Hot Rods Cracked sheet metal..repair or replace

On my 1939 ford pickup I am fixing the bottom of the inner door where the drain holes are. The door appeared to be hit at some point which caused the cracks.

what’s the consensus on welding the cracks versus replacing the metal in that area? I just tacked all of the cracks back together with my Tig and plan on drilling holes at the end of each crack then welding completely. or should I just make a patch for the area? The patch wouldn’t be overly complicated but I feel welding the cracks up would look better but I don’t know if it will hold up.

I’ve cut out the inner structure to repair the dent in the door skin and fix the mounting area for the bottom hinge.

 

My experience with cracks is that they work harden and don't weld that great. That and you need to top drill the ends of the cracks.

 

Definitely drill the ends of the crack. I find they often crack again next to the weld. My experience isn’t necessarily from hot rods- yet…

 

Cut the piece with the cracks in it out and replace the metal. If you just weld the cracks, you will probably be doing it again.

 

TIG should not “work harden” but MIG will, I’ve had more problems with metal fatigue and new cracks in old sheet metal after welding than anything else.

 

Cracks sometimes form due to a design issue.
Like the coupe cracks you see from a body flexing.
Just welding them doesn’t fix the flex. So they will often return.
like cracks in floppy fenders.
I’ve added structure to bodies to eliminate a lot of the flex. Plus boxing frames can help.

 

Those cracks tell me that the area is or was under a bit of stress. Cut the section out and put a new bit in but watch for door not fitting right after cutting. Check door fit before fully welding.

 

Wonder if welding those with a oxy acetylene torch would help stress relieve what's there ?

 

That would be my preference but most seem to sneer at oxy/acetylene welding these days.

 

Well I have something similar regarding coupe cracks on my ‘32 where the roof and 1/4 panel meet. I believe the car is an early production unit and the frame cracked and wasn’t repaired properly and along came the cracks..

I thought I’d just drill the ends of the cracks and weld it up. But then I thought about putting a reinforcement strip behind the area but others Pooh poohed that idea.

So what would be the correct way? Story to say Hi to Jack.

 

I believe the cracks are from being hit, not stress. I would weld it up and go.

 

I would say the cracks are due to when the door was hit. Seems like the safe bet is to cut out the cracked area and replace.

 

I think I’d weld them up and move on. No need to drill a hole at the end on sheetmetal. Preferably use a TIG if possible, but that goes for anywhere on sheetmetal.

Pay attention to the hinge area. I’m guessing you have cracks there too.

 

you would be correct

 

For a body, I’m not the biggest fan of overlapping exterior parts due to it possibly “shadowing” when eventually painted.
If the body cracked from a broken frame plus years of abuse and twisting then if you fixed the frame and possibly boxed it, sounds like the reason for the body cracks have been addressed.
I doubt many of us drive these old cars off road or across creek and river beds like the original owners did.

 

I don’t think anyone sneers at oxy/acet welding. They sneer at brazing. Not the same thing.

 

I personally would cut out the cracks simply based on how many there are. I'd find it quicker to make a full piece to replace the multiple cracks than to try to weld them all up.

 

The old guy that did body work on my coupe told me the corners are prone to crack. He reinforced the by bracing belt line to floor. Straight an angled. He said the flexing of the body allowed the cracking.

 

I had to repair multiple cracks in the fenders on my 41 PU. Mostly due to folks taking off the braces for some reason and allowing the fenders to flap about in the wind. I don't TIG, I need to learn but I can MIG so that is what I did. If the crack was sever and the area around it was weakened, I cut out a small section around the crack and add some nice new steel. It's only metal, you control it not vis versa.

 

Ive recently been learning how to Gas weld and 2 things

1: its WAY easier than I thought it was going to be.
2: if the metal has hardened and cracked Gas welding will anneal the steel.

just food for thought.

 

If that was me I'd weld up the cracks, good idea to drill a hole at the ends first but I wouldn't worry about them coming back, that door must have taken years of punishment to develop that much cracking, which is unlikely to happen again unless you have bad alignment issues at the hinge or pound the living hell out of the car.

 

I would agree if there were only a small crack or two in the area, but based on the number of the cracks, the length of some of the cracks, and the location of the cracks in his pic above, its pretty obvious the hinge is moving on the door frame. It is also pretty obvious that there has been some welding (and attempted welding) of cracks in that area previously. That problem of the hinge moving has to be addressed, simply welding the cracks on the outer skin is not going to fix the problem.

Every crack in sheet metal on these old cars has to be looked at individually to find out why the crack is even there. Some are caused by poor design, some by time, some by abuse, and some by neglect. Some cracks can simply be welded, others need to have a hole drilled at the end to prevent farther cracking, but others need something reinforced or braced. Those last ones might need some serious work to solve the cause.

Cracks in sheet metal are trying to tell you something. Without figuring out what the metal is trying to tell you, and simply welding up the crack gives you a very good chance of revisiting the crack to fix it again.