John H

I have a 93 D250 CTD with three speed auto transmission. This last week-end, I drove the West Virginia Turnpike with 7000# camper in tow. I found that if I wound the truck up to 70mph in OD, I could pull just about all the hills with wide open throttle, and it didn't drop out of overdrive. If the speed fell to about 60mph, I manually took it out of overdrive for the rest of the hill. That didn't happen on that many hills. I did this thinking the prohibition on towing in overdrive was due to not wanting to have the transmission constantly shifting in and out of gear, but this morning someone told me that the high torque from the Cummin's engine is what would trash the transmission.<br><br>Is this true? Should I be changing out of overdrive in the hills, and if so how steep, and is there some criteria that you guys use, to tell you when to change, and that I can follow?<br><br>John

KC

John you said 3 speed auto correct? In a 3 speed there is Not an overdrive as far as I know.<br><br>KC

John H

The transmission has selections for 1 2 and D. Then it has an overdrive lock-out button on the dash. I took that to mean the transmission was a three speed with overdrive. I know that in drive, with OD locked out, I'm limited to about 65-70mph by what feels to be engine rpms. If I leave OD in, I've had the truck up to 90mph (not towing you understand) and still pulling strong. My nerve quit at that point.<br><br>John

bullfrogjim

John,<br>Your trans. is a 4 speed unit with the lockouts for 1st and 2nd on the column and the o/d lockout keeps it in third and out of your 4th gear overdrive. I guage when to shift out of overdrive by my rpms i shift out of overdrive once they get below about 2000. Of course my truck is different but I think that 2000 rpm's is a good rule of thumb to save the tranny.

dan239

John

As a previous owner of a 92 with automatic transmission, I can tell you that it does have an overdrive.

I have towed both in overdrive and with it locked out and my conclusion was to lock it out all the time when towing my 5th wheel which weighed over 10,000#.

However if your trailer weighes only 7,000#, you can tow in O/D as long as the temperature guage does not start to go up or it starts hunting between O/D and 3rd. This is just my opinion from previous experience.

Since you are towing as fast as you do, you should not have a problem. The only thing I would change in the way you are driving is I would take it out of O/D as soon as the truck starts losing speed.

These 1st Gen auto O/D units are known to be weak. Just don't put it in a strain and you should be okay.

The 2nd Gen auto O/Ds are much improved.

Dan

spitzair

Whenever I tow my Bobcat 873 (about 8000Lb) behind my 92 W250 I leave the O/D out. Around here I'm usually limmited to about 60 MPH to begin with, and at that speed the O/D kicks in and out even without a loaded trailer. I also keep the O/D out to get better engine braking. Just my 2 cents...

pwabbott

My 90 had a 3 speed auto with overdrive. There was an overdrive lockout switch on the dash. I lost the first overdrive unit with 1500# load in bed driving I-5 at 75. Underwarranty the tranny was rebuilt and a new (improved) overdrive unit installed. Towed with it till over 150,000 miles without a problem. Used Class IV equalizer hitch. Towed 16 ft tandem axle utility trailer loaded to 8000# in mountains. Always locked it out of overdrive for towing.

SeaRay88

I have a 4.6L gas engine, auto, 4.10. I always tow in OD. Unless you think you're a lot smarter than the computer, let it choose the gear. Up and Down hills-2nd or 3rd. On the flatlands of CA, let the tranny choose the gear. Just my 2 cents. 8) <br><br>PS. My engine and tranny loves to run at 4000 rpm and has over 104K miles on it, so I must be doing something right. Huh???

John H

[quote author=bullfrogjim link=board=11;threadid=6898;start=0#65233 date=1037053833]<br>John,<br>Your trans. is a 4 speed unit with the lockouts for 1st and 2nd on the column and the o/d lockout keeps it in third and out of your 4th gear overdrive. I guage when to shift out of overdrive by my rpms i shift out of overdrive once they get below about 2000. Of course my truck is different but I think that 2000 rpm's is a good rule of thumb to save the tranny.<br>[/quote]<br><br>I wish I could do the same, but my '93 doesn't have such luxuries as tach, or transmission temp gage, or boost gage, or EGT gage etc. etc. I know I should probably add them, and one day I will, but right now I don't have them. Coming off a gas engine, I have no feel for engine rpms, even cruising at 70mph, it felt like it was still at idle. This truck doesn't accelerate, it just gains inertia.<br><br>John

SeaRay88

Well, yeah. So does my 4.6L. It won't snap your neck pulling a 8000 pound trailer. It goes from 0-70, but if you're looking at a stopwatch, it'll run down. I really don't care what the 0-60 speed is, as long as it's not losing speed when I get to the hills. My gasser gets 11+mpg on the highway towing and 22+ solo, so I'm happy with it. Can't see spending 4000 on a diesel. Sorry.

John H

[quote author=dan239 link=board=11;threadid=6898;start=0#65243 date=1037055040]<br>John<br><br>As a previous owner of a 92 with automatic transmission, I can tell you that it does have an overdrive. <br><br>I have towed both in overdrive and with it locked out and my conclusion was to lock it out all the time when towing my 5th wheel which weighed over 10,000#. <br><br>However if your trailer weighes only 7,000#, you can tow in O/D as long as the temperature guage does not start to go up or it starts hunting between O/D and 3rd. This is just my opinion from previous experience.<br><br>Since you are towing as fast as you do, you should not have a problem. The only thing I would change in the way you are driving is I would take it out of O/D as soon as the truck starts losing speed.<br><br>These 1st Gen auto O/D units are known to be weak. Just don't put it in a strain and you should be okay.<br><br>The 2nd Gen auto O/Ds are much improved.<br><br>Dan<br>[/quote]<br>That was what I'd heard, that the 1st Gens were weak in the transmission area, but I thought it was because of the changing in and out of OD, not the high torque.<br>Incidently, at 65-70mph in OD, even at wide open throttle, I got better gas mileage than running at 60-65mph at part throttle.<br>How did you get away with pulling a 10,000# trailer with the '92? My '93 is only rated at 12,000 GCVW with the 3.54 rear end. It still only jumps to 13,000 (I think) with the 4.11 axle. That limits me to about 7-8,000# max.<br><br>John

SeaRay88

Chit. My Ford 4.6L pulls that load with no problemo. Guess them deesels ain't so hot. Running 4.10 gears, auto. Gets 10 mpg in the hills, 11+ On the flats. 22+ on the highway solo. Just like a deesel, but I can gas her up at ANY station. Got over 105K miles on it and it still runs like new. Just like a deelsel.

Commatoze

[quote author=SeaRay88 link=board=11;threadid=6898;start=0#66104 date=1037159869]<br>Chit. My Ford 4.6L pulls that load with no problemo. Guess them deesels ain't so hot. Running 4.10 gears, auto. Gets 10 mpg in the hills, 11+ On the flats. 22+ on the highway solo. Just like a deesel, but I can gas her up at ANY station. Got over 105K miles on it and it still runs like new. Just like a deelsel.<br>[/quote]<br><br>Mmm.... : By your screen name, I say you like boating. Like to fish? Ever do any trolling?

pwabbott

SeaRay88, the computer isn't intelligent in and of itself. By allowing the computer to make all your shifting decisions regardless of road, grade, and traffic conditions you are accepting the ideas of some engineer who programmed the computer without any knowledge of your current experience. The program is based on on the engineer's averaged idea of what you are likely to be experiencing not what is happening in reality. <br><br>We have a Grand Cherokee with tow package and computer controlled auto tranny. We were towing a 2500# trailer along going up an 8% grade. Because of curves we were travelling between 35-40 mph. Suddenly the computer shifted the tranny into low gear and red-lined the engine. The sudden downshift threw us forward against our seat belts. Just as quick I responded by removing my foot off the go pedal. <br><br>I had the computer checked for fault codes. There were none and tranny tech said under certain conditions this behavior was programmed into the computer.<br><br>According to your way of thinking if the computer has a bug in it's program, let it do it's thing, even if it blows the engine, it knows best.<br><br>The saying here applies, &quot;Garbage in, Garbage out&quot;.

dan239

[quote author=John H link=board=11;threadid=6898;start=0#66102 date=1037159654]<br>That was what I'd heard, that the 1st Gens were weak in the transmission area, but I thought it was because of the changing in and out of OD, not the high torque.<br>Incidently, at 65-70mph in OD, even at wide open throttle, I got better gas mileage than running at 60-65mph at part throttle.<br>How did you get away with pulling a 10,000# trailer with the '92? My '93 is only rated at 12,000 GCVW with the 3.54 rear end. It still only jumps to 13,000 (I think) with the 4.11 axle. That limits me to about 7-8,000# max.<br><br>John<br>[/quote]<br>It is not so much the shifting as it is the torque that destroys the O/D.<br><br>The 1st gen transmissions are not weak except in the overdrive area. My son once had a 90 model that was a 3 speed automatic [no O/D] and it was as tough as they come. This was basically the old 727 transmission which was used in motorhomes in the 70s and 80s, and some of them weighed up in the 20 thousand range. The 727s in motorhomes were almost trouble free.<br><br>As to pulling with a 1st Gen truck, they were very underrated as to GCWR. I always felt that my towing limit was 14,000# max and very comfortable under 13,000#. I probably towed 11,000# or maybe 12,000# with mine and no problem. I do drive easy and do not get in a hurry taking off. Driving habits have a great deal to do with how much the truck can handle. Also, I never towed that much in O/D as I could tell the truck was straining and it would run hotter.<br><br>With my 98, I still feel that my towing limit is 14,000#. The only difference is I can tow in O/D if the road is fairly flat and I am not pulling over 10 or 11 thousand pounds.<br><br>Hope this all helps<br><br>Dan