6spd 4L80

[Lundstedt]

so i have seen a 6 spd valve body to bolt on to a 4L80 i guess the only issue was computer but i can program that so i am not scared. i heard jet made a few and quit and i would like to find me some of that! anyone hear of or seen any of these?

[trbankii]

The one I heard about was from TCI (http://www.tciauto.com/Products/6x/) - I'm not sure if there are any others out there.

And this isn't a "bolt it on in your garage" sort of thing. TCI rebuilds the transmission in house. Not sure if you can send them your transmission? Maybe they'd accept it as a core.

[Robyn]

Not sure why you would want to bolt the 6 speed VB on a 4L80 ?????
The GM 6 speed boxes 6L80 and 6L90 are a different critter and have more components inside to make up the different gear ratios.

These boxes have a deep low gear with 4.??? depending on application and then step up through 4th gear and then 5 and 6 are Overdrives with the top one being very tall at approx .6:1

There is not a way to simply bolt on a VB and get a 6 speed from a 4L box.

Too many more planetaries,clutches and such needed to get that done.

The Unit from TCI says "4L80 Based" so they are using a 4L80 case and then from there I can't find any info. Likely that they are keeping that under wraps.

This is a whole different cat than the 6L80/90 that GM is offering.

To get 6 speeds it requires more clutches a different planet/carrier setup and different hydraulics and a different control unit (Electronics)

I have to ask WHY?????? I seriously doubt that the extra parts and complexity are going to net any real gain versus the cost.

The TCI package is priced in the $6000.00 range Other than a toy I doubt any mileage gains will ever be offset especially in a truck.

I have read the reports on the new 6 speeds from GM.
Computer designed, computer tested (No hard part test units beat to death)
These will lilely fall victim to the same failures that all other new models of gear boxes that come down the trail.

I can remember when the 700R4 came out in the 80's OMG by the time the thing was finally working sort of OK there was a shelf of service bullentins 15 feet long on the things.

Then the aftermarlet had to come along and make the thing reliable and work right.
And if you wanted to use it for more than Moms grocery getter you needed a $1500 pile of specialty upfit parts not to mention the labor to install them.

I guess I will have to say that I am not impressed with the super high tech gearboxes.

Give them 10 years and the aftermarket will make them work well.

Robyn

[trbankii]

Yeah, I'm sort of left scratching my head as to how they accomplish the six gears out of a 4L80E - and what the benefits are over the actual GM 6-speed transmissions? Is it a size issue?

[Lundstedt]

sorry let me clearify
it is an aftermarket valve body that bolts in to a 4L80 that applies clutches in a different pattern to allow for 2 extra gear ratios. this is not done for milage even though it could be but rather for gear splitting to allow better towing when needing a "gear between gears" and i would never send out my tranny... nuts to them anything they can i can do. i then i know it was done right.

oh and benni over gm 6 speed is i like to tow with autos cause they work better in all conditions and i dont have the money for a allison

[Lundstedt]

as found @ http://www.performancetrucks.net/forums/showthread.php?t=432654, and he remembers it manual shifting i remember it being auto.... and i can find prices just no inventory for the JET kit my cost ranges but under $1500

This has been done before. Believe it or not, Jet (remember jetchip.com?) sold a valvebody kit that made a 4L80-E six speeds back in the late 90's. It never was popular (http://www.performancetrucks.net/forums/showthread.php?t=432654#) because the conversion made it manual-shifting if I remember right.

Technically, a 4L80-E has always been capable of eight forward ratios because it has three planetary gear sets.

Stock 1st = Forward engaged
Stock 2nd = Forward engaged & Intermediate engage
Stock 3rd = Forward & Intermediate engaged, Direct engage
Stock 4th = Forward & Intermediate & Direct engaged, Overdrive engage

I can only guess they're doing something like this:
1st = Forward engaged
2nd = Forward engaged, Overdrive engage
3rd = Forward engaged, Overdrive disengage, and Intermediate engage*
4th = Forward & Intermediate engaged, Overdrive engage
5th = Forward & Intermediate engaged, Overdrive disengage, Direct engage*
6th = Forward & Intermediate & Direct engaged, Overdrive engage

* Note that third and fifth are both now dual-event shifts. Stock, a 4L80-E has no multi-event shifts - a major reason why they shift so solid.

[john8662]

At the price of a computer and the 2K plus for a used 6L80E unit you'd be money ahead and run a Gear Vendors or similar behind the 80E.

Of course A Ring and Pinion change for higher gears in the rear (or front if equipped) differential is a great move, for economy.

[Robyn]

Hmmmmm Just reading your sig there Lund

Cross drilled brake lines :eek: Now that should be good for at least a 50 HP gain. :D

I think maybe a fully short circuited electrical system to eliminate low speed voltage spikes ;)

Possibly an auxiliary high pressure muffler lubricator. :eek: for maximum torque when towing.


Great stuff :D




Missy

[Lundstedt]

no cost in comp i can flash mine from what i have read in the past

thanks robyn, i will see what my cost is on the muffler lube

[JohnC]

He is correct. The 6 speeds are achieved by using the overdrive gears to split first and second. With closer ratios you are then free to go with taller final drive gears thus effectively adding another overdrive or two.

[Lundstedt]

or keep the same ratio i have now, with less change in the shifts, giving you a "gear between" so if 3rd is too high and you can red line 2nd hard its a good place for a split. so i found another company that offers a 6 spd 4l80e and a life time warranty and i am a wd with them now i can ship anywhere if your interested.


He is correct. The 6 speeds are achieved by using the overdrive gears to split first and second. With closer ratios you are then free to go with taller final drive gears thus effectively adding another overdrive or two.