TrueBlueGTO

So let me get this straight....When 4L80's were in production they were in 300 HP vehicles with 8k towing capacities and now that GM and Ford have invested hundreds of millions of dollars completely abandoned these transmissions and put them behind 500+ HP motors, trucks that tow over 10k lbs, WITH 5 yr 100k warranties and the same basic transmission lives in 1000 HP Bugatti's...its not a transmission built for real high performance because you say so?

Jeremy@RPMTransmissions

iTrader: (12)

What Bugatti runs a 6L80e transmission?

soundengineer

iTrader: (16)

the 1000HP bugatti uses nothing even remotely close to a 6l80....
maybe same principal of dual clutch...but nowhere near the same
the Bugatti transmission is a Dual Clutch transmission with no torque converter...the 6l80 uses dual clutches and still uses a torque converter

and yes... people replace the 6l80 with a th400/th350 or a 4l80

I bet your going to say that the powerglide is a weak transmission too


Just because they changed transmissions for factory production vehicles, doesnt mean the old one sucked...
it means they decided to go for a different route for various reasons...


and I've seen 6l80's fail with far less than 500 hp....as soon as you start removing torque management...they show how fragile they are.
theres a reason that FMVB 6l80's dont exist

soundengineer

iTrader: (16)

and heres the only non GM 6l80 control that I know of
and as far as I know, its a full ECM and not just standalone trans control

From MAST Motorsports
http://www.mastmotorsports.com/2010/news-view.php?id=38

joecar

The 6L80/90 gear ratios are actually spaced close together, do the math (don't let the extra low 1st gear ratio fool you).

The 6L80/90 can't have a FMVB because the hydraulic circuits to the clutches are solenoid controlled and not hydraulic valve controlled (which is how a MVB/RMVB works).

The 6L90 can be built to handle over 500HP but it requires build modification and careful tuning (a forum member has a 6L90 behind an LS7).

s2h Lsx

4.027 2.364 1.532 1.152 0.852 0.667

Since when is a 4.026 to a 2.364 a close gear split
Same goes for the 2-3 split

T56 is 2.66 1.78 1.30 1.00 0.74 0.50
Even the t56 1-2 is a pretty big split...
But you also typically run a bigger rear gear to make up the difference...
With the 6l80 your rear gear is usually pretty low, and putting a higher gear in makes the 1st gear useless...yet you need a higher gear for the rest of the 6l80 gears to be useful at the track

TrueBlueGTO

Reading is fundamental. I said same BASIC transmission. They are all ZF based transmission designs. Anyone who thinks that they are getting top notch parts in a mass produced vehicle with very limited performance applications is on drugs. No the a rare $1 million dollar car's transmission is the same transmission in a mass produced assembly line GM truck or car. GM takes great pains to reduce the costs of any component in their vehicle to the bare minimum required to maintain a warranty.

Nor did I crap on any other transmission including the powerglide. But I understand the realities of economies of scale, mechanics and history. A stock 6L80 (let alone 6L90) will handle with ease ANY engine a stock 4L80, Powerglide, or Muncie came behind....AND some. No a stock 6L80/90 isn't bulletproof. Nor is any 4L80. It's called the learning curve. With understanding of the the physics and designs of the transmission, proper building AND proper tuning the 6L80/90 can hold up to any engine in a street legal vehicle.

Would I put one behind John Force's alky funny car? No. But just as when the GM TH400 came out people complained it wasn't as good as a Powerglide, then the 200R4 came out and people bitched it couldn't hold up like a TH350, The LS1 came out and people said it wouldn't make power like a Gen I SBC, and the 4L60 came out and it couldn't hold up to 700R4, so too will time allow people to realize that progress will and has been made to make new things (intentionally designed to have limited performance) see their full potential.

The point is I recognize there are things I know and DON'T know, so I don't make definitive statements about things that I haven't done extensive research on.

joecar

1->2
6L80: 4.027 to 2.364 = split ratio 1.70;
4L80E: 2.48 to 1.48 = split ratio 1.68;
those are very close;

2->3
6L80: 2.364 to 1.532 = split ratio 1.54;
4L80E: 1.48 to 1.00 = split ratio 1.48;
those are close;

3->4
6L80: 1.532 to 1.152 = split ratio 1.33;
4L80E: 1.00 to 0.75 = split ratio 1.333;
those are very close.

So the 6L80 compares to the 4L80E which has the closest splits of the GM transmissions.


( we're talking AT's, not MT's, you can see this from what is being discussed, T56 has nothing to do with this )

joecar

You use a stall converter to make up the difference... and you don't need as low a rear gear.

Smoke23

Any new news?

greg@paceperformance

I know of one in the works, but can't say much yet.
It is said to even allow someone to use a SBC and 6L80e combo, once it is released I'm sure it will make a big buzz.

8ty8 LS1

iTrader: (3)

any updates?!

Visionxorb

could that be the the PCS TCM-2600?

http://www.powertraincontrolsolution...oduct=TCM-2600

twymenburr

Its a transmission controller....it allows you to manual apply soliniods to diag if the problem is with the wiring or something on the vehicle or in the transmission

Krom

FWIW the DSG used in the veyron is nothing at all like the slushbox 6L




and its made by Ricardo, not ZF

pics of a 6l tranny (works like a normal slush box)

TrueBlueGTO

Good info. Information on Bugatti's was scarce. I guess I stand corrected on that matter.

poorhousenext

TB,

Since your fessing up to mistakes, you might want to take a look at your, "You don't need to change rear gearing when you go to 6L80/90 to be completive."

Well you might want to take a look at what happens if you don't, with 6L Vs TCI 6X. All things being equal like rear gear ratio being the same, they match up real close as Kevin's model showed. Don't match rear gear ratio, and you'll find the 6L's will be sucking a hind tit. Mechanical advantage in every gear except 1st gear is less.

TCI 6X, 3.55 rear gear.

1st 2.97 3.55 10.54
2nd 2.23 3.55 7.92
3rd 1.57 3.55 5.57
4th 1.18 3.55 4.19
5th 1.00 3.55 3.55
6th 0.75 3.55 2.66

6L80E, 3.55 rear gear.

1st 4.03 3.55 14.30
2nd 2.36 3.55 8.37
3rd 1.53 3.55 5.43
4th 1.15 3.55 4.08
5th 0.85 3.55 3.02
6th 0.67 3.55 2.38

Sucking a hine one with 3.27.

1st 4.03 3.27 13.18
2nd 2.36 3.27 7.72
3rd 1.53 3.27 5.00
4th 1.15 3.27 3.76
5th 0.85 3.27 2.78
6th 0.67 3.27 2.19

Also someone mentioned, Kevins model of 6X shifts rpm drops between shift looked like trans was a manual, not and auto. Model is right, RPM lost between shifts is nothing like what you see with 4L's.

Listen for the RPM lost between shifts paddling the 6X.


Little harder to hear auto shifting, since the chase car was a Honda SUV Vs in car Video...LOL Only have 362 RWHP but trans down shifting into 4.19 4th gear makes car a blast to pass another car in on the highway...LOL

https://www.facebook.com/photo.php?v...type=3&theater

TrueBlueGTO

My statics professor always told me that nothing is more devastating to an opinion than numbers. So, thanks, but no...I don't need to rethink that statement because I recognize, unlike most people, that "faster" and "quicker" are subjective terms and gearing is a complimentary function of the engine's power curve and only ONE variable in the long equation that calculates acceleration. In other words, the engine's torque and hp curve must compliment the gearing (and torque converter lock up).

No matter what, the 6L80 has THE BEST mechanical advantage off the line. PERIOD. Barring traction issues and all other things being equal, this will generally lead to a quicker 1/4 time. Afterall, isn't that why everyone is quite obsessed with their 60 ft time? Because it translate to an (for all intent and purposes) exponentially lower E.T. rather than a linear one. Just like manually moving a heavy object, the sooner you get the weight moving with TQ multiplication, the easier the job is to keep it moving ..or in this case, for your HP to do its thing later down the track and up the RPM band.

Performance is more than just random spec comparisons, but actually running the numbers through a full equation and application process....like the engineers who design these things do. That said, what a potential racer SHOULD look at is NOT just their engine's PEAK hp or torque, but their USABLE hp and tq...i.e. where along the RPM band is the engine during its racing time? (See attachments)

The biggest advantage the 6X gives over the 4L80 is a shorter stepped 1st to 2nd gear by way of...wait for it...a numerically higher 1st gear ratio. It's letting the motor rev more quickly (function of time) to get the rpm's up sooner. That's the biggest complaint of people who switch to a 4L80...their 60ft drops (barring mods to the torque converter, gearing, engine)...i.e. their off-the-line performance. BUT it gives that advantage up with a ridiculously short shifted 2nd-3rd. Again, I refer you to the charts. Note where the engine's RPM is after a redline shift with each upshift (highlighted in red). I'd rather my motor short shift 1st-2nd and pull from 37xx RPMs in a 6L80 rather than a short shift 2nd-3rd for a mere 1600 rpms from 43xx RPMs in the 6X. Who needs to shift for a 1600 RPM band? Who is that for? I definitely wouldn't want that if I had a turbocharged engine.

Considering most streetable engine's (particularly production) generate their torque at the bottom of the RPM curve and their HP at the top (as torque falls off), and physics (Force=Mass * Acceleration) dictates that you need more energy or force to get heavier resistance objects to move quickly, then I'd rather have something that can make my motor work easier, rather than harder, when the weight resistance is static (i.e. heaviest) rather than dynamic (i.e. heaviest). So the sooner (time function) you can get an engine up into the high RPM band where max torque AND high HP occur the sooner you get your bulk moving.

So, again, one has to refer to their engine dyno and see how much TQ and HP they are making at each RPM shift. Some engines may have an advantage in the 1-2, the 2-3, and/or the 3-4 upshifts. But as the charts show...the 6L80/90 has better spaced gears...given a 3.55 axle ratio, 6500 redline, and typical Low-Mid RPM tq and Mid-High RPM hp engine profile.

(I can do a 3.27 gearing if you'd like)

And then as an added bonus I get anywhere from a 200-500 rpm drop at highway speed, save God-knows-how-much in the conversion process (assuming you don't have to do floorpan mods), I'll take a 6L80/90 any day.

poorhousenext

TB,

Sorry about the late reply, just got back home form LS Fest where I did a little REAL WORLD Testing with my other 6 speed, that 6X one, not the 6L80E one I have too...LOL

You start off with something that doesn't match up with the way most compare transmission in the real world, but more like what we'd use in the multi level market world to reel in the uninformed...LOL Some more shuck and jive junk to confused me, along with trying to confuse me some more with something about lower stepped second gear. Not sure but maybe you talking about something beside a 6X comparsion.

I know you make your living or part of it doing 6L80E swaps. Like you say, if a 6L80 fits without body mods things are a little easier and cheaper to start off with.

Sometimes one need to look before they leap and research cost of rebuild of a 6L80E/90E. Thats the part that most don't consider. If you just cruise around and say "Look at Me, I have a 6 Speed Automatic" then you may not incur a cost that makes my other 6 speed trans not look so bad as you make it out to be. But if you beat on a 6L80E, what's the cost of rebuilding it when it tears up? Abused 6L80Es have a rep for doing just that, don't they?

Hope your statics professor taught you about the real world.

Your are right about the TQ and HP curve needing to complement gearing. I'll pass on your TQ Lockup, TQ lock up only occurs for me in 6th gear under no engine strain. It unlocks as soon as it feel the engine is starting to LUG. Now to keep converter from slipping when not locked up, It's a dual disc billet one capable of holdding 850+HP.

I grew up on a Farm in the late 40's - 60's and we had a Farm truck, that had what we call a Granny Gear to get Truck moving when loaded. We stayed out of that Granny gear when the Truck wasn't loaded down.

For some reason, GM decide to go backward to the old Granny Gear 1st. Reason is for Gas Milage and because it's used in trucks that may be hauling heavy loads, not just cars and not for true performance or hauling a loads in them, but for the feel of really moving out the gate with that granny gear.

It's nice that the below picture shows comparsion between the two new GM 7sp manual used in 2014 Corvette options as well as your and my 6L80E...LOL

Lets Look at 6X gearing, compared to Z51 option too.

TCI 6X
2.93
2.23
1.57
1.18
1.00
0.75

Now, tell me again why a 6L80E's 1st to 2nd gear step is so out of step with at least the 7sp Z51 option. Could it be it's truck use? Why doesn't the 7 sp manual need that granny gear for performance too, if it's so great?

So lets take a look at GM's new 7 Speed manual trans and it's two sets of gears and compare them to the 6L80E's. With the 7 sp manuals, why have two sets of gear ratios, one they call the Z51 performance one? Some engines can be had with either, but why 2? Seems one is to get gas milage rating up, the other for performance, but what do you do with 3 OD gear ratios, wear yourself out shifting or just lug the engine going up hills?

Why not better gear splits by adding a 5 non OD gear instead. Maybe a 1.18 4th gear instead, or maybe a 4.03 granny gear. That would give the Corvette a 4.03 4th gear ratio with a 4.42 rear gear to help it reach it's top speed quicker, or maybe a 4.03 6L80e 1st gear for off the line performance...LOL

By the way, have you ever tried paddleing shifting a 6L80E into 1st gear? You want but once. You only downshift it with paddle into 2nd, 3th and 4th non OD gears unless you are coming to a dead stop and then only at low engine RPM.



Look at the Z51 gearing steps, wonder why they didn't go lower on the 1st gear so they could get a bigger step between it and 2nd gear like the 6L80E. Could the real reason be for real world performance a 4.03 1st gear is worthless. Remember some of the same engine options are offered with the 6L80E too. Same HP and TQ numbers, right? Or is that Granny gear to give and automatic trans more percieved real world performance, when it's actually there for better gas milage rating instead?



Part of my trip to LS Fest was to Enter Lydia in Show and Shine. Best I could do in S&S was Best Engineered award. Show and Shine and I get Best Engineered...LOL

Shameless EYE Candy Break:



The other Part of trip was to see how well I did with my LS3 Engine and Transmission Choice matching one to the other.

I did 4 runs total, 2 under good air conditions in the morning and 2 under 6:30 to 6:45PM hot air and hot engine conditions. Good air 12.03 and 12.076, flirting with high 11's. Hot air 12.229 and 12.382. One thing all the runs had in common, were high 60' times. Best time, 60' was 1.90, 2nd best 1.946, 3rd best 1.96 and 4th was worst, 2.071 when I tried leaving at converts stall, 2800 RPM.



Why only 2800 RPM stall, my highest RPM lost between shifts is 1550 RPM rest in the 1400s. Trans shifts at 6600 RPM. Engine RPM never drops below engine's peak TQ at 4600 RPM, only drops to 5050 RPM. Don't have to try and get back into engines power band between shifts due to gear splits since RPM between shifts never drops below it, but also because I want to autocross car. You don't want a High Flash stall for that.

I believe 2800 RPM stall is what you think should be used with 6L80E too, so you can't complain about wheel spin due to high stall...LOL

Now all things equeal to what you like (except transmissions). What do think my 60 foot times would be with a 6L80E 4.03 1st, better or worse?

Do you really believe in my real world, not your paper one that the 41% RPM drop between 1st and 2nd shift doesn't matter either. That drops RPM lost between 1st and 2nd gear to 3894 RPMs, 706 RPM below peak TQ. Now engine has to pull back to it's TQ peak with no flash stall to help. Is that a + or a - for the 6L80e?

6L80/90
4.03
2.36 -- 58.56% (high) RPM Retention 41.44% RPM DROP
1.53 -- 64.83% (high) RPM Retention 35.17% RPM DROP
1.15 -- 75.16% (high) RPM Retention 24.84% RPM DROP
0.852 -- 74.09% (high) RPM Retention 25.91% RPM DROP

By the way Car has 300 Tread wear rated Nitto 555 on it, 200 tread wear 05's would help traction some. Remember we are talking street car here, not a racer are even a part time one. Same on the strip as it is on the street.

Now my car has a total weight of 3279 Lbs with between 2 and 3 gallons of fuel, that weight is 50/50. With a full tank of fuel it weighs in at even 3400 Lbs. That extra 121 Lbs is on the rear axle. Car never goes lighter on rear than front. Now that something you don't see in a Car very often, so just imagine what the 6L80E, in your words, performance 4.03 1st gear would be like if I can't get the lowly mechanical advantage of a 2.97 1st gear hooked up with 121 lbs of weight on rear tires to help....LOL

Don't you think you can have too much of a good thing?

Do you really believe a 6L80E with a rear end ratio of even 3.42 is competive on the strip with 6x and 3.55 rear gear all other things being equeal, just because it has a 4.03 1st gear?

This is real world $h!T not Sheets and Spreads sales bull. Remember think all Things being equeal but trans gearing.



PS: Lets not talk about my great Reaction times. Think I got it under 1/2 second one time. Remember your dealing with OLD and Stupid person, not a young and dumb one. I'll be 70 in January so I'll a little slow. So slow I might just have got car into High 11s if I had not filled the tank up but instead left it at about 1/4 full instead...

TrueBlueGTO

No worries, I kept your seat warm. Congrats on the trip to LS Fest and glad you had a safe trip. Maybe next year for me. *crossing fingers*


On to business…we mock what we don’t understand. Further YOUR particular REAL world experience is not indicative of the majority. So to state “real world” is important as if everyone’s perception of reality is the same is not only conspicuously short sighted, but exceptionally arrogant. GM, nor ANY manufacturer, mass produces parts for one very specific and finite customer and condition. So beings you want to talk about real world…let’s talk about the REAL REAL WORLD.

That said, I am not sure where to even start with your reply bc it's 1) kinda all over the place 2) conveniently fails to address the key items to my argument- specifically that gearing (transmission AND rear axle in COMBINATION) along with specific engine torque curves are all a system and cannot be conveniently isolated to support notion. I'm sorry if my (and scientists') engineering math calculations are considered 'shuck & jive' or witchcraft to you. But you speak of things you don’t understand. The fact that your particular Vette with a very specific engine torque curve works well with the 6X is fine. Clearly, you selected/built your engine first with a specific power curve before choosing your rear end ratio, then as an afterthought threw a transmission in there. I prefer to look at ALL the components of a given system to insure they work together before hand. You could use a Powerglide to achieve your ¼ mile times….but oh yeah.. .you’d have to change your rear axle ratio to match up...and might have to push that redline higher.

Now to enlighten all parties involved with regards to my voodoo calculations and the scientific truth about gearing, I'll explain a few things. First my experience comes not only from formal education in high end mathematics, physics, accounting, and computer programming, but also from 3 generations of family construction and trucking which included being an OTR owner operator myself. Cars are just my hobby and passion. Also, I don’t just “build”, “repair”, or “fix” things….I design, engineer, test, and manufacture things. That means essentially creating what doesn’t exist and having to adhere to pesky details like "the scientific method" to make something come into existence.

The REAL REAL world involves more than just two variables (rpm and power). It involves rpm, power and time. [We won’t even get into temperature and frictional forces.] How the rpms and power (independently and cooperatively) relate to a given moment in time is critical to any argument. Engines don’t make the same power at all RPM levels. Just because two engines make the same peak power doesn’t mean they make ANY of the power at the same RPMs. Just because two engines have a 6000 RPM redline doesn’t mean they rev from any given rpm to that redline in the same amount of time (eg. Long stroke diesels vs. short stroke F1 engines). Further, dynos don’t “directly” convey the latter. While ‘how quickly’ the engine revs through a given RPM can be inferred by looking at the HP AND TQ across same rpm range, you have to consider that the gearing and drivetrain friction play a role in that, not to mention wind resistance on the road/track that isn’t present on the dyno… as the following explains.

As you can see from my previously posted “calculations” your Vette upshifts and drops your RPM around 5000, which as your dyno shows, is optimum for your engine because your torque is at peak and your HP is on the rise. So it’s pretty clear from my spreadsheet that I posted BEFORE your dyno sheets, without having to swap transmissions, that the 6L80 gearing would drop you to a lower RPM where your torque may be equal, but your hp is lower...making your engine pull back up to higher power. So congrats, the gearing of the 6X worked for your very specific engine torque curve, very particular gearing, and light weight. That may not work for every other engine curve, axle ratio, and vehicle weight.

To dismiss the impact of your torque converter may be convenient, but it’s not negligible in THE REAL WORLD. A custom tc usually allows the motor to rev faster (time variable) and with less resistance. So your high stall slick piece does more than just what you observed and wanted it to do. Now, unless I’m misunderstanding or misreading something, your motor doesn’t look all that powerful. I see it making less than 200 lb/ft of torque under 3000 rpms. You’re damn near pushing 5000 rpms before your torque and horsepower get to 300. I mean…stock LS2 GTO’s put over 300 lb/ft of torque to the wheel by 2000 RPMs, so, I mean…you NEED a high stall converter to get that motor to move the car along. Plus LS3’s have heads that need high rpm to make them shine. Soooo…to summarize you have a engine spec’d for HIGH RPM power. So yeah, lower numerical gears, a high stall tc, and a transmission that favors keeping the motor running LONG and high in the rpm band WOULD make you faster than a transmission that is geared for low to mid rpm torque engines.