Engine/Transmission (1998.5 - 2002) 5th gear fell off after only 5k miles...what next

[azcummins]

My updated 5th gear nut fell off today after only lasting 5k miles. The transmission shop that put the gear on the mainshaft that swore "it would never come off" is refusing to warranty their work as I didn't order the part from them or let them put the transmission in. The shop simply put the new gear on the mainshaft and gave the transmission back to me.



I don't want to have to go through this mess again in 5k miles so I'm considering doing a straight up swap of a new/refurb'd NV4500. I considered a rebuild with the new mainshaft, but local transmission shops wanted $1k to do it.



Any advice from people who have battled this 5th gear problem and won?

 

[Joseph Donnelly]

call 1-800-std-tran or visit www.standardtransmission.com

 

[azcummins]

Thanks for the advice Joseph! I put an email into them last night so I'll let you know what I do.

 

[TPlasek]

This is a cut and paste from one of my old threads dealing with the fifthe gear nut.



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=74778&highlight=gear+nut





Without the FULLY splinned mainshaft, the new nut is only a temporary fix. I would spend the extra $40 and get the fifth gear too if this is the route that you are chosing. That will make it last a little longer.



Here is my experience with a friends truck.



1. 106k fith gear nut falls off, we installed new "updated nut"

2. 110 updated fifth gear nut falls off. We install new nut and fith gear at the same time.

3. Just last week a 122k fifth gear fell off again, we ordered the fully splinned shaft and rebuild kit for the NV5000.



Hopefully you will have better luck.



Mine fell off at 94k and I fixed it with the fully splinned shaft and new fifth gear. I am at 110k now with many hard miles with no problems.



The fith gear problem does NOT really have anything to do with the nut itself. When the short splines become worn, the fifth gear itself will start to rotate back and forth as you give fuel and then let off. It is this rotating action that loosens the nut. Short or welding it in place a new nut is just a patch that tries to cover up the real problem. Once again if you replace the fifth gear and the nut you will buy yourself a little more time, but after you take the case apart and look at the problem, you will see what I am talking about.

 

[TPlasek]

I sent you a private message as to where to get the parts at the best price.

 

[azcummins]

TP-

thanks for your help. I'm still trying to figure out what to do. I'd really like to sell the truck, but I don't have the $$ right now.

 

[TPlasek]

If you can do the work yourself, you can do it for about $400. I think I spent $550 on new bearing synchros and the fully splinned fith gear fix.

 

[azcummins]

TP-

Dunno if I could do it myself. I can easily get the transmission in and out of the truck, but work inside the transmission looks tough.

I'm taking the truck to the transmission shop tomorrow so they can "see what happened". Perhaps I can cut them a deal where they'll put in the new mainshaft & gear for free since they screwed it up...

 

[Gary - K7GLD]

"Perhaps I can cut them a deal where they'll put in the new mainshaft & gear for free since they screwed it up... "



UMMMm - if you simply bought the "improved" nut, and they installed it for you as you instructed, how did THEY "screw it up"?



Pretty hard to "screw up" simply threading on a new nut and torqueing it to spec...

 

[azcummins]

Gary-

they swore up and down that the nut and gear would never come off. They said they've never had one come off, etc, etc. Now one has come off so they need to fix it since they were so confident of their work and now it came off.

 

[Gary - K7GLD]

To each his own - but I have seen posts from a number of owners who installed the "improved" nut, and experienced the same thing you did - hell, ONE of them even posted to THIS thread.



In MY mind, the "screwup" is not with the outfit doing the work for you, but the poor original design of the transmission to begin with, and then the lame "fix" for that failure... But of course, it's lots harder to get $ati$faction from DC or the transmission maker than it is the poor slob in the local shop who simply followed directions and installed the "fix"...

 

[DDT]

As some of you know I just had the same problem. 40K on a rebuilt 4500. I went with the nv5600. I even called new venture direct. I was told the they new they had a big problem with the 4500 behind the diesels. At this point they were in the middle of the 5600. So they decided to spend no more time or money on the 4500's. since the 5600 was going to replace the 4500's. That is the story I got. I was also told the 4500, 5th gear was not to be used for any heavy pulling. the 5600 can be pulled in 6th with no problem. I can tell the difference between the two. the 5600 takes more power than the 4500 did.

 

[Deezul1]

The only way that nut will stay on is with a fully splined main shaft. I had mine come off twice within 6000 miles and then did the splined shaft and its still on 35000 miles later. The shop that did mine charged $950 parts and labor including R+R. I went to lots of places and found quite a difference in prices and had one shop tell me they just weld the nut on. I couldnt leave there fast enough. Pics in readers rigs section of the staking of the nut with a BIG hammer and center punch in hopes of making it stay on, no luck.

 

[azcummins]

DDT-

the kicker is that this truck has done MAYBE 10k miles of hauling. Of that, around 400 miles was with a 3 horse trailer, rest was with a 2k # ski boat or 500# jet ski. The truck was my daily driver and I never abused it.

How much did that 4500/5600 swap put you back?

 

[SMorneau]

I had a lot of trouble with the NV4500 transmissions. I finally got tired of it and now I am trying a 5600. Beware the 5th gear nut is not the only thing that fails on the 4500 transmissions.



There are several sources for rebuilt 5 speed transmissions with fully splined shafts you should be able to find one for about $1600.

 

[DDT]

azcummins

The 5600 and a 4x4 conversion kit was about $2600 and the drive shafts were about $150, I also put $700 in the tranfer case too. Oh you will need a larger clutch as well, so add that in to.

 

[azcummins]

Hmmm... sounds pricey... for that price it is getting close to a new truck!