Engine/Transmission (1998.5 - 2002) nv4500 5th gear nut

[MKresch]

I just ordered the updated 5th gear nut from pliers and i need some help. has anyone out there done the upgrade? if so is there any tips on changing the nut. i'm told i'ts simple pull the drive shaft and cross member, remove the tail housing and the nut is easily accessed. any advise would be great!

 

[SOOT]

I have done it about 7-10 times. you don't have to pull the crossmember. just make sure that you have a catch can under it when you pull the tail housing loose or you will take a bath in trans fluid:{ you will see the nut and gear once you have pulled the tail housing off.

 

[TPlasek]

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.



edit: it really doesn't 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.

 

[MKresch]

MY TRUCK HAS NO BOMBS ON IT YET, AND I DON'T BEAT ON IT EITHER. I PULL A 30' TT (7000 LBS) ABOUT A DOZEN TIMES A YEAR WE ARE GOING TO CONNECTICUT END OF THE MONTH AND JUST WANT A LITTLE PEACE OF MIND. BUT IT WILL GET A UPDATED STANDARD TRANS & SB CLUTCH BEFORE IT GETS BOMBED. NO USE PUTTING THE CARRIAGE BEFORE THE HORSE! THANKS FOR THE HELP & INPUT

 

[TPlasek]

The good thing is, "WHEN" it falls off, you still have 1-4 to get you home

 

[rashwor]

It's Friday and I am thinking...

That is a deadly combination. Here is my thougt. When the nut comes off, couldn't you replace the nut with a new-improved nut. Then take a coal chisel or something similar and mark the threads on the shaft? My thinking is that with a marked shaft it would be harder for the nut to work off. Just don't mark the threads on the shaft so bad that you can file the marks out and get the nut off, should you ever need to get it off.



This comes from my redneck days of shear-pens in old bushhogs. We were too thrifty to buy expensive locknuts for bolts that were just going to break anyway. Screw a plain nut on the bolt, tighten, and cross-cut the extra threads on the bolt so the nut would not work off. I got pretty good at this and it worked really, really well!



Your thoughts please!

 

[RustyJC]

Piggy-backing on rashwor's post, if you're ready to change out the shaft should there be a next time, you might try this engine building technique we use on crankshaft counterweight stud nuts on large Cooper Bessemer industrial engines we manufacture. Basically, we take a punch that has a 30 degree included angle with a point that's been blunted to give a 1/8" diameter flat face - the same angle would work for you, but since the output shaft is considerably smaller than a counterweight stud in our engines, you might want to go with, say, a 1/16" diameter flat face. Place the punch at approximately a 60 degree angle to the nut face (or a 30 degree angle to the shaft) and stake the nut to the shaft by striking the punch. On a counterweight stud and nut, we require a minimum penetration of 1/16" - this may be too much for the smaller output shaft and nut. The idea is to get deformation of the nut and shaft threads, not to drive the punch below the root diameter of the threads on the shaft. We then repeat this process 180 degrees from the first stake mark.



Done correctly, the only way you'll get the nut off is with use of a die grinder or Dremel to grind out the deformed thread areas of the nut and shaft, or you cut the nut. Obviously, this only works one time - a new nut and shaft would be required if you ever want to remove the nut.



Just something to think about.....



Rusty

 

[rashwor]

Wow Rusty!

I never realized I was using that much engineering and science! I am just a simple minded redneck.

 

[PUMPERDUDE]

I just beat the **** out of mine with a BFH and 3/16 punch. Coonass Locknut. If it goes again Standard Transmission will get a call

 

[Deezul1]

I tried the new and improved nut and the "Coonass Locknut" trick and it lasted about 6000 miles. I dont think the indentations in the shaft were deep enough because after the nut came off the shaft was in pretty good shape. I smacked that center punch hard with a 3lb hammer about 10 places and figured it would never come off. So really hit it hard to get it done right.

 

[MKresch]

still waiting on the new nut . i'm going to get the strongest loctite and use that "coonass locknut" trick. wea are leaving on a camping trip day after tommrow early am so it'll probably get put on next week. thanks for all the imput guys