Hey guys, we are swapping out the 4L60E in our 98 LS1 for a manual valvebody race prepped TH400. Good News is it won't blow up. If anyone can let me in on all the Bad News of what we need to do so that things work properly, it would be greatly appreciated.

Thanks in advance, Rick @ STS
rick@ststurbo.com

 

Do a search someone just posted EVERYTHING you need. It was in the last 2 weeks.

 

The Chevy version of the TH400 will bolt right to the block minus one bolt, but many are running big power this way with no issues.

-Obviously, you can't use a standard torque converter, you need one with the correct hub and bolt pattern for the LS1 flex plate. Most vendors know what to do.
-You can actually use the stock A4 shifter with a little grinding of the shifter plate to rearrange the gates. And then weld a stop to keep the shifter from going all the way back to the last position.
-The cable bracket under the car will work also, but will need to be modified to fit the TH400 pan. New ones are only $6 from GM
-If you get a short tailshaft version, the mount will line up perfectly with a 6-speed cross member, but don't forget a urethane mount for TH400
-You will need a special sppedo sending unit to make the speedo work
-You will need a custom driveshaft
-Would not worry about the dust cover
-You need a dipstick; Madman sells a steel tube with dipstick for the TH400 that looks like a factory tube; ore use a Lokar braided one (but they are kind of short) - Recommend Madmans version if all the stuff is still under the hood (lots of clutter)
-An external tranny cooler would be good

That's all I can come up with for now

 

Thanks, any issues with the computer wanting to control shifting and pulling any codes with harness disconnected?

 

Yes. Since you are already an A4, the PCM needs to be addressed with LS1 edit. Have never done this though. Every car I have seen converted, including mine, started as a 6-speed.

The car will not move if you don't address the PCM. There are "tranny trickers" avaialble also.

 

When you say the short tailshaft version, are you talking about the 4" tailshaft?

 

Yep

 

I'm curious, I always here people say you need a special converter for the TH400 in an LS1, but i'm pretty sure (not positive, cuz I didn't do the install, and I bought the setup off of a friend) mine has a regular TH400 converter and they drilled holes in the flexplate for it to bolt into, is that a problem?

 

i drove my car for mre than 200 miles with out any changes in the PCM but i got engine light, its not bother me
i swap from A4

 

i drilled holes in the flexplate for the TH350 converter to bolt into it, no proplem yet

 

cool, thanks!

 

Shouldn't be a problem. Just easier to order with LS1 pattern.

 

Thanks for all the good info. Who builds a "trans tricker"?

 

Probably cheaper to just get the PCM set up for a 6 speed than go with a trans tricker.

 

The real problem with not using a LS1 TH400 torque converter is the center hub is not long enough to protrude into the end of the crankshaft. This hub is what centers the torque converter on the flexplate, I would be very concerned about ensuring the torque converter is truly centered with the crank.

Any torque converter manufacturer can extend the hub to ensure it works properly.

Ryan K.

 

Good point Ryan, that is why I said "you can't use a standard torque converter, you need one with the correct hub and bolt pattern for the LS1 flex plate"

 

How do you get the speedo and other accessories to work? I have the M6 and will be doing the swap soon. i am sewriously looking at doing the Gear Vendors overdrive unit in it though. Not too sure I want the extra 100lbs of a TH400 over a TH350 though.

What do you guys think is there anyone here using the Gear Vendors OD unit?

 

TTT
i got th350 and it sucks in the HW with unlocked converter

i need the OD

 

The 3-speed isn't the best thing for the highway


with my 3.73's I turn 3000rpms at 60mph........

 

If I get one I will definitely have to get the OD unit. I have 4.10's in the car now