I have not fitted the front subframe in the shell for over 4 years and when I recently tried to fit it, I found that there was a significant change somewhere in subframe compared to the shell. The holes in the subframe front mounts did not line up with the holes in the front apron panel, the brace bar across the front of the subframe would not bolt on to the front mount plates, and the top of one the subframe towers was not quite fitting properly up against the bulk head. The subframe main spars (running forward from from top of the towers) had likely been damaged in transit while moving house a few years ago and it has gone unnoticed until now.
I don't have anything big and strong enough to bend / twist the subframe in back into shape so I had no option but to remove the entire front of the subframe (with a thin kerf cut-off disk) and weld everything back in the correct position. As I started cutting the first weld between one the front mount plates and a spar, some water started leaking out of the cut. It was only a couple of mL, however there must have been a pinhole in a weld somewhere and water collected in spar tube when it was sitting out in the rain for an entire winter so it's probably good that I'm fixing it.
Main subframe section with front mount plates cut off :
Front brace bar with mount plates cut off :
The first step of the rework was to make the brace bar (that sits behind the front apron panel) bolt to the front mount plates :
After this the main subframe piece was installed, the spars trimmed where necessary and the everything tack welded into the correct position. The entire subframe was removed from the shell and then fully welded. The brace bar stayed bolted on during this to make sure every piece would still fit together in case there was any distortion caused by the weld heat.
New and better quality welds for the front mount plate:
When I had cut off the front mounts, I noted that the penetration of the welds into the front mount steel plate was not as good as it could have been. The custom front subframe was fabricated a long time ago when only had an arc welder and I was a relative welding novice. Now that I have a MIG and my welding skills are better, I not only fixed the front section of the subframe, but also took the time to attack and grind back all the major welds on the subframe with a die grinder, and reweld each one to improve the quality, penetration and strength overall.
Removal of old engine mount weld with die grinder and new weld :
I don't have anything big and strong enough to bend / twist the subframe in back into shape so I had no option but to remove the entire front of the subframe (with a thin kerf cut-off disk) and weld everything back in the correct position. As I started cutting the first weld between one the front mount plates and a spar, some water started leaking out of the cut. It was only a couple of mL, however there must have been a pinhole in a weld somewhere and water collected in spar tube when it was sitting out in the rain for an entire winter so it's probably good that I'm fixing it.
Main subframe section with front mount plates cut off :
Front brace bar with mount plates cut off :
The first step of the rework was to make the brace bar (that sits behind the front apron panel) bolt to the front mount plates :
After this the main subframe piece was installed, the spars trimmed where necessary and the everything tack welded into the correct position. The entire subframe was removed from the shell and then fully welded. The brace bar stayed bolted on during this to make sure every piece would still fit together in case there was any distortion caused by the weld heat.
New and better quality welds for the front mount plate:
When I had cut off the front mounts, I noted that the penetration of the welds into the front mount steel plate was not as good as it could have been. The custom front subframe was fabricated a long time ago when only had an arc welder and I was a relative welding novice. Now that I have a MIG and my welding skills are better, I not only fixed the front section of the subframe, but also took the time to attack and grind back all the major welds on the subframe with a die grinder, and reweld each one to improve the quality, penetration and strength overall.
Removal of old engine mount weld with die grinder and new weld :
Comments
Post a Comment