Mounting Woes- Screws keep snapping

[bwantt]

Hello, I have about 60 miles on a new Chinese engine and new Walmart cruiser. Twice in the last 10 days I have snapped one of the mounting screws. These were replaced in the beginning with US hardware, but they continue to be weak. I have heard that you can stick a small piece of wood in there for extra stability. As a shortcut I have a cork in there. Is this a problem?

I am looking for some long term fixes as the rest of the bike is fine. The problem also makes the chain continually loose. I have attached some pictures and would appreciate any advice that anyone can give to firm this baby up.

Thanks, Brad

 

[Bikeguy Joe]

HMMMM. How tight are making them? Using loctite blue? Even good SAE hardware can be overtorqued.

I use lead sheet between the frame and the mounts (4 pcs.) and Loctite blue (medium) and I don't tighten them really tight. No probs.

 

[Bikeguy Joe]

I'd loose the wire under the washer and tighten evenly.....

 

[misteright1_99]

I wrapped all my mounts in heavy rubber gasket material. Got it at Ace, comes in a sheet....

 

[Goat Herder]

I broke a stud on mine, wound up drilling the whole darn bolt out, I didn't get my pilot bit strait enough.I was annoyed and did not want to unbolt the whole moter to work on it.What I ended up with was two 8'mm studs grade 8. I drilled holes through the frame adapter, and into the engine block. Then cut my new theads into the adaptor, and the engine block. This was done to make the whole thing more riged.Drilled out the holes for the outer half moon peice, [the 8'mm studs.] ________________________________________________________________________________________________________________________ Somthing to keep in mind is that these studs try to spread apart when tightening them. I made my new studs just long enough to put a small predrilled peice of metal at the outside ends of the studs to join and hold them together topped off with two nuts to hold that. No more spreading prob,I think these kits should get a homade antispread plate from the get go on all of them. But that might be just me. last all done with blue lock tight.

 

[Goat Herder]

One of your picts looks like the mount is following the curve of the tube when tighening, spreading the studs out I would add one antispead plate topped by two more nuts. hope I could help

 

[Large Filipino]

I found grade 8 M6 bolts at ACE hardware believe it or not. The guy there explained it to me. It's not colored like a grade 8. There are no lines on the head like a grade 8. But it actually says "8" right on the head. It's silver in color and not too expensive. But I went a step further and bought M6 metric bolts high polished chrome in the specialty rack but those puppies are $2.50 EACH!! They haven't broken on mine yet though.
There is a good chance the studs you have on there is grade 2. Using a bolt isn't much of a hassle, Get one long enough and get the nuts and washers in there first,tighten down the bolt then lock the nut down. And look for that number 8 on the head.