heavy towing nv 4500 5th gear?
 

For those who tow regularly and have the nv 4500 5 speed, what rear end ratio do you have? And have you had 5th gear fail? I am curious if those with 4:10 gears have better luck with 5th gear staying on the shaft. I have a 3.50 rear and had 5th come off three times now, even after the longer splined main shaft. Last long trip over drive in the auxilary had two gear teeth break off. Just can not keep gears in this truck. The engine is still stock.

Since 5th is OD and 4th is 1:1, tow in 4th. Stronger. Make sure you have the right lube.

https://en.m.wikipedia.org/wiki/New_...0_transmission

This is why I simply have nothing good to say about an NV4500. Best thing I can recomend for you is to install the pto plate coolers and ad a temp gauge. The coolers give you the extra oil capacity which also helps with temps as do the coolers when running down the highway. Most people don't realize they actually overheat the oil and never know it. I would say it's the cause of 75% of nv failures I've seen.

Good recommendation. I installed the FAST Coolers on my NV5600 when I bought the truck. I run Valvoline, Chrysler-spec MTF, one quart high.

I also tow the TH in fifth gear (direct) if anything more than a flat highway or downhill.

Note the NV4500 GVWR at the end:

1. NV4500 Specifications | Tech Vault | Advance Adapters

Thanks for the specs. Dodge had to have been crazy to use this trans, only 460 torque, and 15,000 gross? No wonder I keep breaking it... What trans are people using, that are commercail haulers? Like the guys running car trailers?

When I had my '98 12v, 2 wd, NV4500, 3.54, I had the 5th gear slide off three times, while towing 10,000#. The last time, in frustration, I had the trans shop spot weld the gear on. I hope the current owner doesn't have to rebuild the trans (I traded the truck in to a dealer so I don't feel bad about not telling the new owner about this problem.) The owner of the trans shop made a profound statement. "If they had put reverse threads on that shaft, the gear would never come of." If a "blue collar" shop owner could figure this out, why couldn't the engineers?
John

They are ruining NV4500's........ Here is a thread from several years ago where one of our members stuck a medium duty trans in.

https://www.dieseltruckresource.com/...anyone-187442/

Thanks for the link. I am starting to think about a medium duty trans like the FS 6406.

For now I just put a second nut on 5th. I do not tow in 5th, but run 4th with the aux in overdrive, except that just broke two teeth. so 4th and direct for now. Put a southbend 13" clutch in a year ago, that is great. I have a bit invested in what I have now, so not feeling the urge to spend a lot more. But will see if a medium duty trans comes up cheap. A friend of mine has a construction and earthmoving business. Might see what he has in his junkyard.

By the way 5th gear nut was just getting loose when I out the second nut on yesterday.

5th gear
 

Need a fully splined shaft with a locking collar

When they replaced the 5th gear nut (two times), once they used a clamp on type and the other time the nut had a set screw. Neither one of these held. A fully splined shaft may be the answer. Just my experience, John

just an update, after double nutting 5th gear in October of last year, it has come off again. Did not even last a year. This is a fully splined shaft too. Will take 5th gear out and forget about it. The truck has lot of miles on it now, so will just keep it closer to home and live with a 4 speed.

Sorry about your problem, but it seems to be a chronic condition with the NV4500 when towing heavy.
John