ElQueFør

I have two 4L80s and I'm going to freshen up one of them to install in a 92 K5 Blazer. It's going behind a pretty stout aluminum headed 350 I built which I'd estimate somewhere in the range of 400 HP and maybe 450-500 TQ. I have built a 4L60 before and I'm armed with an ATSG manual and a bunch of snap ring pliers to tackle this 4L80 build.

I'm not looking for anything super exotic as I think even a stock rebuild will suffice for this. I'm curious where people are getting their rebuild kits for these and how much they typically spend.


QUESTIONS:

1. Where to get a rebuild kit? What needs to be replaced and what doesn't?

2. What is this "bonded piston" I keep coming across?

3. What improvements should be made during this process? I remember in all my reading about leaving a seal off of one of the drums or carriers, drilling a hole here etc.... I've lost that info so if anyone know about these little tricks and could post them up that would be great.

4. The Transgo HD2 shift kit seems to be popular... But if I'm rebuilding the whole transmission what are my other options or is that the best one?

I've been looking at these rebuild kits as I'm about to buy some transfer case parts from them also:
https://cobratransmission.com/index....1_11_19_41_147

ElQueFør

Looks like any of the Banner or Raybestos kits will work good, they seem to be everywhere.

I believe that the bonded piston is a later design revision where the lip seals are affixed to it??? That's the best answer I can come up with so far.

And for parts 3 and 4, it looks like a dual feed mod is the preferred option if you're going into the gearbox so I'll be doing that.

Here is a some reference material I've found on the matter.

Details on the dual feed:
https://www.performancetrucks.net/fo...t-drum-506779/

A nice 4L80 rebuild manual:
https://www.thirdgen.org/forums/tran...nual-link.html

So the next question during this planning/buildup phase of rebuilding this 4L80 is what if any shiftkit to use???? Seems kinda like a waste to get the TransGo HD2 shift kit if you're going to not use some of the parts like the separator plate etc. if you're doing a true dual feed to the direct as described in the post above.

dmaxs10

iTrader: (1)

How much you looking to spend? I got a kit from jakes that comes with mod instructions for a few things that seems to be working well, haven't finished it yet

ElQueFør

Yeah I was looking at Jakes rebuild kits and even the "cheap" one is more than I want to spend and is likely overkill for this application.

Okay a stock rebuild it is then. I'll be looking for those brands of frictions.
Good to know that you can reuse the steels if they aren't warped, cracked, discolored etc.

I'm going to post up what I think are the parts you're describing, if you could please confirm or correct where necessary I'd sure appreciate it.

Is this the shift kit you're speaking of?
https://www.ebay.com/i/112316596995?chn=ps

Are these the high temp sealing rings?
http://www.transgo.com/products.php?...dcountview=Yes

Is this the paper and rubber kit?


You say you need to know things. Can you please elaborate. My only auto experience is a 4L60 I built, I have also done differentials, manual gearboxes, engines etc.. So I don't think I'm too outclassed here, but any thing people like you may know would certainly help me and anyone who might find this thread in the future.

Around $400-500 is what I was expecting to spend to get this thing all freshened up. So that's good to know.

I'm still very confused on when and where the molded piston gets used?

Bronze bushings are preferred I take it???

I see that Oklahoma Transmission Supply is listed as a distributor for some of the TransGo stuff.. That's nice because they're right in my back yard!!!

clinebarger

I would recommend internally dual feeding the directs as it gives you room to grow horsepower & torque wise in the future.

Anytime your dual feeding the directs.....Run "high rate" return springs in the direct drum & a small bleed hole (.055") at the edge of the drum under the piston!
The above are needed because you now have to evacuate 200% more fluid during 3-2 & 3-1 downshifts, It also helps prevent direct piston "creep" at high RPM's in 1st gear.
I like using TH400 Aluminum "wave plate" style pistons in the direct drum for the better work surface & more positive return spring retention. Like this.....http://www.ckperformance.com/View/4L...PRING-ASSEMBLY
I would never pay that because I procure & machine my own pistons, But it may be the best option for you?

Run a HD Intermediate snap ring....http://www.ckperformance.com/View/TH...UTCH-SNAP-RING
Cheap insurance against snap ring/case lug blow out!

Rollerize the Output & Forward Hub. Specifics here, Along with other info......https://ls1tech.com/forums/automatic...-question.html

Line Pressure Booster kit Sonnax part# 4L80E-LB1
TCC Regulator Valve kit Sonnax part# 34994-01K

Replace ALL bushings if possible. I like Clevite. The Forward Drum & Sun Gear Shaft are the highest wearing ones. The Center Support bushing at the very least needs checked.....If you can catch a nail where the sun gear shaft runs Replace it!

Do you have a WIT (Whatever It Takes) near you? They can sell you a master kit with Frictions, Paper & Rubber, Steels & Bushings for a good price along with the Sonnax parts.
They push Raybestos.....But have Borg Warner friction modules as well....
Upgrade to "Turbulator" steels in the 4th clutch & Overrun if you have a '91-'96 core.

clinebarger

You can also remove the Molded Inner Seal on the late 4L80E forward drum.

ElQueFør

Guys this is exactly what I was hoping for. I'm just letting everything that's said soak in and chewin' on it a while.....

Cline thanks for posting up those part numbers. Not sure if I have a WIT distributor near me... I'll be looking into and confirming that come Monday though. And I'll be posting pics to ask you if I have the bleed hole in the right location of said drum before drilling it.....

And you're right Jay... I need to tear down that other core before I get too ahead of myself. First I'll need to take the 2wd 4L80 off the holding fixture I made for it and then slap the 4wd 4L80 up there that I recently found. My plan orignally was to shorten the output shaft of this 2wd unit and use it but since I found a 4wd version I'll use that instead and keep that 2wd unit for something else.

Both of my 4L80s are later model, not sure exactly how late, but they are both center lube and have 7 bellhousing bolt holes instead of 6......

Thanks to everyone for chiming in so far, I have to keep pondering this and get this other core torn down but I'll definitely be back with more questions and/or findings.

clinebarger

You would have NO "rear unit" end-play with that arrangement....Unless they ran a thinner output/case shim to make room.
The Sun Gear Shaft will now run too low in the Stack causing the direct drum to ride to close to the center support.

clinebarger

Nope.....The only adverse effect it may have is a firmer forward clutch apply, I use a TH400 Wave Plate to counteract this. The late 4L80E wave can break.....The "2-Tab" Dished plates found on some TH400 & early 4L80E's can also break.

"IF" you install any TH400 or Direct Piston in a late 4L80E Forward Drum....The center lip seal is no longer effective because the larger counterbore.

ElQueFør

I got it all torn down guys and everything looks great inside. No metal chunks, only the typical clutch and metallic paste in the pan that you usually see.....

I'll post pics up later tonight.

I'm not good enough like you guys to dump it all out on the bench and know right away what goes where so I laid it all out in order just as it came out and have rags over it all.... I will rebuild one sub assembly at a time to make sure everything goes right.

ElQueFør

Well for whatever reason I can't get any pics to upload here, odd since I uploaded some earlier this afternoon.

Cline, do you have any pics of exactly where to put that bleed hole in the direct drum? Also, where can I find the high rate springs for the direct drum?

EDIT: I found this for pics for the bleed hole

https://ls1tech.com/forums/automatic...-screw-up.html

https://ls1tech.com/forums/automatic...ing-4l80e.html

clinebarger

You got it, There are usually "balancing scallops" on the outside of the drum, I drill on one of those locations because that is where iron is thinnest reducing the possibility of breaking a bit.

CK Performance sells high rate springs, In fact here is a kit with a Aluminum TH400 piston included.....http://www.ckperformance.com/View/4L...PRING-ASSEMBLY

clinebarger

As an option....There is this kit that includes most of what I was talking about in my earlier post. http://www.ckperformance.com/View/MA...LY-UPGRADE-KIT

ElQueFør

Thanks cline, I'll be back with more novice questions later

ElQueFør

I've almost got the transfer case back together for this project so I can start rebuilding the 4L80...

I have the LS style 4l80 flexplate laying around but it looks like I need a TH400 flexplate in order to bolt up this LS 4L80 to the SBC I'm putting it behind can anyone confirm this?

ElQueFør

What I meant was the fact that it's a late model with 7 bellhousing bolt holes.

So a TH400 flexplate it is then?

ElQueFør

Ok Cline and Jays.......

I got a box full of goodies from Oklahoma Transmission Supply a few days ago. Will be rebuilding one subassembly at a time here soon......

SORRY for another stupid noob question, but I just want to CONFIRM before I buy parts.....

To stick this 4L80 behind a SBC I need a TH400 flexplate with the little balance weight on it since this SBC is a 1 piece RMS..... AND..... I CAN use a LSx 4L80 torque converter right??? I have two torque converters that were from 4L80s that came behind LS engines... Both of my 4L80s are 2001.........

ElQueFør

Bump. Still can't get 100% confidence that I'm finding the right flexplate and converter info for this.

Here's what I got:
1 piece rear main seal 350
staggered style bolts on the starter
4L80 going behind it is a 2001 model year

I have two LSx 4L80 flexplates and torque converters, CAN these be used with this small block??

ElQueFør

Jay I certainly am not trying to question your knowledge or anything so don't take it the wrong way. I tend to have to ask a bunch of questions over and over, usually stupid ones at that in order to solidify in my mind what I'm doing that's all.

I haven't been on in a few days so I'm just now seeing your post but I called Jegs several days ago, probably a week ago and I spoke to a tech and told him what I had and what I was trying to do. The flexplate below is what he told me I needed so I bought it. If it doesn't work I will send it back.

Chevrolet Performance 14088761
http://www.jegs.com/i/Chevrolet-Perf...88761/10002/-1


It has the "batwing" on it to accept a 1 piece RMS and a 3.00" crank flange pattern, and 11.5" converter pattern.

Now, here is the latest development in my gearhead adventures........

One of my daily drivers is a turbo 6.0 T56 fullsize C1500, maybe you've seen me post about it on here. Well....... Today it got stuck in 4th gear...... Which likely means the slider keys are broken, possibly worse. I can't bitch too much because it's been going for a long time and has many hard hard miles on it. It was originally a LTx T56.... I bought it used and beat on it for several years behind a mild 300HP SBC...... I then converted it to LSx style and didn't rebuild anything inside, just converted it to LSx style!!! I guess the fact that it's from the middle 90s, and has had the **** beaten out of it two decades has finally killed it....... I can't bitch too much considering that.

So...... I'm at a crossroads here...... I have two 4L80s, a 4wd 99 unit that is still going in the Blazer with the SBC that I started this thread for. The other 4L80 is a 2wd 2001 unit...........

So.... now that I'm finally making some real power, and it is in a heavy *** truck, I'm beginning to wonder if it really makes sense to keep dicking around with a T56....... The logical answer is probably no. Stock 6.0 seeing 6ish pounds of boost is somewhere between 450 to 500 HP I think.... I have plans to eventually go up to 12 PSI of boost in the future which would be nearly 600HP.

Point being I'm at a crossroads here. I'm thinking I will take all the stuff I have already purchased for one of these 4L80s and build up the 2wd version to replace the T56 in this truck. I just think a 4L80 behind a turbocharged 6.0 in a heavy 5000# truck is going to be more reliable. What do you think? And probably cheaper in the long run?

Thoughts?

Game ova

Wouldn't this cause a hardship on the pressure plate by the stack "smacking" when applied, and possibly punching the snap ring through the retaining groove?