Engine/Transmission (1994 - 1998) NV4500 5th Gear popping off . . . .

[RBlackford]

For the second time in six months, while towing a small RV, my 5th gear has slid off the splines. Last time, we slid the gear back on and tightened the nut, then placed two tack welds on the nut/shaft. That obviously didn't work for long. Anybody have a good fix for this problem? Is this a symptom of a larger problem in the transmission?



Thanks!



97' 12-valve 2-wheel 5-speed

 

[GAmes]

You really need to learn how to do a search. Lots and lots of posts on this subject. The short version is that 5th gear is a well known problem in the NV4500.



Welcome to the TDR.

 

[bnelson]

Take the time to make the correct repair. This means a new fully splined mainshaft which means pulling the whole transmission out of the truck and taking it all apart. By now all of your local suppliers will have the correct parts in stock. I fixed mine three times, including tack-welding the 5th gear nut (that lasted 65,000 miles on my '97), before I did it right. When you get the correct pieces make sure you tighten the new 5th gear nut all the way to the 400 foot-pound of torque specified. If you are mechanically inclined you can do the work yourself. Enjoy:- Brad

 

[RBlackford]

Thanks Brad,
I will start looking for the new mainshaft.

Robert

 

[RBlackford]

GAmes,

I thanks for the Search tip. I will do as such, hopefully to alleviate the problem. Any thoughts on converting to the six-speed transmission?

Robert

 

[GAmes]

GAmes,



I thanks for the Search tip. I will do as such, hopefully to alleviate the problem. Any thoughts on converting to the six-speed transmission?



Robert

Sure, and take this as a purely personnal opinion. A few years ago, after replacing my 3rd or 4th NV4500 I thought about the NV5600 conversion. This was before New Venture was sold by DC. The first obstacle was cost, then it was about $4000, no idea what it is now. I could have my transmission rebuilt 3 or 4 times for that. I also have a 2WD and the speedo sensor is on the tailshaft. No place to put one on a 5600. Now that New Venture is out of business, 5600s and their parts are at a premium. Standard Transmission in Ft. Worth will not even sell you a rebuild without a trade-in core. I do business there regularly. One of their guys told me that when the 5600 fails it is always catostophic, i. e. the rebuild is always really expensive.



My opinion... ... ... . the 4500 is a damn fine transmission, and if taken care of will last for over 100k, no problem. The fully splined shaft rebuild is money well spent, and the trans (unless you pull trailers for a living) will probably still be in the truck when you sell it.