Towing without overdrive

[Carol H]

Originally Posted by cpaharley2008

Economics, easier to include a $35 part than to add later. As far as the advice given here by others re: coolers on standard shift,, we all know if it is on the internet it must be true

yup must be.

thanks Frank I do full understand the situation with automatics as I pull with one .... it was just the blank Must add cooler statement we all to often see here that made me ask.

[frank_a]

Yup Carol, just about every tow vehicle you see is AT these days. Things have changed a lot since my 1st truck! My next TV will be AT and with much higher tow capability. When I got my Canyon in 2009, we were still camping in tents. A lot.

Gee, how quickly things change as ya get older...

Frank

[LeonardS]

deleted post

[LeonardS]

deleted post.

[Glenn Baglo]

Suggest you read the manual for your vehicle to determine if you should tow in overdrive or not. Doesn't much matter what other people do.

[web3221]

because it the right and logical thing to do for that type of application, auto trans greatest enemy is heat (Quick death), and at's do not cost 350 dollars to have one rebuilt anymore, guessing more like 3 to 5 thousand dollars. if towing, an auto trans cooler and a heavy duty radiator is like adding the lowest cost insurance you can buy to protect your tranny and engine. this why the auto/truck industry recommends these items.

this is why the fleet/leasing industry recommends both items as well, I used to do car/truck specification building and design according to our clients corporate fleet needs. if we under specified the items they needed, and there were broke down cars/trucks all over the country, we would not be in business today, and our clients down time would destroy corporate profits...etc

you may be able to get more info from NAFA - national association of fleet admimistrators.

manufacturers know more of what we need, for our safe journeys out there on the road, than the majority of the customers do. do some over spec, yes. do many under spec - no,not many - to much liability exposure,
or loss of business and reputation

look I have not been this industry since the early 80's... the industry has come a long way since then, and has been by improving designs and safety concerns. no spell check

Originally Posted by Carol H

Thats true currently but again we still have people here telling people over and over to get a trans cooler and many of the manufactures include them in their towing packages -even on manual shifts.

So my question again is why is that?

[cpaharley2008]

Originally Posted by Glenn Baglo

Suggest you read the manual for your vehicle to determine if you should tow in overdrive or not. Doesn't much matter what other people do.

Glenn,
If everyone followed that doctrine, then half of our posts would not appear.

[Brian B-P]

Originally Posted by cpaharley2008

I drove with the trans mission in normal drive on the way out and checked my mileage at every fillip. I was getting between 10.5-11.5 mpg consistently with the engine cruising around 2400rpm under load and 1800rpm cruising. I used mid range and E-90 gas mid range. There were strong headwinds going out and returning.
My return trip I engaged my "Tow Mode" which locks out the overdrive and changes the shift points. Surprising I averaged 11.5-13.5 mpg on the return trip. Other than Missouri in lieu of Iowa, I went thru the same states. I noticed the rpm stayed at 2200 under load and would occasionally drop back to 1800 while cruising.I also noticed it did not shift into the higher rpm range as often as the trip going.

If the engine speed was the same (1800 rpm) at the same speed, in or out of tow mode, then one of the following must be true:

1. the transmission was not getting into the overdrive gear in in normal drive mode, or
2. tow mode doesn't lock out overdrive,

since it was apparently in the same gear in either case.

Originally Posted by cpaharley2008

This 200 rpm difference gave me a 20% increase in my mileage, which in my case was about $100 savings.

The 200 rpm difference (between 2400 and 2200) at the same road speed will be in the same gear, without and without the torque converter lockup clutch activated. It is normal for tow modes to more aggressively engage this clutch, epwhich prevents torque converter slip and thus reduces heat generation and fuel consumption. It is normal for an unlocked converter to slip 10% like this, which really is 10% of the fuel burned being wasted. This has nothing to do with overdrive.

[Carol H]

Quote:
Originally Posted by Glenn Baglo
Suggest you read the manual for your vehicle to determine if you should tow in overdrive or not. Doesn't much matter what other people do.

Originally Posted by cpaharley2008

Glenn,
If everyone followed that doctrine, then half of our posts would not appear.

imagine how far the posts would further drop if people actually read the question asked!

[Hambone]

On my 2007 silverado tow/haul will go into OD, it just shifts a lot later for more pulling power getting up to speed. Pulling my Scamp dont use it. Chevy recommends according to manual you can tow in drive, use tow/haul when your pulling 75% or over the tow rating. Researching it a bit tow/haul increases line pressure, for crisper shifts,less heat. Havent done a real good mileage test on mine, but to me tow/haul on my truck seems to burn more fuel (could be me,my gearing or ?) Ill have to try it next trip (at 4.09 gallon worth a shot)

[gmw photos]

Originally Posted by Carol H

Thats true currently but again we still have people here telling people over and over to get a trans cooler and many of the manufactures include them in their towing packages -even on manual shifts.

So my question again is why is that?

Carol,
I think you might be getting confused or getting some incorrect or conflicting info. I can't think off the top of my head any factory OE cooler on a manual transmission. There would need to be a pump to move the gear oil from the transmission thru lines to a cooler. Such a pump is not part of a manual transmission. To be honest, it is not needed for a manual transmission except in rare cases like for instance in a Nascar racer.
Most manual transmissions probably only run in the neighborhood of 170 to 190 degrees, even when under the load of towing. That is not high enough to worry over, especially if the oil is synthetic, which some manufacturers suggest or require.
Auto transmissions by their very function have a pump in them, so it's an easy enough design situation to include lines and a cooler to attempt to keep operating temps correct. Typically, they also use the transmission "cooler" to warm up the oil from cold starts and during cold weather also. Auto transmissions like to have their oil run within a fairly narrow temp range for best shifting and most efficient operation. Efficient operation is important when trying to optimize fuel economy.

Some of the manufacturers ( Ford and GM come to mind ) state lower tow ratings with some of their manual trans vehicles ( Ranger and Colorado/Canyon ) most likely because they use a rather small clutch, so it become the "weak link in the chain", especially with less skilled drivers.

[Carol H]

Originally Posted by gmw photos

Carol,
Some of the manufacturers ( Ford and GM come to mind ) state lower tow ratings with some of their manual trans vehicles ( Ranger and Colorado/Canyon ) most likely because they use a rather small clutch, so it become the "weak link in the chain", especially with less skilled drivers.

Thanks George! the clutch being smaller makes sense as to my original question in regards to why a manual vehicle might have a lower tow cap than the same car with an automatic transmission.

As I mentioned I do understand why an automatic requires a transmission cooler. It was just that I have noticed that many times here when someone asks about towing with such and such a vehicle we have a number of people who will suggest the poster needs to get a transmission cooler added - with no distinction made regarding automatic vs a manual transmission even though the vehicle comes either way. Same with a number of "how to tow" type websites some of which encourage the use of a transmission cooler - again no distinction made between manual and auto. Its been a bit of a head scratcher, that had me questioning if I was missing something and perhaps using a transmission cooler might also make a difference on a manual in some way.

[frank_a]

This has been a fascinating thread, so thanks!

Clutch size huh? My clutch is 9-1/8", which is small compared to full size trucks I've had. My last V8 truck had a 11-7/8 clutch!

The point is, I don't use my clutch hardly at all when I'm towing. It's the 4 cylinder motor that drives me nuts! I want a 6 or an 8, or a 4 cylinder with a lot more oomph!

Frank

[Hambone]

I think manufacturers downgrade manual transmission tow ratings because the heat generated on the clutch has nowhere to go when being used, automatics pump the heat away just by their nature

[Thomas G.]

Originally Posted by Hambone

I think manufacturers downgrade manual transmission tow ratings because the heat generated on the clutch has nowhere to go when being used, automatics pump the heat away just by their nature

Do most semitrailer rigs use an automatic or a manual transmission?

[gmw photos]

Originally Posted by Thomas G.

Do most semitrailer rigs use an automatic or a manual transmission?

Indeed, virtually all heavy trucks are manual transmissions.

And for what it's worth, not all manufacturers of consumer level vehicles down rate the tow cap for their same vehicle with manual trans. Nissan Frontier has the same tow rating manual or automatic. I believe the Toyota Tacoma was the same a few years ago.

[Thomas G.]

Originally Posted by gmw photos

Indeed, virtually all heavy trucks are manual transmissions.

And for what it's worth, not all manufacturers of consumer level vehicles down rate the tow cap for their same vehicle with manual trans. Nissan Frontier has the same tow rating manual or automatic. I believe the Toyota Tacoma was the same a few years ago.

Exactly. The tow ratings can be a bit capricious.

[gmw photos]

Originally Posted by Thomas G.

Exactly. The tow ratings can be a bit capricious.

For sure. As a for instance, Ford Motor Company would no doubt prefer that you buy a F series truck instead of a Ranger, so it could very well be they rate the Ranger at an abnormally low tow cap, for that very reason ? Pure conjecture on my part..... I am not a fly on the wall in the marketing dept meetiings.....

[Thomas G.]

Originally Posted by gmw photos

For sure. As a for instance, Ford Motor Company would no doubt prefer that you buy a F series truck instead of a Ranger, so it could very well be they rate the Ranger at an abnormally low tow cap, for that very reason ? Pure conjecture on my part..... I am not a fly on the wall in the marketing dept meetiings.....

Lots of fingers in the pie. Performance reviews are in part based on warranty claims. If you own clutch warranty would you set towing at 2000# or 5000#?

[gmw photos]

Originally Posted by Thomas G.

Lots of fingers in the pie. Performance reviews are in part based on warranty claims. If you own clutch warranty would you set towing at 2000# or 5000#?

Very true. I would suspect that the OEM's would prefer manual gearboxes simply go away. An automatic takes most of the driver skill part of the equation out of play.
I just happen to be one of the hard heads that still likes a hand shaker. Not sure what I am going to do when the time comes to replace this Frontier. Ha, may just have to keep doing whatever it takes to keep it on the road.

Having said all that, automatics do in fact work well. We have an automatic ( 5R110 ) in the F350, and it does work well. I'm not sure though how it's fuel economy would compare when towing, in normal mode vs tow-haul. When towing with it, I am ALWAYS in tow-haul. But then, when we're pulling with it, it's always "heavy".