2nd Gen Non-Engine/Transmission over drive off

[rrab1]

with the over drive off @ 55mph and rpm @2100 the motor is screaming how long can you drive this cummins without killing it , not that I would, just a question thank's Don

 

[clong]

Somewhere between 500,000 and 1,000,000 miles with proper maintenance. They are built to run under full load with a mean time between failures of 400,000 miles. Running in our trucks is nowhere near full load.

 

[Fireman Dave]

My favorite activity with my truck is towing cross country. It just cruises along all day with no complaints. Every time I tow my trailer with it, I know I made the right decision and that the extra $ for the Cummins is worth every penny. No overheating, no rattling lifters of a gasser when towing. The thing just loves to tow. Oh yeah - and then there's the fuel mileage.

 

[jimk]

towing

Originally posted by Fireman Dave

My favorite activity with my truck is towing cross country. It just cruises along all day with no complaints. Every time I tow my trailer with it, I know I made the right decision and that the extra $ for the Cummins is worth every penny. No overheating, no rattling lifters of a gasser when towing. The thing just loves to tow. Oh yeah - and then there's the fuel mileage.

Dave I have a question, do you use overdrive when you tow or 3 gear. With 3. 54 gears and you are driving 55 and 65 miles an hour. Do you let the rpms drop below 1750 when in overdrive? Thanks for any help Jim

 

[Fireman Dave]

Jim,



I usually tow in 3rd unless I'm on extended flat interstate where I can keep it consistently around 60-65mph. I also try not to go faster than that to help prevent trailer tire overheating/failure. I went with the 3. 54 gears with the plan of towing in 3rd in mind. I know there are guys here that swear by towing in 4th, but I still think 3rd (direct 1:1) is best for towing. A transmission builder whom I respect a lot also promotes towing in 3rd, so that's good enough for me. I figure towing in 3rd vs. 4th costs me maybe 2 mpg, but that may be going a long way toward preserving the stock transmission for many more miles. Eventually the stock transmission will be modified, but my goal is to put off the necessity of that as long as possible (or at least until the truck is paid off!). For now, being stock works well for me, and it's saving me money. But eventually I'll be into heavy mods - just not as soon as some guys are - and not as soon as a lot of my WI friends would like me to be. And yes, I try to keep the RPMs up over 1750. The other thing I like about 3rd is it just seems to be a real sweet spot for the 3. 54 gears. The truck is definitely much happier in that gear when towing.



I really like the auto, but if I bought a truck tomorrow I'd probably go with a 6 speed. It would save a lot of worry about the weak link. I've probably towed over 12k of the 52k on the truck, so the majority of the time I'm not towing - and loving the automatic. And once the transmission is bulit up, it won't be the weak link anymore.



Dave

 

[Joe G.]

I think I read on here somewhere (I think it was one of Joe Donnelly's posts) that the Cummins 5. 9 is designed for constant operation at 2300 RPM. If that is correct, then you are sure not killing it at 2100 in spite of the noise.

 

[Cooker]

Originally posted by Joe G.

I think I read on here somewhere (I think it was one of Joe Donnelly's posts) that the Cummins 5. 9 is designed for constant operation at 2300 RPM.

I rember reading something similar although I think it was illflem and the number was 2500RPM's. Either way 2100 all day long is just fine.

 

[JR2]

I remember a post that told about an excavator this guy ran that had the same motor as our trucks in it. It ran at 2500 rpm all day long and he even turned it off and back on with out letting resetting the throttle.

 

[jimk]

overdrive

Originally posted by Fireman Dave

Jim,



I usually tow in 3rd unless I'm on extended flat interstate where I can keep it consistently around 60-65mph. I also try not to go faster than that to help prevent trailer tire overheating/failure. I went with the 3. 54 gears with the plan of towing in 3rd in mind. I know there are guys here that swear by towing in 4th, but I still think 3rd (direct 1:1) is best for towing. A transmission builder whom I respect a lot also promotes towing in 3rd, so that's good enough for me. I figure towing in 3rd vs. 4th costs me maybe 2 mpg, but that may be going a long way toward preserving the stock transmission for many more miles. Eventually the stock transmission will be modified, but my goal is to put off the necessity of that as long as possible (or at least until the truck is paid off!). For now, being stock works well for me, and it's saving me money. But eventually I'll be into heavy mods - just not as soon as some guys are - and not as soon as a lot of my WI friends would like me to be. And yes, I try to keep the RPMs up over 1750. The other thing I like about 3rd is it just seems to be a real sweet spot for the 3. 54 gears. The truck is definitely much happier in that gear when towing.



I really like the auto, but if I bought a truck tomorrow I'd probably go with a 6 speed. It would save a lot of worry about the weak link. I've probably towed over 12k of the 52k on the truck, so the majority of the time I'm not towing - and loving the automatic. And once the transmission is bulit up, it won't be the weak link anymore.



Dave

So when you get the transmission built you will use 3 gear for towing? If you had 5 speed, 4 gear is still direct, and the 6 speed is, I guess 5 gear is direct. But is the overdrive in the 6 speed the same ratio? I like the close gear ratio so that I can find a gear that suits my needs to go with the speed, 45 or 50 miles an hour. The towing of my back hoe it is no fun going 70 miles an hour on a counry black top road. I like 60 or 62 and that is where I would have to use 3 gear, lock up and have done so for 95k miles on a stock transmission, when towing. I had thought that a 6 speed would work if the overdrive was not as tall. Now with the 3. 70 gears that are in the newer trucks that may help. All I use my truck 90% time is pulling my trailer and to spend 3. 5 to 4k plus the boxes and pmc to have a transmission that does the same thing tow in 3 gear I dont get it. How ever I am will to listen to reason or different ideas, thanks Doug for any thoughts. Jim

 

[klaybus]

RPM's

It seems to me that I read on one of Cummins press statements that the 5. 9 could run up to "Red Line" all day long with no ill affect.

I regularize pull a #6500 5vr at 60-65 mph turning 2200-2300 rpm's in 3rd gear direct (no OD). I'm also running 3. 5 gears combined with larger tires... . 285's (truck came stock with 245's)

For me to pull above 1750 I would have to be going between 71-73 mph which is just too fast with trailer in tow IMHO.

DTT discourages pulling in OD under 1750 with the automatic trans. I'de say your good to go at 2100.



Clay

 

[jimk]

Re: RPM's

Originally posted by klaybus

It seems to me that I read on one of Cummins press statements that the 5. 9 could run up to "Red Line" all day long with no ill affect.

I regularize pull a #6500 5vr at 60-65 mph turning 2200-2300 rpm's in 3rd gear direct (no OD). I'm also running 3. 5 gears combined with larger tires... . 285's (truck came stock with 245's)

For me to pull above 1750 I would have to be going between 71-73 mph which is just too fast with trailer in tow IMHO.

DTT discourages pulling in OD under 1750 with the automatic trans. I'de say your good to go at 2100.



Clay

That is a idea, do the larger tires effect fuel economy, loaded and unloaded? thanks Jim