One feature of the stock bins that I'd like to change is lockup of the Torque Converter Clutch at 75-80 mph while @ WOT. Glenn's 6EX TDF has a new constant called TCC Unlock Prevention that sounded promising so I got a copy of that TDF from Tunercat. The value of this parameter was defined as 75 MPH in my bin file. So far so good. I increased the value up to 120 MPH so the TCC wouldn't lock at all @ WOT in third gear. Road testing shows the TCC still locks at 75 MPH (no change).

Have I misinterpreted the meaning of TCC Unlock Prevention? Is the interpretation correct but the code not working? Thanks for any feedback.

 

Unless you rework the tranny the cooler only operates with the TCC applied.
Also, as speed increase the areo load increases, and it's far better to have the converter locked just from heat management. If you need more top end that's an issue about HP, not TCC lockup.
Next issue is if you lock it too close to peak torque or HP, you can cause it so slip, and then they fail real easy.
My best tranny life was with a non lockup tranny and converter. My tranny failures turned out to be from the TCC coming apart.
With the GN and it's 200R4 I removed the inputs shaft check ball spring, and retainer, and now TCC feels like 5th gear, so hopefully that will prvent any excessive slippage (at least during apply).

 

Grumpy, thanks for the reply. I definitely wish to retain the lockup but only lock at part throttle. The tranny and converter are fresh and I'm only making about 230 HP at the wheels so no real possibility of grenading them due to too much power. The issue is that my single disk Vigilante is not designed to be locked up at WOT per Terry at Precision Industries.

I had the vendor make this change in the PROM I previously ran. Now I want to do the same since I'm rolling my own.

 

You'll also need to change the TCC Unlock/Lock tables, meaning lowering the values in that mph range to below 99% that they're probably set to from the factory.

------------------
Greg Westphal
'87 IROC 355TPI/A4

 

Just some thoughts:
Don't expect to do any extended WOT then, unless someone has modified the tranny for enableing the cooling system in non TCC locked.
This is one of them times when Tunercats Compbin is nice, compare the files and see what is going on, and if you can improve it. Unless you have one of the encrypted types.

 

You could always put a switch inline with the brake switch and control tc lock up when you want it. By putting it inline with the brake switch you have the advantage of leaving it in the on position and it will operate as normal, ie.. the way the factory made it work, in the off position it will never lock untill you turn the sitch back to the on position. This may or may not be what you wanted but it does work well. Iv'e done this to two Camaros ( 91RS and 86IROC ) with no problems. The IROC has been this way for four years no prob.

Steve

 

Greg, I forgot to mention in my original post that I've already modified the tabular TCC lock/unlock parameters for "not in 4th gear" to less than 99% all the way to 100 MPH. I increment each higher MPH value by 5% maxing out @ 90% at 100 MPH. Max value for TCC unlock is 60%. I picked this up from an earlier thread on TCC parameters. I noticed that Jegs lists a Hurst Lock-up harness. Is this the harness you referenced in an earlier post?

Grumpy, agree with you about limiting WOT if the converter is not locked. You've made some good points. I may try running w/ and w/o lockup next time at the track for a pure performance comparison. The bin from my vendor sourced PROM is indeed encrypted. I've already got the car running much better with the knowledge I've gained from this board so it's no big loss (the old PROM that is).

Steve, I'm trying to do this through software (so far unsuccessfully) but have no doubts that the switch would also work very well. I may end up there yet...

 

Yep, that's the one. I think 1 or 2 other companies make them too, but they're all the same.

------------------
Greg Westphal
'87 IROC 355TPI/A4

 

Mark' are you trying to keep the converter locked or unlocked at wot? I may have misunderstood what you were wanting it to do. Is it possible to get the ecm to keep it locked at wot or is there some type of overide that won't allow it?

Steve

 

I'm trying to defeat the stock GM programming that automatically locks the TC at 75 MPH at WOT. I listed my reason for not wanting lock in an earlier reply (ie. TC not designed for WOT lockup). Every stock and aftermarket PROM I've tried to date exhibits this behavior. Specific data within the bin must be changed to alter this feature. Information on this bin change is what I seek.

 

For the 730 this really isn't a problem. There is a constant in the BIN that is changed in order to modify the Mandatory TCC lockup mph. For the $6E there should also be a parameter (but probably not in the current .ECU file). Find the parameter and change it. If you can't find it then I might be able to track the address down.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

what about changeing the govener to a corvette servo in a 700r4 ????

 

The governor controls when the shifts in the 700R4 occur. The servo controls when the band on the drum is applied. You can't switch one with the other and neither will change when the TC is locked.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

The locking of the TCC can be mistaken with a gear shift. Try changing the speed to 80 to see if you can feel it.

The Unlock Prevention Speed, will still allow your TCC to lock at part throttle. It's WOT that it should prevent it (when used in conjuction with the 4th and non-4th gear locking speeds). By itself, the Unlock just forces the TCC to lock and remain locked. It does not prevent locking by itself. You need to set the other constants to keep it from locking such as the 4th and non-4th Gear locking speeds.

 

I know very little about the exact working of the ecm but of the two Camaros that I drive (91RS daily driver, 86IROC about twice a month) I have never had the converter lock up under wot. Why is this something you want to avoid? I would think you would want to be able to lock the converter in forth during wot.

Steve

 

Emailed Tunercat and he said that Unlock Prevention does not have any affect on the TCC unlock-to-lock transistion. That's consistent with my experience to date.

No fuzz whether it's 2-3 shift or TCC lockup. This is one of Probuilt's street/strip trannies with nice positive gear changes. 2-3 manually shifted at 70 MPH/5000 RPM. TCC automatically locks at 75-80 MPH dropping RPM from 4000 down to 3600.

I'll try increasing the non-4th lockup speed from 38 MPH up to a high value for learning purposes. Even if it prevents 3rd gear lockup it's still not what I want since lock at part throttle in the lower gears will be eliminated.

I ran my car for 11 years before discovering that stock APYU bin along with the previous vendor sourced PROM was locking the TCC at WOT. It became real apparent when I went from the stock converter to the Vigilante. Locking in third gear decreases down the track torque multiplication and shortens TCC life. Grumpy identified the downside which is a potentially dangerous increase in heat buildup if running at WOT for an extended period. WOT lockup in fourth gear is fine with me since that's out beyond the standing quarter.

 

I have a question. How do you figure the cooler only operates with the tcc on? My cooler is run direct from the trans and gets hot when running with the tcc off.
And a comment. The tcc is going to continue to fail by locking it up under load or having it locked during a firm upshift. Removing the check ball from the input shaft and especially the retainer will only make tcc life shorter. Next one that fails have it cut open and see what it looks like. The damper springs will fall out in a million pieces due to hard apply or hard upshifts.
My advice would be to get a converter designed to be locked up under load, like a vigilante.

 

didn't realize this topic was so old.

 

sorry Jay 727, I should have mentioned that the link I posted to this post was from a while ago. But it is still worth mentioning

 

I know this is old, but trying to discuss tcc at WOT further. My car currently locks up at 75 also with a 3200 Coan. For 1/4 performance is that what I want, or should I keep it unlocked during my 1/4 runs. Any hard numbers?

Also what is the preffered way to only unlock the tcc at WOT and not affect normal driving at all



Chris