Question about using Overdrive or no overdrive

[valkyr]

When towing should you keep your transmission out of overdrive or does it matter?

Thanks!

 

[bruceb58]

Re: Question about using Overdrive or no overdrive

Out of overdrive.

 

[jtexas]

Re: Question about using Overdrive or no overdrive

check your owners manual...I tow with overdrive on (explorer v6), but turn it off on hilly roads or anytime it looks like the tranny is hunting. In overdrive, your torque converter will lock up, making a mechanical connection to the drive train, which generates less heat than the hydraulic connection, and excess heat is what causes problems. You can tell when the torque converter locks & unlocks by watching the tachometer; moments after it shifts into overdrive, RPMs drop by a couple hundred, means it's locked up. Give it some gas, you'll see it unlock before it downshifts. You just want to keep the lock/unlock and shifting to a minimum. But if your vehicle owners manual says never use OD, I'd comply.

 

[tashasdaddy]

Re: Question about using Overdrive or no overdrive

i live in the flats of Florida, and use my overdrive, when it gets to hunting, then i turn it off. on the interstate, the only time it shifts back is on the incline of an overpass. Mercury Mariner 2.3L auto. i was totally surprized by it's towing ability. of course i've gone from fiberglass to aluminum, but still 18' center console.

 

[BLLDOGG]

Re: Question about using Overdrive or no overdrive

read your owners manual. every vehicle is different.

 

[Silvertip]

Re: Question about using Overdrive or no overdrive

You didn't explain what you have for a tow vehicle nor what the load is you are towing. If you are towing a 12ft row boat you can use OD. If its a 3500# glass boat and you have a Chevy/Ford/Dodge with a big V8 you can still use OD. Regardless of tow vehicle, if you are towing over half its rated towing capacity, OD is definitely not recommended except on table top-flat highways. If the owners manual says "never" then you better "never" to protect the warranty.

 

[valkyr]

Re: Question about using Overdrive or no overdrive

Good point Silvertip! Its an 04 Jeep Gr. Ch w/ 4.7L V8. The boat is over half the towing capacity.

Based on the responses I've gotten I'll keep it out of overdrive and check the manual to see what it says.

Thanks again!

 

[Silvertip]

Re: Question about using Overdrive or no overdrive

Forgot to add that axle ratio has a significant bearing on how well a vehicle pulls and whether or not OD can be tolerated.

 

[Matt S]

Re: Question about using Overdrive or no overdrive

FWIW ....

I have an 05 ranger 4.0L, 5 speed auto w/3.73's and tow package, and the owners manual doesn't specifically state to tow without overdrive. But my brother, a service director for Ford, says don't do it. He said the OD band is alot smaller than the other bands and is not really made to handle the load of towing in OD even on the flats and by doing so I'm stressing the OD band. They've had troubles getting warantee repairs approved for people who've lost OD because of towing. It's only when he pointed out their consumer literature didn't explicitly say so....

Like I said..FWIW. A call to your vehicles dealer service department might impart wisdom that doesn't exist in the owners manual.

 

[kenmyfam]

Re: Question about using Overdrive or no overdrive

Depends entirely on the individual combination.
Rule of thumb is that if it is constantly shifting in and out of overdrive then don't use it. Depends on conditions and terrain !!!

 

[Silvertip]

Re: Question about using Overdrive or no overdrive

Smaller bands/clutches are not really the issue. Any transmission is designed for a series of engines within a maximum torque range. As long as engine torque is below what the tranny is designed for, it simply cannot be overpowered -- in any gear. The problem with towing in OD is that if frequent downshifts or torque converter clutch locking/unlocking occurs, heat build-up can cause high fluid temperatures and eventual failure. That "hunting" is generally eliminated by towing in Direct Drive. Auto makers have done some stupid things in the past, but they don't put a 275 lb/ft rated tranny behind a 350 lb/ft engine. The current crop of 5, 6, and 7 speed tranny's have become noted for being "busy transmissions" and while most of them are currently found in cars, only time will tell how durable they are. A friend of mine has a Honda Ridgeline and hates it for towing as it gets rotten mileage because the tranny is continually shifting to keep the engine in its power band.

 

[SuperNova]

Re: Question about using Overdrive or no overdrive

The first thing he needs to know is whether that grand cherokee has the standard 4.7 or the 4.7 HO- big difference. Second, most modern transmissions also lock the converter in third, and some of them pulse the converter on and off in third. The real reason to not tow in od is due to the lower engine rpm o/d provides- it doesn't allow the trans pump to circulate the fluid enough to keep it cool and the cooler circuit return is what provides the lube fluid for trans. So you shift to third to get the rpms up and get that cooler circuit working properly. And yes, I stayed at a holiday inn last night.
--
Stan

 

[Texasmark]

Re: Question about using Overdrive or no overdrive

Ditto. If it hunts put in tow position. If not, OD. Ditto on what my manual says.

Mark

 

[Silvertip]

Re: Question about using Overdrive or no overdrive

A pulsing converter clutch is a slipping converter clutch. Which manufacturer(s) use this technique? I was in the room next to you?

 

[SuperNova]

Re: Question about using Overdrive or no overdrive

All the dodge transmissions used in the last couple of years use a solenoid to pulse width modulate the torque converter is second and third. It's not slipping, it's the way it's designed, they call it partial lock-up or modulated lock-up. All this crap about worrying whether the torque converter is locking and unlocking or the trans is "hunting" is partially true and definitely was true in the old days of hydraulically controlled transmissions, but not in todays world of electronically controlled transmissions. As I said, the real reason has more to do with proper fluid flow, at low engine rpm as provided by o/d and a locked converter, even on a flat straight stretch, you are not getting enough flow through the cooler circuit, the return of which is the lube circuit, to protect the trans with a heavy load on it(such as towing). Some of the newer trans have had pump and cooler upgrades to allow towing AND low engine rpms. Such is the difference between earlier versions of the 4l60e (GM) and later versions of the same trans. The earlier ones you couldn't tow in o/d, but by '98 you could. So the moral of the story is, if the trans is hunting- probably not good. Even if the trans isn't hunting- may be not good. That's all I'm trying to say.
--
Stan

 

[Silvertip]

Re: Question about using Overdrive or no overdrive

No wonder Chrysler trannys have been a problem and are likely to continue that trend. Being the inquisitive person I am, I don't buy the the low fluid flow rate relationship to towing. Low fluid flow rate as a design flaw I do buy and that was a problem even without towing. We basically agree that pump output is dependent on engine rpm and lack of flow (or low flow) would kill the tranny. Where my view differs is that this happened whether or not a trailer was attached. A tranny that has the converter locked is generating far less heat than one that is unlocked so that and low fluid flow rate combined with higher heat demands on the cooling system can raise tranny temperature since the tranny cooler is built into the radiator. But again, it was a basic design flaw that required operating in direct, not the fact that a trailer was in tow. Yup -- we are picking nits. I'm done. By the way -- I have been inside nearly every GM tranny dating back to the cast iron Power Glide and a tranny that 99% of the members of this board have never heard of called the TurboGlide. Slick idea but too bad they didn't think about a lock-up converter. Now there was a tranny that built heat when towing a trailer (cars could do that in 1957).

 

[valkyr]

Re: Question about using Overdrive or no overdrive

Geez Tip, you must be as old as dirt!

 

[bruceb58]

Re: Question about using Overdrive or no overdrive

My 3/4T Suburban came with a transmission temp gauge. Probably one of the most useful gauges that you can have when towing.

 

[SuperNova]

Re: Question about using Overdrive or no overdrive

Yes. Silvertip it happened whether or not you were towing, and yes it was a design flaw, towing just accentuated it. If the load wasn't there the trans wouldn't get as hot and wouldn't fail as often. I also have been rebuilding GM and Chrysler group trans since the mid-70's, the only difference with me is I have the factory training and am up to date on my training. Also ASE master in all the auto categories including L1 and Dodge, Jeep, Chrysler, Volvo, and Cummins Diesel factory certified Master Technician. So you can kind of trust me when I tell you what the real failure is and the reason for not towing in O/D on certain vehicles.
--
Stan

 

[Rancherlee]

Re: Question about using Overdrive or no overdrive

converter lockup has nothing to do with what gear its in on ANY computer controlled transmission. There is a SPEED vs. LOAD table in the computer that controls lockup. If you take off real easy most modern vehicals will have the converter locked up by the middle of second gear at around 20mph. Usually flat ground you are fine with towing in OD as long as it doesn't hunt. OD in most transmission isn't built to handle more than 75-100 ft-lbs of torque which is why they come out of overdrive so easy with anything more than 1/4 throttle. On level ground the average car is only using ~20ft-lbs. of torque to maintain 60mph, even a big 3/4 ton truck with light load is still under 50 ft-lbs to maintain 60mph.