Ever heard of locking the converter?????

[Shane]

I have a 3500 stall Yank converter and I was told if you have switch thats locks up the converter at about 20 mph u gain back about 6-9% HP that you lose by having it not locked. Is this true and if it is how do I do it?

[Dominic]

Yes, it can be locked up prematurely - but doing so is very bad on both the converter and the automatic transmission, neither of which is designed for this kind of operation and torque load.

If you have the money for a whole new drivetrain, and want to get slightly better times, this will do it - but its not worth your while if you don't feel like replacing the transmission and TC every 3-4 runs down the track.

[justin00stang]

The info I gave shane is what I was told by THE BEST ford tuner, former powertrain engineer for ford, and now for roush. Ford 4R70W trannies can take locking up the converter, maybe GM trannys are different?

[Shadly]

<blockquote>quote:</font><hr>Originally posted by TheCardinal:
Yes, it can be locked up prematurely - but doing so is very bad on both the converter and the automatic transmission, neither of which is designed for this kind of operation and torque load.<hr></blockquote>
Cardinal is right. You will mess that sucker up quickly. Besides, If you lock it up prematurely, you lose all the benefits of torque multiplication, plus you bought a high-stall torque converter for a reason. Why would you want to lock it up before you're in a prime power band? Just let it do it's job.

[gitman]

<blockquote>quote:</font><hr>Originally posted by Shadly:
Besides, If you lock it up prematurely, you lose all the benefits of torque multiplication, plus you bought a high-stall torque converter for a reason.<hr></blockquote>

because after a certain point that multiplication ratio is below 1, thats when you want to lock the converter.

i don't see how you're going to destroy your transmission.

EDIT: it might be different, not to sound cocky but explain to me how.

that ford tech that justin mentioned said that ford has been locking the converters starting in 2001 on the 3.8L mustangs. It's also been done on the GT since 1998, cop cars since 1997, Mark 8's from the beginning, and the list goes on.

BTW, here's the post on V6Power about it: http://www.v6power.net/cgi-bin/ultim...&f=20&t=011512

[ April 13, 2002: Message edited by: gitman ]</p>

[Shadly]

It's a severe jolt when upshifting/downshifting accelerating/decelerating. The converter acts as a dampener before it locks up in fourth. It's hard on the clutch bands, it's hard on the bearings, the U-Joints, the rearend, and it's especially hard on the converter itself. It wasn't designed to take high doses of torque. Think about it, how many RPMs are you at when you slide into 4th... not too many. Torque multiplication applies when the engine is accelerating under a load. When the weight and momentum of the vehicle is pushing the engine, that's when the ratio is less than desirable. If I'm racing, I want to be accelerating the whole time. The only real advantage I see to locking up is to keep the revs high in a slolem course or to chirp the tires in every shift.

[gitman]

<blockquote>quote:</font><hr>Originally posted by Shadly:
It's a severe jolt when upshifting/downshifting accelerating/decelerating.<hr></blockquote>

ok huh? WOT only.

<blockquote>quote:</font><hr>Originally posted by Shadly:
The converter acts as a dampener before it locks up in fourth. It's hard on the clutch bands, it's hard on the bearings, the U-Joints, the rearend, and it's especially hard on the converter itself. It wasn't designed to take high doses of torque.<hr></blockquote>

i fail to see the logic, the converter would be locked when the speed ratio is below .8, so the converter would not be taking more torque then from a launch.

<blockquote>quote:</font><hr>Originally posted by Shadly:
Think about it, how many RPMs are you at when you slide into 4th... not too many. Torque multiplication applies when the engine is accelerating under a load.<hr></blockquote>

but you get to a certain point where all the converter is doing is slipping and generating heat (and losing power to the wheels).

<blockquote>quote:</font><hr>Originally posted by Shadly:
The only real advantage I see to locking up is to keep the revs high in a slolem course or to chirp the tires in every shift.<hr></blockquote>

are you sure you don't have it backwards? locking the converter lowers the rpms, if you read about Magnus' track runs he talks about his car revving so high with the stall converter. its not locking at WOT.

the stator and the turbine are spinning at different speeds and that generates heat, and you lose efficiency. so in comes the locking clutch, the power gets put to the wheels instead of lost in your transmission.

TheCardinal is right.. but he said prematurely.

[ April 13, 2002: Message edited by: gitman ]</p>

[Shadly]

<blockquote>quote:</font><hr>Originally posted by gitman:
i fail to see the logic, the converter would be locked when the speed ratio is below .8, so the converter would not be taking more torque then from a launch.<hr></blockquote>
The converter WOULD be taking more torque than from a launch because under normal circumstances, it is not locked until you hit 4th gear. If you lock it under WOT, it starts from first, bangs through the gears and sees the high side of the tach while it's locked. So unless you have a way to only lock it when the ratio gets below 1, it's doing damage.

<blockquote>quote:</font><hr>are you sure you don't have it backwards? locking the converter lowers the rpms, if you read about Magnus' track runs he talks about his car revving so high with the stall converter. its not locking at WOT.<hr></blockquote>
We might be talking about different things here. I was giving the negative aspects of locking the converter manually. High stall converters are supposed to rev high. That's what keeps you in the optimum power band. If it revs too high, he's got the wrong converter on his car. When you are racing, I can't think of a single reason to lock up. You're never going to even see 4th gear if you want to keep the RPMs high.

<blockquote>quote:</font><hr>the stator and the turbine are spinning at different speeds and that generates heat, and you lose efficiency. so in comes the locking clutch, the power gets put to the wheels instead of lost in your transmission.<hr></blockquote>
True, very true. If you operate at peak effeciency with NO slippage, something will snap eventually. I'm not trying to prove you wrong here. I see your point and I see your logic, I just think it's overly-abusive to the drivetrain. Race car drivers can get away with super tight tolerances because they rebuild after every race. We drive these cars home from the track and then to work every weekday.

[justin00stang]

Let me clarify something, yes torque converters multiply torque, but only when they are below stall speed, once you hit stall speed you're not multiplying anything anymore.

Maybe GM converters and trannys can't take it, but ford's like having their converters locked, more power to the wheels, higher trap speeds, and better ETs are the benefits. Ford's wouldn't come from the factory with computer programming to lock the converter if it was going to damage stuff. I know when I get my PI 3k stall converter in a few weeks I will be getting a chip to lock the converter at WOT at around 25mph or so.

[gitman]

<blockquote>quote:</font><hr>Originally posted by Shadly:
High stall converters are supposed to rev high.<hr></blockquote>

thats not true, the only reasons stall converters rev higher are because they are slipping so much = mph suffers

[DominusEtDeusNatus]

Every torque converter slips. Aftermarket ones slip more. 4L60E is an electronic tranny and has a lockup switch that locks the converter when there is no more slip, ie in OD.

Locking up the torque converter in the right place takes alot of experimenting. At best you can pick up a solid 1/10 if you hit it in the right spot. It all depends on the slippage of the converter.

You have to lock-up the converter after it's coupling point. This point varies with each converter. At that point your torque multiplication ends and the turbine starts to catch up with the pump, ie efficiency is &gt; 90%. If you add mods or put a different converter in, you'll have to find that point again as it will move. Locking up too soon will cause you to loose torque multiplication. Let's say your coupling point is at 5000rpm, you hit the switch, rpms lower to 4700 and you keep climbing. You can have that locking programmed into your pcm. If you lock it through the shifts then you will hurt the tranny and you will loose ets. Instead of the unlocked converter cushioning the shifts and dropping the RPM to 4500 in second you'll drop to 3500 and hurt your tranny in the process. If you want to do this, do it in 3rd only. Another thing. What do you guys run 3.42s, right? So how many are doing 4500-5000rpm in 3rd at the 1/4 strip? So you probably won't need it. Unless you're running a small converter, then those points will be lower. Either way, at best a 1/10 and 1 or 2 mph if you hit it in the right spot.

[gitman]

the Ford ECU's know when this coupling point has been reached.

do the GM's?

[DominusEtDeusNatus]

<blockquote>quote:</font><hr>Originally posted by gitman:
the Ford ECU's know when this coupling point has been reached.

do the GM's?<hr></blockquote>

So if you change the converter, it knows and moves the lock up point? If you change the torque curve, it knows and moves the lock up point also?

[ April 13, 2002: Message edited by: Dom ]</p>

[Dominic]

Torque Converter lockup was designed to increase the fuel economy of the vehicle and make it act less like a slushbox and more like a manual after cruising speed has been reached.

The lockup clutch in the converter is not designed to handle 300hp, it is designed to handle crusing speed hp with is usually under 50 for most driving conditions.

If you notice, under acceleration your converter unlocks. Also, under braking, your converter unlocks - doing so allows you to not harm your transmission by shocking it.

The *stock* transmission and converter CANNOT handle being locked up all the time. If you want to lockup all the time, buy a manual folks!