Engine/Transmission (1998.5 - 2002) Cruising \ Towing RPM

[GLASMITHS]

Thank You Ray

If my memory is correct there WAS a time limit involved; I believe LSmith said 1 min. However we are talking about towing at the GCVW. Very few instances where you couldn't accelerate out within 1 min unloaded. It would have to be +20 deg.



My requirement for a particular gear is that I am not losing speed and the egt, transmission and engine temps are within reason. If not I downshift. Pulling up a hill with the pedal on the floor creates a lot of heat, so why not downshift and you still maintain this speed and the temps come back in line.

 

[klaybus]

Back to my question

Is 2400 RPM in drive OK when pulling a load (#6000) for an extended period of time? 1-3 hours)



Clay

 

[GLASMITHS]

CLAY

It is just fine. Some time back someone posted a reply from Cummins - the question was how long can I run my 24V in 3 at 2800 rpm. The answer was simple - all day, all night. If you can put up with the noise from the engine and right seat your engine and transmission will love you.



At 2400 rpm there is no worry... ... ... ... ... ... ... .....

 

[RKohn]

Experiments in Lugging...

Shift into 4th under 20mph and floor it. You're adding fuel, your speed IS increasing, it's shaking you to death until you top about 1100 rpm and it starts to smooth out.



Lugging is definitely a SOP feeling.



So's the difference that you feel when you get on top of the torque curve around 1600... . smooth Cummins power. Oo.

 

[CFAR]

Real hard to lug unloaded,



my mpg inproved dramatically from16-18 to 20-22 when i started shifting (unloaded) at around 1700, flat ground, used to shift between 2000-2100

 

[klaybus]

GLASMITHS

That's what I thought, I just wanted someone to confirm it. I don't plan on doing it all the time but with 3. 54 gears & 275's for tires compounded with an automatic transmission I don't have alot of choices. Pulling in OD I would be going over 70 MPH to have the RPM's up at 1700 & with my 5vr in tow I really don't want to do that all the time!



Thanks!

 

[GeneralMachine]

Engine Lug

This is just MHO: When you drop the hammer at any speed and the engine start's gaining RPM she's pulling not lugging. Harv

 

[GLASMITHS]

Harv:



You are correct. As long as you can build rpm - and if you happen to be low, it won't take long to get out of that situation.



Clay: I would not tow in o/d below 2000. If you have a stock transmission, for sure, the pressure and thus cooler flow is governed by throttle position, not rpm. If you tow at low rpm you aren't getting much cooler flow. My stock transmission lasted 72400, towing 22-26K in 3rd. You also remember that when you lock out o/d (on stock) your transmission will remain locked for a long time, almost to the floor. I'm not certain when the unlock occurs going down; however it is a lot easier on it in the long run. When mine was up-graded there was not anything bad wrong.

 

[klaybus]

GLASMITHS

My trans is stock & thats why I'm so nervous about towing with the auto transmission. I plan on always towing in drive. My trans unlocks at about 30-35 mph... ... Stays locked as long as I keep a little pressure on the pedal. I know the wifey will never allow me to spend the big $$$ on my trans until it goes & I'm in no immediate hurry to dump $4000 on a transmission until this one goes! Thanks for the input.



Clay

 

[pwr2tow]

If your looking to keep transmission pressures up you could add a pressure lock from BD. The pressures would be at full as long as the TC is locked no matter what rpm you are at. Another thing if you want to pull in OD is to keep it in third until you reach cruiseing speed then put it in OD, it is best to keep the rpm's above 1700 though when pulling in OD.



Ron