Ok, so I just got off the phone with Brian of BTS ordering the hose kit for my 6.0 tranny cooler (really great guy and easy to talk to). While I had him on the phone I asked him about using the TC lockup switch. I told him how I have been using it, based on what I have read on here, and he told me I was really hurting my trans.

Here's the deal, from what I had been told on here and based on the way it sounds like other people use their TC lockup switch, I would flip the switch on whenever I was at cruising speed (esp when towing) and only really turn it off when I was slowing down to a stop. The problem is, I had never been told that it was bad juju to allow the transmission to downshift from OD to 3rd gear with the switch ON. I understood it to be overriding the torque converter, thus decreasing the heat buildup. Plus, it was nice that when it downshifted, the power was being sent immediately to the wheels and not being burnt up in the TC.

I wish I could explain it as well as Brian did, but in essence what I am doing is slamming a non-moving gear into a planetary gear that is moving the same speed as the engine without letting it slip at all.

What he recommended was to allow it to downshift as normal, then flip the switch on as soon as you can to keep the heat from building up. Once it has downshifted there is no harm done in locking up the TC as soon as possible.

I really hope I haven't done serious damage to my tranny already, especially since I usually use the switch when I'm hauling 13k lbs of 5th wheel. I hate to say I should've known better, but they way I have been doing it seems to be the same way many on here do it. So I'm telling you this so you can change your methods as well.

All the being said, what now? Should I drop my tanny pan and see what kind of metal chunks are floating around in there? I'm honestly afraid to find out, but I know its better now than to wait and be stuck on the side of the road trying to climb a mountain with 5th wheel in tow.

Thanks,
Bob

 

Good Info Bob.

 

I meant to ask Brian about that when I was down there a couple weeks ago but I forgot. He's 100% right though. I've noticed that with the new BTS tranny and Cale's tunes, the tc will unlock right before downshift, it'll shift down, then the tc locks back. IMO there's no need for a lockup switch now.

 

Brian was very reassuring, he said that if my trans is still working its probably fine, but I can't help but worry that I've done some serious damage already. Part of me can't wait to get a BTS tranny, but like everyone else I'm sure, the funds are real hard to come by.

 

Thanks, I think I'm just going to disconnect mine.

Too much hassle, especially if someone else thinks they know how to use it.

IMHO the chances of blowing the tranny from overheating it are pretty close to killing it with improper TC lockup use.

Might as well just let the automatic BE an automatic, and if you have the urge to keep controlling it, buy a stickshifter.

 

From what I read here and IMOA, with proper tuning and trans mods(Shift kit, VB), thats all you need. Never had one so don't know..

 

I have Jody's older version of tow tunes on my Excursion, from a couple years ago. They command the trans differently than his newer tow tunes, like the ones on my F250 installed back in January '09.

When John Wood built and installed one of his 4R100 beasts in my Excursion a couple years back, I also had him install a T/C lockup switch.

Pulling my 10K lb, 31' TT into Yosemite in the summer heat, on the narrow, winding, uphill roads takes it's toll. With the TC switch off, the trans temp runs a consistent 10 - 15 degrees higher than when the TC switch is on, locking up the torque converter.

With Jody's newer tow tunes, would the trans run the same temp as when the TC switch is on? I dunno. Just throwing my experience out there regarding the older tunes and the TC switch, for conversations sake.

Stewart

 

With regards to tunes, from what Brian told me, most of the good tuners lock the TC pretty immediately anyways, so a lockup switch wouldn't be necesary. I am planning to stop using mine except when in conjunction with the EBPV/exhaust brake switch I am installing now - but the truck won't be shifting while the switch is engaged.

 

So, with the new DP tuner it does drop a gear at 45 mph and you can feel the truck slowing down. Is this holding the TC locked through the shift from OD to 3rd?
I can also see the TC unlock at 25 mph.

 

I wouldn't think it holds the TC locked through the shift, Mike, but it probably locks it pretty immediately once it has completed the downshift - which is the way it should work. I am only assuming though, I don't have a tuner, but it sure seems like Jody knows what he is doing.

 

Jody said the same thing to me when live tuning. That with proper tuning, a lockup switch isn't needed. Now with a built BTS and Cale's tunes, I can hardly tell when it locks cause it does it immediately.

 

great info thank you for posting

 

I have a question,, Why would you turn it on and leave it on at cruising speed? And turn it off upon decelerating to a stop ? That is totally backwards to how i use mine. Once the TC locks up on its own, The manual button is useless. Above 40mph(approx), Hitting the button at that time us useless. You are going to be prone to forgetting and accidentally leaving it on coming to a stop, doing it that way
I don't use it much, Mostly in towns and villages pulling the 5th wheel on supper hot days.. Where i am forced to stay below TC lockup speeds. Or those slight inclines from a dead stop that i never seem to get to the top causing your tc to slip really hard for a long time, and you can't get yourself going. For those that pull heavy, You know what i am talking about.

 

Yep, towing 10k construction equipment behind my 1997 f250 hd with the 351w. Its the small block that could, but the damned torque converter slips so much starting on a hill i plan my routes to avoid stopping on hills. Im thinking about adding the switch, but i get the feeling it wouldnt be good in the long run. The trans shifts fine regardless, and when i tow heavy i just manually select the gears and am in no hurry.