Been reading through some of the posts about TCC lockup settings. I am using S_AUJP with some changes to suit.
Anyway I have noticed that for 3rd gear the values in S_AUJP are for lock at 43mph and Unlock at 41mph.
Since most of my driving is done just under 40mph the TCC hardly ever locks from the tests I have done.
Now the stock tables for the unlock and lock are in the 20mph range for 3rd gear.
From what I have read most people say it is a good idea to have the TCC locked up to reduce heat. With the way I drive my car am I better off lowering the Lock and Unlock speeds for 3rd gear?
I don't drive the car in OD unless I am going over 50mph so for 4th gear I don't think it matters leaving it in the 40mph range.
What do you guys think better to have it lock sooner in my case?
I was also just wondering what the reason was for rainsing the Lock and Unlock speeds in the S_AUJP if anyone knows? Or maybe Traxion if you read my post what was the main reason for doing this?
Might as well ask a stupid question too, why is it better to have the TCC unlock when you hammer the gas? I see that the TCC gets unlocked once you go over a certain TPS value vs RPM.
I would say, tune the lockup in the converter to the cam and the stall speed of the converter. And, even if it's a stock engine, you should add an extra tranny cooler. I'm not sure what the current consensus is on when the transmission bypasses the tranny coolers, but I think it bypasses them when the converter is locked, and maybe it has to be in OD too (probably not), but I forget. This doesn't mean to never lock it up though. This means that cooling generally isn't required above a certain MPH when the converter is locked, because there is enough airflow around the tranny, and no churning in the converter (it's locked, eh).
If the cam is a little big, you'll need to tune the lockup to keep the RPMs up for a happy cam, and decent drivability. If the stall speed of the converter is high, it may be undesirable to have the lockup down low, becuase it might cause the RPMS to drop significantly, and that mismatch in RPM may wear out the lockup sooner (but I'm kinda talking outa my arse on that one, an expert will have a better opinion - try the tranny board, and the guy from ProBuiltAutomatics will almost surely help, he's very good with 700's).
Why unlock at high throttle? The lockup may not be strong enough, the cooler is bypassed, the acceleration will be better unlocked (up to a certain RPM), anything else?
Hope this helps stir up a few other opinions (not arguments, I hope)
I basically have a stock engine, no modificatons to CAM or heads or anything like that. All I have done are just the standard mods, Headers etc.
I'll maybe post my thread in the Automatic section after a couple days if I don't get any more responses. The only reason I posted it here was because it is changeable in the PROM.
I was under the impression that the TCC unlocked during hard acceleration to keep from slipping the tranny clutches, especially in OD (there's only 2 clutch disks). As well as above listed reasons.
My tcc won't hold my engine above 2300 rpm in 3rd gear, and I'm only making 280-300 hp. The clutch inside our converters are very weak. I used to have my tcc wired to a switch when I was running a carb. I used to lock the tcc in second and run it out the rest of the track. This lasted about a month and I toasted the converter clutch and then the rest of the tranny not long after that. The converter obsorbes alot of the shock of a hard shifting tranny. Without that it gets pretty brutal. I could actually hear the shell of my car crack when it shifted into 3rd, it was insane for the few times that it lasted. Ahh the good ole days when I was young and stupid.....well not a whole lot has changed, I just don't break as much stuff.
This reminds me of something some mopar guys did in the 60's. I think it was called the torque-flite. They took an auto tranny and fabricated a stick shift clutch on in place of the torque converter. The point was to leave the line at your desired rpm, then hit all the shift points perfectly down the strip. It would also be very positive through the shifts like you said. There isn't much driveability of the thing on the street, but for racing it sounded pretty cool. I saw it in an old transmission book from that era that I have. But this is a diy-prom board, so I'll stop with the transmission stuff.
