make sure to roughen up the surface before you apply the epoxy, You can use rv tank repair kits from NAPA, they come with some fiberglas and a 2 part epoxy that will literally burn your skin off when it reacts. It melts the glas into the part being repaired.

If all else fails - call urethane supply co. and ask them for input.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)