 Austin lakes car and Dick Kraft's roadster mentioned above,pretty high tech for the early 50s. I know Sanchez's is double tubing,but bitchin' none the less.
One of the AMBR winners from the 50's had a frame like you're talkin about. I have the magazine it was featured in and they had a drawing of what the frame looked like bare. Lots of drilled gussets. Pretty cool. Clark
Jim Nelson and Dode Martin of Dragmaster fame marketed a line of tubular space frame T-buckets back in the 60's (?). They were featured in some of the hot rod publications of that time. Very cool !!!
Can't believe how many space frames are being shown... The guy wants to build the frame with two sticks of round tube, one on either side. I'm not up on the Moly/mild steel argument, BUT I think that any point of stress could be easily strengthened with a vertical reinforcement plate inside a mild steel tube in that particular area. Moly I'm not sure... The plate could be end notched to ease the transition of load if needed to prevent cracks, and could also be installed thru the tube in bent areas and welded like Budd Davidson does here... http://www.airbum.com/NeatShtpix/RoadsterFrameSaga.html Thinking of Budd...I sure wish he would add to his roadster rebuild pages!
I would use chromemoly if your budget allows. You stand to save a lot of weight if you do. You can use .058 wall chromemoly where you would use .095 or .120 wall mild steel, in a chassis based on 1.625 dia. tubing. It's all we use for cages and it interfaces with mild steel just fine. Cracking joints would be a failure in the design. My car has mild steel rails and chromemoly tube crossmembers. Properly welded, there's no issue. Here is a tube frame that I think is made by last refuge hot rods. Not sure what material they use...
Pics are of a 1957 Facel Vega FV4 were finishing up the restoration on. Its at the upholstery shop at this moment so I'm unsure of the exact tube diameter . I believe its made from 3" mild steel tube . These were a high end limited production car. The entire body and chassis was hand built.
Chrome Moly has enough carbon in it,that it can become brittle if not welded with the proper technique. This includes the correct filler material,AND preheat. Doug Wolfgang broke his neck when his Chrome Moly cage sheared off in a crash. Toby Tobias Sr. died when his Chrome Moly cage broke. I could go on,but you get the point. Or not.
there is nothing stronger than a circle. a triangle and a square are good but not as strong as a circle.weakest would be angle iron and channel. circle track cars of the sixtys had 2.5-3" single tube frames. something like the cobra.
NOT doubting you one little bit Unkl...I just have NO experience whatsoever with Moly tube! From the sound of it I'd just as soon stay away from it unless you MUST use it because weight is the prime consideration! Too rich for my blood anyway...
It's a method, it isn't key. Oxy-Acetylene is faster and just as good, if not better. The advantage with gas, is you can reheat the whole weld hoints and get the stress out of the joints. Another method, which I don't know if its been mentioned, is you can cut the tube at junction points and insert another tube into the main tube for strength (make it a good length, drill a hole in the outer tube and weld the inner tube and fill the hole). That's also how you repair airframe damage to the tube frame designs.
The Fuller chassis on Tony Nancy's roadster was 3 inch .080 wall chrome moly according to what I have read. The big single tube early drag cars I've seen in person were about 3 inch tube, don't know what thickness. If I was gonna build that type of chassis I think I'd use 3 inch .120 wall mild steel. Right look and easy to work with. By the way, moly air frames can be gas welded - if they're TIG welded the entire frame needs to be baked to normalize it - at least this is how it was in the '60s. NHRA has a different opinion about welding moly.
High quality bicycles used to be built with chromemoly but the jounts were not welded. They were soldered. These frames were strong and stiff. Racing technology does not always translate well to street use. F-1 teams use carbon fiber suspension struts and they are under immense stress but I surely would not recommend using them on the street. One little nick and they will shatter leaving the driver taking a wild, uncontolled ride. I would not advise you to use moly in a ladder type frame for the street. A space frame would be much safer but not without potential problems. Mild steel would be much safer IMHO. I see no reason to use moly tubing for a street build unless someone has given it to you and I doubt that he is your friend.
Oxy-Acetylene can do very nice welds, also good for Brazing and Silver Solder. A lot of home built aircraft,and Formula Cars from England are Brazed. Done correctly,there is nothing wrong with it. Also very easy to overheat the filler material, destroying the intergrity of the weld. ------ TIG is just another tool to generate heat,with a shielding gas. Used with the wrong filler rod,and/or insufficient preheat, can give very unsatisfactory results.
I have an old book from 59 that has some chapters on racing frames. I have to find it so I'll post the scans tomorrow. If your interested for any info on era blowers and engine mods PM me and i will check the book for it.
This is an interesting site; http://www.gilcodesign.com/doc/GILCOdesignAUTO.htm Gilco is an Italian company that fabricated chassis for Ferrari and Maserati in the late '40s early '50s. Click on the cars listed and in most cases you'll see a pic of the chassis and a plan view. They really were simple little critters. Cheers, Kurt O.
That was a very common design up until Colin Chapman changed the world with the monocoque Lotus 25. I have a British car called a Swallow Doretti that has a frame that uses two large dia. chromoly steel tubes. The Swallow company had a license for the chromoly process and built the cars partly to demonstrate their products. Something unique to the Doretti chassis is the large dia. longitudinal tubes have U-channels welded top and bottom for extra stiffness. This is a really strong frame. Before his Ol' Yaller days, Max Balchowski plugged a nailhead into a Doretti and terrorized a lot of Ferraris and Jags on the California road courses. Cheers, Kurt O.
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