I have a '95 f150 supercab with the 300-inch I-6, and 5 speed manual tranny. I plan to tow a 2000 lb trailer. My mechanic says never tow in OD. I think this is just a blanket statement though. Consider that OD(5th) in the '95 turns 1900 RPM at 60 mph which compares to 3rd gear in my '84 which turns 1850 at 60 mph. Surely I wouldn't have towed with the 84 in 2nd gear? My 95 has a 3.08 rear (the '84 had a 2.47 and would turn 1300 at 60 in OD(4th)). With the granny first (3.90) and the OD running like third in the older truck, I am tempted to put a 2.47 rear in the '95 which would still give me a lower 1st, but also a higher OD (in which case I would not tow in OD). The lower rear would spread those five gears into a more useful range, especially with the 70 mph speed limits of the past few years. It just seems a waste to go through 5 gears in the '95 to get to where I was in 3rd with the '84.

 

I have a 90 fs bronco with od....i had a tranny problem that turned out to be electrical.....but anyway....i had an overdrive override button on my dash.....which yours probably does.....i never understood the use of it.....but after i had my problem taken care of, I asked the mechanic what the uses of the system were for..........he said leave the od on all the time except when you are towing.....he said the reason for this has to do with the way the od system works and shifts....it could do damage on the tranny from constantly kicking in and out under such a heavy load..which is prone to happen more when towing naturally. Don't apply to me really cause i never tow anything......but just a comment for your thoughts.

 

As with any manual trans, tow in the gear the engine/trans will handle. The automatic has a button that locks out the overdrive to prevent excessive shifts to increase the life in the trans, you don't have it to worry about. You'll know if you have to downshift.

Trail Rider

 

You shouldn't have any problems towing, 2000 pounds is pretty light. I have an 89 F150 with the same drivetrain (3.08 axle ratio), and I pull a 3500 pound boat fairly easily. I have also pulled 7000 pound trailers, and could do it, braking was the only problem. The only thing is that when going about 70 (like you said) with my boat, you can smell the clutch slipping in overdrive. With that light a trailer, just drive whatever feels right, and I would go down the 4th only on hills. Also, forget about going to a higher gear ratio. You would kick yourself for doing so. I would even go lower to 3.55's for better pulling power. You start to get out of the engines power band below 1800rpm's and the truck should still get 15-17mpg at 2200rpm's.

 

Rob's post above is right on the money. DO NOT REGEAR ANY HIGHER! I pull a 6000 \-lb. travel trailer all over North America with a 300-6/Mazda 5spd.OD transmission, originally equipped with a 3.55 LS, changed to a 4.10 only because I was concerned about starting from a dead stop up some of thse mountain grades. The same logic applied to the 11-in. Dual-Friction clutch upgrade.
This combination works well on the freeway, 2700 rpm at 65 mph in OD, dragging a trailer with the aerodynamics of a Porta-John. I use "Redline" type "MT" synthetic lube in the tranny; added lubricity and heat dissipation over ATF. Makes the tranny somewhat stiffer to shift, but then it doesn't whine as bad as it used to, either (I ran it out of oil and drove it that way for a month or so a couple of years back...don't ask).
Eddie

 

A lot of great responses. Thanks.

To Don: I actually have a manual tranny. I think you could use OD on your auto if you're sensitive to shifting and if the tranny begins to do a lot of shifting, then cut out the OD.

To Trail_Rider: Right on!

To Rob: If your clutch was slipping in OD, I am assuming it is on its way out and that a new clutch should not do that with a 2000 lb trailer. Anyway, it is something to think about if I am towing in OD. I suppose towing in 4th at 2600 RPM is not so bad and it gives me about 25% more torque at the rear wheel (yes I plotted the graphs for rear wheel torque in all 5 gears against road speed. Gets about 3000 ft lbs at rear wheel in first gear.) Speaking of smells, I towed the trailer 2000 miles through Michigan and Wisconsin last October with my wife's 3.0 V6 Aerostar and there was a hot oily/rubbery smell most of the time at freeway speeds and the tranny fluid which has a cooler and has 24000 miles on it needed to be changed when I got back. I wonder? Anyway that is one reason I got the torque monster 300-inch six.

To Ed Trethewey: You are right. The present gearing is a good compromise with a granny first, but a lower RPM at highway speed would be nice in OD. If the second gear were about 10 or 15 % lower, it would be like first in my '84 and I could use granny only for towing. That would be nice. I plan to put the regular/synthetic blend ATF in my tranny.

 

My 91 f-150 300 inline 6, 5-speed manual and 3.55 rear end has towed a 2500 lb boat and 5500 lb travel trailer off and on since I got it. I've always used O.D. at highway speeds. I like the 3.55 ratio because it keeps the rpm at about 2000 on the highway, where my truck seems to pull the best.
96,000 miles and still going strong!

 

fishinbum: Your 3.55 in OD would run about like my 3.08 in 4th. But mine turns about 2500 on the freeway (going nearly 70 MPH). I would assume you are traveling closer to 60-65 MPH. How doews your rig perform at 70 MPH. I would think you would need 4th at 70 on hills or with a strong headwind. I read that the gear involved in OD is very small and is the weakest link in the tranny. My mechanic advised I could tow in OD on level ground but not to accelerate in OD as the torque input could break that small gear.

 

You're right TallPaul, most of my towing is at 60-65 @ about 2000-2200 rpm while in O.D. The truck will perform great at 70-75 as well but runs at around 2300-2500 rpm which seems to be working it pretty hard. On hills and headwinds I do need to downshift to fourth when towing but only if the truck can't maintain it's speed in overdrive with the accellerator floored. I back off enough to keep it below 2500 rpm though until I can up-shift again. Most towing is in O.D. with my foot into it heavy though. After 9 years, the overdrive gear is still holding up and I have never experienced any clutch slipping either.
The truck came originally equipped with a 2.73 rear axle ratio but couldn't even run solo up a hill in overdrive and did most towing in forth and third gears, a real dog! I had it changed to 3.55 at a local driveline shop about 6 years ago and am very happy with it.

 

By the way: I also run with a K&N aircleaner and Flowmaster muffler which help a little.

 

fishinbum: Sounds like the tranny is pretty tough after all. I probably should go 60 - 65, but am to impatient! (Last Fri took a trip in my wifes Aerostar (no trailer) and we were doing 80 most of the way--as was much of the other traffic.) I probably will stay with my 3.08 in 4th. Changine the rear ratio is pretty expensive, so I hear (500 to 800 $$??). I do have a KN filter, but am not sure it helps much as it is mainly for high RPMs. I have heard the 300 six responds well to exhaust mods and plan on a 70 series (quieter) Flowmaster when the old trash can rots out. Also may do a performance computer chip.