How much power will a Torque Converter Clutch hold?
 

Hello everyone, I am wondering how much power a fully applied torque converter lockup clutch will hold before it starts to slip or suffers other damage.

Long story short, I installed a manual lockup switch in my 05 Civic, mainly for performance reasons. With my old trans, I would lock the converter at full throttle for better acceleration. However, I have my doubts about if doing so is good on the TCC.

The TCC is (on my car anyways) only designed to lock under light to medium loads in 3rd or 4th gear, so I don't know how good it is on it to hold the engine's maximum power. And to make matters worse, I added around 30 HP above stock to my engine.

So how much load can the TCC safely handle? I imagine it can't handle maximum power since it was never designed to be applied under heavy loads let alone full throttle, and especially not with the extra power I added to my engine. Is this something I need to worry about?

Thanks in advance for your opinions!

I'm curious, what was the performance gain with it locked?

I have a torque converter that was ordered with a low stall and a high performance lock up clutch. I have it in my one ton Gmc with a 6.5L Diesel and a very custom 700r4. All mechanical with no computer controls. I can pull my 10,000 lb Avion travel trailer in overdrive locked up. The converter never slips, if the tranny is not right the overdrive band will slip first.

Well I don't have any numbers (yet anyways), but from my experimentation, I feel like the car pulls a little harder once I lock it once I get above 5000 RPM or so. The other benefit is that locking the converter allows me to stay in that gear for a little longer because the RPM's drop a little. Normally I can stay in 2nd gear until around 70, but locked it will go to 76 in 2nd.

The most fun (and possibly most destructive) way to use the manual lockup though is to floor it while it's locked going about 55 or so. The trans slams into 2nd gear hard, the RPM's jump to around 5000 (about where my engine makes peak torque) and it takes off so hard! The way it dramatically slams into 2nd gear and immediately pulls makes the car feel a lot quicker than it is LOL.

However, 2nd gear was the first gear to start going out on my old trans (quickly followed by the rest), so I'm not sure that shifting the trans with the converter is locked is healthy for it. Maybe it was just a coincidence since the trans had 243K miles on it when it died, who knows.

Nice! :thumbup: Would you expect that a stock Honda TCC would be strong enough to not slip under maximum throttle? And is there a way to know if it is slipping?

You are forcing the second gear clutches to carry all the load when you drive your car like this, the torque converter is a cushion when unlocked. The converter is not the weak link in this chain. Remember there is always a fuse in a circuit, you may be moving the point of failure to second gear from somewhere else. When I was a young man my pickup went through universal joints, entirely my fault due to abuse. I discussed this with my father and I suggested installing larger and stronger joints. This is when the fuse discussion occurred, if we move the point of failure to a more expensive part we really have not gained anything.

I put a converter lockup switch on my 1996 F250 diesel. I only use it when I'm in the mountains and using an exhaust brake while towing a travel trailer. I don't purposely leave the switch on / converter locked during gear changes because of the possibility of transmission damage due to hard shifting. I don't know if the transmission would actually be damaged, but it isn't worth the chance, IMHO. The hard shifts have to be putting more strain on something somewhere.

could be that the next fuse is 40 amps instead of 20 amps though, in which case you doubled your available current/torque, though via destructive testing. Might just be a sheared key, might be a cracked case.

That's kind of what I figured, thanks. But is the problem the harsh shifts, or is the problem the TCC slipping from not being able to handle that much power?

Let's remove the shifting while locked from the question for now and focus on the actual lockup clutch. Would I be able to push enough power through the TCC to actually slip or damage it?

For example- When I moved to Memphis, I pulled a 2500 pound trailer full of my stuff through the mountains. When I was climbing mountains, the I had the trans in 2nd or 3rd gear under a lot of load. Would climbing with the converter locked cause the clutch to slip, or would it hold the power okay? Thanks

pretty much you'll eat the friction materials in the planetary gear hubs. the TC should be able to hold 1 1/2 times max engine torque, kinda an automotive rule of thumb.