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Technical Thoughts on brazed steel joints vs MIG welded?

Discussion in 'The Hokey Ass Message Board' started by Ziggster, Feb 10, 2020.

  1. Ziggster
    Joined: Aug 27, 2018
    Posts: 585


    For my build speedster build, I had two 11Ga "C" channels made. I will need to start building the frame which means adding cross members, motor mounts, suspension mounts, etc. Instead of MIG welding things together, I'm toying with the idea of just brazing the parts together. In theory, I believe the joint should be just as strong as the base metal if done properly which works for me since as a novice welder, my finished joints have a lot to be desired. Have any of you ever done such a thing or have experience with brazed steel manufacturing? As a side note, my car will likely weigh no more than 1,500 lbs, powered by a 100 Hp V8 flathead attached to a T5 and Model A rear diff.
    loudbang likes this.
  2. G-son
    Joined: Dec 19, 2012
    Posts: 664

    from Sweden

    Lots of bike and motorcycle frames are brazed, as well as some car frames. Done right it works well.
  3. Morris Bresnahan, from New Hampshire, built dragster chassis's in the 60's that he brazed together. I never heard of any of them failing, or coming apart.
    loudbang and Boneyard51 like this.
  4. dentisaurus
    Joined: Dec 11, 2006
    Posts: 388

    from Boston

    You'll need to prep your joints correctly to get a brazed joint to its full potential strength wise. Brazed joints are usually sockets for things like bike frames

  5. Brazing is usually lap joints or sleeved aka circumferential lap joint and sockets. They use it like glue.
    Butts and fillets might not be as strong as the parent metal or a welded joint. You’ll need plates and clips on those
  6. 49ratfink
    Joined: Feb 8, 2004
    Posts: 17,850

    from California

    I suggest learning to weld better. if I had a project where brazing might come in to play I would look it up on the interweb rather than ask random strangers who may or may not have any experience with what I was doing.
    1oldtimer likes this.
  7. redo32
    Joined: Jul 16, 2008
    Posts: 1,731


    Practice your mig until it looks good! I'll stick my neck out here & guess you have a flux core machine. Get a real welder and burn some wire.
    Boneyard51 likes this.
  8. Squablow
    Joined: Apr 26, 2005
    Posts: 14,542


    I don't think I would braze a frame together, that seems like a recipe for failure. Works good on tube frames because of how the joints are put together. I don't think it would be nearly as strong on a car chassis unless you had a really unique frame layout.

    Also, brazing is not easy to make look pretty and do properly. I think if you're really good at brazing, you would be equally good at gas welding. Gas welding gives great results when done right, and it's much more similar to brazing than MIG or TIG welding, if those are things you struggle with.
  9. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,602

    seb fontana
    from ct

    British Car, the TVR, in the 60's and later had a brazed tube frame. Suspension mounts and all..289 SBF engine. Don't think tube sockets but regular joints just like for Mig/Tig,Stick welding.. If YOU are confident in your brazing ability, go for ti..
  10. Jokester
    Joined: Jan 29, 2005
    Posts: 440


    I think if it was a good idea, everybody would be doing. I'm not seeing it anywhere.

    Welding is good.

    kevinrevin and Boneyard51 like this.
  11. bill gruendeman
    Joined: Jun 18, 2019
    Posts: 377

    bill gruendeman

    Are you talking about brazing with brass, some guys call gas welding with steel rod brazing. I was told in school that the brass when it’s hot flows In to the steels grain and could cause minor cracks
    Andy likes this.
  12. How in the hell do you think more than half the people wind up here? :D:p
  13. Yeah make their own definition up, it’s the law of the land today.
  14. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 1,917


    The English cars were furnace brazed together.
    loudbang and anthony myrick like this.
  15. Fordors
    Joined: Sep 22, 2016
    Posts: 2,986


    Cotton Werksman built a mid-engine, 6-71 blown 392 ‘27 T in R&C, might have been called Project 200(?). Independent front suspension, ‘glass body all held on a brazed space frame. He used a specific brazing rod to guarantee strength.
  16. Pop Chevy
    Joined: Jan 20, 2020
    Posts: 17

    Pop Chevy

    I don't recommend brazing a frame together. For the last 23 yrs I been doing antique Harley Davidson frame repair and restoration. All Harley frames up till 46 were brazed together. I have repaired many broken frames of this vintage. These frames were furnace brazed , slip fit and sometimes triple butted. Still broke ! When the engines became more powerful (Knucklehead -Panhead) Harley switched to stick welding (1947 on up). Any repairs I did I used TIG and my repairs would look like brass after paint. Never had one brake. The newer Panhead frames (48) didn't brake unless they were really beat on. Something to think about. I would never braze a car frame and gas welding while very strong would require a LOT of heat. My advice is to go to a local tech school and take an evening welding class. you can learn a ton and cheaply too. Good luck-have fun
    And BTW tig welders a very cheap now and it's just like brazing !
    427 sleeper, jaracer, Hnstray and 2 others like this.
  17. irishsteve
    Joined: Jan 10, 2017
    Posts: 829


    Anyway you look at it a steel weld is stronger.Theres a utube video on MIG brazing verse welding.Brass was good to about 45,000 to 50,000 psi,and steel weld was good to 70,000.Its not just us out there if our car fails.If the car takes out someone else due to a failure they will investigate what caused the failure.When they see brass the lawyers will have a field day with you.Its the way of the modern world.
    1-SHOT likes this.
  18. nochop
    Joined: Nov 13, 2005
    Posts: 1,729

    from norcal

    KoolKat-57 likes this.
  19. chevyfordman
    Joined: Oct 4, 2008
    Posts: 853


    Listen to Cody on Weldingtipsandtricks on YouTube, he will definitely show you what to do. He improved my tig welding by 75% with just 3 tips and its been easier ever since.
    catdad49 and KoolKat-57 like this.
  20. bchctybob
    Joined: Sep 18, 2011
    Posts: 2,500


    If I were you I would carefully fit and tack all of the frame members and high stress mounts and take it to a competent welder to have it TIG welded. You will be time and money ahead. If you want to braze some visible parts to capture the old time look experiment with non-critical stuff like headlight mounts, radiator supports and the like.
    Happydaze and dirty old man like this.
  21. larry k
    Joined: Feb 23, 2009
    Posts: 320

    larry k

    When you weld steel you are melting 3 pieces of steel together , when you braze steel you are bridging 2 pieces of steel with brass . It ain't a good choice !!!!
    belair, treb11, reagen and 1 other person like this.
  22. Stick weld it using a pre '64 buzzbox. That would be traditional!
    chop job, jimgoetz, loudbang and 3 others like this.
  23. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,008


    Hunt some old wire coat hangers and be traditional and gas weld it together.
    A guy in Phoenix built a complete big block altered that way back in the mid 70's.
    Avoid those plastic hangers, they smell really bad when you put the torch to them. :p and they are hard to get a good looking bead.
    belair, bchctybob, catdad49 and 6 others like this.
  24. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 1,917


    That’s not flux on the fuzzy ones either
  25. RJP
    Joined: Oct 5, 2005
    Posts: 1,654

    from PNW

    They gas weld air frames in planes. So it's gotta work. No curb to pull over to up there.
    loudbang and seb fontana like this.
  26. Clik
    Joined: Jul 1, 2009
    Posts: 1,869


    Many car frames used rivets for attaching crossmembers, spring hangers, etcetera. Dump trucks still use this method. Very strong and more crack resistant in many cases than welds.
    chop job likes this.
  27. Ziggster
    Joined: Aug 27, 2018
    Posts: 585


    You gotta love the HAMB. Of course I'm reading up on the subject. My Hobart is a gas machine, but my issue is I just can't see most of the time. Not sure if if is me, my helmet(s), or just the lighting. I have thought about taking welding classes for some time, so maybe I should this year. Brazing is not gas welding, but that is the other issue with even MIG. Without a fixture, things WILL twist and warp which not what you want or need in a frame. I was at the local welding supply shop, and they had a TIG advertised for CAN$1200, but I need to research some more about it. I like the idea of the frame being TIG welded. Rivets would be kinda period correct and cool looking, but I'm clueless about how to go about that. I'm fairly positive a brazed joint can be good enough, but as mentioned, this is a safety issue, so I'm not taking any chances. What is amazing is that it seems in the USA anyone (think of Diesel Brothers, Vegas Rat Rods, etc.) can modify anything with or without the requisite skills and knowledge and just go and drive it on public roads. So when taking about safety and hot rodding, who is the final authoritative judge on what is safe and what is not safe?
    bchctybob likes this.
  28. Dang....o'Jesse where are dad's friend in the Air Force....he could weld anything....I kept breaking my springer forks on my bike wheeling all the time....after the last time he mended it - sure it was brazed....only bent a guys need a picture ?
    G-son likes this.
  29. 31Apickup
    Joined: Nov 8, 2005
    Posts: 2,316


    11 ga, you should be able to gas weld that, it’s be good practice. Get some proper welding rod. The quality of hangers isn’t what it used to be.

    Sent from my iPhone using The H.A.M.B. mobile app
    Lost in the Fifties likes this.
  30. patterg2003
    Joined: Sep 21, 2014
    Posts: 622


    A frame is one part of the car that is best to hold its integrity. One option would be to cut, fold, and bevel edges so that at all the parts are ready to weld and clamp them in position then have a professional welder weld it up. If the work is properly prep'd and the welder is competent the cost should be an hour or two for a good welder. Likely less expensive than trying to purchase equipment plus the cost of gases & materials to experiment long enough to be competent. It would also be good to make similar joints slice them and do bend tests to see how good the work is if you go with brazing. We built an airplane with a 4130 steel fuselage and had to make test pieces to satisfy the inspector. The 4130 was bent back and forth and failed outside the welds and heat affected zones. If the brazing fails in the brazing then it may send you in another direction. Its for your own confidence in the quality of the joints.

    I had a boat trailer that I needed to modify so I made up all the pieces, bevelled the mating parts to get a good V weld, cleaned all the surfaces to be welded then clamped everything in position for welding. I took the trailer over to a local welding shop and when I went to pay the owner, he said it went fast. He charged me for an hour of shop time. He said it took less than an hour as it was well prepared and all the welder had to do was burn rod.
    bchctybob likes this.

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