Putting a simple planetary gear before the torque converter. I'd ask if anyone had done this, but somehow I know nobody has. It could be used to run a bigger stall, or perhaps a looser stall (sy3500) when in 1:1 configuration, but then shift to say a .769:1 engine/converter ratio, effectively lowering the stall from 3500 to 2700, and giving it more acceptable street manners. This would also effect the final drive ratio, so I can see how it could defeat the purpose of stall/gears on setups not specifically designed to run it.

My main question now is how to do it. A direct locking dog gear type mechanism could work. it would have to be reliable, considering it'd be directly connected to the flywheel, and simplicity would be nice as well. So if anyone has thoughts, opinions, wants to tell me how stupid it is, etc, go ahead. I personally think it could be of great use, considering it's not only a 5th gear, but a 2nd stall as well.

 

The early TH400 actually came with a dual stall speed converter:

http://www.bdub.net/tranny/DualPurpo...dding-text.pdf

Google "variable-pitch torque converter"; seems someone has tried to adapt it to newer transmissions too.

Also, a patent for a variable speed stall converter was issued in 2003:

http://www.google.com/patents/US6564546

This might be an application of the patent:

http://www.protorque.com/nprod/np_vstc.htm

 

i have one of the old switch pitch 400's i made, works pretty good
always thought there would be a good market for dual, varible pitch or whatever, esp for street/strip cars
also wondered why nobody made a 400 with overdrive, like the 4L80E but an all mech non elect. setup, like a big brother 700/200R
someone did make a lockup converter for a 400, like the old 350C trans,
but i think he no longer builds them

 

I had a 'variable pitch' TC in my 1965 Buick Skylark Gran Sport,I loved it.
It was actuated by a micro switch on the throttle linkage. WOT would trip the switch and the TC would go to a higher stall mode. I added a couple switches to the circuit and mounted them to the dash. One switch would actuate the high stall mode when I wanted and the other would prevent the high stall mode from occurring.
Back in the 60s'/70s' when running 'cheater slicks' and doing a test burnout,I could select which mode I wanted for the existing traction condition,worked great.
The high stall mode gave me a 3300 rpm true brake stall. The drum brakes with Velvatouch metallic shoes allowed me to apply a full brake stall for launch. Drum brakes,because of the larger swept area, have a higher static hold than disc brakes.

 

Interesting results. I didn't know that any company picked up the variable pitch stalls after GM discontinued them. Also, I wasn't sure of their durability, or effeciency. Now the only thing is cost, and the capability to fit them to the 4l60/80. That was the main reason I suggested the ability to mechanically change the input rpm. Not only variable stall, but also variable final gear ratio, AND it could simply bolt in front of the converter. The versatility of putting it in front of the wide range of currently available stall converters seems to be its greatest selling point to me.

Also, the third design, draining the fluid from the converter to yield higher stall, I can see it significantly effecting the effeciency, meaning more slip EVERYWHERE, even the top end of the rpm range. With a design like that, you'd need to have the converter lock in third gear (at the track) if you wanted to extract full use of such a design.

 

The 4L80E has a planetary gearset on its input which is used during overdrive...

if you could alter the transmission controller, then you may be able to apply/release the said planetary in relationship to torque converter input/output speed difference...

TCI has a controller which applies the said planetary in 1st, 2nd, 3rd thereby giving 6 speeds from the 4L80E, but to my knowledge they do not sync this with TC input/output speed variation.

 

mkay.
with a 2.97 1st gear, and .75 6th, it covers less gear range than a 4l60e (3.06 1st, .696 4th), which (for me) makes it less streetable. You could try running a 3.00 rear gear for similar final cruising speed, but initial mechanical advantage would be 8.91, as compared to 9.88 for a 4l60e with 3.23's. The TCI 6x six speed seems like it'd be good in a dedicated drag car with an engine of only moderate power. Since it has 6 gears close together, the right rear gear might allow you to use all 6 in the 1/4. The closeness of gears would also make it good for autocross, since it'd be in the powerband at pretty much any speed (this is assuming somehow you're using an automatic in autocross. Manual valve body perhaps?). at nearly $6000, and little chance of finding one used, it's out of the budget for all but the most demanding entheusiasts.

Also, about the input/output part. I'm not talking about the difference in speed between the two blades of the torque converter. I'm talking about putting a 1.3 gear before the torque converter (capable of switching back to 1:1), so if the engine is running 2000, the torque converter is getting 2600. Adding gears after the converter is a good way to keep the car in it's powerband, but won't decrease the apparent stall speed. (for reference, try driving off in 2nd gear. rather than loading the engine down more, the torque converter simply slips more (until the stock stall speed of 2000 rpm, where the engine then takes the full load). this is because mechanical advantage has gone from 3.06 to 1.625, and since the torque converter has to eat what seems like nearly double the weight, it slips more. by putting a 1.3 gear infront of a converter, mechanical advantage will go from 3.06 to 2.354, however, input rpm will increase by 1.3 negating the weaker mechanical advantage, while allowing greater acceleration with similar engine input). this, and cost, is the reason I don't think there's a better solution (or replacement) for a simple front mounted planetary.

 

What is the difference between putting gearing before or after the converter (does the converter even know...?)...?

You mentioned variable stall... why not take it further and use input:output speed ratio (of the converter) to select the input gear ratio to provide ideal stall (i.e. helping the converter when it needs it)...?

 

As a matter of fact it does.
Gears before stall = lower stall speed (part throttle and absolute), as well as lower mechanical advantage (due to gearing).
Gears after stall = higher part throttle stall speed (until advertised stall. ss3600 = 3600rpm but slip (due to lower mechanical advantage) may drive it up to 3800), lower mechanical advantage (due to slip and gears).

if all gears were in front of the stall, it'd probably die if you put it in 4th from a stop. But, since all the gears are after, you can put it in 4th and just not really move anywhere.

The idea of switching between the 1:1 and 1.3:1 input ratio just like any other gear was the plan from the start. on start up, under light load, etc, the input gear is at 1.3. When acceleration is needed, the gear drops back down to 1.0, both acting as a downshift and increasing stall. I envisioned it being like an extention of the transmission, and tunable as such.

 

Ah, yes, of course, you are correct, gearing before the converter is subjected to "advertised" stall speed (I was not thinking when I asked).

 

If there's any more ideas on variable stall from some far corner of the racing world, post it up. Eventually one might be better than the planetary idea (the variable pitch stall is close, and could be better in applications where (effectively) changing the rear gear isn't a wanted sideffect). As for the planetary idea, is it mechanically viable? Has there ever been a company that put gears before and after the torque converter? Or perhaps one of the sponsors has tried it (seems like more of an aftermarket technology anyway), and it was deemed to costly, target audience wouldn't be profitable, to weak, or ineffective?

 

GM used a planetary inside the fluid coupler on their old 4 speed Hydramatic aluminum case trans from the late 50s, early 60's.

So your idea is not entirely new...

 

There are (or were, last I checked) people still making
switch-pitch converters for the ST400. You can also
convert a plain TH400 to use them, by drilling at just
the right spot and bringing out the hydraulic passage
needed to feed it.

But those switch-pitch converters are the heaviest I've
ever seen. I pulled a ST400 out of a '68 Wildcat once
for a project, the converter was like 15" and over 50#.
And the base stall choice was something like 800/1500,
nothing like we enjoy.

The truly variable stall speed was, I think, the Dynaflow.

 

There used to be a Buick place (I *think* it was ran by Jim Burek) and he had about 5 options for the switch pitch (he also sold a conversion kit). The biggest one was like a 2000/5000 stall. I bought a 1500/4000, but never got around to using it before I sold it.

 

It seems so. However, the design was (apparently) quite inefficient, since the torque converter was a 5 element (2 stators, eventually equipped with variable pitch blades, 2 turbines, 1 impeller), and actually implemented the planetary into the converter (somehow), rather than using it to modify a conventional 3 element converter from the outside.

Also, I think the Turboglide is a cool idea, and much simpler (and probably more effective) than the Dynaflow. It to is a 5 element converter (3 turbines, 1 variable pitch stator, 1 impeller), and seems more efficient than the Dynaflow. It's also cool how the converter was the whole transmission (they both were, but the Turboglide is still cooler).

Do you maybe have a diagram to explain how the Dynaflow works? It is a bit confusing.

I can stand another 40lbs if it adds more than enough performance to compensate. would you be able to run the converter (with modification) on a 4l60/80? It'd need a lockup clutch as well.

About how much did it cost?

 

Short course stadum race trucks have a gear box before the converter and can tune ratios there, you can adjust torque to the converter and match your RPM to the track.

 

i actually had a varible stall in a turbo 400-it was a manuel setup though, lol
stick turbo(or clutch turbo) slipping the clutch you could make it any stall you wanted-but brutal shifts, lol
i got my switch pitch converter from Jim Burek, i got the 13", he also has a
12"

 

Heavy? Expensive? Gear ratios that don't require a 4.56 rear gear to equal a 3.23/4l60e combo? Capable of being fitted to a 4th gen? Gears both before and after the converter?

If no to the first 3, and yes to the last 2, I'm interested.

So...mechanical viability of the original idea? How tough is the 4th gear planetary on a 4l80e?

 

Interesting thread indeed. I have put the plans in place for a developmental program for a system that will manage torque converter efficiency. It will take a bit of doing... but I have the correct minds in place, a tried and true mechanical system to base the digitized system on, and a plan in place for a prototype.

I'll begin assembling components once the Racing Season formally starts and I can get all my Class Racers out of my hair. It seems like once New Years hits the bottom falls out of it anymore and I get swamped with Powerglides of all shapes and forms!

I digress, the mechanical format listed is a sound idea. It has been in use for some time as Dave mentioned. And, Jake is correct about a planet in converters back some 50 years ago. Do an in depth Google and Wikipedia search on the Hydra Matic group that goes waaay back to the early days of automatic transmissions and you'll find a vast array of combinations that were put into production or were scrapped before they made it out of R&D.

Torque Converter management is a very interesting subject that is very near and dear to my heart. Having been very close to some very fast, high profile regional and national level racing teams I have seen some interesting things done and contributed ideas that were implemented and were successful over the years. And last Fall there was a particular car that sparked my current theory.

Kudos to the OP for thinking out of the box!

g

 

I guess you can't reveal the specifics, (but if you can) will it be completely mechanical (modifying engine input speed), completely hydraulic (variable pitch stator), a combination of the two, or something completely different?

Also, I have lots of questions regarding stall/str tradeoff (in other threads). If you took an sy3500, only modified the stator, and gave it a str of 2.5, what would the stall speed be? If you took an ss3600, only modified the stator, and gave it a str of 1.63, what would the stall speed be?

and would these converters, with traded str's, also trade driving characteristics? (this one might not have enough information)