automatic transmission question

[walt]

This is mostly a question about auto transmission but let’s say we have vehicle with all-wheel drive (so we take slipping on the ramp out of this question) and this vehicle is only rated to tow 2000 pounds.

For this hypothetical case, this vehicle has an automatic transmission and is used to pull a 3500 pound boat up a boat ramp - and the boat is moved maybe a couple hundred yards for mast up storage. Boat does not leave the marina facility.

It’s my understanding that the auto transmission could heat up the transmission fluid doing this. And if done for a long time where the transmission is worked hard, the overheating of the fluid likely could be bad for the transmission.
But as long as there isn’t over heating, will this case of only using the underrated vehicle for launching the boat from mast up storage damage the car?

Please keep in mind I’m ONLY asking about the mechanics of using the automatic transmission to "over work" for a short period of time (hoping to avoid this turning into a discussion of trailer brakes or any legal aspects). Are there any other mechanical issues besides over heating of the transmission fluid?

Ive heard cases like this are fairly common at mast up storage places.. just wondering if this sort of thing is going to actually damage the vehicle. It seems to me the stress of doing this is actually a lot lower than using the same vehicle to tow at under the rated capacity for hundreds of miles at FWY speed..

 

[Winkfish]

This is my (non-mechanical) 2 cents, from me, a guy who tows his boat with a Lexus RX300 SUV (not a work horse). Unless you have a tiny car/engine, I don't think your transmission would have a problem. And actually, I don't think the transmission overheating would be as big a deal as the engine itself overheating. I believe that might be remedied by adding a cooling fan.

Best bet is to ask your mechanic who is familiar with your vehicle.

 

[Calif. Ted]

And the braking capabilities are also part of the tow rating, you won't hurt your vehicle towing very short distances Walt. But, keep it slow and easy on the brakes and trans in the lower gears.

 

[Roadking Larry]

In such a case if the vehicle will competently do the job you described I wouldn't worry too much about it. I might consider a shorter maintenance cycle but that would be about it.

 

[Cool Beans]

2000 tow rating to pull a 3500 lbs load up a boat ramp? How steep is the ramp? I would be concerned first that you might not be able to pull that load up a ramp.

I'd buddy up with someone who has a truck

 

[Bill Roosa]

If you have trouble pulling up the ramp put some guys in the car. the friction the wheels make is proportional to the weight on them. Seen several guys who can't pull their boat up the ramp with a pickup. pile some people in the back and she goes up fine.

 

[walt]

let’s say we have vehicle with all-wheel drive (so we take slipping on the ramp out of this question)

Ok, the above didnt completely work to take the slipping variable out of the discussion.. so now assume this vehicle has studded snow tires and four wheel drive - and a tank track around the tires. It does not slip (no need for extra bodies in the car or a buddies truck)- but its got an auto and pulling a boat up a ramp that is much heavier than the vehicle is rated for.

What I understand is the same situation would fry a manual clutch but with the auto, the fluid just gets hot. If you manage the heat, no damage??

 

[Ted]

Why don't you ask your local automatic transmission expert? They should be able to give you some real insight to your question. If they've been in the transmission repair business for a long while, they will be able to tell you which makes would likely hold up better to some occasional abuse.

 

[Sumner]

As long as the boat comes right out of the water and up the ramp you are not going to heat up the transmission (fluid). That happens on long uphills or towing a heavy load for some time where the torque converter is working hard and heating the transmission fluid. The reason they tell you not to tow in overdrive is that the ovedrive clutch packs in most autos are small and can start slipping or the lock-up clutch in the torque converter starts to slip (not un-lock). Both of these are bad. Then the reason that you need a trans. cooler is that running in 3rd with the converter un-locked it generates heat which needs to be taken away (thus the need for an additional trans. cooler) so that the transmission fluid is not heated to the point that it fails (the cooked smell you don't want to smell).

None of that should happen to you for the case you are describing so I can't see you having a problem as long as the vehicle will pull the boat out,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[walt]

Yep.. and I think there are some car forums that also would have additional info. Most of what you can find is more related to long term towing, i.e., many miles at freeway speeds.

But.. I think I’ve got some good info here also. Part of the reason for asking here is that this particular type of short duration over loading likely occurs fairly often in a mast up boat parking marina so maybe some first hand experience.

edit - thanks also Sumner, I posted the above before I saw your response..

 

[ChattOday]

Higher average auto knowledge than normal here. Keep it in low, or probably 1 or 2, on yours. That short a distance won't pop the transmission.

However, under sized towing (usually proportional to torque) and awd would make me nervous. Why? Awd and 4x4 are totally different. Awe usually, by design, isnt 4wd. It refers to the ability to move power from slipping wheels to non, not power to all wheels at same time. That ius a traditional 4x4 system. Awd is great at helping prevent spinning at tires. This is good for most everyday situations where you do not want free spinning. Awe is horrid, worse than normal semi open diff 2 wheel drives on a truck, in situations where more than 1 wheel breaks free and you still want the tire to spin. Think snow and mud.

This isn't an anti awd towing. Far from it. Awds work great and the computers behind them get better every year. I only take pause at overt loading a vehicle in a place where it matters. Uphill, incline, water and quite often s slick surface on the ramp. If you lose traction, you still want the tires to spin and find traction.


Anyway, just my thought. I have a v8 for towing but a 4cl 4x4 project truck will often be used to move my boat around the back of my house. My boat exceeds my small trucks towing capacity, but I throw it in 4lo and crawl. Never any issue. I, like you are thinking, only go a very short distance and do not overwortk it. I let the 4lo power magnification do the work. So and esdy. Never overheated and transmissiom stays at peak temp.

I am sorry for sloppy writing. Doing this non tablet I just got.

 

[Benny17441]

I believe the recommended 2000# towing limit is based on a straight pull on a flat surface. If you are pulling a boat out of water on an inclined ramp the actual load will considerably exceed the 3,500# weight. It is likely your vehicle may not be able to negotiate the pull. An automatic transmission through its torque converter has the ability of increasing the engine torque but a sustained effort or an excesive load may cause it to fail. As you mention the worst enemy of the transmission fluid is heat and to tow hard without a transmission oil cooler is asking for trouble. Some vehicles may have adequately strong engines and efficiently cooled transmissions but still carry a low tow rating. This comes as a result of a unibody construction which essentially lacks a chasis and could be subject to deformations if subjected to heavy loads. You do not mention the vehicle but to give an example I would feel more comfortable pulling with a small pickup truck than with one of them small crossover SUVs even if both were rated for 2000#. If it were me I would look to purchase a cheap old truck or find one to borrow when I needed to pull.

 

[Crazy Dave Condon]

Sumner and Benny 17441 have good responses. As a small boat dealer for over 30 years, I will put my two cents in.

First, all car manufacturers will put a limit on towing for liability reasons. A frame vs. unibody is more preferrable. Depending on the vehicle, you will be able or not be able ot pull out. As pointed out a light weight truck only, most boats you will not be able to pull out as there is no traction on the rear axle as most of the wieght is on the front axle which made my dodge caravan good at pulling out boats. Therefore, I always suggested putting wieght over the rear axle and also suggested always carrying a broom of sorts to brush away any sand, rock or algae on the ramp which will also cause the tires to spin.

You have pointed out pulling out is not an issue. As one respondent said, your vehicle diescription was not included. Now you throw in 2000 lb limit with pulling out 3500 pounds. If it is a solid frame versus unibody, you are better off. I have seen over the years of many pull outs with a unibody and not the proper hitch actually damaged as a result thereof.

If you are only pulling out maybe once for the season, the cause of fear should be substantially less. However, if you are pulling long distances, then there is a cause of concern as the brakes are not strong enough to handle in an ermergency, the vehicle is so light weight that the vehicle will sway due to the wieght of the boat, the shocks are not strong enough, the automatic can burn up from overheating and the list goes on.

Therefore, I would strongly suggest instead of wasting all of our time, that you fully describe the vehicle, distance to tow, speed limit, that actual boat and so forth that we all can give you a better response. I use to be an investigator at one time of my life and suppositions are not a part of my vocabulary but rather actual descriptions.

If only a one or two time shot during the year, why not go and rent a U haul truck with a hitch which will do the job. It is up to you whether to or not disclose the real purpose for the rental.

crazy dave condon

 

[sesmith]

In a previous life I was an auto tech for a number of years. Even if I knew what car you were suggesting, I probably wouldn't make any recommendations that I knew could be wrong.

You may want to get the input from a local dealer tech (or trusted independent) familiar with your vehicle. Some makes and models are known for tranny problems even without the extra load you are wanting to put on it, so that piece of knowledge might be a deal killer. To put things in perspective, how long do you think an automatic tranny would last if, on a hot summer's day, you kept one foot on the brake, and floored the accelerator pedal for a little while? What if you did this a couple of times, every weekend, all summer? This might be not far from what you are asking an underpowered car to do when you first start to pull the boat out of the water.

I personally would be more concerned with the integrity of the hitch mount on the car. You could do some real damage by overloading the attachment point for the hitch if the car isn't made for that kind of load (which will be more than the 3500 when pulling the boat, loaded with all your stuff, up a ramp and out of the water). An extra 1500 lbs doesn't sound like much, but it is 75% over the rated towing capacity.

 

[kloudie1]

Short term, say less than 2-3 minutes, of high load will not hurt the transmission.. What this is, is a thermodynamics problem.. When the torque converter is "stalled", (wide open throttle and wheels not spinning) almost all the engine horsepower (much less than full rated, because the engine is held at a lower RPM) is converted to heat from fluid shear .. there is a pretty good sized heat sink (the mass of the transmission and the oil) that can absorb this heat and not go over-temperature. You'd start having temperature problems when the thing starts getting around 300F .. so if you were to do something like this, start with a transmission that is not cold, but not just in from a highway run either.. If the boat doesn't come up and allow the wheels to start turning within 30 seconds or so, stop trying.. Once the wheels are turning, (in this case where you aren't going more than a hundred yards or so, at walking speed) the extra load will not significantly heat the transmission.. As others have pointed out, you may have much more trouble with structural things.
DISCLAIMER: I am assuming that the transmission is in good shape with no slipping band brakes and the fluid is in good condition and there are no incipient defects that this will surface.

 

[Sumner]

...vehicle has an automatic transmission and is used to pull a 3500 pound boat up a boat ramp - and the boat is moved maybe a couple hundred yards for mast up storage. Boat does not leave the marina facility......

Walt is talking about pulling out and going a couple hundred yards. I still say that if the ramp isn't real steep and the vehicle can pull it right up the ramp with no apparent problem in low he has nothing to worry about.

He has a different vehicle that he uses on longer trips,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[anchorclanker]

The key question here is: Can the vehicle MOVE the load, or is it just going to sit there and burn itself up?

The torque convertor is the "power fuse" we need to consider, as well as the overall available tractive force the vehicle can put to the ground. Tank tracks as you say. Think of the converter as one fan, the engine, blowing fluid against another fan, the transmission. If the vehicle cant move, and you floor the gas pedal, the fan the engine is turning is just blowing fluid against the stationary fan, and this is where enormous heat can be generated.

So the key here is, can it pull it or not. If you floor the gas pedal and it just loads up and creeps and can not go, the heat in the converter will begin to climb rapidly. This is considered a stall condition, and should NOT be extended more than 5 seconds, followed by approx 20 seconds in neutral at 1000 rpm.

I dont think awd vs 4wd is any big issue to worry about at a boat ramp. Again, the two greatest factors are traction and power. Power isn't even so much a factor so much as torque, which can be accomplished with gearing. A 1/4 HP engine or electric motor can move millions of pounds with sufficient gearing. Put the transmission in low (1st gear). Dont use drive, most transmissions (but not all) actuate an addition hydraulic clutch or brake when shifted manually to low, and many newer electronically controlled transmissions apply other features when shifted to low. Also, just in case you pick up speed and ease off the gas, you dont want it to shift up automatically as that is also hard on the transmission under heavy load. It is actually quite amazing how much pulling power even the smallest cars have. You just have to be smarter than the car in how you apply it. Just stay in low and as it starts moving and you ease off the gas, the heat and energy drops off to normal levels.

Probably the best would be to share what kind of vehicle it is you planning to use.

 

[walt]

Thanks everyone, very good discussion. I dont have a specific application, this was just a theoretical question about auto transmissions and short duration high loads and it was useful to me. Lots of good advice.

 

[Crazy Dave Condon]

Walt;

I may be stepping out of line but in the future sir, please deal with straight facts about specific equipment versus theroitical situations. Others emailed me wanting to say that but I will.

dave condon

 

[Sumner]

I don't see a problem with his question. I think he is looking at a possible vehicle to buy but hasn't narrowed it down to one so this gives him some ideas as to what he should check for and I'll bet it has been informative to some others also.

He also said

For this hypothetical case,

so one could decide if they want to reply to or follow the thread or not,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links