123sugey

Anyone know of a company selling quality A8 stall convertors ?
I think a 4000 will be pretty good with some sticky tires

Jason 98 TA

Its not a easy thing to build as of right now. Several people working on it, but I think it'll be a few months.

I don't see a A8 being happy at 4000 stall! I think you'll find they need to be fairly tight.

Jason
Co-Owner
Texas Speed & Performance
www.texas-speed.com
512-863-0900

tblu92

I agree---The new converters in the C7 is a complete new design and concept for GM---It is called a "clutch to clutch" TQ converter--Unlike any other ever produced by GM-----
Rather than copying the converters used in foreign super cars (which are very pricey) and are called a "dual clutch" design---GM developed their own version---Rumors are that at some point the Corvette will go to the dual clutch design as it is far superior

Higgs Boson

The problem is it still uses fluid to transfer the power and that is slower/sloppier than a direct clutch only engagement. GM is a little stuck going down the torque converter path as the TC is better at negating vibrations from AFM.

glass slipper

No, it is not called a "clutch to clutch torque converter" It's called a "squashed" torque converter because it has a "flattened" appearance compared to "old style" torque converters. What you're referring to is the clutch to clutch shifting architecture of the transmission itself when it changes gears. Basically, everything in your post is BS.

There is a lockup clutch inside the torque converter that engages as early as 2nd gear that eliminates the "slower/sloppier" action you're talking about. GM uses a pulse width modulated signal to release/engage the lockup clutch at low RPM to allow as much as 100 RPM "slippage" to eliminate the vibrations from AFM. GM has used this feature for over 20 years. Porsche finally copied the GM design for their PDK to allow slippage of the clutch at low RPM to eliminate vibrations.

Higgs Boson

can it stay locked through the shifts of a 650 hp car? I guess I could just look at the tune to see what's commanded....

Shaka

tblu92

Hmmmm-----You call up EFILIVE and tell them they are full of BS--They identify the A6/A8 as a " clutch to clutch"-- I doubt the either GM or EFILIVE would call the system "squashed"---- a negative connotation
TQ converter lock-up has been available in ANY gear from day one on the C5- DOD or not---It is nothing new---As has been the "PWM" setting adjustability--
AND the trans will never shift while in 4 cylinder mode--So I don't see your point about vibrations--- The ECM prevents DOD from working---unless the converter is locked---It will never activate while the converter is NOT LOCKED

glass slipper

Yes, the A6/A8 transmissions have a clutch to clutch architecture when shifting from one gear to another...you said the torque converter is a "clutch to clutch torque converter".

GM is the one who calls it a "squashed" converter, not me.

No GM automatic transmission has the lock up function available to the torque converter in 1st gear.

I'm not familiar with the relationship between DOD and the torque converter locked/unlocked (and never stated one), but you have been so far out in left field about everything else, there's no way I'm taking your word on that. You are too clueless to know how clueless you are, do all of us a favor and just stop posting BS.

tblu92

Apparently you have never looked at an A6 or A8 tuning file---
A 2014 locks the converter at 29 MPH--(Z51) in 1st gear ( low TPS)
and only UNLOCKS or stays unlocked at WOT--
In any gear after 1st it locks up any time regardless of TPS
That is in the stock tune--A 2013 would not lock up in 1st in the stock tune however can be made to----

glass slipper

No, I haven't seen the A6/8 tuning file but based on the demonstration of your lack of knowledge above, excuse me if I don't believe you. Even if it's true, it's a driving situation very rarely encountered...really, who drives around in 1st gear with very little throttle opening at 29 MPH with the engine buzzing over 3000 RPM.

I thought I would share with the rest of the forum the nice love letter you sent to me in a PM:

"Here where I live we have a name for stupid people like you we call them a**holes---And deal with them accordingly--the old fashioned way---
Here's a thought--go fuc* yourself moron---
__________________
EFILIVE Tuner "

Really, you're threatening to "deal with" me "the old fashioned way"...good grief. If you're that insecure, maybe you should reconsider your participation in a forum. If you don't want to be called on BS, there is a simple solution...DON'T POST BS!

PS A dual clutch transmission is not superior to the 8L90...more BS from you.

jimman

I believe you started it

glass slipper

I'll say it again, if you don't want to be called on BS, then don't post BS. This is the technical part of the forum and it would be nice if posts in here are accurate. His post was so far out in left field it was ridiculous...and so is yours.

subfloor@centurytrans

I just talked to Dave Myers over at Yank Performance and got some good info.

He doesn't expect to see an aftermarket A8 converter show up for quite a while because of a few different but interconnected reasons.

The primary one is that as of right now you can change pretty much absolutely nothing in the tune. At first I didn't believe him so I downloaded a stock 2015 tune from HP Tuners and sure enough, he was right:



Compare this to what you can currently change in the A6 tune:



Even though he's got one designed and ready to go, given the high cost of tooling he said it didn't make sense to build something that you can't tweak any of the settings for. Can you imagine throwing in a 4000 stall converter and basically just "hoping for the best" as to how it ends up performing?

I'm not sure if the reason HP Tuners doesn't allow for any changes is by design from GM, or if HPT just hasn't figured what to do with the info yet. Dave seemed to think that this was done on purpose by GM so I guess it's a "time will tell" kinda thing. Dave also mentioned that he's gonna wait and see what happens when the A8 transmission starts showing up in the trucks. If HPT ends up being able to support the tune settings for those, that might push him towards building them as it'll open up a larger market as he currently builds a lot of truck converters.

As for why the converter is "squashed", that was due to the transmission being an eight speed. Every time you add two gears to a transmission like that it requires an extra planetary so apparently to keep from making the transmission noticeably longer, they made up for at least part of the difference (6.25" wide for the A6 converter vs. 5.5" for the A8) by shortening the converter.

123sugey

^^^ thanks so much for the details. I'll be patiently waiting for any updates

thegame

I believe it's already available. Trifecta has an A8 tune.

https://www.corvetteforum.com/forums...automatic.html

T/A KID

Trifecta can tune them.

Give it a little time, everyone else will be able to too.

ChucksZ06

I enjoy the back and forth...even if it resembles a p_ssing contest. There is no reason the a8 is not going to work for a performance transmission. Even if a little extra cooling is required. Someday we will be going on about being stuck with that clunky old tech dct transmission.

tblu92

[quote=glass slipper;1588719575]no, i haven't seen the a6/8 tuning file but based on the demonstration of your lack of knowledge above, excuse me if i don't believe you. Even if it's true, it's a driving situation very rarely encountered...really, who drives around in 1st gear with very little throttle opening at 29 mph with the engine buzzing over 3000 rpm.

I thought i would share with the rest of the forum the nice love letter you sent to me in a pm:

"here where i live we have a name for stupid people like you we call them a**holes---and deal with them accordingly--the old fashioned way---
here's a thought--go fuc* yourself moron---
__________________
efilive tuner "

really, you're threatening to "deal with" me "the old fashioned way"...good grief. If you're that insecure, maybe you should reconsider your participation in a forum. If you don't want to be called on bs, there is a simple solution...don't post bs!

Ps a dual clutch transmission is not superior to the 8l90...more bs from you. [/quo

YES IT IS-----It does not have overheating issues----Shifts crispier--and can handle more TQ/HP

He says "I have never looked at an A6 tuning file "
So how can he talk about them if he has no knowledge of their tuning
I challenge anyone to load the FREE Demo program from EFILIVE----and open up an A6 tuning file --Either from the forum or from HTTP://tunefiledepot.com You will read "clutch to clutch" and all the converter lock/unlock parameters as I mentioned fact ---100% true----""Squashed" is just a made up nick name---

This is no pissing contest to me----I am simply stating fact for those who are interested---

tblu92

ALSO------Here is a magazine article where both GM C7 transmission engineers were interviewed---
They describe the new innovations on both the manual trans and auto
GM actually calls the converter a "DUAL FACE CLUTCH"
But are careful not to call it a dual clutch because it is not-- But is a very close version----
EFILIVE on the other hand calls it a "CLUTCH TO CLUTCH" (as I maintain) again not dual clutch on purpose beacsue it is not but more similar in verbage to "DUAL FACE" as GM describes.
A dual clutch converter uses 2 separate clutch plates
A clutch to clutch or dual faced converter uses 1 plate with clutch material on both sides

http://www.superchevy.com/how-to/131...rack-mode.html