What I learned repairing the trunk

[WVJefo]

Spent a couple hours yesterday & some time today putting a patch across the entire bottom of my 1200's trunk. The trunk was badly cracked at each bolt hole and almost all the way across the bottom at the back end.

It tried just gluing the cracks but it did not work the damamge was just too great.

Found a piece of ABS 3 inch pipe to use for the repair. I wanted a big pipe because I needed a big patch. That is when I learned my first lesson. Can't use a jigsaw to cut ABS. It just heats up enough to seal tight right behind the blade. A handsaw and tin snips work just fine. Lesson two ABS smells bad when heated in your oven. Final lesson 3 inch pipe with a 1/4 wall is too thick to work with choose a thinner walled pipe. Lesson four a patch can be too big to work with. If you have a large area do two, three or four smaller patches are probably better.

Lastly form to the patch to the contours before you add the ABS glue.

Got the bottom of the trunk patched. Looks like hell, but is the bottom of the trunk so noone will ever see it. And I am no longer worried about my girl going off the back end if the trunk bottom failed.

Jeff

[WingAdmin]

Found a piece of ABS 3 inch pipe to use for the repair. I wanted a big pipe because I needed a big patch. That is when I learned my first lesson. Can't use a jigsaw to cut ABS. It just heats up enough to seal tight right behind the blade. A handsaw and tin snips work just fine. Lesson two ABS smells bad when heated in your oven. Final lesson 3 inch pipe with a 1/4 wall is too thick to work with choose a thinner walled pipe. Lesson four a patch can be too big to work with. If you have a large area do two, three or four smaller patches are probably better.

Lastly form to the patch to the contours before you add the ABS glue.

All of these are very true. I've used a reciprocating saw that I had go very slowly, and it worked, but it's just as easy to use a hacksaw by hand - ABS is soft and easy to cut. High speed saws melt the ABS, as you found, and it just seals up again behind the blade.

ABS does smell bad in the oven, which is why I always recommend you do this kind of repair when your wife is not home.

[Viking]

Last time I repaired a cracking trunk, was a 1974 Harley, but it was fiberglass. I cut a piece of aluminum to go on the entire bottom outside of the trunk, then I resin'd the inside and bolted through it after it hardened, right through the aluminum, which protected the trunk from being only supported by the four bolts that held it down. It still has not cracked again, and that was at least 25 years ago.

[WingAdmin]

Last time I repaired a cracking trunk, was a 1974 Harley, but it was fiberglass. I cut a piece of aluminum to go on the entire bottom outside of the trunk, then I resin'd the inside and bolted through it after it hardened, right through the aluminum, which protected the trunk from being only supported by the four bolts that held it down. It still has not cracked again, and that was at least 25 years ago.

Reinforced resin is a great way to repair fiberglass - but resin will not bond (permanently) to ABS like it does to fiberglass (which is already epoxy resin and glass fiber). ABS heats and expands at a different rate than cured epoxy resin, and eventually the repair will break away and fail.

[Dogsled]

Try a heat gun to shape the pipe.

[Bamaeagle]

If you did not want to cut the ABS pipe and heat it to mold it you could order flat ABS sheets from several online sources. Here is one below as an example. Not to expensive for a sheet and you get to choose color and thickness.

http://www.professionalplastics.com/ABS ... RMINGGRADE

[Dogsled]

That sure makes things easier, starting with a flat sheet. I had a crack in a fairing panel by the CB. I bought a ABS elbow, used a cheese grater and made flakes and mixed it in with the glue. I started by treating the crack wrong. I ground a V groove and filled it with the flaked ABS/glue and it made a funky filler. By the end I was just gluing the pieces together. Or should I say 'welding' them, because with the primer then glue, it was just like new.
Something like the trunk though, it sure wouldn't hurt to add some extra structure.

[86pearlblue]

I used a fiberglass repair kit on mine. The kit I bought at Auto Zone had just enough matting to put a double layer across the area. So far, so good!

Good luck! Shiny side up!!

[WingAdmin]

I used a fiberglass repair kit on mine. The kit I bought at Auto Zone had just enough matting to put a double layer across the area. So far, so good!

Good luck! Shiny side up!!

As I mentioned earlier, don't expect this to be a permanent fix. ABS and fiberglass/epoxy resin heat and expand at drastically different rates, and the adhesion between the two compounds is not optimal. It's only a matter of time before the repair will break away from the ABS.

ABS panels glued in place with ABS/MEK solvent/cement will become a permanent part of the repaired structure, and cannot be separated even with great force (so make sure it's right the first time you do it!).