Transmision and Torque Converter Tuning discussion

[Jackpine]

Originally Posted by soutthpaw

I love cruise control and use it all the time thats why it annoys me so much when its constantly surging and slowing to stay at the set speed

Thanks, southpaw, I didn't know a diesel throttle controlled fuel, instead of air. But I knew about additional fuel cooling the engine in a gasser - oh well, I'll try to not take this off topic again.

Regarding cruise control, which I use too. I disliked the way my truck's TC would unlock and lock back up on mild hills to maintain speed too. In fact, quite a while back, I think I started a thread on this.

But, I've found that by reducing ALL the upshift/downshift and TC lock/unlock speeds to the max in the Custom Options menu on my Gryphon, I've just about eliminated this "twitchy" behavior. Now it seems to just add throttle without unlocking the TC under "mild" demand. When the TC DOES unlock on a hill climb, it seems to be a more "natural" thing - the steepness of the hill feels like it demands it. And, there seems to be less "lag" between the speed control reacting to changed conditions than there used to be. Before, there would always be a noticeable dropoff in speed (about 2 mph) before the throttle increased and there was always a pretty big "overrun" at the top of the hill where the speed would increase 3-4 mph above the setting before the throttle would back off.

So, I think you are on to something with your thoughts about the TC and maybe % throttle.

I should add, though, if I'm towing the trailer, I'm right back to the same "overreactive" behavior when the speed control is engaged. The added weight and drag clearly causes a more abrupt/pronounced slowdown and the throttle demand must be pushed over to the point where the TC unlocks.

So, if it were possible, I'd try to move the TC unlock point up higher in the % throttle/speed curve. There really does seem to be enough power available without unlocking the TC so quickly.

- Jack