Question about the 48RE and using Tow/ Haul 100% of the time?

[rjohnson916]

Ok a member responded to a thread I posted about the 48RE a few days ago and advised he uses his Tow/ Haul 100% of the time because the shift points are more defined and feels the truck is smoother & more responsive when taking off with ½ throttle input. Anyhow I’ve been driving the last two days in Tow / Haul 100% of my driving time. I have found the 48re does not hunt for the proper gear while driving in this mode empty, the shift points are rougher but I like it. The truck seems to be getting much better fuel economy and according to my trans temp gauge the trans is running a lot cooler. I also notice I get define automatic kick downs at certain speeds while slowing. Are there any side effects or problems that can begin to occur prematurely by driving in this mode 100% of the time? I really don’t want to go back to the regular mode, IMO the truck shifts and drive a lot better in Tow/ Haul.



-Ryan

 

[Hoefler]

I have been driving that way for better than a year and a half. Ever since I went to the dealer for it going into neutral while trying to slow down going down hill, it would disengage at 45 mph and then start to speed up and not re-engage. Very uneasy feeling!! I like the better shifts and it shifts earlier under light throttle letting the torque do its thing. All in all, I can credit about 1-2 mpg to driving with the tow/haul engaged down here in the Ozark mountains.

 

[PGreenleaf]

Well I do agree that theres advantages to the tow haul shift pattern. But I think theres disadvantages also in using it when empty. The torque connverter is locking up and unlocking probably 4 times as much. That wears the TC clutches . As we all know running normal mode it only locks in 4th on easy takeoff. Then unlocks and freewheels on slowdown. On my 06 ,when empty, in normal mode, if I romp on it, it'll lockup in 3rd for much faster takeoff, then shift to 4th locketup.

Yes the trans might run cooler , but then it's not running too hot so I see no gain there. And how much milage do you really gain. ?? I would think milage gain would be so small as to not be measurable.

 

[PGreenleaf]

I have been driving that way for better than a year and a half. Ever since I went to the dealer for it going into neutral while trying to slow down going down hill, it would disengage at 45 mph and then start to speed up and not re-engage. Very uneasy feeling!! I like the better shifts and it shifts earlier under light throttle letting the torque do its thing. All in all, I can credit about 1-2 mpg to driving with the tow/haul engaged down here in the Ozark mountains.

Well I will agree that in the mounains there is a definet advantage to haveing the better controll of downhill motor brakeing even empty.

 

[osiris]

i have also been driving with tow/haul on and my mileage went up from 14. 5 to around 16. 5-17 then to make sure that the engine wasnt just broke in i drove with it off and my mileage immediately dropped back down to 14ish... . hope this helps

 

[cerberusiam]

The torque connverter is locking up and unlocking probably 4 times as much. That wears the TC clutches

In stop and go driving, you will probably only have slightly more as it will spending less time in OD. As long as there is adequate pressure to hold the TC clutch the wear is not really a factor. The quality of the lock event is much more important, for both the TC and the clutch packs.



TH provides a more aggressive pressure curve and later shifts. This will make the shifts and TC lockup firmer which is what you want with the low end TQ the Cummins has. In addition, the sooner lockup and occurs and the longer it stays will keep the heat down on the trans.



These transmissions do NOT like low rpm stop and go operations. They hunt for gears, shift back and forth, etc. In the long run it is harder on the trans doing stop and go under 45 mph empty than it is dropping 10k on it and being forced to pull some rpm's to get things rolling. The 48RE is a lot better at handling it than its predecessors but stock form is borderline for handling the low end TQ with lower line pressures.

 

[B.G. Smith]

I don't have many miles yet but mine does not unlock at 45 coming down in OD. Only difference I can tell in tow/haul is it goes into OD at a higher speed. bg