Is There A Way To Stop The Torque Converter From 'locking-up'?

[CanadaCraig]

Hi Guys!! :)

I hope you're OK.

QUESTION:

Is there a way to stop the torque converter from 'locking-up'?

[To keep the 'lock-up' clutch from 'locking']

Thanks,

Craig!! :)

[Sanpete]

While you're waiting for an answer, mind explaining why you want to keep it from locking up? Just curious.

[CanadaCraig]

Hi Sanpete!! :)

I bought my 1993 LS400 in October of 2003 and have complained about a poor acceleration problem ever since. The car took too long to get up to speed and would often feel as though it was 'towing something'. [A feeling brought on by a 'jerking motion'] MANY things have been done to the car in an attempt to 'fix' the problem. [All of which has been talked about here at lexusownersclub.com] Just a couple of months ago - a 'Lexus Troubleshooter' took my car for a drive and suggested that the problem is most likely the torque converter - specially the locking clutch 'thing'. My Lexus dealer - in response to the 'troubleshooters' conclusion - flushed the transmission and torque converter - replacing ALL of the old transmission fluid with new fluid. It made a BIG difference!! But the torque converter is still causing the car to 'jerk' and is often [so it seems] interfering somehow with the flow of power between the engine and the transmission. When the car is acting up ['jerking'] I can stop the 'problem' by pressing on the brake pedal just enough to cause the brake lights to go on. This causes the locking-clutch in the torque converter to disengage and when it does the car drives beautifully. So my dealer is trying to find out if it's possible to keep the clutch from locking so I can drive the car to confirm that indeed the clutch has been the problem all along.

Hopefully that makes sense.

Craig!! :)

[wwest]

Hi Sanpete!! :)

I bought my 1993 LS400 in October of 2003 and have complained about a poor acceleration problem ever since. The car took too long to get up to speed and would often feel as though it was 'towing something'. [A feeling brought on by a 'jerking motion'] MANY things have been done to the car in an attempt to 'fix' the problem. [All of which has been talked about here at lexusownersclub.com] Just a couple of months ago - a 'Lexus Troubleshooter' took my car for a drive and suggested that the problem is most likely the torque converter - specially the locking clutch 'thing'. My Lexus dealer - in response to the 'troubleshooters' conclusion - flushed the transmission and torque converter - replacing ALL of the old transmission fluid with new fluid. It made a BIG difference!! But the torque converter is still causing the car to 'jerk' and is often [so it seems] interfering somehow with the flow of power between the engine and the transmission. When the car is acting up ['jerking'] I can stop the 'problem' by pressing on the brake pedal just enough to cause the brake lights to go on. This causes the locking-clutch in the torque converter to disengage and when it does the car drives beautifully. So my dealer is trying to find out if it's possible to keep the clutch from locking so I can drive the car to confirm that indeed the clutch has been the problem all along.

Hopefully that makes sense.

Craig!! :)

Almost all modern day cars REQUIRE a lockup clutch since the OD ratio is truly an OD ratio, generally something between 1:1.3 or nowadays 1:1.7. Since the transmission output is turning FASTER than the engine the torque converter would be completely non-functional, making the OD ratio also non-functional. So what is most likely happening when you press the brake pedal lightly is the transmission is not only unlocking the torque converter lockup clutch it is also downshifting into 3rd gear.

The lockup clutch is NEVER in the "circuit" when you are calling for acceleration so that would have nothing to do with your "up to speed" symptoms.

Odo mileage...please...

With enough miles accrued it is quite possible the lock clutch is failing and that would undoubtedly result in a Jerking motion as it grabs and slips, grabs and slips...etc. But it would only do that in "cruise" mode, traveling along at relatively constant speed on a reasonably level roadbed. For the '93 LS that's basically the only time the OD clutch is locked and you are actually in an OD gear ratio.

Oh yes, before I forget, the "direct" answer to your question...

Use the button on the shifter to disable OD.

[tumy]

Dear Craig,

Did you get that problems solved? If yes, kindly write the details. Thanks

[malikqais]

Same is in my case only my car is 2000ls where there is no OD button to engage or disengage and don't know the problem yet

[curiousB]

Same is in my case only my car is 2000ls where there is no OD button to engage or disengage and don't know the problem yet

OP is very old so not likely this will get answered. I'd be a little leery of a dealer that suggest the "fix" to a ride problem is to disable a major feature (lock up torque converter) of the Automatic Transmission that Lexus probably spent upwards of $75M to design and optimize. This sounds more like shade tree mechanic tinkering than sound dealer advice.