I have an 86 trans am that has 200,000+ miles on it. The engine is very weak and TCC lockup would bog it down (esp with a/c on). So I change the lockup to engage at about 50 mph. After driving it through several miles of stop lights and traffic the transmission started to slip. Just remember no/late lockup CAN cause transmission damage. At the very least, the fluid will be hotter, and that is how trans problems develope. Just something to think about before changing the lockup tables. If the car had a trans cooler I might not have noticed....

 

Not to mention some transmissions only enable the tranny cooler, when the TCC is applied.

 

I recently changed some of my TCC lock-up parameters to those recommended in Trax's Super AUJP article. I noticed the trans started having issues with not wanting to shift to OD at WOT. This car has the trans that will run in OD at WOT. Right now the car is speed limited to 130 mph because of this. When I get home I'm going to reset those parameters back and see what happens.

 

Have you reset your TV cable? My tranny a few years ago "started to act funny", turned out to be the TV adjustment. Another time, it was a govenor.

Definitely reset the code, but I would start with the TV adjustment and then your code....and hopefully it goes away.

 

Actually with my case I focused on 4th gear lock up, the other gears did lockup like stock. That is where the engine bogged the most, in OD at low rpms. So right now I have to keep it out of overdrive untill 55mph and manually shift into OD, that way I'm not cruising around below 55mph in OD without lockup. That is how I currently drive the car...


Also there is the actual tq converter function. While in OD, the transmission gear ratio is below 1:1. That is another reason heat can build in 4th, especially without lock up. My formula is running non-lockup all the time. It has a good transmission cooler and I only use overdrive when above 60mph. So not using lockup can work. I guess people should be well informed before doing anything with the lockup function...

 

Bruce,weren't we discussing one time that with the 700R4/4L60 the problem than tranny fluid only flows to the cooler IF it is locked up. But isn't there a "DIY Modification" to one of the parts/valving in the tranny so some fluid would also flow even if the tranny wasn't locked up?

 

There is a non-lockup valve that can be used. Think you guys have it backwards though. The trans bypasses the cooler when TCC in engaged. Maybe a guy from the transmission board can clarify.

 

No, I am pretty sure that it has to be locked before the tranny fluid goes to the cooler. It also makes more sense when you think that the majority of the time, the TC should be "locked" (by factory settings) when on the highway.

Personally, I think you would like to have the fluid flowing ALL the time.

 

i dont have time to dig up and scan the instructions for the dash-2 transgo kit but there is an orifice that can be drilled into the seperator plate to make the cooler be run fulltime. Also i would think that GM wouldn't disable the cooler during the high slip periods and then use it during the low slip periods. all the heat is generated when the converter is in a slip mode.

 

On the 700 the cooler is disabled "when" the converter is locked
because the friction is no longer present and allows that pressure to be directed at the converter lock clutch..

 

Well, I tried searching a variety of websites dedicated on the 700R4 to confirm whether or not fluid only flows when the TCC is locked. All the sites I found were silent on this fact, except (Act Performance) which did say "fluid only flows with the TCC is locked".

But one thing the sites did say about the 700R4 is, "Always keep your TC locked. The 700R4 runs it's coolest when the TC is locked". And heat is the major killer of transmissions. This is one fact the majority of the websites on the 700R4 did emphasis and agree upon.

A few of the "RV websites" recommend when towing that it is better to run in 3rd with the TCC locked than in 4th with the TCC "locking and unlocking" due to heat build up.

And a number of "Off-Road-Sites" are advocates of locking the TCC as soon as possible and have conversions to lock your TCC in any gear.

So, while I am not able to find any info to confirm whether fluid only flows when the TCC is locked, they ALL agree that you want to keep your 700R4 locked as much as possible to reduce heat. Guess you just found that out the hard way. Sorry about your tranny.

 

No. There is always fluid flowing through the cooler in a 700R4. Maximum flow occurs when the TCC is locked, however.

 

They fail to mention torque converter slip is the number 1 cause of excessive heat. Locked up makes it a direct connection, as you know. There is no heat build up then.

That's not right. The last thing you want is to unlock and re-lock the converter while under heavy load. If an RV has heat buildup then the trans cooler is too small. 4x4 guys with 38" tires will convert the a/c condenser over to a trans cooler to get the temps down. I would think an rv might need one at least that big. Maybe a supplemental cooling fan too....

I think that is wrong also. My torque converter is non-lockup type and I disabled the TCC solenoid. No lockup and I get flow through my cooler. I drove my car to the track 25 miles each way throught the summer.The top abient temp I raced in was 95*, track surface temp 125*+ . Have made 17 passes one night in a row (5-10 minute wait staging). Never slipped more than it should. FYI, it's a 10" non-lockup 3600rpms. I have a good cooler on that car (my formula).

Where did you get that info from? thanks....

 

They're saying you don't want it to lock and unlock.

<img src=http://www3.telus.net/~crussel/tcc_released.gif>
<img src=http://www3.telus.net/~crussel/tcc_applied.gif>

 

Your two statements contradict each other. Your first one implies a locking type converter and then you state later that you don't have a locking type converter. You also state in the first part that you don't have a trans cooler and later say you do.

Do you see how you may get different answers?

 

............................

Glenn, guess you are not aware that I own 4 3rd gen f-bodies.

 

Thanks for the info! Could you explain in detail about the TCC solenoid function?

 

Okay, but please understand that I am responding to the "first post" and that car's setup. Then you respond to my post regarding the setup of a different car, but don't clarify that point. You need to keep the discussion regarding the first car or clarify and say "Yes, but my other car...".

Or you'll just confuse everyone...

 

When the solenoid is de-energized, it exhausts the Converter Signal circuit, keeping it from moving the Converter Clutch Apply valve. When the solenoid is energized, the checkball blocks the exhaust hole and the Converter Signal pressure moves the Converter Clutch Apply valve, which routes fluid from the Converter Feed circuit into the Apply circuit.

 

Thanks for clearing that up,
I still do not see where it allows more pressure but I really don't care either.
I have been driving my car all this year with out lock function due to what i believe is from a out of spec input shaft.. long story.
But do know for a fact fluid flows through cooler when unlocked.

opps.. actually I do see now! my bad.

But long story short I have had no problems, nor do I even have a dedicated trans cooler. But I always run with water temp about 160-180. Streetfighter 10" converter- 12" lock disc thats currently not working...

 

Adding to the discussion...
From the diagrams posted above and some I have here I can say there is no continuous fluid flow through the cooler when the TCC is unlocked. The only fluid that will pass through the cooler when unlocking is the returning fluid from the "apply" side of the actuator through the orifice going to the cooler.
When the TCC is unlocked the spool lands block all the passages from the "converter feed" lines (on the left side of valve)
When locked, the spool lands are opened to allow the orifice to pass fluid to the cooler.
I would have thought it to be opposite, but the flow paths are telling the story.
Jp

edit: as a thought, the actuator may have orifices in it or is not a totally sealed deal. That would give flow if not locked by passing through the actuator. (Not a trans guy, just hydraulic )

 

It flows around the grooves. Disconnect your transmission cooler lines and start the car and see if there' no flow with the TCC unlocked.

 

I tried this when I was installing by trans oil cooler, because I wanted to know for sure which direction the fluid travels. Well I got my answer....let's just say I had a bit of a mess to clean up, even tho I only let the car run for a second or two.

 

You solved the mystery! I have a question for you though. What modifications should be done to "convert" a stock 700R4 to non-lock up?