I recently ran across an article in a diesel magazine that highlighted a 1999 F250. One of the “features” touted was a switch to lock out the torque converter lockup. That’s interesting.

Why would I want to lock it out?

On the other hand, could/would it be beneficial to lock it in?

 

Preventing the torque converter from locking allows the engine to develop a little more RPM. This puts the engine in a different spot in the power band, the idea being your engine makes a little more power at that spot.

 

I've never seen anyone run a lock out switch to keep it from locking... You want the thing to lock ASAP so you can put the power to the ground...

 

Thats what the tow/haul buttons did about 10 years ago. When a tranny locks and unlocks repeadidly due to insufficient power, it is very hard on the trans.

 

u can also build one of these lock outs very cheap. i built mine for 12 bucks. works great. i love it

 

One word of caution - slipping causes heat. Watch your trans temps.

 

Jim McCarty,

Get the TS Performance lock up module, locks the TC at your desired MPH, has a trans temp gauge and is great for racing or towing. Helps make MPG too.

Mark @ DPPI

 

SP diesel sells a very nice kit that runs off of the cruise control buttons. Press and hold for 2 sec set button at your desired lock up speed, press and hold for 2 sec the resume at the unlock speed... Very nice! Love mine!!!


www.spdiesel.com

 

Mark at DPPI &
CSIPSD,

I like the idea of locking up the converter quickly and plan to look into the two systems suggested. What's your suggestions for a set lock up speed?

Also, when downshifting while pulling a trailer in tww/haul, will it stay locked up and just downshift a gear?

 

Those kits sound interesting, any idea how much of an improvement in MPG to expect?

 

Thats the beautiful thing about the systems, you can change them anytime you want... I set mine up to lock at about 26-29MPH most of the time but if I know the wife will be driving it I change it to about 35... Mine stays locked to 22 mph, thats where I have the unlock speed set.

I run SP diesels exhaust brake and TC control kit. Best bang for your buck as far as I am concerned.

Mark will have to comment on the TS unit as I have no knowledge of it.

 

Around town I doubt you would see anything, it will take alot of milage at cruise speeds to see a MPH improvement.

 

BD Power does sell a kit called a Torque Unlock, it consists of a 3 way toggle switch to manually lock and unlock the torque convertor, with a 3rd position for stock operation. Unlike most home-made kits the BD torque unlock kit will automatically release the convertor under 20MPH to prevent engine stall and having to switch the controller off every time you come to a stop.

There is some advantages to unlocking the the T/C like building more RPM but there is also issues with building to much heat in the transmission, also getting less efficiency out of the transmission. On the other side of that coin there is huge advantages to keeping the T/C locked up on deceleration especially with a big load or with use of an exhaust brake.

Hope this helps
dave@bd-power.com

 

The SP Diesel kit unlocks at what ever speed you choise to have it unlock. All automatic as well

 

Most "non home-made" lock up controllers DO have the ability to adjust the unlock speed including ours but depending on what rear end ratio you have 15-20 MPH is about as low as you can bring it without dragging the motor down.

We do sell a Tow Loc kit as well that works off of RPM rather than speed allowing you to bring the cut off speed much lower by downshifting but it only works with a BD Exhaust Brake.