Towing in overdrive

[demsvmejm]

Re: Towing in overdrive

Originally posted by Mark42:<br /> I tow in O/D in my 97 Mountianeer 5.0 AWD with no problems. But I probably tow a much smaller boat than most of you folks. In the Mountianeer, you hardly notice the 1200lbs behind you. I am very aware of the shifting and locking behaviour of that trans and it seems to not be affected by the trailer. I just accelerate slowly, and let the truck make its own shift decisions. On long trips I find my speed creaps up to 70 - 75 before I catch myself and coast back down to 60 - 65. I do think it uses more gas towing but I have not checked. We have 150K plus miles on that truck. Its a truly great machine.

You are very aware of what that 5-spd auto is doing? Good for you. Every time I've ever test driven one, it's been hard to tell when it shifted. A good charactersitic. And you obviously pay attention to your vehicle. GOOD FOR YOU!

 

[JRJ]

Re: Towing in overdrive

Ah,10-4 DLM, good to have another OD expert aboard

 

[DJ]

Re: Towing in overdrive

As someone that pays warranty claims, I'll add this.<br /><br />1. Follow the owners manual. The people that designed it know more about it than you do.<br /><br />2. The real test, if the manual says it's OK, is: If the transmission does not "hunt" (shifts in and out of OD with light throttle pressure) it's OK.<br /><br />Most transmissions develop far more heat in the non OD mode than they do in OD. Why? The torque converter is designed to slip (torque amplification). Slippage creates heat in the fluid. In the OD mode, the torque converter is locked and power flows directly through the transmission, not unlike a manual trans.<br /><br />Most "tow/haul" modes do nothing but increase line pressures and change shift points. The transmission works exactly as it does in the normal drive mode except for the properties mentioned above. Ratios are the same, torque converter lock up is the same, just applied later. Tow/hual modes are for increased acceleration and offer engine braking in all ranges.

 

[snapperbait]

Re: Towing in overdrive

Speaking from experience (i've blown up a few of em'), the 4th gear clutch pack in a GM 700R4/4L60 transmission is the smallest clutch pack both in diameter and in the number of plates and steels in the transmission... Lock the converter or don't lock it, it does not matter because the 4th/OD clutch pack does not have the holding capacity for any significant extra weight.. <br /><br />Load it in OD, eventually it is going to slip, period....<br /><br />Best bet on a 700R4/4L60, lock the converter in third...

 

[Silvertip]

Re: Towing in overdrive

Weight has nothing to do with it. Its the engine torque that clutch pack has to handle and it doesn't which gear you are in. If it can't handle maximum engine torque, then there is a design flaw. The engine and transmission management systems determine when shifting is necessary. If that system continuously tells the transmission to lock/unlock, or pop in and out of OD, then its best to be in third. It's the heat created by the constant up and down shifting that destroys clutch packs.

 

[Mark42]

Re: Towing in overdrive

I checked the owners manual for my '97 Mercury Mountianeer (5.0L AWD 3.73 gears) and found this info:<br /><br />- Trans is 4R70W<br />- Max Gross Combined Weight Rating (GCWR) 11,000 lbs.<br />- Max trailer weight 6,500 lbs<br />- Bumper hitch is a Class 2 (3500lbs trailer, 350lbs tongue weight)<br />- Pre-wired for trailer light connection.<br />- Do not drive faster than 55mph when towing.<br />- "Use D (3rd gear) rather than O (Overdrive) when towing up or down steep hills. This will eliminate excessive upshifting and downshifting for optimum fuel economy and transmission cooling." <br /><br />The above bold text is the only reference to overdrive in the towing section. It says 3rd gear is for hills, which would indicate that Overdrive is acceptable for normal towing. Nowhere does it say that the vehicle should not normally be operated in overdrive when towing.<br /><br />David L Moore, I find it easy to determine the shifts in this vehicle either by sound or the factory tach. I'm not sure, but I believe the converter locks before shifting into 4th. I say this because I believe the RPM drop is greater for the gear change than for the converter lock. <br /><br />I see there is both a trans cooler and power steering cooler external to the radiator.<br /><br />In the future, I will drive slower with the trailer. <br /><br />Just thought I would share this info.<br /><br />Mark.

 

[jlshields]

Re: Towing in overdrive

Upinsmoke, regarding your March 8 reply to my post of the same date, I am very well aware what OD does to a final drive ratio.<br />First off, I do NOT tow in OD. That was an experiment. My point, which you missed, was to show that the engine works a lot less in D than in OD.<br />Second, the manual for my truck says to tow in OD as long as the transmission does not 'hunt' gears.<br />I have towed this load at least 5 times a year for 6 years from central Indiana to southeastern Kentucky's Lake Cumberland, a total of approx. 18k towing miles through some serious hills, and have changed tranny oil every 25k miles and not once was it discolored or smell burned.<br />Thank you very much but I don't feel I made a poor choice in rear axle ratio.<br />You tow 3000# with an S10 and you're telling me how to tow 8000#?

 

[Silvertip]

Re: Towing in overdrive

Gee JL -- I just re-read my post and it sounded more like I was agreeing with you. And I certainly did not knock your choice of axle ratio. I did however, say that people tend to overlook it when buying a vehicle. Think back to the time before every vehicle had overdrive automatics. What was recommended as a good towing axle ratio. Yup -- anything higher (numberically) than 3.50:1 which is what you have. I realize that was a test to prove a point. The point you proved, was exactly what I pointed out -- that an 8000# load should not be towed in overdrive. Its great you know the effects of axle ratio and overdrive on towing performance. Many on this board don't. My S10 3000# load was also an example of when OD can be used. My travel trailer & van GCW is just a tick shy of 12,000#. Do 5 and 12-yard gravel trucks count as having load handling experiece. If I remember correctly gravel is about 3200#/yard.

 

[Silvertip]

Re: Towing in overdrive

Yikes -- It's attack "smoke time". Folks, everyone mentions all the things that break in transmissions because of towing in OD and the common theme seems to be "over-torqueing" those plates and clutch discs. One more time - transmissions are designed for a series of engines that deliver torque in a given range. Depending on engine torque in that engine line-up, one or two extra plates may be added. The only thing that can overload a transmission is the engine -- it can only deliver its designed torque. As I said earlier, if clutches are burning up it is not from over torqueing but rather a design flaw or frequent up/down shifting. You can tie a vehicle to a post, floor the trottle and you will do one of three things, explode the tires, or if they don't spin, explode the torque converter because it begins to blow up like a ballon, or you overheat the oil because of inherent slippage in the torque converter which THEN may cause clutch pack slippage. That can't happen with a locked converter. Someone also mentioned that the OD clutch pack is the smallest of the bunch. Obviously it is, for the same reason the others are larger. 1st and 2nd gear are reduction gears, they multiply engine torque. OD is an overdriven gear, it reduces delivered torque. I rest may case. My transmission experience (GM PowerGlide, TurboGlide, TH250, TH350, TH400, 700R4).

 

[Mark42]

Re: Towing in overdrive

BTW, I noticed that when my Mountianeer is in O/D lockout, the locking converter will not lock. So all the time the SUV is in 3rd gear, the converter is slipping, generating heat.<br /><br />Does anyone else know if their Ford will or will not lock in 3rd with od off?<br /><br />Also, do you know which of the Ford locking converters you have? My '98 Town Car Touring Sedan has the 11.25" higher slip converter for better launch. I'm not sure, but I think the Mountianeer may use it also. If I remember correctly, the higher slip converter has a stall speed around 2500 rpm with stock HP. It lets the motor hit its torque curve faster under load for better pulling power, but it sure does boil the oil.<br /><br />If you have the 12" converter and want the 11.25 inch, they were stock in Mustang GT, Crown Vic Police Package and a few other heavy duty applications.

 

[Northern Eclipse]

Re: Towing in overdrive

My Explorer has a 5 speed Auto, I do not Tow in O/D it just does not seem to like it, I can maintain 100kph no problem It appears the Torque converter does lock, I tow approx 4800lbs, I also find that I get better towing fuel economy with O/D off, which leads me to believe that the motor is running at a good torque range, and the Tranny is happy also, since I don't feel it shifting up/down all the time and I don't have to keep pedeling the gas. If never had a Tranny failer, but then again I don't tow if overdrive or jack rabbit start when coming off a stop up to speed.

 

[jlshields]

Re: Towing in overdrive

Mark, when I'm not towing my '96 F150 with the E4OD goes into 3rd gear at about 30 mph and 2200 rpm, then the converter locks up at about 35 mph and 2700 rpm dropping the rpm to around 1800.<br />If you have a tachometer you can tell if your converter locks up if you will will let your speed level out then accelerate moderately. If you get a big rise in rpm, 500 or so, your converter is not locking up. If is is locked up your rpm will rise in proportion to your rise in mph.

 

[Realgun]

Re: Towing in overdrive

Speed limit here is 75 and I just set the CC and leave the tranny to do its thing. Except for the 5 big and I mean big hills. Then I reach for the end of the stalk and switch it to O/D off. I also slow down for the posted 65 mph on the two biggest hills. The truck a 2001 Ford Supercrew with the 5.4L rarely loses the 2100 rpm and only occasionally unlocks the converter to get 2600 rpm. At that point it is making Max torque of 350 Ft/Lbs. Oh and I got 12.7 mpg round trip 280 miles.

 

[demsvmejm]

Re: Towing in overdrive

Originally posted by Mark42:<br /> David L Moore, I find it easy to determine the shifts in this vehicle either by sound or the factory tach. I'm not sure, but I believe the converter locks before shifting into 4th. I say this because I believe the RPM drop is greater for the gear change than for the converter lock. <br /><br />I see there is both a trans cooler and power steering cooler external to the radiator.<br /><br />In the future, I will drive slower with the trailer. <br /><br />Just thought I would share this info.<br /><br />Mark.

My remark about being able to tell when the vehicle shifted was front the actual transmission, not from the tach and the engine sound. I can tell from these too, but I'm normally paying attention to too many other things during my test-drives.<br /><br />After reading all of these posts we are on one of two sides. On one side are those who want to believe they are right and will argue to the death using only information that supports their position. Or those of us who are willing to ask expert, educated professionals. Even some of the professionals among us are willing to ask the more learned.<br />As for design flaws and other anomalies, no manufacturer is perfect. GM had a significant problem with their 700R4 trans with the O/D failing. Ford had a major problem with several of their 4spd Auto models failing aroung 60-80K mi. Chrysler had haunting problems with some of their 4spd Auto rear drive trans, and are plagued with differential problems in the vast majority of their transaxles. So you see, no domestic manufacturer (since that's what we're taliking about here) has sturdy problem free trans. <br />When I stated that you should talk with a reputable tranny shop, I meant one that has a good reputation and is busy. If the shop is busy, it has plenty of work and doesn't need your trans rebuild to make the owners' next yacht payment. They would rather tell you the truth and be honest about what to do to increase the longevity of your trans. This is because they want to protect their reputation. There is nothing more valuable than a good reputation to a business. I know, as in my local area, my professional reputation and integrity is stellar. And I work hard to keep it that way.

 

[Silvertip]

Re: Towing in overdrive

The easiest way to tell if the converter is locked is to get up to about 45 or 50 MPH. Cruise control OFF. Holding the accelerator pedal perfectly steady, watch the tach and then every so lightly touch the brake pedal with your other foot while maintaining the preveious speed. You will see the tach rise as the converter releases. If it doesn't, its not locked up when it should be.

 

[jtexas]

Re: Towing in overdrive

I'm intrigued by all this converter locking/unlocking discussion. Watching the tach, I don't think mine locks before 50, maybe closer to 55.<br /><br />Here's a question, driving along at 45 or 50, take my foot off the gas & coast, the tach drops back to idle speed. No way is the converter locked at that point, right?<br /><br />So the brake pedal unlocks the converter?<br /><br />Interesting.<br /><br />thanks all,<br />jtw

 

[Silvertip]

Re: Towing in overdrive

Its not supposed to be locked when you coast. At what speed the converter locks is variable just as it is for unlocking. Each manufacturer has their own minimum lockup speed. Its not always 40, 45 or 50 MPH. It may be 70. My GM vehicles at light throttle settings lock at about 37 MPH but just tickle the gas and they unlock. There are several computer inputs that control the converter. Accelerator position is one, manifold vacuum is another as it determines engine loading, road speed is another, brake on/off is another, engine temperature is another, A/C on/off is another. If you accelerate hard converter lockup is delayed. If you simply ease up in speed it locks earlier.

 

[Rampart104]

Re: Towing in overdrive

Norther Eclipse: Help me, I have a 2002 Ford explorer, 4.0. Just bought a new boat that is 4,800 lbs with trailer. have not picked it up until may 1 . Am worried about how the Explorer will tow with this much weight. How is the power up hills and take off etc? DP

 

[Johnshan1]

Re: Towing in overdrive

I just had my transmission rebuilt after some hard miles plowing and towing.<br /><br />I asked the shop (who is right out straight might I add) if I should tow in OD.<br /><br />Their answer was: <br /><br />"What are you towing? If your towing a 1000 lbs and the truck isnt shifting all around your all set. If your towing in the hills and it keeps shifting lock it in 3 otherwise I wouldnt worry to much about it, after all you have an aftermarket cooler. If you were towing 4,000+ lbs def. lock it into 3."<br /><br /><br />My truck is a '96 Chevy 1/2 ton 4x4 5.7L V8 long box so with my rig of 1000-2000 lbs (depending on which load I take) I am pretty much at my own choice if I wanna use OD or not, the truck doesnt feel it back there either way. <br /><br />He said just use common sense and I would be fine. <br /><br /><br />So guys if your towing 4000+ pounds it might be a good idea to just not use OD, but his point was that if its not hunting for gears non-stop OD was ok- shifting gears creates heat and heat kills trannys was the final point.<br /><br />So use common sense!!<br /><br /><br />-John

 

[demsvmejm]

Re: Towing in overdrive

Originally posted by Johnshan1:<br /> I just had my transmission rebuilt after some hard miles plowing and towing.<br /><br />I asked the shop (who is right out straight might I add) if I should tow in OD.<br /><br />Their answer was: <br /><br />"What are you towing? If your towing a 1000 lbs and the truck isnt shifting all around your all set. If your towing in the hills and it keeps shifting lock it in 3 otherwise I wouldnt worry to much about it, after all you have an aftermarket cooler. If you were towing 4,000+ lbs def. lock it into 3."<br /><br /><br />My truck is a '96 Chevy 1/2 ton 4x4 5.7L V8 long box so with my rig of 1000-2000 lbs (depending on which load I take) I am pretty much at my own choice if I wanna use OD or not, the truck doesnt feel it back there either way. <br /><br />He said just use common sense and I would be fine. <br /><br /><br />So guys if your towing 4000+ pounds it might be a good idea to just not use OD, but his point was that if its not hunting for gears non-stop OD was ok- shifting gears creates heat and heat kills trannys was the final point.<br /><br />So use common sense!!<br /><br /><br />-John

COMMON SENSE! Thank you!!!! Finally someone used it and asked a professional. When I asked around I was asked the same thing, what am I towing and how much does it weigh? That make a difference too. There's a lot more drag to my 2400# travel trailer than there is to my 3000#(?) boat. It all comes down to common sense, not ignoring the advice of others just because is doesn't agree with your preconceived notion.