Welding After Foam

[Sid_E46]

So my rear subframe mounts have the cavity foam in them but I found a crack on one mount while prepping for my vince bar. Would it be possible to still weld the crack? Do I just spot weld it essentially and not let too much heat into the metal?

[bigjae46]

I think you’ll set the foam on fire. Maybe test it and have someone on stand by with a fire extinguisher?

Check the foam SDS which should have more info.


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[Rkymtnrider]

Or use the epoxy kit?

[Sid_E46]

Or use the epoxy kit?

I am using the epoxy kit. There is a crack I have to weld up first though.

[Sid_E46]

I think you’ll set the foam on fire. Maybe test it and have someone on stand by with a fire extinguisher?

Check the foam SDS which should have more info.


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I ended up just doing a very small area at a time and letting it cool down after every few millimeters. Also had a fire extinguisher ready to go.

[bigjae46]

I ended up just doing a very small area at a time and letting it cool down after every few millimeters. Also had a fire extinguisher ready to go.

Good deal. I wonder if that weakens the reinforcement from the foam. I know it does in composite sandwich structures.


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[Sid_E46]

Good deal. I wonder if that weakens the reinforcement from the foam. I know it does in composite sandwich structures.


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I do have plates and a vince bar now so it should be fine.