4l80E torque converter choice/ General Rebuild Questions

[Joelvv]

I have a bunch I'd like to ask, but I'm sure I'll forget half of it. This will be a bit long winded, so sorry in advance.
I have a K3500 2000 CCLB SRW with 370,000 kms. The transmission has had a slow leak for a while, as well as pretty consistently having code P1870. It's thrown in the towel, so I have to pull it and rebuild it. I was going to inspect and reseal the t-case ( I believe it's a 4401) while I'm at it.
Currently, the truck is powered with a 1997 305, because the 350 failed and it didn't have time, or care to rebuild it at the time. It's gotten along OK with it, but once I have the tranny rebuilt, I'd like to start on the engine, and drop it in at some point. I'll likely do some sort of an RV cam (so long as it will have a decent idle and not kill mpg) and a 411 PCM with a custom tune. I have no plans to make crazy power.

1. Would a standard, run of the mill conveter work, or should i be looking at something better? Any cam suggestions?
2. If a better than stock converter is better, what should I be looking at for advertised stall?
3. For those that have rebuilt their trans, or been closely involved in a shop rebuilding it, what are obvious things to look at. More looking for the ins and outs of a 4l80E. As far as actually rebuilding it, working with teflon rings, etc. I'm an equipment tech, so I won't be too far out of my element.

 

[Christian Steffen]

I have a bunch I'd like to ask, but I'm sure I'll forget half of it. This will be a bit long winded, so sorry in advance.
I have a K3500 2000 CCLB SRW with 370,000 kms. The transmission has had a slow leak for a while, as well as pretty consistently having code P1870. It's thrown in the towel, so I have to pull it and rebuild it. I was going to inspect and reseal the t-case ( I believe it's a 4401) while I'm at it.
Currently, the truck is powered with a 1997 305, because the 350 failed and it didn't have time, or care to rebuild it at the time. It's gotten along OK with it, but once I have the tranny rebuilt, I'd like to start on the engine, and drop it in at some point. I'll likely do some sort of an RV cam (so long as it will have a decent idle and not kill mpg) and a 411 PCM with a custom tune. I have no plans to make crazy power.

1. Would a standard, run of the mill conveter work, or should i be looking at something better? Any cam suggestions?
2. If a better than stock converter is better, what should I be looking at for advertised stall?
3. For those that have rebuilt their trans, or been closely involved in a shop rebuilding it, what are obvious things to look at. More looking for the ins and outs of a 4l80E. As far as actually rebuilding it, working with teflon rings, etc. I'm an equipment tech, so I won't be too far out of my element.

I don't have much for input on the transmission stuff.. but damn that thing has to struggle with a 305..

 

[Joelvv]

Really not that bad, on a 350 tune no less. No worse than the 350. It holds it's own once you're up to speed, and gets 16 mpg on longer trips. I've had a 7-8000lb~ disc behind it, and got to and held 55mph in drive.

 

[df2x4]

I don't have much for input on the transmission stuff.. but damn that thing has to struggle with a 305..

Can't be any worse than my 4L80E swapped 4.3L truck.

I'm not sure about the torque converter question. I re-used the one that came in my junkyard 80E and I couldn't find any markings on it.

The TransGo HD2 shift kit is a highly recommended mod in the 4L80E world, minus one small part. If you're rebuilding the trans anyway I would go ahead and put in an HD2 kit. Here's a link with info on the specific part of the kit to avoid.

https://sites.google.com/site/sloppywiki/everything-ls/4l80e-info

As far as the ins and outs of the transmission, I personally can't help you much. But a couple years back someone posted a thread with a dropbox link to GM's official 4L80E service manual. The link to the PDF file is still active. I haven't read through the copy I downloaded back then but I imagine there's some really good info in there.

https://www.gmt400.com/threads/4l80e-factory-service-manual.35523/

 

[Christian Steffen]

Really not that bad, on a 350 tune no less. No worse than the 350. It holds it's own once you're up to speed, and gets 16 mpg on longer trips. I've had a 7-8000lb~ disc behind it, and got to and held 55mph in drive.

A little extra work and you could probably get it back to a 454. Mileage won't be as good cruising but you will probably be a lot happier towing. Just food for thought.

And +1 on the hd2.

 

[Joelvv]

A little extra work and you could probably get it back to a 454. Mileage won't be as good cruising but you will probably be a lot happier towing. Just food for thought.

And +1 on the hd2.

It never had a 454 in it. I'm honestly quite happy with the mileage it gets and don't want to mess with that too much. I would love the 454 for power, but then I'm down to 12 MPG at best. I'm surprised by what this thing will get on long trips, and would like to keep it that way, because I do occasionally take it on longer trips, and it currently doesn't totally break the bank to do so. I'll look into the HD2. Thank you.

 

[Supercharged111]

I used a Superior shift kit in my 1500. Supposedly that and the sprag are all that needs upgraded to 700hp. I never bothered with the sprag, got 45000 on the rebuild so far.

 

[JayMB]

I dealt with Jake's performance in Texas for my parts/rebuild kit and had a local machinist who does auto transmissions on the side do the work. Jake's stage 2 kit was about $850 but it came with a bunch of upgrades including valve body modifications equivalent to the Transgo HD2. What started me talking to him was that I was on a quest for a better torque converter. He built me basically a stock high stall unit (B82?) with a better lockup clutch and a billet front housing. Was $500 but all I could find were cheap remans. FYI the 4L80 changed sometime in 1999 to use a longer pump drive snout on the converter. The old one was roughly 2 1/16" and the new one is 2 5/8" IIRC. Be careful buying a converter because lots of folks think that GEN1 small blocks stopped in '98 and everything 99+ is LS based. You need a sbc converter that fits into an LS-style 4L80E (the new 99+ 4L80E's tend to have a 12 o'clock bolt hole in the bellhousing for the LS motors even if they came behind SBCs. My '99 K2500 is like that). Good luck!