255 Degree NV5600 ... Cause for Concern?

[JeffBob]

Okay, that's good to hear -- but from what I've gleaned from the message boards (hardly a statistically valid process), the manual transmissions in these trucks, while more robust than their automatic counterparts of the same era, appear to be "spent" by 100,000 to 150,000 miles and undergoing rebuilds when used for 10K lb + towing applications.

In other words, I'm not under the impression that 200k+ miles is something one would expect from this trans, esp if used for pulling heavy trailers. Does that sound reasonable? Or am I falling subject to an adverse selection where people with 200K miles of fifth wheel towing just aren't bragging about it, or I'm missing it (I should search for that ... ).

 

[S.Morris]

I think the 5600 is a good transmission and will run a lot of miles IF it is treated properly. IE: running in direct (5th) on any hard uphill stuff if loaded heavy. Running a little higher oil level than fact rec. (1-2 qts more). And changing oil on a regular basis especially if runnning in high ambient temps.

Running in 5th when temp is high should help it cool off some.

 

[HBarlow]

Okay, that's good to hear -- but from what I've gleaned from the message boards (hardly a statistically valid process), the manual transmissions in these trucks, while more robust than their automatic counterparts of the same era, appear to be "spent" by 100,000 to 150,000 miles and undergoing rebuilds when used for 10K lb + towing applications.

In other words, I'm not under the impression that 200k+ miles is something one would expect from this trans, esp if used for pulling heavy trailers. Does that sound reasonable? Or am I falling subject to an adverse selection where people with 200K miles of fifth wheel towing just aren't bragging about it, or I'm missing it (I should search for that ... ).

No, that's simply not true. I bought a new '01 HO/six speed (NV-5600) in June '01. I used it to pull my own travel trailers until it had 150k miles on in and then started pulling trailers for hire for an RV transport company every day. I abused it always allowing the mighty Cummins to pull grades in sixth gear down to 1600 rpm, under load and at full throttle. I used ordinary Pennzoil Synchromesh Lube and only changed it every 50 to 100k miles. It developed a slight lube leak around the top cover and I neglected it and allowed the fluid to get a little low, didn't know at the time the recommendation to overfill it. At 302k miles I had it rebuilt by Standard Transmission in Fort Worth because the big bearing got rough and noisy. On tear down, the transmission showed wear on sixth gear and the syncronizers as well as the big bearing was bad. I ran it another 20k or so before I sold it.

If they are shifted slowly like the large gears require not speedshifted like a sports car they are excellent transmissions. Much stronger, IMO, than the lightweight aluminum case G-56 transmissions chosen by Daimler when they owned Chrysler and made the decisions.

 

[JeffBob]

Now that's what I want to hear! And that's why I bought a 6-speed manual. So my 13k trailer shouldn't be any problem for my 60k mile truck; I don't think I can afford the time and diesel fuel to burn up the trans based on your mileage experience, even leaving it in 6th.

I'm going to throw on the oil cooler and throw in Redline MTL and it should be fine. Let's see, to get it to 300k for a trans rebuild at 10. 5 mpg pulling my 13k trailer is 23,048 gallons of diesel fuel at $3. 90 a gallon ... about $90k in diesel fuel to go. Nope, can't afford to wear the trans out, never mind rebuild it!

 

[macdaddy]

Okay, that's good to hear -- but from what I've gleaned from the message boards (hardly a statistically valid process), the manual transmissions in these trucks, while more robust than their automatic counterparts of the same era, appear to be "spent" by 100,000 to 150,000 miles and undergoing rebuilds when used for 10K lb + towing applications.



In other words, I'm not under the impression that 200k+ miles is something one would expect from this trans, esp if used for pulling heavy trailers. Does that sound reasonable? Or am I falling subject to an adverse selection where people with 200K miles of fifth wheel towing just aren't bragging about it, or I'm missing it (I should search for that ... ).

You need to goggle "2001 Dodge Ram with 1. 4 million miles"



Remarkable story. Almost a million and a half miles on a 56 Honey!!



Mac

 

[orhusky]

JeffBob,

Can't wait to see how the lab test looks when it comes back!

 

[JeffBob]

They should be here any day now, will advise. The oil should be at least "medium well" I would think, if not "well done. "