Engine/Transmission (1994 - 1998) Nuts , Fifth Gear Kind

[Dick R]

Well it finally happened , the dog gone nut came off , 87000 miles on the truck pulling my fifth wheel at 65 M. P. H. and fifth gear just went away , now for the repair , over $350. 00 in parts and tools so far and I don't even have it apart yet , as soon as it cools off outside here in Wisc I will start the job , 94 is to hot to be crawling around under the truck , ( got a question hope some one know the answer ) their is a washer that came with the new nut , concave or convex depending on how you look at it , which way does it go on the shaft ? also the nut has two brass or bronze plugs , just how important are these things ? any input would help , this thing is going to get welded in place , seems this is something a lot of owners are doing with good luck , still love that Cummins though . thanks

 

[SRadke]

The concaved/convexed washer is called a belvue (sp. ) washer. Put it on so the inside sticks out to contact the nut. The bronze plugs are suppose to go under the two set screws to protect the threads on the shaft for the event of removal. If you intend to weld they have no purpose. I personally have rebearinged way too many NV4500's with around 100k miles on them, there is no way I would weld the nut. After it's welded you buy a new shaft to change the bearings. My $. 02 tax free.



-Scott

 

[Dick R]

thank for the reply , referring to the bronze plugs , why couldn't a couple of indents be put into the shaft using a diamond or a carbid tiped drill after tightening the nut and somehow marking the shaft ? at the vary least the indents would give the plugs or the set screw something to bit onto maybe holding the nut from backing off , it seems from everything I have read this nut is not the fix, my thoughts on welding the nut it would buy me some time so as to replace the transmission with one from Standard or Quad 4x4 at a latter date . thanks

 

[SRadke]

The dual set screw nut combined with a generous dose of high strength loctite on CLEAN threads works well to secure the nut. There is a small lip on the back shoulder of some nuts that can be pushed (punched) down into the keyway in the shaft, this would be cheap insurance as well.



I'm not saying you can't weld the nut either, just that from my history with these transmissions and my background in metallurgy I wouldn't weld it. If you have no intention of ever rebuilding it and instead buying a reman unit then I suppose you have little to loose.



-Scott

 

[woodsrat]

Dick R



did you get the spical wrench to tighten the nut?? That has been alot of the problem not getting it tight enough then it backs off again. For what it worth i welded mine too.

 

[jbrowne]

Fifth gear nut. Why does it back off?

Well maybe I have that answer. A good friend and TDR member put me on to this. He swears that you must shift down when the RPMs drop to 1700. And when shifting up you have to rev to 2300 or better in order to stay in the 1700 to 2300 range. Remember there are only three combustion shots per revalution and at low RPMs and heavy power settings it will vibrate the drive train severelly enough to loosen the nut. My $. 02 Worth.

Oh by the way I have the wrench to fit the nut and would be willing to mail it to anyone that needs it as long as I get it back. And I hope you know someone that has a torque wrench capable of 350 foot lbs. Oh I have the splined socket to hold the shaft from turning if I can find it now.

jbrowne in Idaho