Tow/Haul Trickery

[gnar13]

Ok just a quick question since i'm still getting used to the way the Allison acts....put it on tow/haul today unloaded just to see what the other shift points were like. I just reset the TCM with the PPE about 200 miles ago, but haven't been in t/h mode since, or ever for that matter. Anyway, it was acting all crazy, rpms jumping all over the place, doesn't seem like it has the same power as it does with t/h off, sticking in gear when decelerating, all that. Could it just be because it is completely unlearned after the reset? I'm assuming the t/h has been used before since there's the mounting holes from a 5th wheel left in the bed from the previous owner. Anyway, just curious if this was normal or if i should stay out of t/h. I'm still trying to learn about the ally since as of now i know squat.
BTW, the PPE is set on 120 but i drive like a grampa

 

[darkness]

perhaps your rpm acting crazy is just the converter locking. it locks shortly after shifting into second. do you have larger than stock tires? my grade braking was never the same when i went to taller tires. even the 285's on pyo's would hold the gear longer than it would with stock size tires. and definetaly let that thing learn. jmo but you may want to beat on it a little harder in t/h so it learns more agressive driving for a load or racing.

 

[gnar13]

i've just got 265's on it. so, how do i know when the torque converter locks up? like i said, i really dont know anything about the ally yet and im not really used to it. also, is the grade braking what makes it hold in gear like that?

 

[THEFERMANATOR]

If you haven't driven it in tow/haul mode since resetting the TAPS in the trans, then you need to drive it in tow/haul just like you normally would to let it re-learn. When you engage tow/haul it has a completely seperate set of adaptives it uses for shift times and defule. SO until it adapts, it will do all kinds of crazy things, ESPESCIALLY if you get on it before it adapts. If you get on it much before it adapts it will throw the trans into a similiar state as limp sort of as it will throw the adaptives for a major curve ball.

 

[jmac5058]

When in H-T mode shortly after shifting into second gear the torque converter locks-up (this happens in 4th gear above 46 mph with H-T off) this seems to be the next gear except the sound and feeling is diffrent and the rpm drop is less than the next gear,from this point on through the gears it shifts with the converter locked.This gives a harsher shift to the next gear if there is no load on the truck.Why you might even chirp the tires if on the throtle hard.

 

[DMAXchris]

Its not sticking in gear. It holds the gear longer with the TC locked to assist with braking.

 

[gnar13]

thanks guys..i'll try to let it learn, but i don't really ever get on it. i don't think i've gone past half throttle since i got the truck a couple months ago

 

[DAVe3283]

The Tow/Haul mode never seemed to make sense to me, until I actually had a trailer behind the truck.

With a trailer and Tow/Haul, it is a sweet machine. The shift points make perfect sense, it will hold gears on hills to prevent riding the brakes (even downshift if it needs to), and in general drives very nice/smooth. Without a trailer, the motor is revving much higher than it needs to (bad fuel mileage), and the shifts will be quite harsh (there is no 10,000 lb trailer to absorb the power).

Just my .02, but I only use Tow/Haul when actually towing, or occasionally to help slow the truck down a hill in the mountains. Running it any other time just doesn't make sense to me.