We just got a 02 SCrew FX4 5.4 and 4r70w trans and 3.55 gears. We will be towing a 24' pontoon boat some and a 20' bassboat every once in a while. Should we keep it out of overdrive? The road we go on we usually go about 55-65 mph and there are quite a few hills. I'm not sure what either boat weighs.

Just for reference here's the stuff.

Here's the new truck.


Here's the 20' bassboat.


Here's the 24' pontoon boat.


Thanks

 

You should be able to tow the bass boat pretty much effortlessly. At 55/65 mph, with the 3.55 gear you will be at the lower end of the torque curve so it may struggle a little climbing the hills in OD. It should be fine on the flat but you will probably want to cancel OD to climb the hills. Try both and if it hunts between gears in OD, stick with 3rd.

I would assume the pontoon boat may a little heavier and have a lot more aero drag so it may be a little more sensitive to pulling OD.

I put 235,000 miles on my 4R70W towing a 4800 lbs car trailer on mostly interstate in OD. I always downshifted at the bottom of any hills I didn't think I could pull in easily in OD. I rebuilt it at that milege more for piece of mind than anything else.

Steve
'95 Clubwagon XLT

 

Tow in the tallest gear that the torque converter will stay locked. An unlocked torque converter is the major heat generator in an automatic transmission.

 

Maybe a stupid question. But how do you tell if the Torque converter is locked?

Thanks

 

Not a stupid question at all and not always easy to tell. Converter clutch engagement is more obvious on some transmissions that others. On an E4OD/4R100W it is quite obvious and feels alot like a shift. The 4R70W is somewhat more subtle because the converter clutch comes on very slowly and smoothly. You don't feel it so much as notice a gradual drop in engine rpm of about two to three hundred rpm at cruise.

Once the clutch is engaged it feels more like a manual transmission in that if you ease into the throttle the rpm tracks road speed directly where as if the clutch is not engaged you will feel (and see on the tach if so equipped) a disporportional increase in rpm compared to road speed when adding throttle.

In the 4R70W you can cause the converter clutch to dissengage by easing into the throttle until it is forced off. At that point you will feel (and see on the tach) a sudden increase of two to three hundred rpm. Easing off the throttle will cause it ro re-apply. The clutch can also be cycled off by lifting off the throttle at cruise. Once you are at steady state cruise above 50 mph the clutch is applied. At that point you can lift off the throttle for a couple of seconds, then re-apply the throttle (to the same setting). The clutch is dissengaged when you lift off the throttle and will take a couple of seconds before it is re-applied after you re-apply the throttle. As the clutch comes back on you will notice the engine rpm gradually fall about 200 rpm as the clutch is re-applied.

Steve
'95 Clubwagon XLT