NV4500 - 5th Gear Nut, Final Fix

bbtank45 · Jul 19, 2016

I bought a 260k mile 1998 Dodge Cummins 2wd with an nv4500 as a tow pig back in December. I knew when purchasing the truck that it did not have an easy prior life (stack, South Bend DD clutch), but like most of my purchases (similar to Kels Texas motorhome trip)....I try to buy things when people feel like they arent worth anything (or often tight on cash and selling on a whim). Then of course, I spend my own time and effort (and $$) sorting out the PO's problems until I get it to suit my needs.

Accoding to the PO, the truck had a rebuilt nv4500 with the 5th gear repair done during reassembly. I did not ask about them the repair method, as I was purchasing the truck regardless. In January, while unloaded and driving on a 55mph state route I lost 5th gear. For those of you that arent aware (and interested in more information), Quad4x4 has a lengthy write up on the cause and reasoning for the 5th gear failure. I pulled the tailshaft housing off, welded the 5th gear nut to the mainshaft and rolled on down the road. A little less than a thounsand miles later, and the 5th gear is gone again. It is recommended, and strongly encouraged to replace the mainshaft with new when significant wear is visible around the press fit area. Either way, Ill be replacing this one because I welded it.

My question to the Hardline group; what is your recommended method of repair and with what parts? There seems to be an array of aftermarket repair solutions, but nothing has stood out as the most reliable or preferred solution. Im not turning the truck up or looking for high performance, just looking for dependability to take my rig to parks within 6 hrs. I dislike the thought of dragging a 30' trailer back from Harlan, KY in 4th gear with 4.10's for 5 hrs...

Just after I welded

Pulled the trans on Friday.

Quad4x4 Article
https://www.quad4x4.com/NV4500%205th%20Gear%20Failures%20and%20Solutions.htm

Thanks for the help.

mr.mindless · Jul 19, 2016

I put a RoadRanger 13 speed in mine after my second 5th gear failure. Lots and lots of floor work, and it drove like a big truck. I loved it.
My buddy put a Fuller FSO 6 speed in his after his second 5th gear failure. It's the way the truck should have come, and you wouldn't even know it wasn't stock if the interior was finished.

I never did the Quad 4x4 shaft, but it's the only way I'd go if I wanted to try and keep a 4500 together behind a Cummins.

You could always swap it out for a G56 or find an NV5600 instead... but I'd go FSO myself if I wanted something that anyone could drive for reasonable cost of doing the swap.

MoparMan · Jul 19, 2016

From what I've seen and heard there is no way to permanently fix it, I could be wrong but just letting you know what I've seen and heard for several years. From my understanding they will always come apart at some point.

I really wanted to buy the clean 12 valve dually that was on here for sale but I knew I would have to swap in a 6 speed very soon, and they can have problems as well.

Nuts · Jul 19, 2016

Did it actually have the repair when 5th fell off the first time? "EVERY" 12v has the KDP fixed and "EVERY" nv4500 has 5th fixed. 9 times out of 10 those are just BS someone uses to sell a truck. I've had 4 nv4500s and as far as I know none were fixed, and none fell off while I owned the trucks. I look at it like this, if you're not dragging 15,000+pounds every day for 100s of highway miles a stock replacement shaft will defiantly work. And, not being a **** but the truck pictured doesn't look like a new truck, so if the factory shaft lasts 200k-300k miles are you really worried about a stock replacement falling off next week?

hokie_yj · Jul 19, 2016

Mine came loose in my old '97 dually. I took it to a buddy at a local diesel shop and they put some type of upgraded locking nut on it. I'm not sure what brand or type it was. But his exact words were, "You'll never have to worry about it again. I torqued it to oh holy **** plus two turns."

I drove the truck for about 3 years after that and then sold it to a buddy at work 2 years ago when I bought my '04. He's still driving it today, and he's not had a problem out of it that I know of.

Hillbilly · Jul 19, 2016

It might let go tomorrow, but I've had good luck with this product sofar. http://www.fifthgearrepair.com. I'm in no way affiliated with them. I myself lost 5th gear a few times. First time I put it back on with loctite and tightened the heck out of it. Lost it shortly afterwards. This time I put the upgraded nut from Dodge on it. It lasted longer than the first fix, but still let go. This last time I tried the above mentioned product and sofar so good. Think I installed it in the fall of '12 and haven't lost 5th gear yet. :driving:

grcthird · Jul 20, 2016

The nv5600 is a good upgrade but holy **** they are expensive, looked for one for a while to put in a friend's truck before we found a decent used one on craigslist. He has a good core and a rebuild kit if you go that route and need some parts.

collinmaune · Jul 21, 2016

Kennys pulling parts built me an awesome nv4500 billet input shaft 5th gear nut fix and everything it was only around 1200 with the billet shaft and core transmission with out bell housing. I'm more worried about 3rd gear in mine then 5th honestly. But its behind a twin turbo 12 valve but i would highly recommend calling them they will point you in he right direction. They are based out of Kentucky.