OK - I have the 400 Turbo Automatic Transmission in my 69. I know that upgrading to a 4 Speed OD 4L70E or whatever is in my future. BUT, while my 2008 Suburban was in the shop, they gave me a 2009 Suburban with a 6 speed Automatic. Wow - it has a manual mode that I can shift by pressing a button with my thumb. The transmission didn't quite feel that all the bugs were worked out of it yet - but hey....6 speeds !.

So the inevitable - is anyone/has anyone beefed one of these up and doing anything with it?


And yes, NOW I am open to a manual transmission - but that's another story...

 

Sure it wasn`t an Allison transmission?

 

TCI makes a 6 speed auto based on the 4L80E

http://www.tciauto.com/Products/6x/

 

I'm lookin' for a new tranny and was wondering about a paddle shifter implementation.

 

That TCI looks attractive. Supposed to handle 850 hp and has a paddle shifter too.

 

yea, what was the price. $5700 if i remember right.

 

yeah, it cost a few bucks and some change, but it sure is nice! LOL! Hmmm, wonder if I could get the wife to spring for it for Christmas??? LOL!

 

You could also just a Gear Vendors overdive unit to replace the tail cone on your Turbo 400 and get six speeds.

If you're going to go manual, at least go for a Tremec T-56 six speed manual (or one of it's derivatives) That's what I'm going to do to replace my Turbo 350.

Didn't Lexus just come out with an 8-speed automatic? Hmmm......

 

I got that same transmission in my 2007 Denali, its a GM 6L80E transmission and its a really great feature that you can "paddle" through the gears, I've also noticed that this transmission is really huge and tall, I'm not sure if it will fit the tunnel without major cutting and glassing.

 

yeah thats another good thing about the TCI, its in a 4 speed case, but gives you 6 speeds.

I agree on the gear vendors unit tho. cheapest and easiest way to get 6 speeds. kinda feels like cheating, but I'd be ok with that. I hear theyre tough too.

 

So the 6L80E is designated for 6 speed and 4L80E for 4 speed? I had been planning on spending $3000 to do one of the 4 speed OD's, but 6 speeds could do alot of gas savings for a big block.

The TCI is expensive and I have heard of the Gear Vendor. Maybe I need to read up on the Gear Vendor again - I just thought it halved the gears.

 

.... so the 6 speed just offers more gears in the 'middle', whereas they all have the same ultimate OD.... say in my case below will be 2.91. So the next to last gear is always 1.00?? and the last gear a true OD?

Gear Vendor for a TH400 3-SPEED AUTOMATIC Axle Ratio 3.73

Gear.....Trans.......Final
1st .......2.48 .......9.25
Over .....1.93 .......7.22
2nd ......1.48 .......5.52
Over .....1.15 ......4.31
3rd ......1.00 .......3.73
Over .....0.78 .......2.91

hmm I gues I was always mistaken and thought Gear Vendor made first gear higher (quicker)

TCI is (2.97, 2.23, 1.57, 1.18, 1.00, 0.75) which is basically the same.

So.... with a gear vendor - you do not get more mph, you just just get more shifts that offer betters gearing for that speed/rpm range. The 'top end' does not change expect for the 1 extra OD gear???

EDIT: I see on the Gear Vendor site for 4 L80E's that the gearing does go down to 0.55 - that would enhance your top end. SO I now see the advantage to doing a gear vendor with a 4L80E over an old Turbo 3 speed. I need to study the charts more. That said - it could be challenging to figure which gears are best for perfeormance and would vary from car to car even going down to engin torque ranges, power bands, etc

 

The GV unit was good for only .80 overdrive, not enough to make any difference, why bother for the money....hard to fit into a C3 also....

not worth the effort/cost....and then behind any non lockup auto, makes even less sense.....

they maybe have changed ratios these daze...but IMO you can't beat a junkyard source rebuilt unit on a cost benefit ratio....that pretty much limits you to a 4L60, 4L80 core....

I fail to see how in hell over 4 speeds does jack diddly for you in a auto tranny, we are running gasoline engines now, not a diesel...
the slop in the converter is such that on the upshifts you barely feel even a Trans Go modded unit when going into 3-4 gears....

in 4th gear lockup--o/drive that is with .70 ratio about as good as it gets.....