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Discussion Starter #1 (Edited)
Alright, I spent the last year and a half now restoring a 1968 Ford Mustang Coupe. I've had a fair share of welding experience with this being my first project and all, but I never did frame work before.

To the point, I saw on someone's post that they used 2" x 3" x 1/8" rectangular tubing and used it as a super strong subframe connection in place of the front subframe rail. So I got it in my head that it would be a great job for me to try out since I always wanted to extremely solidify my car. Even though for my little experience with frame engineering I should have just used a set of weld on subframe conenctors from somehting like TCP, or Global West. Anyway, I did not brace the car and just went at cutting out the front subframe rail that is attached to the floor pan only on the passengers side.

I then cut the path out of the floor pan for the 2" wide steel beam to fit into the car flush with the rear frame rail. In result, I wind up getting the this 2" x 3" Beam all the way to the back of the car and spaced off from the rear frame rail by like an inch or so. Anyway, my biggest concern is that during the time that subframe rail was removed and the transmission cross-member remains unconnected to it, as well as the floor pan being cut, if there's a chance my car could have warped a little.

I mean I have a hardtop coupe and not a convertable, so I am hoping that the roof braced the car somewhat in the time of a few hours I was ignorant before realizing I should at least shove a 2" x 4" in the door jam to prevent it from folding into itself.

Now after everything was cut up, I slide the beam into the slot on the front frame where the subframe rail once was. Now my worry is if I weld the beam now to the frame if it will snap at that cut line. I know I am going to need to rent at least a 150 amp mig welder, because the one I have is only a 90 amp gasless mig that is unable to penetrate the 1/8" thick steel tubing. I realize what I should have done in the first place is just cut the bottom out of the subframe rail and slide the beam right up into it. Then I could butt weld it to the subframe rail at the bottoms, and as well to the cut out floor pan.

I am very worried for my pride and joy.
 

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Welcome to the club Goodman,

First off, I have found that these old unibodies are pretty flexible in any state. Even with the Global sub-frame connectors I have welded in, I can still notice by eye some flexing when I jack up a wheel on my 67.

I don't think you need worry about what you have done so far. Really all you have done is remove the last section of the front sub-frame rail. This section has more to do with keeping the front portion (firewall forward) of the unibody from folding upward. Don't get me wrong, every little ounce of steel helps, but the real strength lies in the rails. Body twist, however, is really a combination of it all - sheet steel and the rails. Maybe more so in the sheet steel (roof, pans, firewall, etc). I would consider welding the sub frame and connetor back into the car as the car would normally sit. Not sideways like your photo shows on a rotiserie. The sag from gravity could pull to one side and cause undo panel alignment issues.

As far as your butt weld concern - Butt weld it as planned, grind the weld flush, overlay some additional 1/8 plates in and you should be good.

Let's see what others have to say, I'm no frame expert, but unless you see buckling of panels or spot welds popping free on there own - I think you're doing fine.
 

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Discussion Starter #3
Thanks for the support. Just to clear thinks up, the picture I attached is someone else's project car that I used as a reference to explain what I was talking about. It was this exact picture that inspired me to go ahead and take on this tuff challenge.

My car looks like this also, except it is not on a rotiserie, it is on floor jacks. So far the beam is welded to the floor pan in certain spots, and the transmission crossmember that is supposed to connect to the subframe rail is currently not welded to this beam yet. Also for now, I only have the beam tack welded to the frame rail along the cut line I showed in the attached diagram.

I did not touch the driver's side yet at all, which I am going to try and match up evenly to the passenger's side once i complete it.

But also, like you said, I am going to slide the beam up into the subframe rail with removing it, so I can keep the car following it's original shape and design so nothing else will be thrown out of allignment on the car.

It just sucks that I did not think of this before hand because the passenger's side does not do that, and could potentially warp on that side.... So much for my girlfriend now....
 

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No worries Goodman, hope I have helped. I know how you feel. My 67 gave me the go around with replacing most of the floor, the tail panel, sections of the rear frame rails, and both quarters.

One thing you should consider, keep the doors on or at least put them on from time to time while doing your frame work. They will tell you if the chasis is moving on you. You can expect them to show signs of twist/sag by how the gaps at the jam, rocker, and firewall change. Keep in mind that these gaps change even when you jack up the car to change a tire. Not so much with sub frame connectors, but certainly without them. You don't want to weld 'er up solid to find out later that the doors fit funny.
 

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Discussion Starter #5
Alright, well I started welding the beam to the floor pan. Just the only problem is, with my gasless 120v 90 amp mig welder using .035 tip and wire is welding really sloppy bumpy welds rather than flat streming welds.

So what is happening is, it is welding up real strong but there are very small pin hole like spots in the weld. For example on a part where the floor is welded to the extruding beam in the rear footwell, looking at the weld I can see that there are pinholes of light shinning through from underneath the car. The weld itself looks really sloppy with bumps everywhere never mind the actual spatter.

So what is happening is I am feeling I am not getting a sealed weld but a strong one no less. I'm worried this is going to cause leaks into and under the carpet when I put in a new one.

Is there anyway to fix this problem? Is there a sealer or filler to put over the weld to prevent water from getting into these pin holes? Should I go back and find all these little tiny holes and weld into the weld? What is the smarter and rust preventing way here?
 

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I get the same thing alot with my 110 FluxCore welder. Prepping the weld area is the best thing you can do to avoid it. Make sure their is no rust, oils, paint/primers in the area and they make a spray thay helps eliminate splatter. I have also found that setting the heat as high as you can on the welder will help so long as you don't get it too high and just melt the snot out of everything.

My 67 has most of an 11 pound roll of welding wire in it (if not more) and almost every seam has been laid down, ground flush, and hit again to fill the holes and clean up the buggary nature of fluxcore welding. Welding upside down is the worst and I haven't found much to make it perfect. I also put my welds down for any frame work and the floor pans in a stitching pattern. An inch here then skip some and lay down another inch there and so on. Then wire brush the slag and put down more stitching. Once it looks complete I hit it with a grinder and ultimately find more holes. Like you said, the welds are solid and sound, just kinda unsightly, hince the extra efforts for cosmetic purposes. Stitching helps avoid splatter build up in the immeadiate weld area which really adds to the bumpy texture. Splatter stilll builds up, but about the time that it does you skip 2,3 or 4 inches and start a new stitch where it
is nice and clean. Patience and persistance! The results will be good.

3M makes some seam sealers that come in a caulk tube, Napa carries it. There are two types, one for interior and one for exterior. They feel, act, and smell the same, but one specifies NOT TO BE USED in the interior. Propbably has some nasty fumes to avoid? I sealed up as much of the pin holes as my patience would allow and seam filled over most of the welds just to make it prettier.
 

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Discussion Starter #7
Wow thank you,

That gave me a lot of information I needed. I'm glad someone else must have been having this problem. I am going to have to grind all those bumps down flush then see where the holes are. From there I'll weld them in, and then grind them flush again. Seems like a lot of work, but if thats the way to do it then it must be done. Thanks again for the tips.
 

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Discussion Starter #8
You know there is someone that really just wants to put me down. Has no consideration to my hard work, my stress, and my concern for my car. I feel as if those of us that work on these cars, go out of our way to restore them, we put our lives and soul into restoring them so we can say we did that. So we can drive the car that is, "you." Someone I know really cannot see that in me and just loves to put me down.

This person mentioned that what I did was completely wrong and that my car definitely tweaked itself after I cut off the subframe rail attached to the floor pan. Looking at my car however I do not see any distortion. I even did what you told me to and closed the door on the car and saw no distortion in it's fit. It closed perfectly when I shut it, and the contour lines all lined up with the body as well at the door jams. The lines look horizontal to the door at the bottom where it meets with the rocker panel as well.


So now I am scaried again because this guy literally hates me and wants to make me feel regretful like I already did before talked to you. If the car did so happen to permanently warp about a quarter of an inch, in what so ever direction, how much of a difference will that make in the car's driving saftey and or performance?


I figure the only way I am going to feel confident with my car again is if I finish up this nightmare subframe disaster on both sides of the car and take it out for a harsh driving test. Maybe I can do some sharp turns in an open lot and have a back seat passenger look at the beam welds as I do them to see if there is anything going wrong. After a while of driving the car I could go look at the frame from underneath the car and see if the welds snapped or distorted somehow. I really am worried the car is going to drive slanted or sideways from being, "Warped," in some way like that evil guy told me.
 

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I bet that a-hole drives a prius. Dont worry too much about it. Like Sick467 said, if the doors line up, she will be just fine. Doors are the biggest and easiest signs to show frame warpage. If you have trouble with your welder getting the materials to flow together, try using a cheapo butane torch to warm up the work area just before you lay a bead down. Even warming the metal up just a couple hundred degrees will make for much prettier welds. Good luch to you and dont worry about that guy. Some people just truly dont get the cost of sweat and love that guys like us put into our cars.
 

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The car should be fine ignore them,Once you get the car a roller take it to a body shop let them check to see if its straight.Its a old unibody car over the years things move so if its not straight its probably nothing you did.
 

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I bet that a-hole drives a prius. Dont worry too much about it. Like Sick467 said, if the doors line up, she will be just fine. Doors are the biggest and easiest signs to show frame warpage. If you have trouble with your welder getting the materials to flow together, try using a cheapo butane torch to warm up the work area just before you lay a bead down. Even warming the metal up just a couple hundred degrees will make for much prettier welds. Good luch to you and dont worry about that guy. Some people just truly dont get the cost of sweat and love that guys like us put into our cars.
Well said. "Drives a Prius" HAH! lmao! You might also try to reduce your wire speed to keep the spatter down. The first time I rebuilt my 65 ( with oxy-acetylene), my buddy looked at the bare body and said, "No way." Sounds like the guy's jealous. Probably don't have the cajones to do it himself. Hang in there.
 

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I bet that a-hole drives a prius. Dont worry too much about it. Like Sick467 said, if the doors line up, she will be just fine. Doors are the biggest and easiest signs to show frame warpage. If you have trouble with your welder getting the materials to flow together, try using a cheapo butane torch to warm up the work area just before you lay a bead down. Even warming the metal up just a couple hundred degrees will make for much prettier welds. Good luch to you and dont worry about that guy. Some people just truly dont get the cost of sweat and love that guys like us put into our cars.
Thank you for your comment 67 moneypit, look like my picture. I must be the A-Hole that he got the pics from one off my post. It is nobody fall if he cut up is car without bracing it.


goodman, get a frame diagram chart for a 68 mustang, measure from rocker to rocker. if it is off use a bottle jack and a couple 2x4 to bring it back and brace the car using 1x1 square tubing before you weld any thing.

Here a couple pics You could have used too and a 65/66 mustang from diagram to give you an idea
 

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Well said. "Drives a Prius" HAH! lmao! You might also try to reduce your wire speed to keep the spatter down. The first time I rebuilt my 65 ( with oxy-acetylene), my buddy looked at the bare body and said, "No way." Sounds like the guy's jealous. Probably don't have the cajones to do it himself. Hang in there.
HaHa, I dont drive a prius, I ride a Moose from my igloo to work.
 

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Zr2 - I was talking about his "buddy" that keeps putting him down and telling him he is doing a terrible job. That guy is an a-hole. I may be mis-reading your post, but it seems like you are taking offense to what I said. If you are, I apoligize for the mis-understanding. My statement was directed towards the author of this thread and was simply to remind him not to worry about the guy that keeps talking down to him and yet probably doesnt have the nads to go through with a project like this himself. I think that goodman and rodbender understood what I was saying. Again, apologies for any mis-understading.
 

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Probably don't have the cajones to do it himself.
Very true, bender. Seems like the ones that would never dig into a project like that are always the ones who have the biggest opinions of how it should or shouldnt be done.
 
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