Engine/Transmission (1998.5 - 2002) Driving with O/D off.

[rmrc]

Just a simple question. I've read where you should have the O/D off when traveling at 50 mph and under, especially in hilly areas. Most of these threads were people who were towing a load.



Should you do the same when empty, and if so, what is a safe RPM to cruise at with the O/D off?

 

[jandtjil]

As far as I know, OD can be engaged at any speed when empty.

Driving on Beale AF Base I often was at 45-50 MPH in OD climbing a slight incline. Hasn't died yet.

When towing the info you mentioned is right on target, a good rule no matter how light the load!



JJ

 

[y-knot]

I like the OD to be locked out around town, let me use the PacBrake and it is more fun. Never locked it out while towing though, I don't think I would like running 50-55 tops.

 

[klaybus]

I personally prefer to keep OD off around town and on the freeway until above at least 55. With 3. 5's I never tow with OD on. I was told RPM's should be at 1800 or above to keep trans line pressure up & clutches fully engaged while towing... .....

Also, heard of many Chev & Ford transmissions dying prematurely from running non-stop in OD fwiw.

I'm sure theres got to be a transmission man out here that can possibly elaborate furthur on this fwiw.



Clay

 

[Theconcreteguy]

GOING UP... MORE INFO PLZ

 

[Cooker]

It is important to keep the RPMs up to aid in the life of the transmission. More RPMs equals more line pressure. Therefore it is important to lock out OD around town. I would stay out of OD unless your RPMs can be kept above 1700 or so.

 

[ToolManTimTaylor]

Not only that but think of the all that extra shifting your trans does not have to do ... . thus saving for better shifts in the future. My smart controller I have set to make the shift at nothing less than 55 mph (With the 33's it really is 50)

 

[RobbyRam]

In addition to the above true comments, keeping the OD off under 45 mph will keep your Turbo cooler, and make your transmission happier!

Bob in Sacto

 

[rmrc]

Thanks for all of the replies. Looks like the O/D should be left off to a max speed of 55. I was always worried of over reving the engine. That doesn't seem to be the case!

 

[Challenger-II]

I don't know about the rest of you but, when my OD is off and I'm cruising in 3rd gear..... my converter locks up at 25mph and my RPM's are really low! The OD off is a good thing to keep RPM's up when driving 35mph - 50mph but does nothing when going through town at 25mph. I really have to mash into the pedal to get it to unlock and then it just relocks when my speed increases. :{ Is there an adjustment for this??

 

[RSchebesta]

Rmrc, just remember if you still have the stock trans and it is automatic, the overdrive on runs on a much smaller gear, I would hall my 5th wheel with O/D off for the whole trip. I then figured out to put a DTT VB and smart controller in it. and I still will run it with the O/D off untill 55-60 it keeps the exsaust temp and trany temp down. get the gauges and you will realy see this.

 

[rmrc]

DTT rebuild

RSchebesta,



Believe me, I'd LOVE to get a DTT overhaul! I know that it's not too far off. The only problem presently, is the lack of funds to do the job. As long as the stock transmission is holding up, I'll just baby her until she totally gives up, or I finally find a decent paying job!

 

[rweis]

my . 02



Go to the websites of DTT / ATS / ??? and read there about driving with the O/D out.



I think you are going to find that to keep line pressures up you need 1700 - 1800 rpm on a stock transmission, ie O/D out below 55.



However you should get good info from the transmission guys web pages.



Bob Weis



I drove with O/D out until I had mine rebuilt at 20k to tow heavy. When they went to do the rebuild there was zero dammage from towing a 8k with the stock transmission because I hardly ever went into O/D unless on the interstate. The ability to hold the clutches is a key point.



As stated above, more rpm = more air, cooler, better combustion, MUCH better torque (find torque curves on TDR).



I tow 13k now with O/D out @2450 - 2500 rpm. I like the torque, better response, more air, no lugging, etc.

 

[RSchebesta]

rmrc, Just a note I always towed with the O/D out and just thought I would share with you that the old trany came out at 51,000 miles and the installer of my new trany said it was in great shape, rweis is correct. I towed a 9,000lb toy haular loaded with my old trany. baby it.