Frame rail welding question?

[toddscharger]

I have to replace/(or splice in a new aft section) the right rear frame rail on my 70 Charger. Has anyone done this, and if so do you have any pictures that you could share?
I would also like to know wether a 115vt MIG welder (Lincoln, Miller, Hobart, etc.) would have the power to do the frame repairs or would I have to get a 230vt unit?
Thanks, Todd

[Sweet T]

A 115 should do it without any trouble.  I've had all sorts or repairs done to the rear of me car, basically everything. We used a Hobart Handler 135.

[Chryco Psycho]

I agree the thickness of the frame rails is well within the capabilities of a good 110 mig 

[moparguy01]

a 110 is adequate for the rails. if you look at them you can see they really arent very thick metal at all. Just crank up the heat to make sure you get real good penetration.

[lilwendal]

Typically its only the last 14 inches or so of the rear frame rails that experience serious rust issues. The car I'm doing now i spliced the last 2 feet of frame rail in.  The previous car I replaced the entire frame rail.  Doing the last 2 feet splice is definetly an easier way to go and if you take your time can be impossible to notice after. Unless you have issues with the frame elsewhere do the splice.  The key is making good measurements prior to your cut out.  First verify the frame rail in the car is straight.  No prior collision issues. The charger coronet shop manual gives frame dimensions to verify your original frames.  Next  I get the car in the air with 6 jack stand supporting the sub frame in various locations forward of the planed cut.  Then start measuring.  Measure frame to frame, drip rail to top of frame, bottom of frame to floor.  Do this in several areas.  I use a sharpie and right my numbers right at the measuring points.  And here a tip. Use a plumb bob.  Place masking tape on the floor below the rail and drop the bob through fixed points like spring shackle holes and bumber bolt holes.  These will help you maintain left and right, fore and aft position.  When your sure you have adequate measurements cut the frame well forward of the rusty areas.  Try to pick a good spot to cut.  Heres my method. There is a drain hole on the lower surface of the frame about 2 feet froward that I cut about 3 inches fwd of. Then when the frames off the car I'll cut the old frame 2 inches behind the hole.  This gives you a 5 inch section of frame with the drain hole in the bottom.  Mark the piece for inboard and outboard sides and forward. Then slice the piece in half front to rear through the drain hole on the bottom.  This gives you the lt and right side of the frame rail. Now to your donor frame.  I always use an original donor frame so I cant vouch for the match up with the repo frames but if they are like all the other repo sheetmetal then I expect a little more work would be involved.  The original frame rails were all stamped from the same die and are identical.  So now your 2 halves cut from your old frame become a template for the cut line on the donor frame.  Line the drain holes up and be sure you have the template in the right direction and transfer you cut lines.  Now when your done cutting the donor frame it will be a perfect fit onto the remaining frame with little to no trimming.  Then break out the welder and get buisy.   This method has never failed me.  If you wanted additional strength at the joint the same 2 halves that were your templete can be trimmed and placed in the inside of the frame to act as an internal doubler.  I've never actually found that necissary though.  The car That I just spliced, the frame rail is still in bare metal  and it is near impossible for me to find the joint and i'm the one who did it.   I'll try to post some pics tonight.

[bill440rt]

If you have any other doubts, you can always visit the I-Car website for archives on how to properly section in a frame rail.

According to I-Car, they recommend using a sleeve in the inside for added strength. It's basically a fabricated "U" channel that fits inside the joint where you are sectioning the rail. They also suggest offsetting your sides. One side is longer than the other & vice-versa. Kinda like a zig-zag.

[lilwendal]

That I car site is cool.  That sleeve your talking about is basically the internal doubler I mentioned.  Again, If your a compitent welder the doubler is not needed.  Your weld will be as strong or stronger than original.  I've seen other frame splices were they simply cut reliefs into the end of the doner frame to collapse the end a bit so that it will slide into the matting frame an inch or 2 but I've never really cared for that method.  I'm kinda anal about my metal work.  All joints are flush welds. All sheet metal gets stitch welds. That goes for floorboards and other unexposed areas.   Went over to a friends the other week. He was finishing metal work on a V code 6 pack 70 challenger.  There were scab patches welded all over the thing. Floor boards, inner wheel wells, The fire wall. True none of this will be seen when the interios assembled but I believe that type of car deserves more attention. Really is no reason that a floor board cant be over lapped but it  doesnt take that much longer to make it right. Kinda cool when all the metal works done and you can spin the car on the rotisoire and have a hard time picking out the repairs.
Back to the frame rail.  Remembering that these are unibody cars the attachment of the frame to the rear cross member and to the trunk floor are all equally part of the structural integrity equation.  It is important that these are good welds also.

[Mike DC]

 
I've done this job before.  I also like to put a sheetmetal "sleeve" of some sort into the inside of the framerail in the area of the splice.

It's very important to do a totally professional welding job on this operation.  But at the same time, the framerails are basically just sheetmetal like the rest of the bodywork on the car.  They're a little thicker, but the difference is nothing more than a change in settings on the welder.  The principles are the same for butt-welding on the framerails as they would be for trying to butt-weld patches in the outer skin of the car.

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Also: 

Just because the framerails are load-bearing, that doesn't mean you need to go overboard with it.  If you repair a framerail into being way TOO strong in a certain area (unlike the way the factory originally built it), then that's not always good for the crash & stiffness characteristics of the chassis either.

I don't think this particular case (the rear ends of the subframe rails underneath the trunk area) is a big risk of over-beefing problems or anything.  But I'm just making a comment about working on subframes in general.

 

[mopar0166]

Can you use flux core on a frame rail ?

[nvrbdn]

 

[Indygenerallee]

The rear frame rail section I am using on my driver side of my 69 goes to the bend where the rail turns to go down (directly above axle) the replacement rail has a lip that fits inside the existing rail that way you have more material to weld on the inside. And yes a 110 Mig will do the trick I would not weld a continuos bead though, do it as if you were welding a quarter on, I would jump from one side to the other and only do about 1/2" bead at a time and quench with water after each weld. you can distort the frame rail with too much concentrated heat.