Tow in OVERDRIVE or NOT ?

[6MISFITZ]

I am not new to towing but this is my first boat and trailer and I have seen many posts in this forum about not using O.D.. <br /><br />Not to stir the pot too much, but I tow my 21 foot boat/single axle trailer with my 97 Astro Van. <br />Trailer, boat and full fuel weigh in around 3600 - 3900 lbs. plus the van has a family of six inside as well.<br />The owners manual does say to tow in overdrive. If I am on a secondary highway below 55 mph then I do lock in third. If I am going up a good grade, then I shift the transmission in 3 to keep it from hunting gears but, 3rd is just screaming to be used all the time on the highway.<br /> <br />I have not towed with the 5 speed Alison tranny in the new duallies but have towed a race rig - a few years ago (460 Ford 1 ton 3spd auto & 454 Gmc Dually 4spd auto) and also used top gear on the highway (except in the hills) with no problems and no overheating.<br />I have seen many posts saying to tow only in 3.<br />Other than the Ford having more torque than the Gmc, I am curious to see what other opinons are on this topic to see if you agree with the way I tow or not?

 

[Finger Lakes Boater]

Re: Tow in OVERDRIVE or NOT ?

Its a matter of torque. Your Astro van is maxed out with your rig, and the tranny will be hunting for gears all over the place. Keep it in three. A big block Ford, allison tranny, towing the same load wouldn't downshift until you found a 4% grade or better. OD is fine in that case. Put 8,000 pounds behind the Ford, and lockout OD unless you're in Iowa on the interstate.

 

[RJS]

Re: Tow in OVERDRIVE or NOT ?

as a general rule of thumb, it's better to avoid towing in overdrive. Most car/truck manuals will recommend not towing in high gear.

 

[DJ]

Re: Tow in OVERDRIVE or NOT ?

Mike,<br /><br />First rule-FOLLoW THE MANUAL!!<br /><br />Second rule-You can tow in OD if it does not take extra pressure on the throttle to maintain a cruise speed. In other words, if you are putting the same amount of pressure to tow in 3 as you would in four, four is probably OK.

 

[Finger Lakes Boater]

Re: Tow in OVERDRIVE or NOT ?

Its a matter of torque. Your Astro van is maxed out with your rig, and the tranny will be hunting for gears all over the place. Keep it in three. A big block Ford, allison tranny, towing the same load wouldn't downshift until you found a 4% grade or better. OD is fine in that case. Put 8,000 pounds behind the Ford, and lockout OD unless you're in Iowa on the interstate.

 

[6MISFITZ]

Re: Tow in OVERDRIVE or NOT ?

FLB, Fully loaded boat with equipment and Family of of 6 (4 kids under ages 3-9) comes in way under the G.C.W.R. The Astro is rated to tow over 5500 pounds with the trailer package. <br />I find on slight grades that the transmission will stay in O.D.. On Medium grades the transmission will shift to 3 but it will hunt fo O.D.. To stop that, I shift to 3rd at the bottom of medium or bigger hills, to stop any hunting before it happens. I find if I leave it in 3 the entire time, the temperature gauge will start to climb along with the engine turning much higher rpm's. <br />I have one escarpment between me and Lake Ontario when ever I trailer away from Lake Erie or Niagara River and that is the only place I need to shift to 3rd. I do shift to 3rd going down the hill to keep from riding the brakes and then on the way back home to get UP the hill. Either than that the van and the temp. gauge is happy in O.D..<br />Does shifting down for going down hill hard on a trany? <br />How long can I use 3 for down hill?

 

[dustydiesel]

Re: Tow in OVERDRIVE or NOT ?

I have a 86 astro van and have the same symptoms when towing my 20'house trailer.On flat land it's ok in od, 3rd is to low if you are trying to stick with the traffic on the four lanes. I think you are on the right track by keeping a close eye on your heat gauge, with mine you can tell that you are pulling even a slight uphill grade by the gauge with out even looking out the window

 

[skier]

Re: Tow in OVERDRIVE or NOT ?

Here is a perfect test to take to see if you have the CID or Gears to tow in O/D. On a flat and straight piece of road get up to say 55 or 60 and hold that speed. Then down shift into the next lower gear without moving your foot on the gas. If the car/truck/van speeds up then do not tow in O/D.<br /><br />I hope that this helps.<br /><br />Craig