Coming home from work, accelerating mildly in 5th and it feels like it slipped out of gear. Nothing there. I tried shifting back into 5th...nothing. No noise, no nothing. Drove home in 4th.....

What happened? 5th gear nut come off? What to check first? How difficult to fix?

Thanks!

Dave

 

Do a search. You'll have enough reading material for weeks.

 

I looked in the FAQ and didn't see anything....

Search it is...

Dave

 

Been there done that twice. Nut backed off and gear slipped off. You can try a new nut and weld the nut to the main shaft and it might get you by but then again it might not. My welded nut only last 250 miles of RV towing. When they go it is usually because the gear has worn the smooth race on the main shaft and only way to truely fix it is replace the main shaft. You might as well get an overhaul kit and put new syncro and bearings since you have to tear it all apart to replace the main shaft. Look up QUAD4X4 on a search engine. Their tourque king main shaft and gear are a long term fix but the fully spline main shafts work well to. QUAD 4X4 has a good write up on what happens and why and the design flaw with it and how they have fixed it.

 

If you plan on keeping the truck for long there is only a couple of long term fixes. None involve the nut.
The problem isn't the nut, it's the shaft.
Read this> http://quad4x4.com/NV4500%205th%20Ge...0Solutions.htm

 

This may be true, but I would guess the motor cause some kind of harmonic that cause the nut to back off when the motor is lugged in 5th gear. My gear had no play and was hard to get back on the shaft, made a socket to tighten the nut and have had no problems, I never run 5th under 1600 rpms. Also I would not weld as you will cause a weak spot in the shaft.

 

I'm going to do this tomorrow.

I have 4 quarts of the Mopar trans oil ($101...) and I will take off the tail shaft, clean the threads around the nut, use red Loctite and tighten the crap out of the nut. And hope that works.

I WILL see how loose the gear is, though.

One solution I saw was to get a new nut, grind the old one down enough that BOTH nuts can fit on the shaft and use the second one as a lock nut. Sounds good....

I'll consider that for NEXT time....

Thanks for the replies!!

Dave

 

$300 later and it's back on the road. I didn't have time to do it so I took it to a local shop and told them what the problem was and how to fix it. They had never done it before but this guy has always done a good job. I supplied the Mopar gear oil.

He said the nut had the set screws in it so I guess this has been repaired before! Guess the new nut isn't all that good..... Hope I don't have to do this again anytime soon!!

Dave

 

Nope. The Dodge repair nut sucks about as bad as the OEM. Been there. Only fix is the shaft. Problem is in the splines. Not just the nut. Other fix is a good heliarc weld of the nut to the shaft. Did mine 100,000 miles ago and it still tows my 5th wheel beautifully. The shaft is an alloy so you need a good TIG man.

 

Some good advice by Purplezr2, don't lug the engine down in 5th below the 1600 rpm mark. It has been reported over the years that with Stock and especially aftermarket power, it does harmonically hammer the nut loose.

 

Actually the best fix is a Gear Verndors overdrive unit. I have had the nut problem on 3 trucks. I fixed the last one permanantly, but I fixed it best by not towing in 5th gear at all! Funny, Dodge tells you not to tow in overdrive. The unit lets you run in 4th which is made to handle the full load of the Cummins, but then at a rpm right in between 4th and 5th gear. I now have an automatic that I use a gear vendors in. Don't have to worry about the OD in the trans anymore, best addition to a CTD anywhere!

 

I've been hearing instead of welding to the shaft weld the nut to the gear

 

Just dropped 5th gear myself on the way home. Somebody said something about "design flaw", seems this truck is one giant design flaw that Dodge won't fess up to! More money spent. Gonna park the turd and finish off the week welding in my wifes explorer and towing my trailer! Need to buy another truck I guess. Tired of this thing costing me jobs and money.

Wow, funny thing is the Torque King stuff is going to run me $600, can get a reman tranny for a $1000. This truck is killing me....darn money pit from haydes! Guess I need to pull a 12 hour day tomorrow to pay for the trans.

Ok, that's weird. According to Quad 4x4 the NV4500 is, "Now, when you consider the NV4500 is rated for up to 460 ft-lbs. of torque and 19,000 lbs. combined truck and trailer weight, you can see why part of the responsibility for transmission problems must rest on the shoulders of truck owners who grossly exceed the vehicle design limits and insist on making their ¾ or 1 ton work like a 2 or 3 ton truck".

Now if I'm not mistaken does a 2002 Dodge not come from the factory with over 500lb-ft of torque? I thought they had 535 or something in that neighborhood factory. Which means it was overloaded from the time the new tires touched the ground in Mexico. Please correct me if I'm wrong.

 

I think its an engine vibration issue not the trans its self, I have never seen a gm have the issue

 

The more I read about this truck the more I wonder why it is they put the "HD" behind it? Don't tow heavy in overdrive? Vibration causes nut to work loose when towing in overdrive. Use 4th gear when towing heavy? Really, 60mph on the interstate? According to Quad 4x4 it's a problem in anything that has an NV4500. Seen some things on an search talking about Chevy's having the problem. Thought it was fixed on my truck due to the year model but found out not fixed when I did not have 5th gear. Going to pick up new nut today, don't have time to let truck sit around waiting on parts from mail order. Band aid it back together and seriously start looking around. Would not mind an F550 that I could ram the Cummins off into!