lykan

Previously before coming to the board I had many misconceptions about how a Torque converter worked. After A while I thought I had it all figured out, now I don't think I have even the slightest grasp on how they work.

(I.E. when they are locked and why.)

I was looking in Tuner Cat at my engage/disengage vs. MPH vs. TPS I just don't quite understand I get kind of the grasp but not the whole concept.

I was under the impression it worked a lot like a clutch (wroong!) Keep in mind in 32 years this is the first auto I have owned.

The engage, and disengage tables in 2nd gear are set to 125MPH. This being true I am assuming either there is #1 another qualifier to engage/disengage in second gear, or it is just left unlocked in second.

I guess my misunderstanding here is that using manual transmission logic(doesn't apply), spin is bad. Why wouldn't the TQ be locked up during 1'st and second gear when you would think you would want all the power available, and no slip.

Does this possibly explain why I can't burn off the tires in first and second? If the TQ is not locked, is energy wasted?

Keep in mind I am way out there as far as feeling comfortable with changing any settings in the bin. I am probably months off from changing anything. It's just here I have read about final answers, timing, fuel, how to tune, best ideas, and explanations. Not many here have the 460le, or the 480le so I don't see it discussed as often.

It looks to me that these PCM controlled transmissions are a tweakers/fiddlers dream. I just don;don't know what I am fiddling with

My thoughts..
I would want lock up on decell for engine braking

I would want lock when lifting lightly on the pedal(no throttle) to continue momentum and save petrol

I would want lock up on cruise to save fuel as well, no slippage direct drive no energy wasted.

Also this is the part I don't get. I assume I would want lock up on take off for power/accel/tire roasting. I may be wrong here.

Anyhow if anyone wants to push me in the right direction I would appreciate it. If there are articles here on how the 460le/480le work and I have missed them, don't bother to answer, push me towards the link, and ill read up some more before asking questions that have already been answered.

BTW i spen about 3 hours reading through the final answer stuff.. great posts Grump, I don't know how many read them and don't comment, but i sure appreciate everyone who was involved in those.. lots of good reading.

There is an advantage to buying your program supplies as budget permits. Lots of time to read before I start burning. Have everything except the ppII, so not too far off

Low C1500

One neat thing I found out the other day is that the TCC unlocks whenever the break pedel is pressed.

Also I have great results tuning the fuel and timing curves (especially on high stalls) by settign the TC forced lock to 15 mph, then slacking offf the TV cable. This alllows me to reach high engine loads at low rpms (up a hill is the best).


Heres a TCC paper, if you havent already read it. http://www.diy-efi.org/gmecm/papers/tcc.txt

lykan

I am also noticing the line pressure VS TPS, at a TPS reading of 0 there is no line pressure. Wouldn't it be a good idea to keep a minium of line pressure at all times to provide a slight flow for cooling/tranny cooler?

Something else odd
Downshift pressure MOD VS MPH
From 3rd 4th downshift there is no pressure mod
Also from 2nd to 1st there is no pressure mod
But, from 3-2 it ranges from +9 to -22
Is this because the shift from 3rd to second is sometimes manual, and when you manually shift, your doing it for engine braking purposes?

I guess I just want to understand the purpose for this table Attached the image of the three tables

lykan

I wasn't aware you could force the TQ to lock on a 700r4, and I also wasnt aware of a TV cable.. is there one on a 460le?

Low C1500

I not sure is theres a TV cable on the 4l60E, I don't think so. I think what your seeing with the values mentioned about 2nd and 3rd gear is that on a gm electric tranny, when you put it in second from a stop, it starts in second. A 700r4 will always start in first not matter what gear your in.

About the line pressure for cooling, I heard first hand from a GM mechanic that they regularly plug off the tranny cooler lines when they leak. I guess it doesn;t hurt em.

lykan

Ack! I cut off the table labels, they are downshift line pressure VS MPH so the valuse are for downshift pressure at certain speeds, some of he table might have to o with 2nd from a stop,but the rest are for pressures at speed. I just don't understand them.

This is a copy of my stock bin BJLH8070.bin

I am wanting to completely understand the transmission before I make any, even the slightet of changes. From what I remember, with the wrong pressures, and or/ ettings 5 minutes at idle can smoekl a transmission.

I'm sure on a car that doesnt do much/no loads the cooler won't make a differnce but if you have any load it might keep it from overheating.

On a humoruous note. The front seal on my 64 ford falcon was leaking. I pulled the transmission, and replaced the seal, thought I would change the filter while I was there. Well, there were a couple of loose bolts behind the pan. I figured if I tightend them all up a tiny bit maybe I would get firmer shifts/less slipage.

Hah, In neutral the car went backwards. In drive it acted like it was fighting for control of the direction it wanted to go. Needless to say the car was sold a month later. This is why I have always owned a manual since.

Unfortunetaly I have that rhuemetoid arthritis, and can't shift a manual anymore.

Grumpy

The torque converter is a shydralic coupling, there is no direct mechanical connection between the input and output shafts. So there is always some slippage. It might vary from only 3-4% to over 12%. The TCC is added to the TQ to make a mechanical connection, so that slippage is dropped to 0. It's original design was just to eliminate that slippage to aid in improving gas mileage. Over time they've been improved in some cases to be able to with hold WOT.

Setting the enable MPH to like 125 in first gear just effectively disables it.

Lugging an engine can be bad on gas mileage. It's about keeping the engine happy.

JP84Z430HP

To further what Grumpy says, the torque converter also is a torque multiplier. I don't totally understand it all, but I know there is more to it than just stall speed, and that is where some of the aftermarket converters are better than others with the same stall speed.

As for having the TCC locked in first gear, the valving in the 700 won't allow it (I think it's the same story for the 4L60E, also.) The torque multiplication is nice to have on acceleration anyway!

I'm not gonna get into stategy for locking and unlocking the TCC at this time, because I have no EXPERIENCE in changing it. I know how it works, and a good idea of how mine will be in the end, but I'm not even close to the point of playing yet!

Whatever you do, DO NOT bypass the cooler! If a transmission tech tells you it's ok to do so, don't trust anything else he has to say! He'll probably tell you that the B&M Shift Improver Kits are a good idea also! I've had problems with clogged coolers before, and yes, they do go for a while, but eventually, about $500+ in hard parts fail.

In another post someone mentioned checking out Full Size Chevy in the performance forum.

There's a post there that talks about the "E" tranny stuff, and probably some other posts, but I didn't do much digging there yet...

Good luck!