4.8l to TH400
Thread Starter
Teching In
Joined: Feb 2016
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4.8l to TH400 Finally fired up my LS swapped '42 dodge pickup. All was well until the engine reached around 180° to 200° range. At this point the transmission begins to produce a squealing noise from the bell housing area.
What I've done:
-dropped the pan checked the filter seal and fluid all checked out
-swapped in a known loaned good transmission and torque converter same issue same whine.
What I used to adapt:
https://m.summitracing.com/parts/pio-fra-450
Could the torque converter to flexplate spec be out? Has anyone had similar issues? Thank you!
What I've done:
-dropped the pan checked the filter seal and fluid all checked out
-swapped in a known loaned good transmission and torque converter same issue same whine.
What I used to adapt:
https://m.summitracing.com/parts/pio-fra-450
Could the torque converter to flexplate spec be out? Has anyone had similar issues? Thank you!
Thread Starter
Teching In
Joined: Feb 2016
Posts: 6
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The accessories are all new. I pulled the belt and the same noise occurred. Is there a such thing as a long crank? I thought all LS we're right around .400 short. I used the 1999ish 6.0l flexplate that comes with the adapter.
Yes there are long cranks 99-00 LQ4 with iron heads had long cranks Do you know what year and trans your engine came from? If you're 4.8 is a 99-00 and had a manual transmission in it orginal then it's a long crank. Long crank will stick out .400 from the cover. If you want to verify the casting number will end in 312 for long crank 4.8.
what year is your 4.8 out of? Mine is a 2004 tahoe, and I have a th400 with a midwest converter with your same adapter.
I used the flexplate that came with the motor and this adapter.
https://www.summitracing.com/parts/s...saAr8MEALw_wcB
I used the flexplate that came with the motor and this adapter.
https://www.summitracing.com/parts/s...saAr8MEALw_wcB
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Thread Starter
Teching In
Joined: Feb 2016
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I bought a complete truck which was a 2002 Silverado 1500. The transmission came out of a 1988 2500 Suburban. I used the 6.0l stock flexplate and adapter with this set up. It's a stock flat flex plate. The way I put it together was the flexplate and then the adapter. Should it be the adapter then the flexplate maybe it's to far out of the pump? That's where shimming it would come into play.
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11 Second Club
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If using the GM adapter.... Flexplate, then adapter.
Your converter is probably hitting the adapter.
Get a hughes adapter what I use, https://www.summitracing.com/int/parts/hup-hp3795
which is just a machined spacer that you hit into the back of your crankshaft and extends the crankshaft spigot for your TH400 converter to locate properly.
The GM adapter is too bulky. And the way it tightens on with the flexplate bolts it's not even guaranteed to have a true center point. The Hughes piece above is much simpler, lighter, and best.
Your converter is probably hitting the adapter.
Get a hughes adapter what I use, https://www.summitracing.com/int/parts/hup-hp3795
which is just a machined spacer that you hit into the back of your crankshaft and extends the crankshaft spigot for your TH400 converter to locate properly.
The GM adapter is too bulky. And the way it tightens on with the flexplate bolts it's not even guaranteed to have a true center point. The Hughes piece above is much simpler, lighter, and best.
Launching!
Joined: Aug 2012
Posts: 203
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From: harrisville R.I
I am running a 2001 4.8 and a turbo350 tranny. I also had the whole truck, what I did was use the flywheel from the truck and ovaled out the holes so the torque converter could bolt up and no spacer. I'm thinking that is your problem try it without the spacer.