use/not use OverDrive

[MPatrick]

First off, I love my new truck, I will never own a 1/2 ton again or non-Diesel .

I have a question about pulling loads. Can I pull a medium to large load (4000 lb to 8000 lb) on the Interstate over 60 mph with the overdrive engaged? I have been told the auto trannie for a diesel is not like the one found for a gas trannie.

 

[Bob Wagner]

Only tow in OD if your RPM's are over 1700

 

[BK]

... and if you don't anticipate a lot of shifting from passing and grade changes...

In other words, nice flat straight run, take advantage of the OD and keep the RPMs up. .

 

[chuck3]

Sure

You bet, I do it all the time, no problems just keep the RPM's up and you'll be fine. And I'm with you on the half ton and gas rigs, no more after owning a real truck.

 

[pwr2tow]

I have found it to be easier on the transmission if you leave it out of OD until your at cruiseing speed then let off the throttle put it in OD and push down on throttle slowly until it locks up. Once you know where your RPM's are you can do the shifting faster just bring your RPM's to that reading each time.

Ron

 

[Crazy Horse]

MPatrick-

I would give you the advice to keep it out of overdrive (Loaded) unless you are "Up On Step" (Cruising speed), on the flat runnin' highway 60-63 MPH or above. Don't use OD below 60 MPH. If you let it lumber (Low RPM's & Slower Speeds) and accelerate with a load on you'll tear the trans out, the way a lot of people have. That trans is the weak link and it will not last if it's not used right. I just got done driving over 20,000 miles with a 4,800 lb camper in the bed towing an 1800 lb trailer. The entire truck performed flawlessly.

 

[cwsoules]

Towing in OD

When I first started using my truck I only towed in OD. But after reading many posts here I have started using OD when at speed. I too do not use OD below 1700 RPM (about 57 mph). As is usually do not exceed 62 mph towing I have a rather small window in which to use OD.



I shift to OD when I have gotten the rig up to over 57 mph. If the transmission starts to shift out of OD on a rise I take it out of OD. In fact I prefer to manually take it out of OD before the transmission decides to do it. When towing I watch my transmission temperature gage to ensure that the transmission is not heating.



So far so good. I hope to go the DTT way in a few months to bullet proof the transmission so I will feel good about using an exhaust brake.

 

[Crazy Horse]

That's the main thing, Do Not Accelerate, with a load at these lower speeds and RPM's. Prior to accelerating manually down shift to get the RPM's up. Whether it's Disenguaging the OD with the button or manually selecting a gear with the shifter, don't let it "Lumber". Do it (shift), before you put your foot into it.

 

[Steve M]

We just returned from a weekend trip with our 5th wheel. While cruising along a stretch of 50mph suburban roadway, I realized I was in O/D at 1250rpm. I looked down at the gauges and when I saw 450*EGT and 4-6psi boost, I decided to leave it in O/D. It was barely working the motor and no need for downshifting. With no hills in sight, I don't see a problem easing along in O/D at an almost coasting situation. I use O/D for all highway cruising and shift out of O/D before any incline that I know will slow me down to the point that the transmission will downshift on it's own under load. I try to avoid shifting to and from O/D under heavy load. This is my second auto/3. 54. No problems with either.

 

[KB0OU]

To save the TC clutch install a mystery switch to unlock the tc, will work very well after you get the DTT. If you want a discription of my mystery switch just email me and I will send it to you.



John



I will put the basics here, I have a Word file with pictures I can email to you;



Basically mount a double throw, single pole center off switch on the dash, put ground on one of the outer pins, bring B11 from the transmission control to the center pin, then put B11 on the other outer control (the wire to the transmission relay).



put a jumper on the two forward pins on the transmission relay on the driver's side, solder the jumper and reinstall the relay. This keeps the computer from putting you in safety mode.



Put a pilot light on the line B11 going back to the computer and power it with switch on 12 V. This make the computer think the relay is still there. also comes on when computer says to lock up.



Center position on the switch will be NO LOCK, the other positions will be NORMAL and LOCK. I only use lock for downhill braking, I run in NO LOCK a lot, when I want the tc to lock I put it in NORMAL or in LOCK.

 

[Prostock]

I have noticed with my 94 auto that when I use the o/d lockout button at highway speeds (55 - 60) they truck doesn't feel like it has near the power it does when I have the lockout turned off.



I pull a car trailer that loaded is about 5,000 pounds.



It often doesn't downshift when climbing hills, and doesn't seem to be lugging. Also, my EGT's have never gone above 1,000.



Am I hurting my truck by driving it like this? If I should be using the lockout button, it will be awfully disappointing because the truck just doesn't seem to make power with it off.