Welding strut rod cross member

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Joined
Aug 14, 2014
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Location
Madison, WI
My Car
1971 Mach 1 w/408C stroker
I am replacing the strut cross member due to it being bent 1/2" further back on the passenger side. A few years ago I measured the squareness of the frame and it was good. I will remeasure now that the engine is out. I have the Dynacorn replacement so I would like to know where the correct welding points are. Are there any pictures that will show the weld locations? I am assuming that the edge of the tabs are welded to the front rail, but I would like confirmation. I think I could add holes in the tabs for plug welds.

Also, could someone measure the distance from the engine cross member or from the stabilizer bar bracket to the strut cross member? Thank you.

 
I am replacing the strut cross member due to it being bent 1/2" further back on the passenger side. A few years ago I measured the squareness of the frame and it was good. I will remeasure now that the engine is out. I have the Dynacorn replacement so I would like to know where the correct welding points are. Are there any pictures that will show the weld locations? I am assuming that the edge of the tabs are welded to the front rail, but I would like confirmation. I think I could add holes in the tabs for plug welds.

Also, could someone measure the distance from the engine cross member or from the stabilizer bar bracket to the strut cross member? Thank you.
Tony,

The correct information for the weld placement and quantity are defined in the Weldment and Sealant book from Jim Osborn Reproductions.  I would put a screen shot here, but I cannot afford any copyright trouble.

Definitely plug welds, and NOT for the amateur.   It requires some very robust welding there.  Is your old one out already?  How did you cut the welds on that?

kcmash

 
I am replacing the strut cross member due to it being bent 1/2" further back on the passenger side. A few years ago I measured the squareness of the frame and it was good. I will remeasure now that the engine is out. I have the Dynacorn replacement so I would like to know where the correct welding points are. Are there any pictures that will show the weld locations? I am assuming that the edge of the tabs are welded to the front rail, but I would like confirmation. I think I could add holes in the tabs for plug welds.

Also, could someone measure the distance from the engine cross member or from the stabilizer bar bracket to the strut cross member? Thank you.
Tony,

The correct information for the weld placement and quantity are defined in the Weldment and Sealant book from Jim Osborn Reproductions.  I would put a screen shot here, but I cannot afford any copyright trouble.

Definitely plug welds, and NOT for the amateur.   It requires some very robust welding there.  Is your old one out already?  How did you cut the welds on that?

kcmash
Can you tell me how many plug welds per tab?

The old one still there, but one side has definitely been rewelded. The other side I am not sure if it is still original either.

 
I am replacing the strut cross member due to it being bent 1/2" further back on the passenger side. A few years ago I measured the squareness of the frame and it was good. I will remeasure now that the engine is out. I have the Dynacorn replacement so I would like to know where the correct welding points are. Are there any pictures that will show the weld locations? I am assuming that the edge of the tabs are welded to the front rail, but I would like confirmation. I think I could add holes in the tabs for plug welds.

Also, could someone measure the distance from the engine cross member or from the stabilizer bar bracket to the strut cross member? Thank you.
Tony,

The correct information for the weld placement and quantity are defined in the Weldment and Sealant book from Jim Osborn Reproductions.  I would put a screen shot here, but I cannot afford any copyright trouble.

Definitely plug welds, and NOT for the amateur.   It requires some very robust welding there.  Is your old one out already?  How did you cut the welds on that?

kcmash
Can you tell me how many plug welds per tab?

The old one still there, but one side has definitely been rewelded. The other side I am not sure if it is still original either.
View attachment 39402

View attachment 39403

 
I would make sure to use the biggest hole possible and make sure your welder is set for VERY good penetration. Maybe try some practice runs on a similar thickness material to make sure your welds are penetrating good. Good luck!!

 
On a 1971 you may find some odd welds. I think there was a recall where some 71’ cars were not welded properly there, so the fix was to lay a few beads at the dealership. If you research it a bit you should be able to find more info. I know my 71’ coupe was not welded like the shown in the guide.

 
I would make sure to use the biggest hole possible and make sure your welder is set for VERY good penetration. Maybe try some practice runs on a similar thickness material to make sure your welds are penetrating good. Good luck!!
Do you guys think that 1/2" holes would be enough?

 
My 71 was subject to the recall and has extra beads along the mounting flanges.

1/2" holes should be fine. As suggested, get some scrap of the same gauge and do a few practice runs.

 
My 71 was subject to the recall and has extra beads along the mounting flanges.

1/2" holes should be fine. As suggested, get some scrap of the same gauge and do a few practice runs.
Definitely. I will have enough scrap metal on the old strut cross member.

 
Can someone measure the distance from the engine cross member or from the stabilizer bar bracket to the strut cross member?
I could take measurements this weekend, but I thought it aligns with the front of the frame rail box and has an alignment hole on the bottom.  Look at the post of the weld detail.  One tab from the cross member goes across the front of the frame rail( 2 welds),  one wraps under the frame rail(4 welds), and one is folded back 90 degrees to run along the frame rail toward the firewall(4 welds).

Did I miss something?

kcmash

 
Can someone measure the distance from the engine cross member or from the stabilizer bar bracket to the strut cross member?
I could take measurements this weekend, but I thought it aligns with the front of the frame rail box and has an alignment hole on the bottom.  Look at the post of the weld detail.  One tab from the cross member goes across the front of the frame rail( 2 welds),  one wraps under the frame rail(4 welds), and one is folded back 90 degrees to run along the frame rail toward the firewall(4 welds).

Did I miss something?

kcmash
Yes, but I will have to make sure that the front of the frame rail is straight once I remove the cross member. I just wanted one more measurement point. I see that the oval hole is one of the measurement points from the frame diagram - I will have to try mesuring.

 
Finally got to weld the strut rod cross member. The straight measurements from the floor pan rail to the oval holes were the same, while the diagonal measurements were off by 1/2". I think this is not terrible. I welded the cross member in place with a very slight offset of the oval holes to partially compensate for this deviation. As a note, the tabs of the repro cross member are of different width, which threw me off for a while since I was double checking straightness measuring the distance from the stabilizer bar brackets to the edge of the cross member tab. Once I figured out that the tabs were not equal I measured to the oval holes.

As you can see the passenger side front rail is dented and the radiator cross member is not straight. I didn't feel that the radiator cross member was a critical element to be straight and didn't have the energy/time to replace it so I left it as it was. I drove the car as this for three years with no issues. I tested the fit of the radiator support brackets and it required a bit of persuasion on the radiator cross member side. You can also see that the bottom of the panel behind the headlights is dented and poorly repaired. I cleaned this all before the RustBullet coats. There was some surface rust on the passenger side, but now is all clean.

I practiced welding and settings on the old cross member to assure penetration. In total there are 11 plug welds per end so I expect it to be okay. I made the plug welds between 1/2" and 3/8" in diameter to be able to fit the plug welds per the weldment book.

A picture of how it looked before I started:



These pictures are after the welds were ground and the surrounding sheetmetal was prepped for paint. Painting is tomorrow.







 
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