Unknown material found
 

Hi, I just completed sandblasting a frame from a 72 c10 and where the rear coil springs mount to the frame there is some rust through. I thought I could just build the few holes with some weld but what I thought was metal is not. Does anyone know what this filler material is between the frame and spring perch, a magnet will stick to it and it's very brittle. I've repaired the holes by welding a 1/8th thick plate over the spring perch but I'm now concerned about this filler material that is falling out, hope I'm making sense.

Re: Unknown material found
 

Permatex 25909 Liquid Metal Filler that meets all the description you gave. I found it online here Amazon.com: Permatex 25909 Liquid Metal Filler,... but see it in my local autoparts store all the time usually wrapped part way around a penny hanging from a chain.

Re: Unknown material found
 

If it's between the spring perch and the frame my guess is that the "filler" is road dust - gravel, grit, sand, etc.

Re: Unknown material found
 

Yes there was gravel,grit and sand but this stuff is solid and can be picked up with a magnet, shatters if you hammer on it and explodes if you hit it with a mig welder. I found it between the halves of the trailing arms as well and it seems to have swelled up and pushed ( bulged ) the c channels between the rivets.

Re: Unknown material found
 

Sounds like some PO couldn't find his JB weld and jammed some permatex in as a "suitable" repair

Josh