Last night I was coming back home when I floored it 1st 2nd, shifted to 3rd and heard a loud bang, slowed down and the clutch peddle was vibrating, the whole motor didn't want to rev and the motor had shiit going on inside, thought It was the transmission or clutch

Towed the car to the garage, took apart the tranny and the oil pan to find out that the 4g64 crank had split in half right where con rod no.4 is, the part the connects con rod no4 to the last main bearing before the flywheel, I have never seen a crank break like this, ever,

I have eagle rods, wiseco pistons and an exedy twin plate, I'm getting another 4g64 crank and putting it back with new oem bearing instead of the acl's I have now

What could've caused all this ?

 

Any possible explaination ?

 

Dam homie!

 

damn did it mess up the motor (pistons, rods etc)?

 

Where did the crank come from? Out of a wrecked car, bought re-manufactured, or bought new? Looks like there had to be an imperfection (or crack) there that given enough time finally just gave out.

 

The pistons and rods are fine, Only damage was this crank the balance shaft belt got stripped, the block and the mains


I bought this crank new with the eagle rods and wiseco pistons, Few days before this happened I have adjusted my clutch peddle, but I doubt that was the reason ...

 

I have seen this before and usually it is from a lot of 2step launches and general abuse to the motor. I had a friend break two cranks this way within a thousand miles. At first we thought his original crank was a junk crank so we got a brand new mitsu crank and he did it again. I think he did a lot of rolling clutch dumps to break the tires loose along with tons of two stepping the motor for no reason. I put a 3rd crank in before he sold the car and the new owner has not had a problem 4 years later.

Later

 

+ 1 definitely need more info on this and its replacement.

You may want to have your engine and internals inspected by a machine shop before reassembly.

 

I do not have 2step as I'm running a power fc and no, I dont't dump my clutch after breaking my t-case !

 

wHOa! That puppy refused to walk! :}

 

It's a piggyback correct? Who did your tuning?

 

This is serious.

 

Holy crap!! Forget the crank!! You better get your 2nd toe straightened out first!! LOL. jk, That sucks.

 

+1 any ideas why this would happen?



I actually know what you mean, because this happened to me like a month ago, just cruising and BOOM same exact thing loud noise, clutch vibrating... getting rebuilt now... Broke right at the same spot around journal 4 of the crank. Didn't even look like a twisting break was just clean. And i was on a stock crank w/ 33,000 on it and i dont two step, let alone beat the car unless i need to show some one up lol. Question tho to the OP, when you would hit boost and then shift, in between the shift would you hear a whining noise?? I started hearing this noise on the day the crank broke? I would only hear the noise when i hit boost though.

 

wow thats kinda cool. Maybe the harmonic balancer failed.