Towing and Overdrive
Can someone explain to me why towing and overdrive
are a bad combination? I keep seeing the comment
cropping up, but never see the reason behind it.
I'm guessing it's something to do with having the
tranny continually shifting up and down or is it
more subtle and unpleasant?
are a bad combination? I keep seeing the comment
cropping up, but never see the reason behind it.
I'm guessing it's something to do with having the
tranny continually shifting up and down or is it
more subtle and unpleasant?
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Comments
- Do not tow over 55 mph ( ya right )
- Select a gear that will allow the trans to not hunt.
I Try not to tow over 65 mph. With a 3 ton truck equipped with an automatic with 3.73 rear end and a 3 ton trailer thats over 9' tall running in over drive is at the torque / hp limits at 2000 rpm / 65 mph for the V10. To keep the torque converter locked up at 65 mph + it requies me dropping it out of O.D. Other V10 owners with a 4.30 rear end can keep it in O.D. when towing, but do not use it because there afraid of hurting the transmission.
My thoughts are if your towing at 60-65 mph on flat land with no head wind use the O.D. to save on fuel if the trans doen't hunt and the torque converter will lock up. If you intend to tow over 2 tons of tall trailer at 70-80 mph then shift out of over drive on a automatic to keep from over heating things..........
I feel for you and wish there were better OEM information available on towing with an automatic trans.
I did some experiments with putting it into O/D when up to speed on flat or downhill sections and it had no problem maintaining speed and gear. But that doesn't mean I wouldn't be storing up a problem for myself. All the owners manual says about this subject is:
"Use a lower gear when towing up or down steep hills. This will eliminate excessive downshifting and upshifting for optimum fuel economy and transmission cooling.".
I wonder if "excessive shifting" is once every 10 seconds, minute, 5 minutes...
Ryan
Buy the Truck
Ryan
Ryan
Put the silverado in 3 and drive around town. It too will seem to shift (coverter lock up).
- Tim
Trust me you would be very happy i went from an S-10 to a silverado. Moving up in the world. Oh boy did i move up
Ryan
My truck doesnt fit in the garage bumper is in the way. IT sits out no problems. Only thing that scares me is hail and the time it hailed my truck was in the shop thank god. Little trucks come in handy i agree. What kinda boat do you pull? (sorry if u already said this)
Ryan
I wouldn't like to leave my new truck outside - too tempting for some of the neighbourhood kids. About a week after I bought my RAV4, we found a hole punched in our garage door where someone had tried to break in. We have a stronger door now.
Hail is scary, you're right. We had a big storm through here (Mpls, MN) a couple of years ago. My RAV4 got hammered in the company car park, as did the roof of our house. I was cowering in the basement at work 'cos there was also a tornado passing by.
Boat is a Lund Rebel 1650V with a 40HP Honda. A nice comfortable fishing rig.
Nice boat next yr ill probably be getting a nitro or bass tracker.
Ryan
However his new old lady wants a house soon and some kids....so look out!
- Tim
No house or kidds till im outta college.
I have bills
shell,mastercard, insurance
Ryan
Ryan
Any transmission be it manual or automatic normally has a gear that is 1:1. In most truck automatic trans missions it is "3rd", "Drive" or "D". When at 1:1 the power is transmitted with minimal loss in power, least friction ( lowest heat build up). The power transfer gets to the drive wheels like there was no transmission there (assuming converter lock up and or no clutch slippage). The torque loads mainly see only the in put and out put bearings of the transmission when in the 1:1 ratio. No great loads on secondary bearings used in gears that multiply the speed of the out put shaft that occurs when the ratio goes from 1:1 to .75:1 or .70:1 as seen in most truck transmissions.
So when some one uses the drive or disables the O.D. it is in a 1:1 drive ratio. This causes the least amount of ware in conditions like towing. While it is the least ware on the trans there is more wear on the motor and lower mpg.
Not all transmissions are design to handle high torque loads when transmitting the power indirectly through a planetary O.D. like the 700R4 trans in my old chevy. Towing in O.D. lead to it's early death at 135,000 miles (only 1/4 was towing miles).
I hope the Automatic in my new 2000 SD Ford is up to the task. Only time will tell. If it dies an early death, then I be setting my sites on an Allison 5 speed around the corner. Until then I tow in O.D. at 60-65 mph at approx. 2000 rpm and see how long the trans will last when towing 3 tons around.
EEE
1st gear = 2.47, 2nd = 1.47, 3rd = 1.00, 4th = 0.75, reverse = 2.10.
which fits what you're saying above.
I always tow in OD with the cruise set near 75-80. However, when I tow my 3500# boat with my F-150 and I come to a large hill it will lose speed until it has to shift down into third. When it does it regains the speed quickly, BUT once it gets back to that speed it doesn't shift back up into OD. That is until I top the hill, then it will shift. It's like the electronic control on the tranny has the ability to tell that there is an increased load, i.e. the hill, which made it have to downshift, and it won't let it hit OD until that increased load is gone, i.e. topping the hill. Anyone with any knowledge about this would be greatly appreciated. Thanks.
You are all wrong on the 1:1 minimal friction and torque loads on only the input and output bearings. Your frictions are going to be about the same no matter what gear you are in, and the torques are going to be through all the bearings in the path of the gear you are in. Your bearing loads will be least on the input shaft when you are in the lowest gear, but you will run at a higher engine rpm. I have always heard that heat is the biggest by far cause of problems with transmissions. I believe the main causes for heat are slippage (like under loads and shifting), and slow fluid flow (like in OD). If we believe the manufacturer on max tow loads, then we should believe them on towing recommendations. My info from Ford says that it is OK to tow in OD unless it starts to "hunt". Since I am only towing about half of the rating, it does fine leaving it in OD all the time (so far). When I am towing uphill or in high winds, the transmission automatically downshifts out of OD and stays there as long as it needs to. That is why they call them "automatics". I have a Ford Probe that the transmission went out at about 130K with no towing. Think towing in OD lead to it's early death?
bigsnag,
Your F-150 does what all transmissions attempt to do. Some are more successful than others, though. Before electronic controls, transmissions used engine vacuum to try to determine when it needed to downshift or upshift. Now with the electronic controls, we have throttle position sensors, air mass flow sensors and other information for the computers to figure out much better when it needs to shift, and when it should wait a little longer. So, to answer your question, yes it sort of does know there is an increased load based on it's sensor inputs.
My 99 F-250 Super Duty truck that I have now does an excellent job of shifting, whether I am solo, or pulling about a 6000 pound trailer. That and the V-10 engine are two things I am very happy with so far. Most all the rest of the truck I am much less than thrilled about.
If I'm the Rich that you're asking....
Yes, 3.73 LS, PSD and LT 265 75 x 16.
(Weight is almost 7100 lbs. with me and fuel.)
blight,
I'm surprised that you are not happy with your truck. In my SD my only real complaint is that there is no light in the cup holder. And, no, I'm not being sarcastic. I actually installed a couple of lights in the cup holder so I can find the holder in the dark.
Rich
My truck has been at the dealer for the last week and a half. They are replacing the Cruise control servo twice (the first replacement was worse than the defective one) and the valve body assembly in the transmission. After the 5th or so time, they finally took me seriously enough to finally figure out the transmission noise.
I also have an A/C squeal on initial startup after the truck has been sitting for 2-3 days. The line from Ford is that the compressor is the low point in the system and after sitting like that, it gets a slug of oil in the compressor. When you then start it, it sends that slug on through and hits the orifice. There is no fix, and is "normal" and will not hurt the compressor or the system.
I on the otherhand, know better. A compressor trying to compress an incompressible fluid is not a good thing, not to mention a DAMAGING thing. Also, a slug of oil hitting the orifice is also DAMAGING. I believe once again that Ford doesn't want to fix the problem so they just try to tell us that it is normal and won't hurt anything. I for one am not buying at any price, much less $30 freaking K!
I am glad you have had good luck with your truck. I would also love this truck if I could only get the problems fixed and not have a new problem almost every time I drive it. I may have to pull together a long list of all my problems and post it on one of these topics.
Note just had the Mass air flow sensor replaced at 6000 miles and mpg is back up.
EEE
Bookitty
The farm boy in me makes me think that towing a 3-5 ton trailer that stands 9+ feet off the road at above 65 mph in O.D. with a 3.73 rear end on a current Ford SD auto trans may be outside of the design safety margin. I have not done the math on the HP required to make this happen, but I have an gear head ME buddy who loves this type of challenge. You figure in a 20 mph head wind, a six pack and you'll have to check our math.
Wouldn't be great if a Ford development engineer responded to one of these chat sessions?
EEE
Sales: Yeah, don't worry about it. No problem.
Service: You did what???
OG: Silence.
I am a Mechanical Engineer, so yes, I am familiar with Newton's laws. I believe trying to count the number of gears turning and attributing the heat to that is nowhere near the whole story. Transmission fluid does a pretty good job of reducing bearing and gear frictions. I believe it does well enough to prevent you from explaining transmission operation and towing gear selection in one easy step. The only people who will really know where all the different places the heat comes from is probably the engineers at the manufacturers who know them intimately. Since they are hopefully the ones that set the shift points and wrote the recommendations in the Owners Manual, we can only trust what the manufacturer tells us about towing capacities and what gear to tow in. I do happen to agree with you about towing a 3 ton trailer in drive at 65+ mph. The reason I agree is because when I tow in OD (which is most all the time), it downshifts out of overdrive and stays out under this condition just the same as when you manually disengage the OD. I am sure Ford counts on people towing in OD since they tell you to. I still say let the transmission and computers do their job. They can do it much faster and better than we can.
obyone,
This is my second dealer, and I have called a third on the warped rotor problem. The first dealer was the worst dealer I have ever dealt with in my life, and the third dealer pretty much told me the same thing on the rotors. I get the strong impression that Ford has set up many road blocks to keep the customer isolated. I am actually reasonably pleased with this dealer. They have taken care of all but 3 of my problems quickly and have done a good job. Two of my 3 problems (rotors and A/C) I believe is Ford tying their hands. Of coarse my biggest problem is that something new breaks practically every time I drive the truck. I am almost afraid to use it because I wonder if the next thing to break will keep me from getting home.
1- pay for new rotors and a/c
2- start arbitration
3- trade for 2001 Chevy HD 2500/3500
good luck. I know I wouldn't want to drive any make of truck if I had to worry about getting home...
My '01 Dodge 2500 came with RT265-16 tires, which I think are too big for what I need. I want to get a few more RPMs in OD so I won't have to run in 3rd with my 5th wheel in tow. For some reason Dodge puts bigger tires on the 2500 than the 3500, and this is not good for towing. I have to wonder why Dodge would do this when the truck is ordered equiped for heavy towing.I now run about 1750rpms at 65mph. Can anyone tell me what to expect from RT235s or RT225s? Ken
"They give me almost 100rpm more at 65 and
they ride and handle much better than the Michelins did."
I'm assuming that you're speaking of the indications of your dash board instruments. I don't understand how the indicated RPM and the indicated speed could change by changing tire size.
Rich
obyone:
I've never paid much attention to the figures given out by such testing agencies, they tend to favor certain manufacturers for various reasons. All I know is I hated the way this truck drove with the original tires and wished I had my '98 Ram 1500 back with it's Goodyears. Now this truck drives just like the old one. If you choose to believe the commercials with the cute little kids, go for it. I know what I have experienced is real.