Front engine mount

sboricic123 · Jun 20, 2014

Any suggestions on repairing my front engine mount where it bolts on? My bike frame is 2 1/2" thick so I had to make a metal plate and u-bolt it to the frame. I didn't realize that 1 of the bolts that held the plate on had broke and caused a bigger hole until yesterday when I was checking to see if they were tight.

Greg58 · Jun 20, 2014

Do you have any threads left at the bottom, if you have any good threads left you might be able to repair it. I'm not a fan of j/b weld but it may hold if you coat the stud with j/b then screw it into the hole . let it cure completely before using the engine.

2door · Jun 20, 2014

Greg and I usually agree on about 99.9% of things but he knows I'm not JB Weld fan too. I call it dime store glue. My feeling is that it won't hold. I would suggest using a Heli-Coil thread repair. NAPA auto parts sells them in SAE and metric sizes. The instructions come with the kits. They aren't cheap so be prepared to spend a few bucks but the repair will be permanent. I'd stay with 6mm or you could consider going up to SAE, 1/4 X20 thread. There isn't a lot of meat there to go much bigger.

http://www.bing.com/search?q=Heli-C...hread+repair+kit&src=IE-SearchBox&Form=IE8SRC

Just another opinion and suggestion. You might get more.

Tom

Greg58 · Jun 20, 2014

Tom the heli.coil was my first though but from the oval shape of the hole in the picture I couldn't see getting good enough threads in it. I could be wrong. With the stud hole wore toward the inside it almost would need the engine chucked in a vice on a milling machine to drill the hole in the right place for stud spacing.

2door · Jun 20, 2014

Good point, Greg. He does have his work cut out for him. A machinist would be a good alternative but they can be pricy.

I've tried and also watched repairs using epoxy based materials and it's been my experience that they just don't hold up in applications like this one. Devcon liquid steel would be a better choice than JB but it is costly and the results questionable. One problem would be the possibility, if not the probability of overtightening and stripping the epoxy threads leaving you back at square one.

Metal threads such as you'd get with a helicoil repair would be his best route, me thinks.

Tom

sboricic123 · Jun 21, 2014

Thanks for the suggestions. I believe I have a helicoil kicking around that I purchased before. I've just never used one before. Do they just screw in then the bolt screws in to it? I did purchase some dime glue but haven't opened it yet. If it's going to cost me a few bucks then I might as well buy a new kit and keep the old for parts. But, I'll try the helicoil first to see how it turns out.

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Front engine mount

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