Under Engine Crossmember Replacement?

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At some point, I'm going to be replacing the engine crossmember in my car and would like input from any of you who have experience with this. I want to know if it's necessary to weld in a brace between the lower shock towers/control arms before cutting the crossmember loose from the rest of the car?

I've searched the forum and see that it's been done both ways. I guess the first thing I should do is get out my homemade Tram and see if it's going to need some tweaking. I've got the engine out right now but anxious to put it back in....planning to pull it again fairly soon to swap cams and the idea was to do the cross member at that time.
 
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Yep, the #1 crossmember is your workhorse. I believe the one between the shock towers is more for steering geometry stabilization. So with the engine out you should have no problem with frame geometry going out if the rest of the car is solid.

Always measure before welding to make sure though!

Kcmash
 
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Yep, the #1 crossmember is your workhorse. I believe the one between the shock towers is more for steering geometry stabilization. So with the engine out you should have no problem with frame geometry going out if the rest of the car is solid.

Always measure before welding to make sure though!

Kcmash
Which one is considered the #1? Is that the strut rod crossmember?
 
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Yes. The core support is farthest forward with the front, or #1 crossmember about 6 inches behind it. That front crossmember is where the strut rods attach, and it is very stout. Engine crossmember is also very stout and kind of a pain to replace, but it's very doable. If the engine is out and front crossmember is attached, R&R of the engine crossmember should not require any additional bracing to keep things in place.
 
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How are you planning to weld it in? Plug weld or using a spot welder? I plan on replacing both of my cross members due to the previous owners running over a drainage culvert and was considering buying a small spot welder just for the job. Don't know if the metal is too thick for the spot welder.
 
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If you are not going stock you might want to look at AJE.

they now have a 71-73 part number.

click on the 1970 must and select 71-73

 
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How are you planning to weld it in? Plug weld or using a spot welder? I plan on replacing both of my cross members due to the previous owners running over a drainage culvert and was considering buying a small spot welder just for the job. Don't know if the metal is too thick for the spot welder.
I'll be using a MIG welder. Looks like you can drill the welds completely through and end up with accessible holes to plug weld.

I would not recommend a small (or even a large) spot welder for something critical to the structural integrity.
 

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I'll be using a MIG welder. Looks like you can drill the welds completely through and end up with accessible holes to plug weld.

I would not recommend a small (or even a large) spot welder for something critical to the structural integrity.

+1 to this. While spot welding seems like a great way to make clean repairs, the home restorer is never going to be able to reproduce a weld remotely the same strength as a factory spot weld. The hand held 120V/220V units sold through various outlets are not capable of the job at all.
 
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