View Full Version : Hauling the TM with my Minivan first time

Debian Dog
02-23-2006, 08:21 AM
I was getting questions via PM's about how my Trail Manor (http://trailmanor.com/) tows with my Minivan so I figured I would post up the first time I hauled it around.

It was not a "super long" trip but it was 2 hours of solid driving on different roads (mostly highway). The only thing I have ever hauled around before (of significant weight) is my 17' Searay (boat) and I had that some years ago.

My Minivan (2006 Quest) gets about 24 miles to the gallon normal highway driving and we pulled the TrailManor from Chesapeake, VA (almost North Carolina) to Chester, VA. (115 miles) No problems! and... when I was not paying attention I did exceed 70 MPH. People told me I would forget it was back there... and I did. I hesitated to use the cruise control because people said "it was bad" but I have no idea why it would be. But I would like to use it to keep my spped down. My foot does not seem to be calibrated right.

We did need to add an Equalizer hitch (http://www.equalizerhitch.com/) to get the minivan to sit right but I do feel better about BIG trucks passing me. As a matter of fact, the first time it happened I did not think about it... till after... at first I thought, "Dang! He is flying in that rig".

The trip was uneventful and we managed a respectable 16.7 MPG with overdrive disengaged. I am still not sure if I am on a relative flat highway if it is "safe" for the transmission to let it go into overdrive. Thoughts?

Anyway when the company says "Trailmanor tows like a dream" they mean it. ;)

02-23-2006, 08:37 AM
I asked the fellow who services our Toyota T100 if it was necessary to stay locked out of overdrive when towing our TM 26 (3023). He said that it was OK to use overdrive as long as our truck wasn't shuttling in and out of overdrive. I think that level ground and possibly slight inclines will be OK. I'll just need to pay attention to the transmission.
We haven't taken any trips since I got this advice.

I don't know if this applies to your Mini Van. I'd check with whoever services your TV.

02-23-2006, 11:20 AM
Ford says the same thing. As long as the transmission is not constantly shifting in and out of overdrive it's OK to use it. I don't see or have any problem using the cruise control and can't think of a reason why it would be a problem.

02-23-2006, 12:29 PM
Check your owner manuals on operation in overdrive. Also do a search on this forum as it has been discussed in detail. For most vehicles, the OD gear is not as robust and evenutally the tranny gives up.

Debian Dog
02-23-2006, 12:40 PM
Check your owner manuals on operation in overdrive. Also do a search on this forum as it has been discussed in detail. For most vehicles, the OD gear is not as robust and evenutally the tranny gives up.Yep the owners manual says 'NO' too... Ah well, I should learn to enjoy my 16+ MPG huh? As someone else told me, "Better than an empty SUV"

02-23-2006, 04:28 PM
I can't speak with any authority, but I did talk to a transmission guy about it. He told me that the main cause of transmission failure is heat (i.e., overheated transmission fluid), and the main cause of heat is a torque converter that is unlocked.

The torque converter (which used to be known as "fluid drive") is the clutch between the engine and the transmission. It is what allows you to sit at a stoplight with the motor rotating and the wheels not rotating. It is a slip mechanism, in other words, and slip causes heat. And heat is wasted energy.

In the bad old days (50's through 80's, more or less), the torque converter always slipped to some extent. However, when gas mileage got be really important, the torque converter was redesigned so that it will slip when you are stopped, but will lock up (no slip) once you are moving. All automatic transmissions operate this way now.

In today's transmissions, the torque converter momentarily unlocks as the transmission shifts from one gear to another. Then it relocks. So if your transmission stays in one gear (such as overdrive) and hardly ever shifts, the torque converter remains locked, and no excess heat is produced. And that's a good thing.

However, if the transmission is constantly shifting back and forth between two gears (such as overdrive and the gear below it), then the torque converter is constantly unlocking and relocking, and each time it unlocks, more heat is generated. This is NOT a good thing. So Blake's Toyota dealer, and Bill's Ford manual, are telling you the right thing. Overdrive is OK as long as it stays in overdrive. But if it starts shifting back and forth and back and forth between overdrive and the gear below, this is bad. In that case, you should turn OD off, and it stays in the gear below.

The tricky part is that if you want to leave overdrive on, you MUST remain aware of the gear changes, so you can tell when the transmission starts to "hunt" - the technical term. If hunting starts, that is the time to defeat the overdrive. But if it shifts only once every 5 or 10 minutes, it is OK to leave the OD on. A tachometer helps in this awareness. Without one, I find that it is too easy to miss the fact that it is hunting.

By the way, the word "overdrive" sounds like some kind of magic word. It is not. Overdrive is just another gear, the top gear. My Ford Explorer has a five-speed transmission, and the 5th gear is called Overdrive. New (2006) Ford Explorers have a 6-speed transmission, and 6th gear is called Overdrive. Many vehicles have a four-speed transmission, and 4th gear is called overdrive. For the purists among us, yes, the term "overdrive" has a specific meaning re gear ratio, but from a layman's perspective, it is just another gear.

Hope this helps


02-23-2006, 04:54 PM
Not only purists, but some of us old people remember when only manual shift cars had overdrive and there were many combinations of how to shift into overdrive from a manual lever to an electric switch. Sometimes an electric switch was placed under the accelerator to switch out of overdrive back to a lower gear, thus a "passing gear." I also remember a Columbia overdrive differential on some older Fords that was shifted with a vacuum setup. Just rambling.

02-23-2006, 05:25 PM
"Overdrive" as has been stated, is basically another gear, but it is unlike the others in that it is "overdriving" the output shaft. This means that the input shaft on the transmission is actually turning slower than the output shaft. This also means that you have more "speed" and less "power" to the wheels. "Power" (torque) and speed are related in an inverse equation, so as you overdrive or shift to a higher gear, your engine has to work harder so the transmission wants to downshift. This is where the problem arises in that it down shifts and then if the hill isn't steep enough it shifts back up - back and forth. This is called "hunting" - the transmission is trying to find (hunt for) a gear that matches the load put on it. If you have a tach, you can see the engine RPM increasing and decreasing as the transmission shifts back and forth. This can happen in other gears, too, not only Overdrive. If your transmission starts hunting, shift to a lower gear- OD to 4th, 4th to 3rd, etc. Some transmissions, particularly those on vehicles with a towing package, come with a "Tow" button which takes a lot of the problems out of towing in overdrive. The tow button changes the shift points on the transmission and doesn't allow it to leave the torque converter out of lockup for extended periods. This makes the transmission run cooler. Cruise control is OK to use as long as you monitor the transmission for hunting or for downshifting more than one gear at a time. If you hit too big of a hill the cruise may downshift too many gears, making the engine red-line. That's not good!

02-23-2006, 07:39 PM
I always understood overdrive to mean one of two things:

1. A gear ration higher than 1:1. This has already been mentined.
2. On an old Jeep, it is pretty common to find a Warn All Range Overdirve. This contraption doubles the number of gears, bot forward and revers, by adding a gear inbetween all of the other gears.

Having said this, I believe that the main topic here is with regard to overdirve with an automatic transmission, not a manual transmission as the old Jeeps had.