Engine/Transmission (1998.5 - 2002) max safe speed

[kenny61]

The weakness is in how much torque they can handle. I may be wrong but I do not believe it is soley based on an RPM issue. If it was there would be transmission parts on the ground behind every gasser.

 

[steved]

The weakness is in how much torque they can handle. I may be wrong but I do not believe it is soley based on an RPM issue. If it was there would be transmission parts on the ground behind every gasser.

When towing, it is the thrust washers in the OD unit that are prone to fail.


edit... thrust bearings,not washers... engage brain before fingers.

 

[SRath]

If you have an automatic you will have to rebuild it anyway no matter what you don't do. If you have an NV4500, you will have to fix 5th gear.

Rumors about Dodge transmissions are well founded.

 

[Tractorat]

His question has to do with the od off. So, shouldn't the question really be "what is the highest sustained rpm I can run without damaging the engine". I think I would be interested in that as well (for academic reasons of course).



TRat

 

[barryg41]

Back in 2000, I emailed Cummins about this very question. They wrote back and said I could run out of OD at 2750rpm for ever. I think it was 67mph. If you can stand the noise it was ok. The transmission liked it because it stayed locked up and was at full pressure all of the time. I did this on a trip up to Rocky Mountain Nat Park, up to Rapid City over to Sioux Falls and back down to Baton Rouge. Around 4200 miles at 10. 5 mpg ave. This was all stock back then. I am still on the stock transmission at 140K with no adjustment left on the front band.



Matter of fact, I am calling DTT tomorrow morning to set me up with a new transmission from them. Will try to get James to do it for me. I generally drive out of OD in town and in OD on interstate, solo and pulling our 5ver all at 70mph getting 20mph solo and 11 with camper. The Edge EZ was put on right after that long trip. Made a big difference in pulling our camper.

 

[steved]

His question has to do with the od off. So, shouldn't the question really be "what is the highest sustained rpm I can run without damaging the engine". I think I would be interested in that as well (for academic reasons of course).



TRat

That's why I posted the RPM chart for a 1:1 ratio...

 

[madmanmanick]

thank you, all your replies were very helpful.

 

[JMcCoy]

We need to be provided with an axle ratio. Besides, this question has no real answer. If you run it at the rev limiter, it will not last as long as if you run it at 1500 RPMs. If you run it at 2500 RPM, it will probably not last as long as if you run it at 1900 RPM, just due to wear. Your rev limiter should protect you from any instant catastrophic failure. There are so many factors to consider. Vehicle weight, load, axle ratio, incline, decline, wind, 4x4, 2x4,tire size.



That said, the best thing you can do, is to drive it at a comfortable RPM. You "should" be able to feel if the engine is over reving. When you are over reving, you will lose any additional throttle response. If you are at a selected RPM and you step on the throttle the rest of the way to the floor, and you don't increase speed very much, you are probably over reving. Back off some and try it again. Do this until you throttle response returns. This should indicate you are within your usable power band.



I have a 12v with stock govenor springs(3ks are on a shelf, in the closet ) 3. 55 gears, and 35" tires. I can comfortably run around 2200 rpm (65mph + or -). Your 24v will probably be happy up to around 2800 crusing. Fuel milage would be in the tank though (No pun intended). Hope my rambling made some sense. Good luck.

 

[Sticks]

You can over rev an engine with a manual transmission (downshifting) but an auto... not without a lockup.

If it is stock, or even mildly modified, just drive. These engines can take an astonishing amount of abuse without complaint.

 

[jpickens]

GPSd 132mph 35" tires 3. 55 gears 6spd in OD obviously

I forget the RPMs (maybe just north of 3300?) but that was it - wouldn't spin anymore, or I was running out of highway - whichever...

It was singing for sure...