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Discussion Starter · #1 ·
I broke the crankshaft in my MCX turbo car with the STM clutch a while back. I bought another used 2012 engine, swapped the pistons and the clutch, and threw it in. It ran great for a while but the splined end of the crankshaft just broke off again! That is now 3 broken cranks with the STM clutch, one was on my friends stock motor.

The worst part is that It was under full load at full boost when it let go and the motor zinged like an F1 car for about a second before the compression went away and it coasted to a stop. This one is going to need more than a crankshaft!!

The 2012 engines suck! I put a new crank in my good engine case (the newer replacement case that I got under warranty because my original case cracked) and put that in my friends car. Now I have his old motor with the broken crank and the motor that just broke and I'm trying to decide what to do.

I could throw a crank in the spare motor and hope for the best. (not much confidence in this)

I could try putting a 2014 crankshaft in the spare motor and getting the STM primary for it. (has anyone put a new style crank in the old case? Is it the same? Does STM make a primary to replace the Team clutch?)

I could build it back to completely stock, sell the 2012 Cat, buy a 2014 Cat, and put the turbo on it. (unfortunately I got rid of a lot of the stock parts so I would need to pull them off the new car before I sold the old one)

I could sell the turbo setup and the STM primary and secondary and do the EVO DIY Z1 swap (but there is almost no information about it and that worries me)

I could stop eating and send a lifetime of lunch money with my car to Pace Offroad (I'm already hungry from just thinking about that)




hmmmmm
 

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Discussion Starter · #3 ·
How much boost you running? Sounds like you may have to do the z1swap....
About 13psi. And I finally had the clutch dialed in really well. The thing ran awesome!

The big problem is the STM clutch on the 2012 crank. I don't think the early cranks were strong enough at the splines for the load that the clutch puts on it. I'm sure the turbo doesn't help, but when my friend's crank broke with a stock motor I knew it was going to happen again.

All 3 were early first production run motors. The same crankshafts as the one that stripped the splines with the Airdam clutch.
 
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