Bonding Carbon fiber motor mounts into a hull

[davelc56@gmail.com]

I can't find info on how to bond CF mounts into a CF hull. I would expect to tack the parts using epoxy, once set, sand and fillet both sides of the entire joint with a epoxy filler mix. Then put a layer of CF cloth over the fillets. The strange thing is I have studied any pictures of similar motor mounts I can find and it looks like there is no layer of cloth used, just bonded in with glue.
Am I missing something. This is a 41" ZONDA cat hull going 12S crazy.
Thanks

[srislash]

I can't find info on how to bond CF mounts into a CF hull. I would expect to tack the parts using epoxy, once set, sand and fillet both sides of the entire joint with a epoxy filler mix. Then put a layer of CF cloth over the fillets. The strange thing is I have studied any pictures of similar motor mounts I can find and it looks like there is no layer of cloth used, just bonded in with glue.
Am I missing something. This is a 41" ZONDA cat hull going 12S crazy.
Thanks
You got it right. That is how my Fantasm/Zonda is done. BTW, also 12s x 2 TP 4050’s

[Nevs]

Í think the english word is joint glue. I made a test last year with different types types. wood /carbon, and carbon/carbon. All the joint glues were stronger then any epoxy.
https://www.rcgalleri.dk/forum/generel-diskussion/161627-alternativ_til_epoxy__staerkere
When using epoxy the WIKO 05 is better then anything else I tryed..But its a 5 min. epox. Maybe they make one that hardens less fast.

[davelc56@gmail.com]

Can anyone recommend what glue or epoxy? I have west systems epoxy in stock. (In Canada.)

[srislash]

Can anyone recommend what glue or epoxy? I have west systems epoxy in stock. (In Canada.)
I use System Three laminating resin. I can’t remember the West System that everyone uses. The resin used on the hull will be different but we’ve had no issues bonding to it.

[martin]

A lot use JB Weld original for bonding mounts etc with great success.

[Luck as a Constant]

west systems is great. in particular their G Flex line for bonding stuff. or the 105 is great too

[photohoward1]

Marine adhesive 5200 is great too. Never coming out. It bonds everything.


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[davelc56@gmail.com]

Thanks Gentlemen!

[30nitro]

I second the 5200 marine adhesive..!!

[snehpetsffej]

z poxy this has held my motors in for years with a lot of abuse
https://www.amazon.com/Pacer-Technology-Zap-Finishing-Adhesives/dp/B0084UAPMG/ref=sr_1_1_sspa?ie=UTF8&qid=1542318327&sr=8-1-spons&keywords=z+poxy&psc=1

[kfxguy]

I'm very picky with my builds. I use jb weld and use a heat gun on low heat to help it flow and smooth out. Then if i want it black, i scuff up the jb weld and go over it with 5 minute clear epoxy, tinted gloss black (or whatever color i choose).

[kfxguy]

Bare jb weld

https://i.postimg.cc/15mpcn0C/3-BD8-BDE2-26-AC-42-E1-85-E6-10-ED72-FD72-F5.jpg (https://postimg.cc/V5hrzNVn)


After coloring

https://i.postimg.cc/9FLyxmJW/6539-B2-ED-A9-B2-4370-A13-E-FB85-CF56-F14-E.jpg (https://postimg.cc/dLT73KbX)


https://i.postimg.cc/BZcTKcFP/D349-EEED-C0-B5-4-F8-D-9792-46-C25-A45-A14-B.jpg (https://postimg.cc/pyr5NjqP)

[30nitro]

How does the JB weld hold up on motor mounts..? I've only used it on sponson water pick ups...

[kfxguy]

How does the JB weld hold up on motor mounts..? I've only used it on sponson water pick ups...

I’ve flipped boats at 90+ and it holds up. I flipped one boat at 100mph but the crash was 1 in 1000 and the way the boat came to an instant stop, it broke all kinds of stuff including the motor mount lose. But. Had the mount not let got it would have ripped a hole in the hull. I use jb weld every time. In my opinion it’s the best choice.

[kfxguy]

Here’s the video. It’s unreal how fast it stopped.



https://youtu.be/KcOjPpFBzJI

[30nitro]

OMG..... Hope it wasn't damaged too bad.....

[kfxguy]

OMG..... Hope it wasn't damaged too bad.....

It broke the motor mount (big heavy motor) and I think broke the jb weld on one side and the motor hit the hatch so hard it broke the hatch. Boat didn’t sink tho. I repaired it. Had I had an epoxy even stronger it would have ripped a hole in the hull and probably would have filled with water and maybe sank. I’d honestly pick repairing a motor mount any day than ripping a hole in the hull. Think about that for a minute. That was a very hard crash. Very hard. Like hitting a brick wall at 100mph. Something is bound to break. I’m extremely surprised it didn’t crack in half.