oldred95

I'm doing some research on the 4L80E as I'm thinking of doing a 60E to 80E swap and came across the topic of a 6 speed 4L80E. I remember seeing this mentioned on an episode of HPTV and doing a search here I didn't find much other then its either done by software or there may be a different valve body required to make it work. Does anyone know anymore about this illusive 6 speed 4L80E setup? I'm wanting to know how its done and what kind of gear ratios result from it. If its just software then thats just a matter of changing the shift routine is it not? Any info is greatly appeciated.

AlkyIROC

It's a valve body change plus a custom chip and an on dash controller.

Standard gear ratios for the 4L80E are the same as a TH400 plus an overdrive.

2.48
1.48
1.00
0.75

The 6 speed conversion splits 2 gears with the overdrive to give

2.48
1.86
1.48
1.11
1.00
0.75

Because the valve body is computer controlled with electric solenoids, the valve body swap is not cheap. The 6 speed conversion was most popular with trucks since it allowed the engine rpms to stay in the sweet spot by only dropping half a gear. Using OD as an extra gear isn't a true 6 speed since the OD gear is always small and weak. The OD gear is never a performance gear because of this.

oldred95

Interesting. So overdrive in the 4L80E is really that weak huh? It was kind of my understanding it would split the load and put less strain on the internals but maybe not. Is there any place online that has more info on this? I would like to see some pics of this setup if at all possible.

AlkyIROC

All overdrives are weak because it needs a small gear driving a big gear. Automatic transmission OD is no different. OD is not designed for power. The final OD is designed for high speed, low rpm highway operation to cruise at a much lower rpm to save fuel. Splitting the gears with an OD still needs a small gear driving a big gear. In an automotive transmission, you just won't get a big enough small gear to take any abuse.

In a highway tractor, it's a little different. It's common for a big truck to have an 18 speed transmission but it doesn't really have 18 gears. It's really just a 5 speed with a high and low range for 10 gears plus an OD that can split all the gears to give a total of 18 gear ratios. The OD gears are in the back of the transmission and are separate from the main gears. They use 2 countershafts to increase the load strength on the output shaft. the only time you need to split a gear is when you need to change the engine rpm one or two hundred rpm. Running empty, you can start in low gear and go through to high in only 10 gears or less, not needing the OD gears at all.

The 4L80E 6 speed conversion is the same thing. The split gears is only needed when in a truck as a tow vehicle and you need to drop down half a gear when climbing a hill to keep the engine in a slightly higher rpm range until the rpms drop down again for another 1/2 gear split. In a lighter vehicle, the extra gears are not required because it doesn't need as much HP to move the lighter vehicle. Climbing a hill, it's unlikely it won't even drop out of high gear. When I towed my car through the mountains years ago with my 454SS pickup which has a 4L80E, the transmission never dropped out of OD at all going up the mountains.

A proper 6 speed tranny would be more like the 6L80E with a very low first gear. It would give good acceleration off the line with something like 3.23 gears in the diff and have an OD for high gear on the highway.

Trouble with most 6 speeds transmissions is they're not really a 6 speed. The T56 has the gear ratios of a 4 speed tranny and has 2 OD gears. Unless you cruise down the highway a lot, you'll probably never use the OD gears.

oldred95

I see what you're saying. I thought it was odd that such a thing as a 6 speed 4L80E conversion kit existed yet nobody seems to know much about them and I've never known anybody that used one. My only beef with the 80E is the tall first gear ratio but that can be overcome with a high stall converter. Thanks for the information.

ls six

You realise that the same 2 planet assemblies are used for both under drive one to one and over drive right?

Planet assemblies consist of the sun gear planet gears and the ring gear.

Depending on how torque is routed each assembly has 6 ratios. 4 forward and 2 reverse.
The only thing that varies is which element of the planet set is static which is input and which is output.

Rob Allan

There are some errors here. Automatics do not use straight cut gear to gear as manuals do. This gear train strain has unbalanced loads from single point contact on side of the gear to its parent support shaft. ... Automatics use planetary gear sets. old ones used bands, newer use multi plate wet clutches.
planetary gears are balanced because two sides of the gear stay in contact, and are 180d apart. Automatics. This refers to the planet pinions and sun gear there are few performance gains or et times to gain. These autos can drastically improve performance by adding clutches, change line pressures. Increase number of pinions, changing planet ring gears, or sun gear teeth.
More gears keep engine in optimal rpm band. For torque development. Gear splits are not an issue there is no special small gear. Planet pinions are always small. Torque development flow path's change but that is fine.
Semi truck 18... Not all Eaton fuller 18sp Have overdrive at all. They use straight and helical gears but run double counter shafts to improve strength and. Yes the range and splitter are in the back A and B boxes.
Running fully loaded in ridiculous terrain rarely Warrants splitting all gears. But you will commonly split high range and they all handle full pull down torque. The only gear you shouldn't use is high range lo gear. The Lolo her will massively overdosed and gets hot fast.
13sp are similar but you can't split low range.
Mack triple shafts are different yet. And can get 10 fwd and rev.
This 6 sp 4l80 sounds great. But I'm not sold on the paddle shifters. Those are suited to cars not pull trucks. This trans is designed for trucks and heavy vehicles. That's why they use the 4l80 and not the 4l60e
I'm out

OrangeBird

iTrader: (1)

Digging up a 12 YEAR dead thread to play expert , yep , that's an error called "Thread Necro" ......

Rob Allan

Your absolutely right pardon me! I suppose your excellent board is best served by providing factually incorrect information to those searching through it.... Really adds value to this message board. Enjoy!!!!

ULTM8Z

Just to get more infomration out there on this subject...

Don't waste your money on a 6speed 4L80E. I tried one a couple of years ago and the damn thing whined like a UPS truck in first gear. It was so annoying I pulled it out and returned it and went back to my TH700R4.

Since that time, I put a Gear Vendors behind the TH700 and now have 8 speeds instead of what would have only been 6. Should have done that in the first place when looking for more speeds. It's such an awesome combination. TH700 + 3.42 axle ratio + GV....

Having those "1/2 gears" to downshift into is a ton of fun.... or going up freeway on-ramp and always staying within a couple hundred rpm of peak torque through all those shifts... it's a totally different car to drive.

Not to mention the double overdrive now getting me into the high-20's on mpg.

scooter

iTrader: (11)

I have a 6 speed behind my 4.8 and I use the OD gears around town all the time. With only a 3.45 rear I can use 5th down in the 35mph range to cruise down the main drag and I use 6th around 45. Not sure why people think you can't use OD a lot more, it's not only for going 80 mph

skinny z

Do you have thread about the GV install? I'd like to see how all that fits together.

ULTM8Z

Not really, but also it's in a 2nd gen Camaro. The details might be significantly different for a thirdgen.

Simply bolting it up to the transmission is actually a no-brainer.... just remove tailhousing and bolt up gear vendors in it's place. Shorten driveshaft accordingly.

Where it gets complicated on the 2nd gen is having to remove a center brace within the transmission tunnel due to clearance issues with the GV housing.

Then you wire up a switch to power the solenoid that activates the GV unit. They say to use a foot switch similar to the old floor mounted high-beam switches on the 60's/70's GM cars. But that seemed like it'd be too awkward to use in a performance application, so I wired up a momentary switch into the shift **** (which is actually a third gen ****) with a way to convert it to toggle.

http://nastyz28.com/threads/my-gear-...-setup.327437/

skinny z

Yes, a third gen complicates things further with the torque arm in the way. There's a thread here somewhere (by Badman?) and the build direction indicates that there will be a GV involved.
As for the GV itself, we had one behind the TH350 in a Chevelle. This was before the days of being able to split shifts reliably. Things have changed for sure.

ULTM8Z

I will say, the GV shift is definitely firm. Though the looser the converter you run, the less firm it becomes. My 2500 rpm converter makes it feel like a decent shift kit, so it's nice for a muscle car... during normal driving if you time the GV actuation just right with the upshift and downshifts, you can miniimize it even further.

I did have a stock converter at one point and the firmness was to the point of being objectionable. The 1st to 1st-over shift is the worst in terms of firmness, but even that isn't that bad with the 2500 rpm converter.

The quickness of the shift is based on how fast you're going since the fluid pressure is driven by the pump that's tied to the vehicle speed. So the 1st to 1st-over isn't as fast as the other shifts (it takes about a second or so if you're driving normally and shift at lower speeds) since the vehicle speed isn't that high at that point. All the other shifts when you're at speed are pretty instantaneous.

So it's not perfect, but the benefits everywhere else more than outweigh that particular drawback. I don't drag race the thing, so for me it's not at all big deal.