i'm a manual trans guy and am debating on going A4 to take full advantage of my setup on the track
but i have no clue what the differences of lockup and non lockup converters are and what each can achieve?
looking for pros and cons of each as well as a basic rundown of what is what

thanks
Steve

 

If you're planning on putting a th-400 or something in, a lockup feature is going to be EXTREMELY expensive.

I'll assume you're going with some version of the 4L60E/700R-4. In this case, definitely without a doubt, go with a lockup converter.

basically there's a clutch inside the converter that the PCM will engage at around 45 mph under light throttle/cruise conditions (you can program it to engage at any speed you want really with tuning software. Mine engages a little below 40 just to save a little more gas). this mechanically LOCKS the transmission to the flexplate and eliminates the slip from the converter. (basically it makes the trans equivalent to a manual with the clutch fully engaged, no slippage.) it's usually used as a fuel-saving feature as it will make your cruise RPM approximately 400 or so RPM lower. when you step on the throttle, the TPS sends a message to the PCM that unlocks the converter so the car can accelerate without bogging the motor. an added benefit is the elimination of friction (and therefore, heat) from the slipping converter.

you can also install a manual lockup switch to control the TCC (torque converter clutch i believe) solenoid yourself. a lot of drag racers like to manually lock their converters at the top end of the track when the RPM is nice and high. it's usually worth about a tenth of a second in ET if you do it right (if you do it too soon, youll bog the motor).

here's an overview...

PROS:
1)Fuel economy
2)the ability to pick up a little ET,
3)MUCH less heat in the transmission

CONS:
1)More expensive than a non-lockup (however, most 4L60E converters are built with a lockup clutch anyway since the f-body has a lockup feature from the factory.),
2)MUCH more excess heat produced in the transmission. (my TCC solenoid has acted up once or twice and watching the trans temp gauge climb fairly quickly while cruising on the highway UNlocked is not fun at all.)

as i said, overall, for a street/strip car, go with a lockup converter. hope this explains it all for you.

 

If the car is going to be street driven I'd definetly go with a lock up type.

One thing to keep in mind if you are wanting to lock up the converter while racing you need to have a converter built with the correct clutches intended for that use. If you do it too much on a regular lock up converter you will have alot of problems, and a burn't transmission.

 

thanks fellas, looks like i'll be eyeing a lockup converter if i do this then (and a big ole trans cooler)

anyone else care to add anything for me?

 

how does the converter know when to lock and unlock?

 

The problem is that the A4 is not a very sturdy transmission. I can be built up to take a fair amount of abuse, but it won't be cheap. If you are building a car for racing, you need to think carefully about swapping in a 4L60E. Converter lockup in the 4L60E is controlled by the PCM, as is the rest of the tranny. "E" = "electronic".

Rich

 

i know what "E" means , what i dont know is alot about automatic transmissions, thats why you see me asking all these questions in here to get a better understanding of them.

i understand the reliability vs. price issue. i'm just trying to learn more about automatics in general

so how is the lockup feature controlled in a non "E" transmission?
my plans when i do this is too use a 200-4R or 700R4. Buick owners have proven that the 200 can be built too last. i'm also seeing more and more places offering stout 700's too

 

Lockup and release is controlled by the PCM or ECM as is the case with 93 cars which have 700R4 transmissions. The PCM has lockup/release tables which are fairly simple on older cars, but dependant on a number of factors (and thus more complex) on newer cars. Like it has been mentioned above, it will normally lock up at around 45 MPH on a stock 3.23 gear factory tune. In a 93 or older 700R4, the transmission reports the current gear to the PCM and if all the other conditions (such as speed, throttle position, rpm etc) are met, the PCM or ECM will decide whether to lockup or release the TC.

Lock up converters clearly have an advantage in daily driving over a non lockup converter, but as far as track times are concerned, it is not exactly clear. Dyno numbers will be lower (and often will be lower than what the track times would suggest) with a non lockup converter or with an unlocked lock-up converter, but I have seen plenty of non lockup cars get the same times and sometimes even better times than cars with locked up converters.

That being said, my car gets about 1 MPH more with the converter locked up for half of the run, but the ET stays about the same.

I'm sure Frank (12SCNDZ) who builds performance 700R4s/4L60E and preffers a non lockup converter will have a different opinion though.

 

There is another issue with lockup converters, if you are making big power, and by that I mean really big (at least 5-600hp) you should not lock up the converter under WOT. The clutches in these converters were simply not designed for that kind of hp and will quickly fail with that kind of abouse.

You can install a free-standing controller or a simple relay to operate the solenoid that locks up the converter if your PCM/ECU doesn't have that function or if you simply want to independently control it. Here is an example: http://www.bmracing.com/products/kit...ockupCont.html

But again, if I understand you correctly you are talking about using a 4L60 for drag racing. You need to carefully consider this as it has been shown repeatedly that a stock 4L60 simply won't take the abuse of racing. There are plenty of people who have gone through more than one "race prepped" 4L60's as well. If you have a mild combo, a race prepped 4L60 may be ok, if you are making big power I would advise against going this route. If you really want to go racing with an OD auto, there are better choices. Talk to one of the vendors here on the board or to Carl Rossler at www.rosslertrans.com about this before you make a decision.

Rich

 

Rich, i'm after the low 11 second timeslips, the 60ft time of sub 1.55 and mph around 120. many do it with OD's.
my setup should be in the 420rwhp and ~400rwtq (sig has everything in it and the for sale link breaks down the combo) when it is dialed in
i see plenty of cars on here and at the track (and know people personally) with my power level using OD transmissions over and over and over

i'm not sure if we're on the same page here (i dont consider my car to be making "big power")
the trans definately wont be a stock piece, it will be made too handle some abuse
my car is 90% street driven but i want to drive to the track (98 miles) and achieve my goals, then drive back home
i'm not making more power then alot of the people that have used OD trans' repeatedly that are in the range i want to be in

thanks for the info about the lockup
i do see alot of Turbo Buicks using manual lockup controllers