We do from time to time get asked to repair plastic on bikes that are more than thirty years old. These panels present some unique challenges. Panels made of ABS, age, this leads to deterioration that shows it’s self in a couple of ways. The first are fishers appearing in the panel as you pass heat over the area to be repaired and secondly moisture leaching from these hair line cracks. It is well known that untreated ABS is hydroscopic.
Recently we had a gent in with two very old Triumph battery covers that had stress cracks. I say stress but to be honest these were signs of their age. The next indication was the way little rivers of water came running out of the plastic as heat was passed over the repair area, with numerous fishers opening as well. This complication turned a straight forward repair into a bit of a challenge.
It is difficult to know how far to to take repair’s like this. It was handy that the owner was in the workshop to experience what was happening. We agreed between us to only make good the cracks and some of the fishers that lead into those creaks. Otherwise the repair would have become very expensive.