Fiberglass crack in boot

I have a large crack in the fiberglass of my S4 just above the tailpipe. The whole bottom of the boot seems to be sagging. The exhaust was bolted through it, but I’ve now relocated that to the end of the frame. If I jack up next to the crack, all comes back together OK. I was thinking doing fiberglass repair from the inside, but it feels like the gas tank (aluminum) is sitting right on the floor of the boot. I am afraid the repair will just pull apart again. Suggestions? Thanks. Dan

Give up “Autocrossing”

If you are going to repair the crack properly you will be applying glass fibre to both side anyway. If done correctly there should be no loss in strength although you could add an addition layer of mat over the whole area to spread the load (the original lay-up can be rather thin).

What about the gas tank? Does it just sit unsupported on the bottom of the boot? Seems like it should be braced somehow towards the center of the boot where the floor is raised to accommodate the exhaust? Dan

Dan, as Carl said you will need to repair on both sides, top and bottom. I would start inside and place a board or plywood on jack and raise from underneath to get to correct height. Then carefully grind or feather out the edge of the crack and I would go back from crack about three inches each side. Once done with that you can glass in the new layers of matt. I would let that setup for a few hours or so and remove jack and board. Make sure nothing drops down. If good then do they same with the under side. This is a little harder to do since the resin will drip down. I work on most matt with a roller to keep air bubbles out and would put on extra resin on the bottom side so you can grind smooth when finished.
Should be every bit as strong as new or stronger.
Good Luck
Mark

Dan, as Carl said you will need to repair on both sides, top and bottom. I would start inside and place a board or plywood on jack and raise from underneath to get to correct height. Then carefully grind or feather out the edge of the crack and I would go back from crack about three inches each side. Once done with that you can glass in the new layers of matt. I would let that setup for a few hours or so and remove jack and board. Make sure nothing drops down. If good then do they same with the under side. This is a little harder to do since the resin will drip down. I work on most matt with a roller to keep air bubbles out and would put on extra resin on the bottom side so you can grind smooth when finished.
Should be every bit as strong as new or stronger.
Good Luck
Mark

tank should not rest directly on glass - I have seen various bizta’s of rubber and closed cell foam used to stand the tank off.

I would offer an alternative to the jack and board method - use strips of aluminum and cleco clamps to hold the mess in place -