4L80E Performance Rebuild PT2: Center Support Through Gear Train Assembly 

Hi Nadar53, thank you for watching! I'll be starting a "4L80E Information" thread sometime this weekend in the Transmissions sub-forum on GMSquarebody....Will be similar to my TH400, TH350 and 700R4 threads already on there now.

Sounds good. Thank you for sharing and watching, Michael.

Thank you, Tim

The Transgo kits are great for when the transmission is in the vehicle, otherwise healthy and someone needs more performance but at $150+ doesn’t make financial sense when the transmission is all apart on the bench. The center ring on the fwd drum was put there to soften engagement into drive but isn’t necessary. I also like to leave out the center seal on the direct drum.

Thanks again, man! Have you watched my 4L80E tear down and inspection video? If not, it's in my 4L80E playlist and goes into fine detail about what to inspect as well as how to do assess parts for reuse or replacement: ru-vid.com/group/PLMqgQ_reThtIAoJjdlytIWnmlH04YqYz- Lastly, check out my valve body and pump Vacuum testing videos were I demonstrate how to properly assess sealing integrity and general condition of the transmission's hydraulic circuitry.

You're welcome, Ed and thank you for watching...Without being able to see what bearing you're referring to, I can't really answer your specific question. The 4L80E has a traditional torrington bearing between the forward drum and OD planetary carrier. It also has three multi-piece torrington bearings in the gear train, which I show their locations and orientation in the video you just watched. You may also have a large TH350 pump thrust bearing at the rear of the case if someone rollerized the output shaft flange-rear case thrust location.

Thanks for the quick response! So looking closer at 1 exploded view I do have, there is no torrington bearing between the center support/direct drum, or the direct drum/forward drum? @@nickstransmissions

You're welcome! Re-watch this and the first 4L80E video in this series as I show every bearing and thrust washer location and orientation. I know it can be a bit tricky for first timers so I ensure placement and orientation is shown in detail. If I don't show a bearing or thrust washer in a given location then none goes there.

How many torrington bearings are in a 4l80e??? I think I actually have an extra! Everything I lok at says there are 5, but I have 6???@@nickstransmissions

There are four total t bearing assemblies in that transmission from the factory, as mentioned above. One can be added to the rear of the case while two more can be added to either side of the forward clutch hub if the factory hub was swapped for a billet steel hub that accepts t bearings.

Its a great question because i was going back and forth about doing it but didnt see any references to doing so in a 97+ trans and a couple builder friends of mine weren’t sure as they do the same mods i show in the vid but don’t touch the sun gear. Im trying to find out if there’s any downsides and if not will do a follow up video on drilling the sun gear to .125

Hi David, I actually discuss those in that video series; I think starting with the direct drum build up.

@@nickstransmissions Thanks Nick. These are just parts i had laying around.

Yep, for sure. There's another benefit to not soaking them and that has to do with checking the fully assembled case for any issues...I cover my rationale for not soaking them as it's a controversial topic either way and get a lot of questions about it (in case you haven't seen it): ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2j6XYCblG5I.html

@@nickstransmissions ah yes, you mentioned that you went over your reasons in another video and I was wondering which one. Thanks.

You're welcome, man and thank you for watching!

Thank you for watching, Quarter Bubble Garage. You need to add the apply plate travel measurement to the measurement you get when measuring the distance from the apply plate's ledge/step to the surface of the top friction. In your example above, you'd add .062 + the apply plate's travel from it's rest postion on the step to full compression against the snap ring when air is put into the drum. So let's say your plate travels .020" from it's rest position on the step to full application against the snap ring, you'd have .084" total clearance (.062"+.020" = .084"). That's just an example as you'd have to share your actual apply plate travel figure with me for me to know your total clearance in that drum. Reply if you have any questions.

@@nickstransmissions The apply plate travel was the 10 thou measurement so I am at 72 Thou total with a 5 friction stack. If I understand that is about 10 thou too tight, correct?

Assuming you're working on a 4L80E, generally you want to stick to .010 per friction so .072 should be fine if a little on the higher side of spec for clearance in the direct drum (assuming you're asking about the direct drum). Your clearance will make a difference in shift quality as well based on how wide you drill the 2-3 feed hole and whether or not you're deleting 2-3 & 3-4 accumulators and internally dual feeding, not mention the appplication, engine power, converter stall, rear gear ratio, etc...

Thank a bunch, Patrick! Unfortunately, you won't be able to run the 4L85 gear set in your 1995 4L80E. The 4L85E went into production in 2002 and that entire gear set had all the same design changes that took place in 1999+ changes which affected the planetary carriers, sun gear, intermediate shaft, and sun gear shaft, output shaft and none of those parts can be installed into a 1995 unit as it had the traditional rear-lube design.

So, it's not so much a dimensional thing, but a lube circuit thing?

It's both - the 99+ planetary pinion gears are taller so that required changes to the sun gear, shaft and the addition of a .041 spacer to the immediate rear of the center support-sun gear thrust bearing to re-center the sun gear...The other, bigger problem you'd need to solve is the lubrication circuitry. You'd have to completely re-engineer everything in the rear gear train to run a 1999+ 4L85E rear service pack in a 1991-1996 4L80E. So I guess if you really wanted to, had the time, knowledge and resources to do it, you could (true for pretty much everything when it comes to auto repair) but you can't retro that stuff "as-is" into an early case.

Thank you!

Hi Jazz, I've been building transmissions for over 10 years. Thank you for the kind words.

Your welcome man keep up the good videos

Will do, man.