Can the TCC be taken under manual control?

When towing my camping trailer, always in 3rd, the TCC engages shortly after reaching 80kph. Then it disangeges on almost any slight hill, depending on the power it takes to pull the trailer up (steepness) and on speed/rpm.

Best towing speed was 96kph @ 2200rpm, with a minimum of 92 to run smoothly --- but it requires a fairly flat road etc. to go that fast. And I'm allowed only 80kph --- which is actually an undriveable speed, both technically and considering the flow of traffic. Going faster than 96kph continously is too dangerous, as the trailer could get out of control then, eventually. 96 is also a good speed for the TCC, as it requires a fairly steep hill before it disengages, and when it does, RPM goes up to about 2400 so that you hardly notice what it's doing.


The TCC works very well the way it is supposed to, but I've found it utterly annoying that it disengages so soon. It efficiently prevents you from really making use of the power the engine supplies, and I'm worried about the wear on it.

What I've in mind is a switch in the cockpit that allows me to toggle between default operation of the TCC and locking it up so that it doesn't disengage. Hm, better would be a triple switch: permanently unlocked, default, locked.

If that can be done, what would be required? And would it be a good idea at all? Maybe the TCC cannot withstand the full power of the engine, or the transmission could overheat?

BTW, what's the stall speed of the converter? 2500, I'd guess?
Edited by: 0lee

BD's TorqLoc does what you want. However, there are some issues with it and OBDII trucks. HowieE can fill you in. It works great on my 95 OBDI truck. It lets me engage the converter clutch in second gear as long as the speed is above 36 mph. It even automatically unlocks the converter when speed drops below 31 mph to keep you from stalling the engine. Check out this article http://www.thedieselpage.com/reviews/torqloc.htm.Edited by: ronniejoe

A manual switch would be great.
My truck is always engaging and disengaging the TCC when I crest a hill in OD.

ronniejoe,

the TorqLoc seems to be nice, but BD doesn't seem to offer it any more for the 6.5/4L80E. In their price list, there are some for Fords and Dodges, at $299/$499.

That's rather pricy; just a simple switch would do the trick as well ...

I didn't read the artikel thouroughly yet, but what I don't understand is why the TCC could slip at 1700rpm and below while holding tight above 1700. You'll be making considerably more torque at, for example, 2200 than you do at 1700.

That is BD's comment, but I'll venture to guess that it has to do with line pressure being lower due to low pump speed. That equates to lower clutch apply force.


Here's a link for the TorqLoc http://www.bd-vfi.com/gmc/product.php?pn=TorqLoc%20Transmission%20Controls&t t=gmc. It is still sold for the 6.5/4L80E package.


There is an electronic box that interfaces with the computer to ensure that the converter clutch will not engage below 36 mph. It also includes controls to work with the BD Exhaust Brake (if you have one). It is more sophisticated than a simple switch and gives you protection that you don't get with a simple switch.Edited by: ronniejoe

THX for the link! I'll have to think about it for some time ...