Originally Posted by 99BoggerTJ
Hey hows it going. Well here is the story, my company bought a E550 toter home. Its 35 feet long, weighs 11,500 empty, and we tow a 36 foot gooseneck trailer with it. The trailer with 2 Jeeps on it weighs about 14000lbs. So this trans has to pull about 25,000 lbs. As far as we know its a normal 4R100, with 33,000 miles on it. So we want to upgrade it before it blows up.
Heat is going to be the hardest on a heavy tow rig. More so with your rig having a high profile and the van grille. It's not going to blow from heavy tow if you change fluid reg, keep temps normal and check cooler flow with atf changes. Unless it was used to climb steep grades all the time with high heat cycles, it should have many more miles to go than 33,000. You could put in a temp gauge, than larger cooler as needed if nothings wrong now.
Piston seal life will do in anybodys build in time. They are nitrile and like hydraulic cylinders begin to leak with time and heat speeds the wear process. Brittleness sets in, apply sealing is lost and shows up as a slip. Just like a manual transmission will need a clutch disc, you can't avoid wear and seal brittleness. Death and taxes for an automatic transmission.
The coast clutch is a weak spot for heavy tow. You can test it by canceling od and see how well it brakes the engine. If it's down shifting and slowing down the truck it's working right. Check converter for shudder when it locks. If good, then you may as well wait until you need a rebuild and save the $ instead. That would start the clock ticking on new seals then, instead of now. A shift kit or VB
works well for keeping heat on frictions and piston seals down with a faster shift. Good for extending tranny life. A clogged cooler will cut off lube oil and make her blow. If you pass a flow test, tow on.
If your adding bigger injectors, fuel, racing, chip, etc like Diesel Dog, then you have a legitimate concern of higher rpm's breaking transmission parts on an otherwise good tranny. Whatever you decide a tranny temp gauge is $ well spent. High temp reading will alert you of lube cutoff from a clogged cooler.
I pull right around 30K. Weight breaks down as follows: JD 450 bull dozer 14.5K, Goose trailer 5.5K empty wt, truck fuel and cargo. Big cooler, transgo kit, and maintance and it's alive and well with 205K. Flat ground helps, stopping is a bear. My dually had a bad tranny when i bought it. Ford's outsourced rebuild was toast. Got a good deal due to that