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Old 11-30-2014, 10:22 AM   #1
woody82
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Bent flexplate?

I got my motor done and put back in.I fired it up and it has a pretty bad vibration.I replaced the harmonic balancer but not the flex plate could it be bent or could it be in the torque converter.And can it be changed without pulling the motor.
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Old 11-30-2014, 10:36 AM   #2
truckster
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Re: Bent flexplate?

Which motor do you have? Is the flex plate the one that was originally on the motor? And are you sure you got the right harmonic balancer?
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Old 11-30-2014, 11:14 AM   #3
hamjet
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Re: Bent flexplate?

Why did you replace the balancer? Did it vibrate before the rebuild? Did you make sure the converter is seated correctly to the flex plate? could be rockers are over tightened, plug wires crossed, one or more cylinders not fireing,check and recheck...
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Old 11-30-2014, 11:52 AM   #4
woody82
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Re: Bent flexplate?

Its a 402 big block I replaced the balancer because the old one had a sleeve on it and was held on with about 10 washers and a metric bolt its a wonder it even stay on.I ordered a new Doorman balancer specifically for that motor.The motor runs smooth and don't shake but when you sit in the seat you can feel it shake.Flexplate was on motor and looked fine.New hydraulic cam lifters pushrods and rockers.set valves myself 0 plus 1/4 to 1/2 turn.
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Old 11-30-2014, 12:49 PM   #5
no1udknow
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Re: Bent flexplate?

Is/was the flexplate installed properly? I know this happened on my brother in law, the guy he had build his engine bolted the flex ate on backwards. So the mounting indentations were facing the wrong way. My brother didn't know any better so he just torqued the flexplate together with the torque converter and warped the flexplate... it eventually cracked and started making horrible noises.... but that was on a small block.
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Old 11-30-2014, 12:51 PM   #6
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Re: Bent flexplate?

Another question. I thought I remember reading that big blocks are externally ballanced. So flex plates are weighted? Can anyone elaborate on this?
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Old 11-30-2014, 01:04 PM   #7
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Re: Bent flexplate?

366, 396, 402 and 427 were internally balanced so have a neutral balance flex/flywheel.
454 was externally balanced.
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Old 11-30-2014, 03:43 PM   #8
woody82
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Re: Bent flexplate?

I will check those things out I am positive I put the flexplate back on just like it can off but that don't mean it was on right in the first place.Thanks for your help.I just put her away for the winter.Talk to you next spring.
I have a picture I want to post but I haven't figured out how to do it yet when my daughter gets back I will have her help me.
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