Arc or Gas welding suitable for chassis repair

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Dumindu
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Arc or Gas welding suitable for chassis repair

Post by Dumindu » Fri Jan 24, 2020 11:13 am

My car is a Toyota Tercel 1987 DX Wagon.

I have found some wide apart bottom chassis bars. One that connects the rear lower arm.

Perhaps they may have disconnected from the interconnecting longitudinal main bars. Or near to disconnect. Still cannot be clearly visible due to undercoating. Will scratch it and see.

If found disconnections, what is the best way to repair?

Continuous metal connection with Gas welding or apply dots with a arc welder?

teranfirbt
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Re: Arc or Gas welding suitable for chassis repair

Post by teranfirbt » Fri Jan 24, 2020 11:36 am

Either can work, choose the one that you are more comfortable with. If you are making welds to hold panels on you will want to make a series of small welds with an arc welder. This will prevent panel warp. If you are making structural welds for suspension mounts and such you will need to make continuous welds that have good penetration.

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Petros
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Re: Arc or Gas welding suitable for chassis repair

Post by Petros » Fri Jan 24, 2020 3:55 pm

gas welding on steel body/frame is usually easier and requires less costly equipment. gas welder has other uses too, brazing, heating, cutting, etc. arch welder is only good for welding, and it takes skill and experience to arch weld thin sheet metal parts. Either will work if you only have one available, be careful to do not blow big holes in thin sheet metal, get all the paint and oil off the parts before you try to weld them.

All body welds should be done in a "stitch weld" style, short 2cm welds along the seam with perhaps 4 to 6 cm between them. this will prevent warping, and allow the frame to flex without cracking the welds
stitch weld.jpg
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'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Dumindu
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Re: Arc or Gas welding suitable for chassis repair

Post by Dumindu » Fri Jan 24, 2020 8:18 pm

Thank you all for your valuable advice.

I have a arc welder and I can even weld metal sheets without making holes.

I want to confirm that since arc welded spots are not strong as gas welded spots, whether would that can bear the strength needed for frame. I arc welded a metal handle for my household axe. Within few days handle was broken apart when I split timber with it.

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LowBuckCanuck
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Re: Arc or Gas welding suitable for chassis repair

Post by LowBuckCanuck » Sat Jan 25, 2020 12:22 am

Allow me to interject.

Oxygen acetylene welding or "OAW" is NOT stronger than a proper arc weld. The maximum tensile load of an OAW joint is 45000 psi, An arc weld is usually between 60000 and 80000 psi depending on the process and the filler metal used.

In your case, I would recommend an arc weld of any process (SMAW, GTAW, GMAW, etc.) over OAW. Most, if not all of the common arc welding processes perform better out of position than OAW, which in important when making repairs underneath a car.

A few tips:
-When arc welding, cleanliness is next to godliness
-Joint design is critical. Try and get as much weld to metal surface area as possible (likely why your axe failed)
-Practice plenty before doing your actual weld, dial in all the machine's settings
-Avoid sharp edges in the finished weld, i.e. stress risers
-If you think the metal to be welded is clean, clean it again.

Feel free to ask any questions, welding is something I am quite knowledgable about.

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Dumindu
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Re: Arc or Gas welding suitable for chassis repair

Post by Dumindu » Sat Jan 25, 2020 12:28 pm

Thank you for your comprehensive advice.

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Re: Arc or Gas welding suitable for chassis repair

Post by Petros » Sun Jan 26, 2020 12:54 am

Your arc weld would also be much stronger and more reliable if you can heat up both sides of the metal to be welded, so you get more uniform penetration. Perhaps after cleaning the metal, heat it up with a blow torch or high temp heat gun, than do the weld. it would make a more reliable weld.

I once watched a skilled welder repair a big(costly) heavy cast iron part by heating it to near glowing red, and than welded the damaged part back together. than he annealed the welded part by heating it up again to glowing red, and allowed it to slowly air cool. This special drilling head assembly was broken into several pieces (it was used to bore underground tunnels, they hit a steel pipe that was not on their underground maps). he had to build a fire brick oven larger enough for the auger head to heat it up. The part was stronger when done than before it was broken.

likely same on your ax, the heavy head and thinner handle (I assume it was a pipe) did not make a good bond because of the temperature difference due to the difference in metal thickness. if you heat both in an oven to as high a temp as you can get, the weld would be more reliable. concentrate more of the "heat" into the heavy ax head. heat in the oven again after the weld for over an hour, than allow to cool.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Dumindu
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Re: Arc or Gas welding suitable for chassis repair

Post by Dumindu » Sun Jan 26, 2020 6:23 am

Thank you again.

I have a simple butane torch. Would that enough if I heat with it?

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LowBuckCanuck
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Re: Arc or Gas welding suitable for chassis repair

Post by LowBuckCanuck » Sun Jan 26, 2020 12:04 pm

Dumindu wrote:
Sun Jan 26, 2020 6:23 am
Thank you again.

I have a simple butane torch. Would that enough if I heat with it?
Any sort of pre-heat will aid in penetration, as well as chase moisture out of the joint. I think you'll be good.

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Petros
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Re: Arc or Gas welding suitable for chassis repair

Post by Petros » Mon Jan 27, 2020 6:08 pm

yes, as stated, any preheat will be helpful.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

Theodore K. Kitts
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Re: Arc or Gas welding suitable for chassis repair

Post by Theodore K. Kitts » Fri Aug 21, 2020 9:59 pm

i think both kinds of welding are equally suitable for this purpose. although, each has its own in depth complications. you should choose the best available thing to you.

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