I think the retainer nut lock from fifthgear is very good for 4x4's. Quick and efficient.
Now For 2wd models:I am a welder of 40 yrs. I have fixed 2 of these with a double nut and a good tig bead with preheat and post heat of 350degrees on the shaft and a filler rod of 308 stainless steel. They both are good after over 100k. I temper steel almost daily, and if done right it will not hurt the shaft. But I have also done a good fix with a machined shaft to hold the double nuts in place by locking it against the nut with a thrust washer and C clip in the slot where the older speedo clip goes. Almost a 100k on that one and I just looked at it the other day and as good as the day it went in. And this truck tows constantly. The newest mainshaft is best but I would even back it up with this process.will be doing another one of these soon. I'll try to post pics.

 

Do the two wheel drives have this same issue and is their a fix for them? Mine is an automatic but I was looking at a stick not too long ago.

Rick

 

rick the fix above is what I do for 2wd.

 

DUH, I guess I should have read it. Is this a very common thing? I know it sounds that way on a forum but I would bet percentage wise it is not as bad as it sounds.

Rick

 

Its common enough that there's plenty of aftermarket fixes available and as you've probably read, a few backyard fixes too. But I understand that aside from basic design reasons, the 5th gear failure rate depends more on driving habit than anything else.

 

i agree totally. Some of us just seem to work them harder than they were thought to be able to handle. But ain't we supposed to work'em hard? I have found the best fix though is to go with a Gear Vendors and tow in 4th with the GV kicked in. Never work loose the 5th nut that way.

 

I read that running under 2,000 rpm in 5th is very hard on it.
do you agree this is what knocks the nut loose?

 

Yes.....and no. First you have to understand the principle design of the NV4500. It was originally a 4 speed with the 5th gear added later on to the outside of the case. So for that reason unlike 1st through 4th, the 5th gear shaft is only supported by a bearing on one side of the gear. Also, the 5th gear shaft splines do not extend the full length of the 5th gear itself. Well this isn't that big of a deal for most applications except when you add an engine that produces 300 ft lbs of torque.....at idle stock.....and can perform most everyday driving tasks just off idle too. Double or triple the torque and you get the point how things can get far from the trannys limitations. Load stress on the splines causes the 5th gear to rock on the shaft and essentially wiggle around whereby the only thing holding the gear on the shaft is the nut. Eventually the nut cant hold the gear back which allows the gear to fall off the splines. Thus the reason why all the "easy" fixes entail new nut designs. Fixing the shaft is the "real" fix since then only is the gear fully supported but even at that, a better nut is necessary. So what kind of driving is hard on the 5th gear? Well that would be any kind of high stress low RPM load and any kind of ON/OFF load. Either of those would give reason for the nut to work its way off the shaft. Which means, if you tow really heavy then you'll probably want to stay out of 5th gear unless driving in very low load situations and also if you have a habit of harsh transitioning between accelerating and decelerating while driving in 5th gear then you'll probably experience an issue simply because of the ON/OFF load you're creating on those splines. Lastly, if you have an exhaust brake, dont use it in 5th gear.