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TH350 converter/flexplate problem

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Old Mar 15, 2009 | 09:20 AM
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Default TH350 converter/flexplate problem

i'm doing a 370/A3 swap into my '01 Z..... here's the problem i ran into, yesterday i was doing a test fit with the tranny/converter, while bolting the trans to the motor i found that the converter hit the flex plate, this happened about 3/16" before the bellhousing was tight against the motor, and yes the converter was all the way back in the tranny. the flex plate is a stock LS1 plate, the motor has a crank from a '99 6.0L 2500HD, which i believe is the problem, since the crank hub is much thicker than a LS1........ i know that others have had this problem and i need input from anybody that has run into it before. i would prefer not to send the converter back to get it changed...... so i'm thinking the best way to get around it would be a flexplate that is stepped back to let the crank go up in it, i'm sure somebody makes this, but i havent found it, yet, or would a 6.0 flex plate help? any help will be very appreciated

Last edited by sprayinLS1s; Mar 15, 2009 at 10:19 AM.
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Old Mar 15, 2009 | 11:30 AM
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I think the flat 6.0 /4L80 flexplate will work for you.

I have some if you need one.
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Old Mar 15, 2009 | 05:35 PM
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Originally Posted by jakeshoe
I think the flat 6.0 /4L80 flexplate will work for you.

I have some if you need one.
how much would you need for 1 of those........ i'm also wondering if the length of the pilot on the end of the converter that goes in the crank will also cause a problem

Last edited by sprayinLS1s; Mar 15, 2009 at 05:42 PM.
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Old Mar 15, 2009 | 11:17 PM
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I've been selling the flexplates with spacer and bolts but I think you would only need the flexplate.
$45 plus shipping for a new GM piece sound fair?
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Old Mar 17, 2009 | 12:36 AM
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Originally Posted by jakeshoe
I've been selling the flexplates with spacer and bolts but I think you would only need the flexplate.
$45 plus shipping for a new GM piece sound fair?
that is a good price, and i may get it anyway..... but what kind of power will they hold up to?? i will probably need an aftermarket sfi plate..... ive found plenty for the LS1s but havent found none for the 2500hd, im sure somebody makes it, i just havent done the right search yet
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Old Mar 17, 2009 | 12:42 AM
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I've used stock flexplates at well over 800 HP.

Thick flexplates can also contribute to thrust bearing issues.
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Old Mar 17, 2009 | 08:43 PM
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you sure it wasnt going completely together?? maybe your mullet was in your eyes and you couldnt see very good...how much MadDog 20-20 did you drink that night??
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