I don't understand "leaving the factory first gear in there". Maybe you think "adding gears" means there's room for additional planetaries, it's not like that. The 4L80 has 3 planetary gearsets, so does a 6L80-E. When you change the ratios of first and second it's the two rear planetaries that are REPLACED. The overdrive has it's own dedicated set and achieving more than 4 forward ratios on a 4L80-E is accomplished by overdriving the first two gears through valvebody and control trickery.
Get a ATSG manual for it and read. Very informative.

Totally based off this transmission, which is supposed to be an actual 4L80E with extra gears. I don't know much on how transmissions work, always treated them like a single unit before so I'm not ashamed to admit ignorance on what may or may not work.

While searching the web for reviews of the TCI 6-speed 4L80E, I came upon a description of how they worked. Overdrive is added to first and second to split the gear. I don't understand completely what that means but I know there are no "additional" gears added to the transmission.

Dude, I'm with James on this one. WE blow 60E's up because our feet can't stay off the floor. (WOT) You're wife doesn't drive like that, man. And if she does, make sure she stays in OK. We have enough crazy drivers in Dallas. I occasionally tow some pretty bodacious loads and have ZERO problems. Then again, I'm not trying to pass Z28s with a boat behind me either. If it were me, I'd visit a yard, pick up a trans for a couple hundred bucks and slap it in. You don't drive it every day, what do you care?

Dirtnap wrote:

While searching the web for reviews of the TCI 6-speed 4L80E, I came upon a description of how they worked. Overdrive is added to first and second to split the gear. I don't understand completely what that means but I know there are no "additional" gears added to the transmission.

lets say it was completely manual transmission and had rods that you would have to move for whatever gear your in.
it would look like this

1 2 3 4

forget park and reverse and all that crap. lol

all sticks start in the up position, you pull 1st and your in 1st, 2nd, your in 2nd, and so on.

what the TCI 6 speed is doing, is playing with the OD or 4th gear (stick)

it starts in 1st, then the computer pulls 4th(od) - which is actually 2nd in this case, then puts it back as it pulls 2nd - which will be 3rd, then the computer puls 4th(od) again, which will be 4th - that was 4 gear changes right there - follow? the only difference being the engagement of OD - which, unless im mistaken, has its own section/planetary/gearset - however you want to look at it, separate from the other "gears".

really, they could make a 7 speed - i think, 1-1 over, 2-2over, 3-3 over, then 4 - but i dont know enough about transmissions to say for sure.

but thats all it is - if you break it down, the magic gears are just overdrive added to 1st and 2nd, which i think is pretty lame - but cool at the same time.

i would just get a gear vendors unit and do it yourself, but thats me, then you could be cool like James and have an 8 speed.

James B. wrote:

valvebody and control trickery.

Speeder it's that simple !!

Thanks folks.

Daddy, I do care. Really. It doesn't matter if I drive it all the time or not, I want my team to have the best I can manage.

Speeder wrote:

Thanks folks.

Daddy, I do care. Really. It doesn't matter if I drive it all the time or not, I want my team to have the best I can manage.

I hear ya man. I'm exactly the same way. Just givin ya a little shit.

James B. wrote:

Better choice would be a Gear Vendors O/D behind a stock-geared 4L80-E.

Holy rusted metal batman, that's pretty cool. Pretty pricey though. 3k was a bit of a shocker.

well for the price of a rebuild and a gear vendor you can get the TCI 6 spd 4l80e or look into the 6l90e which is a 6spd auto offered in the newer 07/08+ trucks.... The gear vendors are still going for quite alot of money last time I checked like $2K+..... The TCI 6spd I believe revalves the trans to go into over drive after each gear meaning:

1st -->1st OD (2nd)-->2nd (3rd)-->2nd OD (4th)-->3rd (5th)--> 3rd OD (6th)

I haven't gotten ahold of TCI yet but thats the only way I could even remotely comprehend how it works and for just a trans its around $4200 with paddle shifters and a stand alone computer system its like $6000+ I would imagine its really close ratio but as i said if you are rebuilding and going with a gear vendor it would be cheaper......just my .02 but paddle shifter would be how you say F#CKING AWESOME! LOL pardon my excitement, but I am imagining my 8.1L equipped 1-ton blazer on 38's with paddle shifters.....

Nytmarek5 wrote:

well for the price of a rebuild and a gear vendor you can get the TCI 6 spd 4l80e or look into the 6l90e which is a 6spd auto offered in the newer 07/08+ trucks.... The gear vendors are still going for quite alot of money last time I checked like $2K+..... The TCI 6spd I believe revalves the trans to go into over drive after each gear meaning:

1st -->1st OD (2nd)-->2nd (3rd)-->2nd OD (4th)-->3rd (5th)--> 3rd OD (6th)

I haven't gotten ahold of TCI yet but thats the only way I could even remotely comprehend how it works and for just a trans its around $4200 with paddle shifters and a stand alone computer system its like $6000+ I would imagine its really close ratio but as i said if you are rebuilding and going with a gear vendor it would be cheaper......just my .02 but paddle shifter would be how you say F#CKING AWESOME! LOL pardon my excitement, but I am imagining my 8.1L equipped 1-ton blazer on 38's with paddle shifters.....

until they come out with a separate 6 speed auto and not modify a 4 speed, the gear vendors is the better option.

I think a 2.75 - 4L80E would be just fine. I'm sure the 4L80 can handle overdriving gears (unlike the 4L60)
running two gears at once (1st over, 2nd over) is going to chew up more HP.

We'll find out. I'm gearing up to go with a 2.75 4L80E in May barring any unforseen circumstances. The wife's even suggested I buy a premade trans mount rather than try to have our existing one modified.

Does anyone know if the 95-97 4L80E has the same trans mounting position as the ones designed to go behind an LSx engine? The trans that FLT is going to build is going to use a 95-97 core, which he says will bolt up to the LSx engine. He's also going to make sure that I have the correct torque converter to bolt to the back of my engine, and advised I may need a new flywheel that will let me bolt all 6 bolts to the transmission. I'll be getting the full details sometime this week.

There's a writeup on ls1truck which should answer most of your questions.

I remember way back when I actually bought a Jet Performance product (before I came to this forum and wised up) Jet was selling a valvebody for the 80e that made it either a 6 or 8 speed. It used valvebody "trickery" as James describes to split up the gearing.

IMO There isnt another transmission that GM ever needs to build if someone would "simply" make an OD ratio for the 80e/85e trans in something like 0.60:1-0.65:1. That would allow the use of lower (top speed-higher numerical) rear gears to get the acceleration we want, while at the same time keeping the revs down on the highway at cruise. Then I could run 4.56 gears on 28" tires and still cruise 75mph at 2400rpm usingthe 0.60 OD. With a stock 80e those same specs will rev 3050 rpm.

But the stock gearing is good for the 2500+ series trucks they were designed for. For heavy OD towing, the 0.75:1 OD ratio is where its at.

peace
Hog

This is getting closer to happening. Does anyone know where a conversion crossmember might be located? I know the existing one can be modified, but I'd like this to be a bolt-in process.

I looked at the one offered by PATC since their parts are supposed to be god even if their finished units aren't, but 330 bucks plus core with no offer of Vaseline? I don't think so.

I was able to move mine. I posted my pic directory a while back www.EFIMuscle.com/L31Sleeper

What kind of truck do you have? Your userID indicates a GMT400, and I have a GMT800. The 800s have a different mount style than the GMT400s, almost as though GM were trying to make it harder to change transmissions.

IIRC, L31Sleeper has a 98 ext cab.



Last edited by daddy_dandy on Mon Apr 05, 2010 9:56 am; edited 1 time in total

Speeder wrote:

This is getting closer to happening. Does anyone know where a conversion crossmember might be located? I know the existing one can be modified, but I'd like this to be a bolt-in process.

I looked at the one offered by PATC since their parts are supposed to be god even if their finished units aren't, but 330 bucks plus core with no offer of Vaseline? I don't think so.

It's a GMT800 and red:

http://www.ls1truck.com/forums/front-page-news/14163-how-4l60e-4l80e-trans-swap.html