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Rebuilding My 4L80E Transmission

1-ton

1-ton

3/4 ton status
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I got my 4L80E transmission out of my 1991 V3500 Crew Cab. It had about 300,000 miles on it, and was starting to develop a wine. Also at 300,000 miles I am sure the clutch bands and bushings have to be starting to wear out. I got a top of the line rebuild kit from Jakes Performance transmission that cost me about $1000. I am going to do all the modifications to my transmission like "internal dual feed" and "rollorize output shaft".

The truck this transmission came out of.
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My 4L80E on the bench stand.
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This is the rebuild kit I got from Jake's Performance Transmissions. With tax and shipping it was about $1000. Comes with a billit forward hub.
screenshot_9__37c7013b091de4ced98083935258879953b43e10.png
 
I have a few of these that are going to need rebuilt. Auto transmissions are the only part of a vehicle I've been pretty much scared of trying to rebuild though lol.
Too many things that have certain places that I'm afraid I'll not remember.
 
The auto trans is the only thing I have ever had to buy a book to put back together and I have rebuilt pretty much every thing on a vehicle without a specific book. The reason being is, I took apart a TH400 to sell the tailshaft. Well, when you do, unlike every other engine or machine that you can just put it back the way it was, when you take certain pieces out of an auto trans, pieces fall all over and you have no idea where they came from. So I put it back the way it was, but couldn't get the center support bolt in, turned out a spacer inside the planetary gear assembly had shifted out of place, that's all it was.

Anyway, I bought a TH400 book, and have since rebuilt a couple TH400s and a couple 4L80Es with success. I recommend you buy a book, not just the ATSG book, but another if you can, even buying a TH400 book can help because the 4L80E shares a lot of parts with the TH400, from the center support back they are extremely close and share parts depending on the year.

This book was not out when I did mine, but I will order it to have as a reference.

www.cartechbooks.com

GM 4L80E Transmissions: How to Rebuild & Modify

Learn how to rebuild and modify the GM 4L80E transmission!As the successor to the venerable and popular Turbo Hydra-matic 400 (TH400), the 4L80E was the next flag bearer in GM’s line of automatic transmissions. While serving as the smaller, lighter cousin to the 4L85E, the abundance of 4L80E...
www.cartechbooks.com www.cartechbooks.com
 
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Truckman4life said:
Looks like you have to buy the 4L80E video series but after watching his other YouTube transmission videos it would be worth it in my opinion. The Transmission Bench does excellent videos on trans rebuilds and has a really good website for parts also.

videos page

transmissionbench.com
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I used his videos to do my 4L80E and also the kid's 4L60E.
Jimmy gave them to me when I bought a rebuild kit through him 2 years ago. He had a deal going then. I feel that they are worth his price, after using them. He did a great job with his videos!
 
Do his videos show any mods? Or stock rebuilds? A video is easier to follow than a book, that's for sure. And once you understand reassembly mods are easier to understand.
 
folkenheath said:
Do his videos show any mods? Or stock rebuilds? A video is easier to follow than a book, that's for sure. And once you understand reassembly mods are easier to understand.
Click to expand...
For the 80, he went through installation of the Transgo HD-2 kit, and I believe a few small modifications. I don't remember the fine details right now.
He showed how to check clearances fairly well, if one didn't understand, too.
But he doesn't the work while leaving wide open views for the camera, while speaking slowly and very clearly.
 
Truckman4life said:
Looks like you have to buy the 4L80E video series but after watching his other YouTube transmission videos it would be worth it in my opinion. The Transmission Bench does excellent videos on trans rebuilds and has a really good website for parts also.

videos page

transmissionbench.com
Click to expand...
I bought this flash drive from transmissionbench.com
 
My advice for any build on a high miles 4L80E is to look into AFL and Pressure regulator mods/restoration to get a good line pressure base line, and don't forget to replace the filter behind the manual valve. All the fancy kits and clutches will amount to nothing without the integrity of the hydraulic system , it is the foundation of any build.
 
Are the pressure mods necessary if you have electronic control of the pressure?
Like with a Holley terminator Xmax.
 
Greg Ducato said:
My advice for any build on a high miles 4L80E is to look into AFL and Pressure regulator mods/restoration to get a good line pressure base line, and don't forget to replace the filter behind the manual valve. All the fancy kits and clutches will amount to nothing without the integrity of the hydraulic system , it is the foundation of any build.
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About 15,000 miles ago when I installed a new crate 350 engine in my truck I did a half @SS job on my transmission, and replaced the pressure regulator valve with a Sonnax one that has the bleed off spool in it along with all the internal electronics. I also had a torque converter built for it. I bought another new regulator valve from Sonnax for this rebuild just for the hell of it. The rebuild kit I bought from Jakes Performance Transmissions come with a regulator spring that Jake claims holds a more consistent pressure than the Trans Go kit does. I also did the valve body AFL bore and sleeve deal. the one where you have to buy like 7 of them, in order to use just one.
 
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I removed the torque converter from my transmission, and dropped it off at a guys business that has the machinery to rebuild torque converters. He rebuilt the one I dropped off a few years ago, and installed a billit piston, billit stator, and new friction material in it. That torque converter is working perfect. I just want him to open it up, clean it up, and insect it so that I know it is good to go with this new transmission build. This guy also has the equipment to reman transmission pumps. I am going to drop of my pump to him to inspect it for any wear it might have, and resurface it if it needs it.
 
shady said:
Are the pressure mods necessary if you have electronic control of the pressure?
Like with a Holley terminator Xmax.
Click to expand...
You would have to ask Greg Ducato on that one. I am not aware of controlling transmission pressure electronicly on a transmission. I am only familiar with controlling transmission pressures mechanicly with valves and springs.
 
Removed the pan. The pan is clean as can be...no clutch material or metal. Filter was correctly in place. Even the torque converter shaft wear marks indicate the torque converter was engaged into the pump gears properly.

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shady said:
Are the pressure mods necessary if you have electronic control of the pressure?
Like with a Holley terminator Xmax.
Click to expand...
Yes, it is critical to stabilize pressure and remove as many leaks as possible internally, adding pressure through the EPC on a leaking system is a bad idea.
 
I got the internal wire harness, valve body, and servos out of my transmission today. I am glad to get rid of that Trans Go 3-layer separator plate. Those things are a back door way of dual feeding a transmission. Those things are known to sometimes leak internally. Those plates are a waist of time because they are meant to be installed without removing the transmission or taking it apart, and if the direct clutch apply piston modifications are not done, which can only be done by taking the transmission apart, then the dual feeding will not work to its full ability.

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I agree, I always dual feed internally to, I leave the corresponding seal off the center support and the direct piston, while plugging the case hole with a cup plug.

However, those plates are better than nothing if someone has the trans in the vehicle and needs to upgrade it over stock.
 
imiceman44 said:
I need to do this to my 4l80e.
At least one of the 3 I have
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rebuilding this transmission myself is going to cost me somewhere around $2000. If I had a transmission shop do it probably cost about $5000 to $6000. So far I have about $1300 into it, and I have not even gotten to the hard parts yet that may need replacing.
 
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