FRP Repair

[@logangrimsley958]

Great information. Well done.

[@benh4086]

Thank you.

[@alejandrofuncasta8887]

Hello. I have the same broken part on my motorcycle and I want to try to repair it. I would appreciate it if you could tell me what type of adhesive you use since it is not clear to me in the video or any specific product or brand that you have used, since I live in a place where there is not much variety of products and if I ask for an adhesive for thermoplastic he will not have any idea what I am talking about and he will sell me whatever he has regardless of whether it works for me. Thanks

[@mikelov47]

Really good job Ben. Was wondering if using long-fiber polyester autobody filler would be useful to reinforce the open areas in the part. The key would be to get the correct bonding between the nylon12 FRP and the PE thermoset filler. Any thoughts on this?

[@benh4086]

Thanks for the comments. Polyester does not adhere well to these substrates. But you can certainly consider adding fibres to the resin when completing the repair.

[@conman8221]

Excellent video. Any link with the specific repair materials?

[@benh4086]

The materials can be purchased through your local Auto-Parts store, Auto-Body supplier, or other retailers (depending on the specific product you choose to use).

[@Kevy_Sr]

Can you list the products you used ?

[@scottb7600]

Why would you use adhesives and not weld it with fiber reinforced nylon filler rod? Nylon in particular is not all that receptive to bonding with adhesive and tends to crack at the repair. I would use Polyvance R21 series nylon welding rod with a plastic welder, embed a few plastic staples and maybe some stainless steel reinforcing mesh to really boost the flexural strength.

[@benh4086]

Hi Scott, thank you for the comment. I think you may have missed the point of the video which is to demonstrate a bonded repair procedure which I indicate is not ideal. Additionally, I have many other repair videos (and will continue to make more including plastic welding). With that said, the specific composition of plastic and fibre used in this particular part does not respond as well to plastic welding or hot stapling as other forms of fibre-reinforced thermo-plastics. I agree, though, that plastic welding can be far superior for certain types of plastic repairs and the Polyvance products are excellent, we teach this to our students.

[@scottb7600]

@@benh4086 Thanks for the comment. Yes I saw those parts of the video, however not having success welding fiber reinforced plastic may be the result of not using the correct filler rod, welding at too high/low of temperature, or lack of prep. Fiber reinforce plastics, in particular nylons, are pretty sensitive to how they are welded and what they are welded with. When welding fiber reinforced plastic, you must use fiber reinforced welding rod made of the same material. I have found that welding fiber reinforced nylon without fiber reinforced rod is possible, but no where near as strong as when you weld it with fiber reinforced nylon. Another thing that can be done, although not practical for the DIYer is to use nitrogen hot air welding. Using a jet of heated nitrogen instead of a jet of heated air to make the weld, acts as a shielding gas and produces and even stronger bond. So what happens when this part fails on a dirt bike? Does the rider end up on the ground?

[@benh4086]

@@scottb7600 when this particular subframe fails, the back end of the motorcycle tends to come loose, but still stays largely intact and is generally rideable. Repairing (thermoplastic) FRP is not common in the Auto Body trade as FRP repair is not typically an OEM approved procedure. Although I do not have a video loaded, I do teach hot air and nitrogen welding. My videos are mostly aimed at training apprentices, but this particular one is directed towards DIYers using easily accessible materials to make a temporary repair. As you mentioned, nitrogen welding is not practical for non-professionals. Thanks again for the comments, great conversation on a topic that isn't understood well my many.