CharlesinGA
Well-known member
You need to read the owners manual, period. Many Ford automatics from the '90's and early 2000's have a very weak OD and the OD should never be used when towing. Even if there is not prohibition against using the OD when towing, as noted above, you do not want the transmission "hunting" between gears and you would be best to lock out the OD. Some of this depends on the rear end gear ratio.
Your Owners Manual has little to say about transmission operation (P.209 and on) Beginning on p.186 you will find information on towing, including charts on weight capacities depending on how the vehicle is equipped.
Transmissions heat up when the power is being "run thru the gearing", and thus OD, which is a gear ratio that makes the drive shaft turn faster than the engine, means that the torque is all being put thru the gears, causing the fluid to heat up. In your 4 speed automatic, 3rd gear is a direct drive where gears are moving, but carrying no loads. Thus very little heat is being generated by the transmission.
In my Sprinter chassis motor home I noticed this. I would start out and lock the transmission out of 5th (OD) and it would run, at a slightly higher RPM, in 4th which was direct drive. I could drive 50 miles or more before the transmission temperature would pass 150F. If I let the transmission shift to 5th right off and not restrict it, the temperature would rise to about 175F rather quickly. There was no measurable fuel economy penalty running in 4th so unless the terrain was table top flat, I would frequently restrict the transmission to 4th and below.
My current tow vehicle is a Dodge RAM 2500 with a Cummins diesel and a 6 speed manual. As I have no exhaust brake, and diesels generate a minimal amount of engine braking otherwise, I have to be very aware of long down grades, and slow v e r y slow and gear down to 3rd or 2ed to maintain a safe down hill speed.
Charles
Your Owners Manual has little to say about transmission operation (P.209 and on) Beginning on p.186 you will find information on towing, including charts on weight capacities depending on how the vehicle is equipped.
Transmissions heat up when the power is being "run thru the gearing", and thus OD, which is a gear ratio that makes the drive shaft turn faster than the engine, means that the torque is all being put thru the gears, causing the fluid to heat up. In your 4 speed automatic, 3rd gear is a direct drive where gears are moving, but carrying no loads. Thus very little heat is being generated by the transmission.
In my Sprinter chassis motor home I noticed this. I would start out and lock the transmission out of 5th (OD) and it would run, at a slightly higher RPM, in 4th which was direct drive. I could drive 50 miles or more before the transmission temperature would pass 150F. If I let the transmission shift to 5th right off and not restrict it, the temperature would rise to about 175F rather quickly. There was no measurable fuel economy penalty running in 4th so unless the terrain was table top flat, I would frequently restrict the transmission to 4th and below.
My current tow vehicle is a Dodge RAM 2500 with a Cummins diesel and a 6 speed manual. As I have no exhaust brake, and diesels generate a minimal amount of engine braking otherwise, I have to be very aware of long down grades, and slow v e r y slow and gear down to 3rd or 2ed to maintain a safe down hill speed.
Charles
