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Will a 99 Flexplate work with a th400 swap?

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Old Mar 13, 2005 | 01:58 PM
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Default Will a 99 Flexplate work with a th400 swap?

like the title says....
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Old Mar 13, 2005 | 08:02 PM
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Come on someone, please! I know someone knows!!!
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Old Mar 14, 2005 | 09:46 PM
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dont think so man,i am doing same swap as u and everybody says only 98 flexplate will work,u have to do a little drilling bout 1/8 of an inch,hope this helps
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Old Mar 15, 2005 | 02:17 AM
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I used my '99 flexplate on my th400 swap. I just had to use the second set of mounting holes.. if your flexplate has two sets of holes it should work.. see if the converter holes match up. I bought the GM 4L80E spacer and bolts so the th400 converter I had would seat correctly.

I didn't have to drill anything either. My converter did have two sets of holes drilled in the mounting tabs too.. I don't know if that helped at all.

Also the engine to trans bolts were too long or short or something so I had to buy a new set. I had a forward man. valvebody so I just re-used the stock shifter. I used a madman dipstick tube and a custom driveshaft and that's it.

Last edited by aram; Mar 15, 2005 at 02:26 AM.
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Old Mar 15, 2005 | 02:12 PM
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thanks!
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Old Mar 15, 2005 | 03:18 PM
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I'd strongly suggest getting an SFI flexplate. Your feet will thank you.

Just my .02
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Old Oct 8, 2008 | 09:35 PM
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Originally Posted by sprayinss
dont think so man,i am doing same swap as u and everybody says only 98 flexplate will work,u have to do a little drilling bout 1/8 of an inch,hope this helps
Sorry to hijack an old thread, but I have a 98 flexplate and a TH400. Will I need a spacer?
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Old Oct 9, 2008 | 07:38 AM
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From one of the stickies

Converter-
Can I use a standard th400 converter? Yes but certain conditions exist..The converters typically used are standard SBC converters that have two minor modifications. The first is that they use a LS1 Pilot diameter. The second is that they should have the pilot extended 3/8" to make up for the difference in length between the LS1 and a traditional SBC. If you want to run a "standard" TH400 converter, and the TCI flexplate, the TCI spacer can be replaced with one with a longer nose. This is because a standard converter doesn't have a pilot long enough to engage the back of the crank.

With the use of a stock flexplate and standard converter, you will need some special spacers.

I highly recommend to just buy a TC from a company such as Yank, Fuddle, Vig., etc.. and tell them you are putting a Th400 in your car. The TC will then come with the proper pilot and bolt pattern. The use of spacers is to much of a hassle in my eyes.
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Old Oct 9, 2008 | 08:53 AM
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Looks like I'll be making a call soon; reading the stickie now, thx.
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Old Oct 9, 2008 | 09:15 AM
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No problem
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Old Oct 9, 2008 | 10:01 AM
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Ok, I read the stickie - says they highly recommend getting a new converter specifically for a TH400 and an LS1 but that you can use spacers also. Are these spacers similar to big washers? Do transmission companies sell them? I have a 98 flexplate, a TH400, and a 3200 stall converter (sbc).
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Old Oct 9, 2008 | 10:44 AM
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Ah found something: https://ls1tech.com/forums/showthrea...t=spacer+th400

I'm pretty sure that Hughes spacer will work with my 98 flexplate and sbc torque converter.
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