Manually locking up the torque converter

Diesel fapper!!-j/k. When the trans shifts with the converter locked under load, it is extremely hard on internals, shafts mostly. Coming from a diesel racing background I've seen first hand what happens to internals when you lock the converter. And those were sometimes even built trans with billet shafts. Most of the time is was dingus with a programmer and a stock trans. Those go boom in a hurry.

 

It's the shock loads that are the worry, not the horsepower. You can generate a lot of shock load with even a stock 4 banger. The hydrostatic coupling makes a huge difference in protecting from that. I'm not saying you will break it, I'm just saying it's a consideration. That's why the shaft in the manual version is massive by comparison.

 

hmm. You guys are bringing up some dam good points.

I'm still really tempted to try it, just for controlling descent speed (of course not shifting through gear when locked).

 

There are many mods that are fine if used with a full understanding of the unintended consequences and a little maturity.

 

yup. I never really intended to shift through gears with it locked up, but never gave it thought that it would hurt it.

 

OP, did you ever try this?

 

Revival...

So if my thinking is right, and you had this mod, you could push start your vehicle in a pinch... is the lockup clutch designed to grab like that though? My thinking is that it is only designed to lockup when the engine RMP and the trans RPM are very close, and RMP's are moderately high meaning the torque is much less... Would locking it with a 0 RMP engine blow it up or could it take the back-torque.....interesting.

 

No. You can't have the TC locked with the truck stopped. Conceptually to pop start with the TC locked, you'd need to push it fast enough to get it past whatever speed would equal idle with the TC locked. I had a TC lock up in my former Cummins for a short time. It's very, very (ok one more), very hard on the internals. Stock transmission input shafts don't like the shock that you'd put on them. Posts 20 - 22 give all of the details.

 

So revival again...If anyone’s still interested in this idea, like myself. I agree with all the great things y’all have brought up with the Toyota engineers making it perfect the way it is. People like to mess with stuff to see if it can be made better for their person needs and I believe thats possible with understanding and maturity like it was mentioned on this thread.

I was towing through hills recently and the transmission wants to keep dropping into 3rd gear for power from 4th (yes I leave it in direct (4th) for towing. Problem is on hot summer days especially, the transmission gets up to 215F which is still manageable in temp, but maybe unnecessary if you temporarily lock the Torque converter in 3rd for the duration of the pull up the hill then unlock and allow the transmission to go back into 4th.