MRC first....Cracked Crankshaft..
02-21-2008, 12:40 PM
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MRC first....Cracked Crankshaft..
Some of you remember a while back we posted this thread:
https://my350z.com/forum/showthread....=oil+pump+fail
Where we broke a stock oil pump in 2 pieces comming off the launch control at 6500RPMs....Well We since have taken the motor apart and found 1 thrust bearing and one main bearing were ruined.Not fully spun, but damaged badly. We sent the crank shaft out to get polished and Magnafluxed, and got the report back today that the crank had several hairline cracks in it.. Bummer..
I guess the VQ crank does not like launch control..I am heading over to our machine shop tommrow to pick it up and will post some pictures, however I doubt it will be visible to the human eye..
Back to the drawing board.
Here is food for thought...We dont know if the actions caused the crack or if the crack was pre-existing on the doner motor we used. The motor we used was out of a BADLY totaled 350z that suffered a MAJOR side impact and broke such things as the CF drive shaft and the Motor mounts..SO in theory, the crank could have suffered some structural damage from the shock of the impact. We didnt Flux the crank in the beginning cause it never came to mind, but the motor did have about 6000, built miles on it prior to this failure.
https://my350z.com/forum/showthread....=oil+pump+fail
Where we broke a stock oil pump in 2 pieces comming off the launch control at 6500RPMs....Well We since have taken the motor apart and found 1 thrust bearing and one main bearing were ruined.Not fully spun, but damaged badly. We sent the crank shaft out to get polished and Magnafluxed, and got the report back today that the crank had several hairline cracks in it.. Bummer..
I guess the VQ crank does not like launch control..I am heading over to our machine shop tommrow to pick it up and will post some pictures, however I doubt it will be visible to the human eye..
Back to the drawing board.
Here is food for thought...We dont know if the actions caused the crack or if the crack was pre-existing on the doner motor we used. The motor we used was out of a BADLY totaled 350z that suffered a MAJOR side impact and broke such things as the CF drive shaft and the Motor mounts..SO in theory, the crank could have suffered some structural damage from the shock of the impact. We didnt Flux the crank in the beginning cause it never came to mind, but the motor did have about 6000, built miles on it prior to this failure.
Last edited by Julian@MRC; 02-21-2008 at 12:43 PM.
02-21-2008, 01:22 PM
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Originally Posted by Julian@MRC
Where we broke a stock oil pump in 2 pieces comming off the launch control at 6500RPMs....Well We since have taken the motor apart and found 1 thrust bearing and one main bearing were ruined.Not fully spun, but damaged badly. We sent the crank shaft out to get polished and Magnafluxed, and got the report back today that the crank had several hairline cracks in it.. Bummer..
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02-21-2008, 02:42 PM
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Originally Posted by Zivman
I only had my car on the street and I took out a crankshaft... or should I say my UR pulley did?
02-21-2008, 02:46 PM
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Originally Posted by Julian@MRC
It was the 3rd main from the front of the motor..and respective thrust.
02-21-2008, 03:04 PM
#13
Originally Posted by Julian@MRC
Come to think of it...I had a god darn UR pulley on that motor!!
You may want to consider an ATI super damper on your next build.....even a stock crank pulley (with dampner) would be better at comtrolling harmonics and vibrations than a UR (undamped) puuley.
02-21-2008, 05:06 PM
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Originally Posted by eagletanggreen
You guys are crazy! Busting a crank!
crank that!
http://youtube.com/watch?v=sLGLum5SyKQ
02-21-2008, 05:58 PM
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Originally Posted by r0mey
I didnt know if you were going to post this or not Julian but I should have known that you post everything and hide nothing from any forum members. If your car blows up you tell the world. My vote is you get a 4.2 but you know that already
02-21-2008, 05:58 PM
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Originally Posted by r0mey
I didnt know if you were going to post this or not Julian but I should have known that you post everything and hide nothing from any forum members. If your car blows up you tell the world. My vote is you get a 4.2 but you know that already
props 4 honesty!
Last edited by IIQuickSilverII; 02-21-2008 at 06:05 PM.
