Engine/Transmission (1998.5 - 2002) Towing in 5th gear

[jsnyder]

Just wanted to get some thoughts and advice on this issue. I haven't done the 5th gear nut fix on my NV4500. About a third to half of my driving miles are towing a gooseneck horse trailer. Gross trailer weight varies from 7000 to 10000 lbs depending on the number of critters.



Before bombing, I spent most of my towing time in 4th simply because 5th gear didn't have the oomph to cut it unless it was dowhill or level with no wind (doesn't happen much here in Montana).



I recently installed a VA. Now, the Cummins has the poop to pull in 5th, but is this a good idea? I have Castrol Syntorq in the gear box, and change it ever 25k miles. Most of my towing is about 65 to 70 mph, depending on freeway or highway, traffic, etc. 70 mph in 5th on the freeway puts me about 2000 rpm. 65 mph in 4th puts me at about 2600 rpm.



Should I keep it in 4th all the time to save 5th gear, or am I merely prolonging the inevitable? TIA.



Jason

 

[Gary - K7GLD]

Personally, I'd say you're prolonging the inevitible - if 5th gear is gonna go, it's gonna GO - and why avoid using the VA's benefits in EXACTLY the situations you BOUGHT it for to begin with?

 

[Joseph Donnelly]

I much prefer 2000 rpm and above when towing. The vibrations under that rpm are hard on a lot more parts than just the 5th gear.

 

[illflem]

You almost have to use 5th gear if you want to go the speed limit in MT. I say use it till it falls off then fix it right. If 5th does fail you'll just be back down to 4th anyways with no other damage, same place you started in the beginning.

 

[Joseph Donnelly]

When fifth gear spits off, the threads on the nut are stripped off and the metal is circulated in the lube. Not good.

 

[ADSmith]

I've always towed in 5th (trailer weight 10000lbs) - I don't much like listening to the noise it makes going 75 mph in 4th. Besides that, the fuel economy is better, at least on my 12 valve. 80000 miles and still going strong.