68 RFE Transmission Tuning tips and tricks - Keeping that TCC Locked

[guimond47]

Lets get a thread going for 68RFE trans tuning.

If anyone here willing to talk about this. Much insight would be greatly appreciated.

in a 900HP Truck, Assuming the transmission is built to support the mods.

What would be the initial "minimum tuning parameters" you would suggest starting at to avoid slipping of clutches and TCC Clutch.

MM3/warp has what's called " Torque converter shift schedule 1 & 2" Parameters. Would you happen to know what these parameters alter? the units in these are set to "None"

Partial Lock tables vs Lock/unlock tables. Graphed in Excel does not make much sense. I've attached the Excel file with my shift points I have made to accommodate my large turbo. These are new shift points are great. But the TCC tables needed to change as well. I'm having a hard time trying to keep the converter locked under higher loads. Is that just a 68RFE thing? It will be locked then unlocked while getting into the throttle. I was hoping to do lock to lock shifts to help solve this but maybe higher experienced guys can help out.

Keep in mind Fuel to torque maps play a role in getting these shift points to work right. Essentially i cruise at around 25% TPS. factory Flash i was cruising around 40% TPS.

UpDown shift plotter (OEM TPS Values).xlsx

[Jim P]

Lower your lockup and unlock rpms in the throttle ranges you want and make sure you leave a couple hundred rpms between lock and unlock to avoid crossover and offsets. Torque to fuel will have a play on throttle to maintain speed but not when shifts occur.

[guimond47]

There has to be a way to just use the lock and unlock tables and disable partial lock. Would you know how this is accomplished.
Partial Lock is ruining my converter under WOT pulls. I cant afford to have it partial lock anylonger.

[Jim P]

Curious how you determined part lock tables are ruining your converter. At 900hp at WOT you are far more likely to snap shafts and grenade the transmission with forced full lock upshifts than you are to have the part lock tables ruin the converter. There is a reason most tuners won?t do forced full lock shifts and companies like Revmax and others will not warranty their parts if things like forced full lock upshifts is used.

[guimond47]

I am saying this because you can hear it in the RPM of the engine and i am watching the RPM TCC slip on my mm3. It will be locked then go WOT then pull back to 200-300slip under full power then fully unlock. Partial lock is dragging the TCC clutch. the life of the clutch will be decreased with partial lock under full load.

[Jim P]

Part lock applies lower frequency pulsewidth modulation to maintain a specific amount of slip during upshift to reduce the risk of snapping parts. You can reduce the time of hand offs of clutches during shifts as I had described to you in pm previously but be careful to not go too much and cause overlapping of on-coming and off-going clutchs or you?ll end up having more to worry about than the transmission operating as designed. 99% of anyone else that knows what?s going on with these transmissions and what they do and why and tunes them is pretty much going to tell much of the exact same things I have said here and in the pm?s.

[Jim P]

Honestly it?s unreasonable to expect to be hammering down on these things with 900+hp and not wanting to pay the cost that comes with that kind of power which can and does result in broken parts. It is something that?s gonna have to be expected and accepted to happen at some point.

[Jim P]

If you are insistent on running full lock upshifts, tread carefully with, tcc schedule parameters #1 set to 10 and tcc schedule parameters #2 set to 20. Last time I tried this on Warp Tuning, they had errors in their software and it didn?t actually apply those changes and I had to custom map those parameters in to get it to work. Don?t know if they actually fixed it or not.