Reglassing Exhaust

[stevezie]

I would appreciate any guidance on which material(s) to use for reglassing fiberglass exhaust mufflers from a 2014 Prostar. While I suspect just about anything will probably work temporarily, I’m suspect some are better suited and will provide longer lasting results. 

[DvarianDan Johnson]

When fiberglassing anything I’d highly recommend using epoxy resin vs poly resin. Epoxy is far stronger , longer lasting, and better bonding. It’s no contest. If using cloth also use high quality cloth appropriate for the job. I can recommend fiberglassSite.com as offering high quality products snd information on both.  There are a number of sources for high quality fiberglass supplies, but definitely go all Epoxy. You won’t regret it . 

[chrislandy]

I'm going to differ, and say it depends on your glassing experience, personally I've used polyester resin fixing exhausts as it matches the materials already used and you can get a mechanical and chemical bond to the original materials whereas epoxy is only a mechanical bond.

 

Prep is the most important, sand off the glossy finish around the main tubes to get down to the actual fibreglass. (use work gloves,  googles, cover all skin and wear a mask, fibreglass dust is nasty stuff and will screw your lungs and make your skin itch for days)

key with 240 / 320, vacuum the surface and then clean down with distilled alcohol.  

Using CSM (chopped strand mat) rip into small sections no greater than 2" for fixing the tube ends, or strips to the right size for fixing tube rub through, keep a torn edge rather than cut.

Reactivate the polyester surface using acetone and let evaporate off.

Mix polyester resin (1.5x weight of csm) and thinly brush onto surface, working it into the surface using  stippling action. Add a layer of CSM and wet out with resin quite thickly, wait for a minute for the resin to dissolve the csm binder, then stipple with the end of the brush from centre outwards to work out any air bubbles and move the fibres around, add another layer and repeat for 3-4 layers minimum. Keep working it, bubbles will look like a lighter part.

 

Until you have got a rhythm going, work on one end / section at a time, calculate the catalyst based on the temperature and a 20-30min working time. Clean brushes for re-use using a pot of acetone before the resin goes off.

[Jody_Seal]

no epoxy for exhaust.  epoxy will soften with heat. 

standard fiberglass and boat yard resin will withstand 500 plus degrees before ignition or melting. 

 

[DvarianDan Johnson]

7 hours ago, Jody_Seal said:

no epoxy for exhaust.  epoxy will soften with heat. 

standard fiberglass and boat yard resin will withstand 500 plus degrees before ignition or melting. 

 

@Jody_Seal Interesting . Good information . I've never applied fiberglass to an exhaust. So I'll revise - for any construction/fabrication (non mechanical) applications  - go Epoxy vs Poly.  Thanks again. 

[BraceMaker]

I'll add feather out any cracks and the movers saran wrap on a handle can be used sort of like vacuum bagging starting on one end you get it started then pull tight and around and around with good overlap.  Will squeeze excess resin out of your layup.