jim_c

I have made various posts re the transmission and torque converter issues with some TLs. I have to be honest and admit that I was speaking from general knowledge and some of my comments may have been inaccurate in relation to Acura. So I've been trying to update my knowledge and have read many of the documents on the Acura.com site which provide a lot of technical background on the different model years.

For example : http://www.honda.com/newsandviews/ar...spx?id=5934-en

which has a lot of detail about the 2012.

The first mention of the lock up TC that I found was on the 2011 AWD. Apparently the AWD has a different 5 speed trans than the FWD car, even though they are both called sequential sportshift 5AT. The 2012 car introduced the 6AT and has a new multiclutch TC. Again, I think this only applies to the AWD.

So here's my question. If you have an answer (please) tell me how you have confirmed it because I cannot determine the answer from the documents I have seen.

Does the FWD only TL also have a TC with a lockup clutch?
I assumed mine would, but I cannot detect it if it is there. There is no indication in feel or in tach readings to indicate that there is a lockup function happening. I have driven other cars where it is easily detectable, e.g. on my wife's Camry.
I'm somewhat embarrassed about this since I consider myself knowledgeable about transmissions and how they work. I have rebuilt hundreds of automatic transmissions in the past but never an Acura and not for a long time!

Acura11TL

Jim - the dealership did a software update on my 2011 FWD TL which fixed an issue with the RPM bouncing up and down. The issue I still have is with the shaking/rumbling/shaking noise between 1 and 2 rpms, specifically when the rpm drops right below 1.5 to 1.4. I've heard this is related to the Torque Converter. I'm still under warranty so I plan on taking it back in.

Torque converter related?

Blaze9

Same issue w/ my '12 TL FWD. It used to drop RPM when coming to a stop, causing a heavy shake. They updated the software on the transmission and that issue was resolved. Now I still feel some shaking/jerkyness around the 1.3-1.5k RPM range. Next time it's due for service I'm going to take it in for that.

jim_c

I still have not figured out if the FWD car (mine is a 2010) even has a lock up torque converter, but according to the documentation online, the TL AWD car got a lockup TC in 2011 and a multiclutch (even more complex lockup) TC in 2012.

I can't say much to answer questions about your symptoms but I will repeat what has been posted a few times. When the TC "locks up" it means you have a mechanical connection between the engine and transmission. It's like a car with a manual transmission in that sense. When you slow down or come to a stop you don't want a mechanical connection because the engine will stall. The main purpose of the TC in an automatic is so that the engine can run but the transmission can stop when the vehicle is stopped but still in gear. It's the fluid connection in the TC that allows that.
Acura has designed a very complicated system now with multiple clutches in the TC and lockup operation in speeds other than top speed (5th or 6th) so I am not surprised if this system has growing pains. It could potentially cause all sorts of weird shuddering, surging, gear hunting etc. but I have never driven one of these new AWD cars so I have no first hand experience. If the lockup was going on and off it would cause rpm bouncing up and down.

Lockup TCs were invented about 1980 and they are supposed to provide better fuel economy. I for one think their benefits are not enough compensation for the problems they cause. Just MHO.

Without meaning to be critical, I would bet there are not many techs at the dealerships who fully understand the system, and certainly none of the "service advisors" do.

jim_c

You probably already know this, but it would be a good idea to get all your concerns documented on the computerized file for your car at Acura. Ask them to show you or print it out for you. Trans and TC repairs not under warranty would be quite expensive.

dtrayers

The FWD 2012 TL also has a multi-disc lockup:

http://www.honda.com/newsandviews/ar...ura&id=5933-en

Scroll half way down.

Pretty much any car with an automatic transmission in the past 25 years has a lockup torque converter. It hasn't been until recently though that they lockup a speeds other than highway speeds.

dtrayers

BTW, I think the reason is it's so hard to tell if the TC is locked it's because they lock well before the final gear. Historically, TC's locked after the final overdrive gear, effectively feeling like another gear (the revs drop about 500 RPM).

With the TL, the TC locks as low as 3rd, so by the time you get to highway speeds it's already locked and you can't tell.

Experiment in manual mode. You can be in 3rd (or even 2nd) and goose the throttle without the revs jumping up 500 RPM. Instead, they will increase only as road speed increases. That means the TC is locked.

jim_c

Hey, thank you very much for posting dtrayers!

I had missed that info that you referred to.
And (duh!) I had not thought of the idea that the TC was locking up (in my 2010 fwd) in an earlier gear. I was just pretty sure that it was not locking up noticeably in "high" gear (like our old Camry). Your post is very helpful and now I need to do some more driving to see what I can feel.

I had figured like you said that almost all automatics have lockups now but I didn't see it in any earlier references so I wasn't sure. It's interesting to me that Honda/Acura posts so much technical detail.

Finally, two questions for you: are you a mechanic or just an amateur gearhead? And not to argue with you but do you think the lockup varies the rpm by 500 rpm? I don't think it would be that much of a difference since it's only going to cause about a 5 - 10% increase in efficiency. Maybe more like 200 rpm? It will depend on engine speed of course.......

dtrayers

No... not a mechanic. Just another gear head.

From my observations trying to understand how the TL lockup works, it's about 500 RPM. But that could be because I'm *trying* to induce some TC slippage by goosing the throttle.

The way I understand how it works is that torque multiplication happens as a result of a speed difference between the pump and turbine. That's why maximum torque is available when stalled (the engine spinning but the car not moving). As the car speeds up, the actual difference in speeds between the pump and turbine decreases until a steady state is reached when the car stops accelerating (maybe 90%?).

But if the TC isn't locked, give it some throttle and the pump will increase in speed (indicated by engine RPM) but the turbine won't (indicated by road speed). This difference is generating torque and accelerating the car.

On our TL's, you can really only observe this in third gear and at low road speeds. At any appreciable engine/road speed combination I believe the TC locks because when I give it throttle the RPM hardly moves. In fact, I think that it is initially *unlocked* at lift-throttle for coasting and quickly locks once power is applied.

I have a long commute every day (one hour each way in mixed traffic), so I have to find ways of amusing myself.

A long time ago I was given my grandmother's 1979 Buick Century to drive for the summer and I remember thinking it was a four speed transmission when actually it was a three speed with a lockup. That lockup dropped the revs about 1000 when it reached highway speeds and "felt" like another gear.

jim_c

Thanks again.
In a basic TC (no lockup clutch) the item you called the pump is usually or formerly called the impeller. The fins of the impeller are actual bonded to the TC shell which is bolted to the "flywheel" or flexplate turning at crankshaft speed. (The whole assy looks a bit reminiscent of a curling stone, lol.) The impeller drives the ATF against the fins of the turbine which is splined to the input shaft of the transmission which is usually part of the so-called forward clutch of the transmission. After the ATF acts on the turbines blades it is redirected via a stator and then back to the impeller. You may be right about the rpm variation and I think your comment about torque multiplication is correct.
Lockups were introduced in the late 70's or early 80s when I was in the trade and they often had to be "adjusted" so they would not lockup and unlock off and on e.g. on a grade at moderate speeds. The original Lockups were only supposed to work in "high" gear. The lockup clutch "locks" the turbine to the shell of the TC so the whole thing is turning as one unit and driving the input to the trans.
As you mentioned earlier, the locking up in lower gears is now part of the system which makes operation even more tricky.
BTW, the original lockup TC clutches were incredibly flimsy affairs with only a small amount of friction material. Not very durable.
I have seen the insides of an older style TC but I have no first hand experience with these newer ones.

jim_c

I just downloaded the Service Manual that Art linked us to and it's great.
The section on the trans is very detailed and Yes, as dtrayers suggested, the 09/10 TL does have a lockup. It locks up (or can lock up) in all fwd gears except first. It locks up in D and S.
I still can't detect it by feel or by watching the tach.