What, if any, difference is their between tow load and carrying load on tranny?

[Mark42]

I read this statement in another thread that made me think about the wear and tear on trans and drivetrain.

a Highlander and the like can tow, but starting power and stopping power are not what most folks want when towing AND it wears on the tranny like crazy.

For discussions sake lets talk about light SUV's and Minivans and not pickups, and the other larger vehicles.

If my minivan has a tow rating of 3500lbs and I'm towing a 1800lbs boat and 500lbs people and cargo, is that any more of a stress on the drivetrain than just carrying 2300lbs of people and cargo? Its the same weight, and there is some additional wind drag of the trailer and rolling resistance of the tires, but other than that extra drag, would there be any more advanced wear on the vehicle caused by towing vs carrying?

Anyone use synthetic trans fluid to help reduce trans wear?

 

[Silvertip]

Re: What, if any, difference is their between tow load and carrying load on tranny?

There are a couple of things to consider in your example. Carrying a load (2300# in your example) would likely exceed the "load capacity" of the vehicle. While it places stress on the drive train increases as you add load, it also stress all of the suspension since it is not designed to "carry" that much weight. Second -- towing a trailer adds some rolling and wind resistance so there are "drag forces" that add stress to the drive train of the vehicle that you would not have if the load were inside the vehicle. As for the statement about the starting and stopping power NOT being what people want, is totally incorrect. Getting the load moving, being able to stop it, and having good trailer handling at highway speeds are all very important in selecting a tow vehicle. Many on this forum would have you believe you need a Peterbuilt to tow a row boat but fact is, sizing and equiping a tow vehicle to the trailer can provide a very safe and economical towing combination.

 

[blouderback]

Re: What, if any, difference is their between tow load and carrying load on tranny?

Are you considering ditching the trailer and hauling the boat on the roof or something?

 

[dingbat]

Re: What, if any, difference is their between tow load and carrying load on tranny?

I read this statement in another thread that made me think about the wear and tear on trans and drivetrain.


For discussions sake lets talk about light SUV's and Minivans and not pickups, and the other larger vehicles.

If my minivan has a tow rating of 3500lbs and I'm towing a 1800lbs boat and 500lbs people and cargo, is that any more of a stress on the drivetrain than just carrying 2300lbs of people and cargo? Its the same weight, and there is some additional wind drag of the trailer and rolling resistance of the tires, but other than that extra drag, would there be any more advanced wear on the vehicle caused by towing vs carrying?

Anyone use synthetic trans fluid to help reduce trans wear?

It would depend on if you have brakes on the trailer. If the trailer had brakes then the brakes would reduce the braking demand on the truck by roughly 10-20%, (co-efficient of friction) less the inefficiency of the brake mechanism.

Drive train wise there would be little difference other than those you already mentioned.

Heat is your enemy and while synthetics can withstand the higher temps, that's not your problem. You need to get the heat off the components and the only way to effectively do that is with some sort of addtional external cooling.

 

[RubberFrog]

Re: What, if any, difference is their between tow load and carrying load on tranny?

As far as the tranny is concerned, there is no difference between "carrying" and "trailering" weight. Lots of guys use synthetic in their tranny for the same reason they use it in their engine- it makes things last longer.

 

[Lakester]

Re: What, if any, difference is their between tow load and carrying load on tranny?

hello,

as a clarification... there is no such thing as synthetic oil. all oil is petroleum/fossil based. now i would like to tell u that i have a Phd in chemistry and am a Shell Oil director in R&D development...

but, alas, i am not!

but my neighbor is.

we got to talking about oils the othe day, and he made that statement. i believe him!!

what the difference is: is the number of carbon atoms attached to the molecular string. synthetic called oils have more carbon atoms attached.

so, technically, all oils used in auto trans, for example, would be synthetic while your typical 30 wt Pennzoil would be what is called... fossil based.

hope this helps some.

regards,

lakester

oh, my gosh... another promotion!! it is... christmas!! [blush]

 

[Mark42]

Re: What, if any, difference is their between tow load and carrying load on tranny?

There are a couple of things to consider in your example. Carrying a load (2300# in your example) would likely exceed the "load capacity" of the vehicle. While it places stress on the drive train increases as you add load, it also stress all of the suspension since it is not designed to "carry" that much weight. Second -- towing a trailer adds some rolling and wind resistance so there are "drag forces" that add stress to the drive train of the vehicle that you would not have if the load were inside the vehicle. As for the statement about the starting and stopping power NOT being what people want, is totally incorrect. Getting the load moving, being able to stop it, and having good trailer handling at highway speeds are all very important in selecting a tow vehicle. Many on this forum would have you believe you need a Peterbuilt to tow a row boat but fact is, sizing and equiping a tow vehicle to the trailer can provide a very safe and economical towing combination.

Just to clarify --- all the number I used in my example are well within the specs of my Toyota Sienna minivan. Towing capacity = 3500lbs, load capacity = 2600lbs or more. I think the Sienna weighs about 4200lbs dry. (Almost identical to my 97 Mountianeer and 98 Lincoln, both of which tow my boats with no problems and remain well within their respective capacities. )

So given that the vehicle is not exceeding its rated capcities, will advanced wear occure when trailering vs carrying?

 

[DJ]

Re: What, if any, difference is their between tow load and carrying load on tranny?

As far as the tranny is concerned, there is no difference between "carrying" and "trailering" weight. Lots of guys use synthetic in their tranny for the same reason they use it in their engine- it makes things last longer.

I do not agree. A towed load can add wind resistance which robs horsepower just as much as weight does, if not more. Horsepower taxing wind resistance can tax the transmission. You may notice this by the transmission "hunting".

In the heavy truck biz, we look at three things.

1. Startability. The ability to get the load moving. This is a function of torque, gearing and final drive gear ratio.

2. Gradeability. The ability of the vehicle to pull said load up a given grade, at a certain speed, measured in percent. This is mostly a measure of horsepower.

3. Cruiseability. The ability to maintain a certain speed within the engines peak fuel economy/power band. Again, mostly a function of horsepower.

This is where wind resistance comes in to play. It takes exponentially more horsepower to pull a load 70 miles per hour versus 55, depending on "frontal area".

Many tow guides refer to "frontal area". They will give a tow rating with a footnote that states: "Not to exceed _____ sq. ft. of frontal area.

I doubt there would be any issues with a boat. However a small travel trailer, of the same weight, would be a whole different picture (more frontal area).

 

[Mark42]

Re: What, if any, difference is their between tow load and carrying load on tranny?

DJ, I have read the "frontal area" spec in various publications I found on the web. It seems the bigger the frontal area, the worse off the tow vehicle has it.

I am of the opinion that the faster the speed a tow vehicle is traveling, the less in control that vehicle is. Slower puts the vehicle in better control, both braking and steering. It also yeilds better gas milage due to the reduced wind resistance, and less stress on the entire drive train and brakes.

60 mph on the highway is plenty fast for me.

And those little cars towing big boats and trailers in Europe do not go very fast. They are perfectly competent little tow vehicles at 45 - 50 mph. For some reason, in the USA, people feel the need to travel at 75 mph with a 6000 lbs load behind them. Totally out of control.

 

[DJ]

Re: What, if any, difference is their between tow load and carrying load on tranny?

I am of the opinion that the faster the speed a tow vehicle is traveling, the less in control that vehicle is. Slower puts the vehicle in better control, both braking and steering. It also yeilds better gas milage due to the reduced wind resistance, and less stress on the entire drive train and brakes.

60 mph on the highway is plenty fast for me.

And those little cars towing big boats and trailers in Europe do not go very fast. They are perfectly competent little tow vehicles at 45 - 50 mph. For some reason, in the USA, people feel the need to travel at 75 mph with a 6000 lbs load behind them. Totally out of control.

Agreed.

 

[reelfishin]

Re: What, if any, difference is their between tow load and carrying load on tranny?

I read this statement in another thread that made me think about the wear and tear on trans and drivetrain.


For discussions sake lets talk about light SUV's and Minivans and not pickups, and the other larger vehicles.

If my minivan has a tow rating of 3500lbs and I'm towing a 1800lbs boat and 500lbs people and cargo, is that any more of a stress on the drivetrain than just carrying 2300lbs of people and cargo? Its the same weight, and there is some additional wind drag of the trailer and rolling resistance of the tires, but other than that extra drag, would there be any more advanced wear on the vehicle caused by towing vs carrying?

Anyone use synthetic trans fluid to help reduce trans wear?

Towing can add another stress that carrying the weight may not, that is impact on the drivetrain, especially with a trailer that's not properly loaded or hitched.

A vehicle can pull far more than it can carry, for example, take a 100 lb bag of sand and toss it on your shoulder and take it for a walk. Then try putting that same bag in a cart or wagon and pull it that same distance, which is easier?
You can push your car but you can't carry it. A rolling load is far less than a carried load. If a trailer is properly set up and some common sense used, you would be surprised at what a smaller vehicle can tow.

I would much rather tow a heavy load than try to carry it, especially with a smaller truck or van.

 

[kenmyfam]

Re: What, if any, difference is their between tow load and carrying load on tranny?

DJ, I have read the "frontal area" spec in various publications I found on the web. It seems the bigger the frontal area, the worse off the tow vehicle has it.

I am of the opinion that the faster the speed a tow vehicle is traveling, the less in control that vehicle is. Slower puts the vehicle in better control, both braking and steering. It also yeilds better gas milage due to the reduced wind resistance, and less stress on the entire drive train and brakes.

60 mph on the highway is plenty fast for me.

And those little cars towing big boats and trailers in Europe do not go very fast. They are perfectly competent little tow vehicles at 45 - 50 mph. For some reason, in the USA, people feel the need to travel at 75 mph with a 6000 lbs load behind them. Totally out of control.

I will second that statement !!!!