New 5 and 6-speed auto tranny's?

[MAP]

Hi Folks,

I have a general but important question: what's the status today on aftermarket or OEM 5/6-speed auto transmissions that could be retrofitted into A/G bodies? Some important constraints would be: 1.) lock-up converter; 2.) weight with fluids not to exceed 200lb; 3.) high reliability behind as much as 1,000 lb-ft of engine torque on an indefinite basis on the street (but with high-end DR-levels of traction, let's say); 4.) engine bolt pattern to match, or to be adaptable to, Chevrolet or BOP engines.

A top-to-bottom gear ratio spread of 5:1 to 7:1 would be desirable.

I know this is a very tall bill, but I also know that the best of the best are reading here!

Thank you,
MAP

 

[GNVAIR]

GM has the new 5 speed automatics in the Sigma platforms as the 5L40-E/5L50 and the 6 speed automatics going into the full size trucks and performance cars as the 6L80/6L90 and 6L50.
You can read about them here List of GM transmissions - Wikipedia, the free encyclopedia

 

[MAP]

Thanks, GNVAIR - nice to hear from you again. That's a good, handy link. It seems that the 6L80/90E and/or Allison 1000 may be the likeliest candidates, but I suspect that these transmissions in a stock state won't live reliably behind 1,000 lb-ft of torque, unless GM is making a very high output motor I'm not aware of.

I'd imagine that builders of high-performance 200R4's would be starting to look into these later-generation transmissions as future hotrod candidates, being that 1.) gas is probably heading toward or above $3/gal for the indefinite future, 2.) hotrodders always want to go faster, and more gears usually gets you more acceleration, top-end speed, and economy in the same package. Plus, as A/G body enthusiasts get older (generally because the cars are getting older too,) they tend to acquire more disposable income, and no doubt these later tranny's will constitute pricier alternatives to a similarly-modified 200R4.

That's the business argument, at any rate. But back to the immediate question - are any tranny's available that fit the constraints, or come close to fitting the constraints, in my first post?

Thx,
MAP

 

[GNVAIR]

Thanks, GNVAIR - nice to hear from you again. That's a good, handy link. It seems that the 6L80/90E and/or Allison 1000 may be the likeliest candidates, but I suspect that these transmissions in a stock state won't live reliably behind 1,000 lb-ft of torque, unless GM is making a very high output motor I'm not aware of.

I'd imagine that builders of high-performance 200R4's would be starting to look into these later-generation transmissions as future hotrod candidates, being that 1.) gas is probably heading toward or above $3/gal for the indefinite future, 2.) hotrodders always want to go faster, and more gears usually gets you more acceleration, top-end speed, and economy in the same package. Plus, as A/G body enthusiasts get older (generally because the cars are getting older too,) they tend to acquire more disposable income, and no doubt these later tranny's will constitute pricier alternatives to a similarly-modified 200R4.

That's the business argument, at any rate. But back to the immediate question - are any tranny's available that fit the constraints, or come close to fitting the constraints, in my first post?

Thx,
MAP

The issue with the late model transmissions mentioned above is that the computer programmed controls are proprietary at this point in time. So until someone breaks the code OR comes out with a stand alone controller you are locked into readily available transmissions.
I did find an article on the 4L80E. The 4L80E has three sets of planetary gears - the thirds set is for OD. This is one of the reasons the 4L80E is so durable.
The programming trick consists of flipping the OD gearset in and out between 1,2 and 3. Seems like the OD clutch would wear out. But this mod is considered an enhancement (by some) for heavy towing vehicles. Not sure how it would pan out for performance and longevity. This info was paraphrased from another site.
The new 6L80E used in the Corvettes, STS-V, and XLR-V looks promising once the conventional rear drive versions become available in the trucks. It is a 6 speed double OD auto and it is paddle shifted in the vette. The gear ratio's are 4.02, 2.36, 1.53, 1.15, .085, and .067. GM only rates it to 520 lb/ft of torque.

 

[MAP]

Hi GNVair,

Interesting you should mention the Corvette - a friend is heading up the development of the C7 motor, and he's looking for some very, very big numbers. I'd have to imagine that the tranny would follow suit, so I think I'll look in that direction.

But as far as handling 1,000lb-ft of torque, are four speeds (if even that) the most that can be gotten nowadays? If it took roughly 25 years after the OEM introduction to arrive at robust four-speed auto tranny's, are we looking at another 25 before 6-speed (BMW's up to 8, btw,) auto tranny's will be similarly improved? (That's a friendly challenge to the outstanding tranny builders here, incidentally.)

Or, will the OEM now take, and keep, the lead?

Thanks,
MAP

 

[Roger]

Interesting.

How dificult will it be to incorporate the necesary electronics?

520 lbs torque is a might week. What's the torque capacity of the Duramax? What's the gear ratios of the Duramax? I've heard from another source, that the gear ratios were much closet - for fuel economy.

 

[GNVAIR]

Interesting.

How dificult will it be to incorporate the necesary electronics?

520 lbs torque is a might week. What's the torque capacity of the Duramax? What's the gear ratios of the Duramax? I've heard from another source, that the gear ratios were much closet - for fuel economy.

As previously stated, the new GM transmissions are so new that no one has cracked the coding or made stand alone controllers yet. There are however, controllers for the 4L80E.
The Duramax uses and will continue to use the Allison transmission which is even larger than a 4L80E.

 

[MAP]

Hi Folks,

I believe that the 4L80E with fuids may exceed 200lb.; I'd imagine that the Allison 5 or 6-speed could even top that.

Coming back to the business aspect, and speaking from a position of experience as a design engineer, I'm concerned about a trend I see here. Until the early 1980's, OEM design development was generally slow and centered on mechanical assemblies. Until that time and maybe even a decade later, it was easy for the aftermarket to stay ahead of the game from a performance perspective. (The extra decade or so came from a cushion afforded to the aftermarket in that they didn't have to adhere to the strict per-part cost limits that the OEMer's had to.) But by the 1980's came stiff Asian competition and low-cost CAD/FEA software, and the race for OEM performance/reliability really took off. Today the OEM sector is progressing at a much, much faster pace than previously, and is taking advantage of computer-aided controls and actuators at every point.

Contrast that with the aftermarket, which still largely operates in the same copy/tweak/paste mode that the OEMer's did decades ago. If this trend continues, then the gap between the OEM and the aftermarket will continue to widen at an accelerating pace. 20 years from today, I think people looking for performance will look to OEM options first, second, and third. Fourth, fifth, and after, will be relegated to the aftermarket, which will probably shrink to a small kernel of mostly drag-strip enthusiasts who are still comfortable with methods and technologies that lag years after the OEM cutting-edge.

My point is that for the aftermarket as the OEMer's, the solution is the same: pour more resources into R&D: that is, innovate or perish. If it took us 25 years to get to strong 200R4's, then maybe 5 years is all we have to get strong 5 and 6-speed auto tranny's. If not, then maybe the OEMer's will be building strong 10-speed tranny's by then! As such, I think a rapid weeding-out process is about to descend upon the aftermarket, in that only profitable, well-funded, large, and engineering-focused enterprises will survive. The backyard-mechanic specialty shop will become a thing of the past.

(Disclaimer: This argument is simplistic and far from comprehensive, but still conveys some essential truths that I think the aftermarket would benefit from.)

Best,
MAP

 

[MAP]

Greetings,

And coming back once again from the business aspect (and I want to emphasize once more that I was speaking in broad generalities in the previous post - I believe, or at least hope, that there will be exceptions to the scenario I described.):

1.) On the matter of an auto 5 or 6-speed tranny known to satisfy the following parameters:

a.) lock-up converter
b.) weight w/fluids not to exceed 200lb.
c.) high reliability behiond 1,000lb-ft torque
d.) bolt pattern adaptable to C-BOP engines

The answer presented thus far is "unknown." Item (c.) seems to be limited to the 520-620ft-lb range according to OEM spec's (bearing in mind, however, that the OEM tends to be a good deal more conservative in torque/hp capacity claims than the aftermarket. The aftermarket doesn't have the deep pockets to research and verify reliability as the OEMer's do, and neither do they have the liability exposure that the OEM has.)

2.) I don't mean to imply that more gears are necessarily always better. As gears are added, weight, size, complexity, and cost all increase. But acceleration, economy, and vehicle speed range will increase too. The trick is finding the right balance between the two sets of tradeoffs. If we now add the constraints I cited at the beginning, and concede that a 5 or 6-speed tranny that fits the bill is still TBD, then we are forced to reduce the number of gears under consideration. If a four-speed can be built to be reliable behind 1,000 ft-lb of torque (and in saying that, I don't even know if that's true: I hope the expert transmission builders will chime in at this point,) then the closest transmissions that would fit the bill would seem to be aftermarket 200R4's, 700R4's, and possibly 4L80E's, built with only the very strongest of parts.

Is that right?

And, by the way, when built to handle such extremes of torque, doesn't the tranny create more parasitic drag on the motor, since higher pump pressures are needed to engage the clutches?

(I'm afraid someone will now tell me - yes, and that's why you should use a manual tranny! But that's a whole 'nother topic...)

Thanks and best regards,
MAP

 

[Brad-Man]

I'll weigh in saying that for turbo'd engines, more gears may be a detriment on the strip. For daily driving it might make a bit more sense - especially with smaller engines that are turbo'd.

For NA and supercharged engines I would think they're great. Lots of gear multiplication in closer increments, so engines can be kept nearer to their torque and horsepower peaks during acceleration.

With turbo'd engines, that philosophy isn't needed as much, except with the smaller engines (2-3.5L) that are tuned to high specific outputs - especially in heavier cars. For daily driving in those cases, the 5 and 6 speed autos should be a godsend.

Take a look at the OD gear (6th) in the new vette tranny - it's higher than the 4L60E and is the same as the 200 4R, so TB's aren't gaining much with that swap. .67 vs .73 for the 4l80e not much gain there.

For the bigger turbo'd engines (3.8L and higher), I'd stick with a 4 speed auto. This is where the 4L80E shines - except that it really isn't DESIGNED for the amount of power the stated requirements list.

I wish the aftermarket would rise to the occasion and build one tranny with swappable bellhousing parts that meets the requirements stated above that can be a drop in and forget. By swappable bellhousing parts I mean you have the tranny case and 1/2 to 3/4's of the bellhousing (possibly 1 piece), then the front part of the bellhhousing which can be machined to get the correct dimensions/bolt patterns/starter provisions for ANY of the 3 or 4 speed autos they are replacing, Possibly using a spacer/adapter plate for whichever torque converter is used to the flexplate for the engine it is going on.

Start out with one with gearing like the TH400 only with a better/longer OD, then work on some gears more for smaller engines (4L60 gearing).

I would imagine that it would have to have its' own controller (I can't imagine NOT having an end all tranny WITHOUT one given the electronic environment cars have today), but I suppose they could design one for electronic control and one for normal vacuum/tps position control).

Build it and I WILL COME!

 

[MAP]

Hi Brad-Man,

Great points! You mention that more gears could be a detriment under certain circumstances - how is that? (Aside from added weight to the car, however - or is that exactly how you mean it?)

Aside from the factor of added weight to the car, more gears should always have the potential for higher average acceleration and fuel economy in the same package. I don't remember where I read it, but GM (powertrain?) was reported as finding for a particular car that going from a 4 to 6-speed automatic would increase acceleration by 6.8% without any changes to the motor.

And you're right that some motors need more gears more than others. Those with a wide torque bandwidth need it less than those with a narrow bandwidth for maximum acceleration, but converesely, those with a wide bandwidth would benefit in the aspect of a higher gain in fuel economy with more gears. So either way, more gears should pose a benefit.

To determine the gains in acceleration for a particular regimen (0-60mph, or 1/4-mile, or what-have-you,) I'd go to some good modeling software. Then there's the matter of fuel economy if the car's a daily driver - and there's good software for that too. At that point, I'd weigh the factors of acceleration and economy against the added cost and weight of a tranny with more gears to make a final call on the matter.

But overriding all of these concerns is the matter of reliability: if a 4-speed will live behind a certain high-output motor, and a 6-speed won't, then that's the end of the story. And that's exactly where I suspect we are today if we're in the vicinity of 1,000 ft-lb of troque.

Thanks,
MAP

 

[Brad-Man]

Turbo'd engines like LOAD. Too many gears = less load.

The car manufacturers rely on more gears for NA engines to keep them closer to torque and hp peaks during acceleration.

An example:

Engine makes peak torque @3800 rpm and hp @ 5200.

If the gear ratios are such that you drop below 3800 when shifting, you lose some acceleration. More/closer gears have less rpm drop.

Ideally, you would want all full throttle acceleration to shift @ HO peak and drop to torque peak after shift for max acceleration.

On small high output engines, more gears mean less rpm drop and you can have narrower range between hp and torque peaks which is more efficient.

More gears also means that at part throttle, you have more gears to choose from depending on load for economy purposes (as long as you have the torque to turn them).

Turbo'd V6 and V8 engines generally are not lacking for torque, and don't spin all that high, so the need for more speeds in the tranny is a bit moot.

What we REALLY need is a good 1500 HP 4 speed Automatic.

Even NA engines that produce 700 - 1400 HP NEED a good 4 speed automatic - they're all BIG engines with lots of torque - no need for more gears.

 

[MAP]

Hi Brad-Man,

1.) What do you mean by "load?"
2.) The RPM difference in torque and HP peaks can really be summed-up in the term I used in my last post, namely, torque bandwidth. But we're actually talking about the same thing.
3.) I said that more gears ought always to be a benefit, but I never claimed that it would necessarily be a big benefit. That's one of the reasons why I described using software to model results so that one can make what is by nature a very subjective call (e.g., for $1.2k more money, and 60 lb more weight in the car, I can reduce 1/4 mi times by 5% and increase EPA economy by 13%. Do I buy or don't I? Subjective call.)
4.) If one is only concerned about acceleration, and one has a wide torque-bandwidth motor, then more gears than roughly four probably won't be of much benefit. And I certainly agree that for such people, having a very robust four-speed could be of far greater practical benefit.
5.) If one is concerned about acceleration and economy (i.e., for a daily driver,) then more gears offer greater practical benefit.

Best,
MAP

 

[GNVYUS 1]

I would rather have a pitch shift Th400 then risk trying any of these new expensive tranmissions behind 1000hp. The 400 can take it and is way cheaper to take care of.

If you look at the gear ratio of that tranny mentioned in GNVAIRs post you will get close to the .67 ratio in 4th with the locked up converter ( but you don't need it for racing anyways ) and who cares about a 4.02 1st gear behind 1000hp, you don't need that either for racing.

 

[MAP]

Folks,

This thread is veering too far off-topic and is getting irrelevant for me. I'm not asking my questions within the narrow constraints of drag racing; in fact, I deliberately avoided the encumbrance by phrasing the opening post as I did. But I will say that concerning a low first gear with 1,000 lb-ft of torque (I didn't say 1,000 hp; that got inserted by others,) it can still be useful if running a very tall rear for high top-end speed.

Since no one has come back with solid evidence for good reliability behind 1,000 lb-ft of torque with a five or six speed - or the biggest surprise - not even with a four-speed, then I'll consider the topic essentially closed here.

And to the big-guns tranny builders out there - I'm disappointed there wasn't a single response.

Best,
MAP

 

[Drac0nic]

I think your goals are unrealistic at best. I suspect that if you include the fluid my 700R4 probably weighs ~200lbs, and it doesn't have 5 or 6 gears nor can it take anywhere near 1000hp. Even a 4l80E would be in violation of this weight limit and only has 4 gears. 6 speeds also introduce more parasitic loss to the system as well as more to go wrong. If you notice, people with cars making that kind of power and using an auto usually go down in gears not up.....

 

[MAP]

Hi Draconic,

"...Unrealistic at best" - that was part of my reason to come here - to go an updated reality check. The numbers I quoted in my first post (aside from the number of gears and ratio range,) were the very best I thought a four-speed could yield if built to the very highest standards and the very strongest materials, considering the state of the art since roughly five years ago when I last checked. And even then, I was liberal with the numbers I used, because what an aftermarket vendor is likely to claim as, "able to withstand 1,000 lb-ft..." may actually translate to only 500-700 lb-ft if driven daily for 100,000 miles, and yes, even considering the traction-limiting factors of hookup with street tires and such (which rather begs the question of hard-parts versus soft-parts failure, but that's another topic.)

By increasing from four to five or six speeds, I went from a marginal probability to a virtual impossibility. But five years have intervened since then, so I was hoping the aftermarket would have caught up. Or, if it didn't catch up, I was hoping that in posing the question here, that the segment of the aftermarket represented at this website, would at least take note and perceive a challenge as a result.

About the number of gears going down as the torque or hp go up: precisely my point. As motors get more powerful, the diminishing choice of tranny's means that the combination is increasingly restricted to the dragstrip. And that's one of the reasons why I predict that the aftermarket will increasingly shrink to a tiny core of dragstrip enthusiasts. If the aftermarket is to flourish, then it's time to step-up tranny R&D at least to match the advances in motor development, even if we concede that they'll never match the rate of growth we have today in the OEM segment. "Innovate or perish," as I wrote before.

I've seen this kind of thing happen in other industries before, including in my field (I design assemblies used in some GM vehicles.)

Best,
MAP

 

[Drac0nic]

It's only been within the last few years that a 4 speed has really been considered a plausible transmission for a higher powered car. A lot of people who race cars work against change, and to some degree I'm not any different I guess. The other thing is that it takes a certain amount of time for cores to start appearing at the salvage yard for these newly introduced into production parts, custom things of this nature are insanely expensive compared to used OEM hardware that's adapted to the purpose. Building a control system for something like this is involved, but at the same time doable if not easily done due to the current controllers being adaptable to the application.

The choices of transmissions will go up not down, but you're thinking of the motivation for change by the wrong source; the change will come due to CAFE regulations and the rising prices of gasoline, not from performance; don't forget engineering is compromise and COST is a big part of that equation. it can easily cost $1000 to have a four speed built much less a 5 or 6 speed, compared to the typical 3 speed at about half the cost.

 

[MAP]

Thanks for that good input, Draconic.

About your first paragraph: yes. And that's why if the aftermarket is going to stay anywhere near cutting-edge, R&D costs (as well as cost to the consumer) will probably need to rise dramatically. But then again, the cost of top-performing cars from the factory is increasing too. Bottom line: staying on the cutting edge will be increasingly expensive, but to stay at a given level of performance will probably remain roughly stationary.

About your second paragraph and the motivation for change coming from fuel economy concerns: this isn't necessarily the dominating factor for top-performance OEM cars (in fact, I know it's not for the C7, even with gas at $3/gallon: the demographics for the likely buyer of such a car would probably show a gross yearly income of $150k or so. With the low fleet profile accounted for by the Corvette, GM can easily recoup CAFE numbers by focusing on economy for the high-volume runners in the lineup.) And fortunately, it's these same platforms that would likely get allocated the kind of budget to afford exactly the kind of transmission that would eventually be of interest to people reading here.

Best,
MAP

 

[Brad-Man]

MAP:

You and I have both said the same thing:

For driveability with smaller, narrower torque/HP bands, or smaller turbo'd engines more speeds is desired.

However, we are in the TurboBuick forums and these small NA engines are generally not thought of. Plus the power requirements in the listing above would tend to rule out most smaller engines.

So I concentrated on engines most of us would be using with those HP levels - with emphasis on turbos of course!

I STILL think what is needed is a good 4 speed automatic DESIGNED for 1000 HP/TQ with normal type clutches/bands that could be built to 1500 or more with the aftermarket type mods. One that can be easily adapted to any engine as described earlier.