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Discussion Starter · #1 · (Edited)
Haven't had a chance to throw my truck up on the rack, been too busy in the shop. Listen to the video. I start my truck then shift into gear. If idle is high when shifting I hear a knocking when the time dip. If idle is low and I shift the noise is not present. If I keep it running after it makes the noise it will never do it again? Replaced my starter with a motorcraft unit easier this season because my old one made a grinding noise once. I built the trans & replaced the converter 2 years ago, has approx 1k miles on it. Converter is a PI 2400.

What do you think? Sound is from Bell housing area...
Starter hitting flywheel when converter moving forward? Cracked flywheel? Torque converter problem?

I do three different starts, each gets more noticeable.
http://youtu.be/XNH47W_7-6s
 

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Discussion Starter · #3 · (Edited)
It sounds like loose torque converter nuts or cracked flywheel to me.
Yeah, I am thinking cracked flexplate too. If so, time to get an SFI unit... Thinking I should send out my PI2400 converter to get checked out.
 

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I once replace a 79 302 with a 83 302 in a F100 with a C6 tranny. The 79 is externally balanced and the 83 302 is internally balanced or visa versa. Anyhow it had a vibration that would come and go at different speeds and rpms. After a month or so I was hearing similar sounds. Upon inspection I found the converter nuts loose so I tightened them up. About 2-3 weeks later I was driving home from work and the truck went into neutral with a high pitched screeching sound. The Flywheel was sheared off at the flange.
 

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Discussion Starter · #5 ·
ttt
 

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Discussion Starter · #6 ·
ttt
 

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When I put my motor in I messed up and didnt line the trans up right. Went a head and torqued it up anyways and bent the flexplate take the inspection plate off and watch it spinning. See if it gets louder.
 

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Discussion Starter · #8 ·
Pulled the inspection cover today & ran it. Could not see any cracks in the flexplate, may be some near the center. Trans fluid & engine oil is super clean.

Looks like my converter is not spinning true closest to the pump?

Made another video
https://youtu.be/ncGxOndyV7U
 

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Discussion Starter · #9 ·
ttt
 

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What HP level are you at? You may have so much torque running through the connection between flex and converter you may have deformed, or warped the converter. Or a combination of flex and converter. Just spit ballin here. But I figure your pushing some serious torque with a 3.4.
 

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Discussion Starter · #11 ·
What HP level are you at? You may have so much torque running through the connection between flex and converter you may have deformed, or warped the converter. Or a combination of flex and converter. Just spit ballin here. But I figure your pushing some serious torque with a 3.4.
608 torque now. Pulling trans & engine this fall.
 

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Discussion Starter · #12 · (Edited)
Pulled my transmission today. Flexplate is "not" cracked, all bolts were tight, flexplate to crank bolts were tight... Trans fluid looks like new. The flexplate is warped. Second video around 2.03 you can see the starter helix moving. Getting a new oem flexplate. Sending my pi converter out for inspection.

I built the trans 1k miles ago and reused the flexplate. At that time I installed a pi2400 converter so I am wondering if it is not welded true.
 

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Discussion Starter · #13 ·
Sent my converter to PI and they said it has zero runout. Converter pump shaft has scoring from the pump bushing so they replaced that portion for free. Whatever caused the flexplate wobble wore the bushing.

Looks like the pump is getting a new bushing & seal. Flexplate is getting replaced.
 

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Good call. I just watched the vid and it sounds identical to what mine sounded like. When I did mine it was my first time seating the Tranny. Warped it. Bought a new one from ford. Been working great for over 100,000mi!
Glad you figured it out takes time.
 
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