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Auto trans question

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3500 miles in 11 days

Shoshoni, Wy TDR memeber

This is my third try at getting a post on the forum.



My neighbor bought a RAM 3500 Cummins with auto trans. He pulls a 5er that weighs 8,000 lbs. His previous truck, Ford F250 was a diesel with 5 spd. He wants to know if he can pull the 5er in overdrive. Also, should he shift through the gears or leave it in drive and shift itself. My truck is a 5 spd and I never has an auto so I can't answer his questions.
 
He can tow in O/D but it's a good idea to lock out O/D in town and while accelerating up to highway speed. You didn't mention what year truck he bought or the ratio. My 01. 5 auto does a really good job of managing O/D on it's own. My '95 was quick to shift into O/D and bog down. If he has 4. 10 gears, O/D will work in the hills above 60mph. If he has 3. 54 like mine, he'll have to lock out O/D for hills. I can cruise 65mph/2500rpm in 3rd with plenty of hill power. I use O/D for the flats at 68-70mph/1800-1900rpm. My truck is stock power 235/460.
 
Cobra,

I have a 4500 lb travel trailer and I lock out the overdrive anytime I have an uphill grade. Truck is bone stock. We have some serious hills here and there is no way the truck can pull the trailer up hill in OD. I generally run 55 - 65 mph up the major hills in 3rd. The Brenda Mines hill on the Coquihalla Connector is so long that I run in third from 2500 - 3000 rpm for about 15 to 20 minutes without letting off the throttle. Certain trucks were programmed from the factory to defuel in OD. Do a search and check the TSB's for a "low power in OD" complaint. I had mine reflashed to restore full power in OD, but still not enough power stock to pull 4500 lbs uphill in OD!



:(



Dave



Clarification: trailer is 4500 lbs, but I haul another 2000 lbs worth of stuff when I pull it for an approximate 6500 lbs.



Hope this helps
 
My trailer weighs 10,200#. Before I did the DTT mods I towed in OD on flat land and as soon as the truck started to shift out of OD I'd manually go out. Or I would try to anticipate and shut off OD myself. I tried to not go into OD manually until the rpm was up to 1800 rpm. For me that is about 57 mph. At this point the torque was adequate in OD. I also towed in cruise control and discovered that if I came to a hill whwere I wanted to control my down hill speed at, say 50 mph, I would top the hill in cruise control at 50 mph and out of OD. If the down grade did not exceed 6% the cruise control would keep the transmission locked up and I would gwet some engine braking down hill. If the hill was steeper than 6% the rig would accelerate, the cruise control would unload the transmission, and it would be brakes only the rest of the way down hill.

When I had my DTT mods made to the transmission I got an exhaust brake and a DTT Smart Box. Great combination. A few days ago I went down the Cresta Grade on 101 (7%) and the exhaust brake and Smart Box kept my speed at about 50 mph all the way down. My Smart Box will shift to OD when I'm going 57 mph. If I'm on a hill I usually will shift out of OD.
 
The engine should handle just fine if he leaves it in OD, but if the torque converter is stock, the clutch will eventually slip and wear out, sending debris throughout the transmission. It will probably evenually happen if the engine is stock. It will most certainly happen if it is BOMBed at all.



Blake
 
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