Tranny question

**scooterboi** · 02-12-2006, 05:57 PM

I wanted to know do I have to change the flexplate on a LS1 to bolt up a th400 tranny?

**lrader99** · 02-12-2006, 07:15 PM

why would you want to bolt it up to a TH400?

**scooterboi** · 02-13-2006, 04:07 AM

Originally Posted by lrader99

why would you want to bolt it up to a TH400?

The LS1 is getting carb'd put the tranny is for holding power.

**jay_lt4** · 02-13-2006, 06:26 PM

i just put a carbed ls1 into a s10 with a turbo 350 trans, you have to use an adapter for the crankshaft hub to work with the 350/400 style converters, and the flex plate on the ls1 does not have the correct bolt pattern for the old style converters but you can oval out the holes with a dremel or die grinder

the crankshaft adapter is made by hughes here is a link:

sorry i cant post links yet, just enter in hughes trans adapter in yahoo search and click on the summit racing page, its only $44 from them

**scooterboi** · 02-14-2006, 04:01 AM

Originally Posted by jay_lt4

i just put a carbed ls1 into a s10 with a turbo 350 trans, you have to use an adapter for the crankshaft hub to work with the 350/400 style converters, and the flex plate on the ls1 does not have the correct bolt pattern for the old style converters but you can oval out the holes with a dremel or die grinder

the crankshaft adapter is made by hughes here is a link:

sorry i cant post links yet, just enter in hughes trans adapter in yahoo search and click on the summit racing page, its only $44 from them

How does your truck run with the LS1? I'm just starting to get everything together.

**jay_lt4** · 02-14-2006, 05:58 AM

its at the exhaust shop now, actually it is a 5.3 silverado engine with a ls1 hot cam and valve springs

runs great, just drove it around the parking lot and then took it over to get exhaust done, should be ready by thursday