First off I want to say that i love yoyojam. Im really just curious to see if anyone has had the same problem as me. Every yoyojam i have owned and I own about 7 has gotten cracks in it. Even the newer ones I own. My ex con pro got a hairline crack in it within the first ten throws. Non of the cracks I have had in my yoyojams has affected the play. I just want to know if this is normal or if im possibly tightening them too much.
Never gotten cracks in the many YYJs I’ve owned.
Well, except for my SpinFaktorX which got a crack because I liked to do higher aerials with it, and dropped it a lot, but it lasted a really long time before cracking.
My DM1 
And yeah your over tightening. My older YYJ models are crack free.
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Nope. I’ve had a few yoyojams. No cracks. Usually due to human error.
The cracking issue w/YYJ has been around a long time. It’s primarily due to unequal expansion and contraction of the metal rims and the plastic body. The metal rims constrain the plastic shell causing stresses to build in the shell. Stresses cause cracks. It doesn’t happen in all cases. I have quite a few metal rimmed YYJs. Some have cracks, some don’t. It has nothing to do with tightening. Overtightening just loosens the metal insert the axle screws into.
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Boom. Science for ya.
Who else thunk it? Hahaha 
I noticed this problem a loooong time ago when i started throwing. I was in an area with temperatures varying daily, my science teacher and I sat on top of a mountain together discussing it. Lol intense stuff science is, but also everything we know we have taught ourselves. Over a long period of time what we have come to know and believe, could just be merely fictional nonsense.
Boom.
Cracks in 2 clear hitmans, a nm3, lyn fury, SFHG, and xcons for what I can remember. Enyo always tended to be the worst when it came to cracking. I remember when RSJ left his enyo lyn in his case without ever touching it and it dissintegrated
Wow nice.