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NV4500 failure?

rompinstompinmudmonkey

rompinstompinmudmonkey

1/2 ton status
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Has anyone ever experienced an input shaft failure on an NV4500?

I was driving home last night pulling a light trailer at 55mph when.....ZING!!! I lost 5th gear. I assumed that the 5th gear nut had backed off( which is fairly common on dodge 4500's)even though I had installed an updated main shaft and fully splined 5th gear to take care of that issue. I pulled off to the side of the road and shifted through all of the gears just fine, but the truck won't move in any gear at all. Instead I get a metallic grinding noise any time the clutch is engaged, whether it is in gear or not. I just rebuilt this trans about 20k miles ago and put expensive parts into it so as not to have issues like this...

Anyway, has anyone ever lost an input shaft and/or clutch while cruising down the road? What is really odd to me is that the engine was under almost no load when whatever it was failed. I guess I'll be pulling the trans today to see what came apart.
 
search front input bearing lube problem .

lots of guys over fill the case 1/2 qt to help lube the bearing better .

seen a lot of pictures on line of wiped out gear or bearing for the input.
 
Transfer case didn't jump out of gear did it?
 
Fordum said:
Transfer case didn't jump out of gear did it?
Click to expand...

LOL. Funny you should mention that, thought I lost my clutch out in the woods a couple of weeks ago. First got some grinding noises while doing a 60 point turn, but no movement. Then, no engagement at all.

Turns out I had somehow knocked the t-case shift lever out of gear just enough and that was the only problem. Embarrassing, but far better than having actually lost the clutch or trans!
 
Our other work truck lost one a few months ago running down the interstate loaded. It had been replaced/rebuilt not too long before. Never found out what caused it, I'm interested in hearing what your issue was if you find it.
 
Well... I tore it down and figured it out. The front input bearing is smoked and the input shaft is broken. I overfilled the trans thru the shifter when I installed it. And oil came out of the fill plug when I pulled it to see if it was low.

At this point I'm confused on why the bearing went and the shaft broke. I need to tear town the rest of the trans now to see if there is any other collateral damage..
 
My input shaft went out last year and took the countershaft with it. The cause was a thrust bearing being installed on the input shaft. (It was in front of the gear, it should have been behind it)
image.jpg

image.jpg
 
Well, I tore the trans completely down and the only thing that's wrecked is the input gear, bearings, and the 4 the gear cone and clutch.

I filled the trans with Amsoil MTG when I installed the trans and when I drained the fluid it was burned and almost black. I only have about 20k on the trans since the rebuild but I do tow heavy trailers quite often . I think I'm going to add a pair of Fast Coolers to the PTO covers to help keep the trans cool and add another 2 qts of capacity to the trans.

As far as the input shaft goes, the cheapest replacement on EBay is $63 (imported) and a new OE spec replacement from quad 4x4 is $200. I'm a huge believer in "you get what you pay for" but the expensive shaft is imported too. I've thought about switching out to the larger 1.375" input shaft but my South Bend Clutch wasn't cheap and doesn't need to be replaced. I've done some reading in other forums and it sounds like South Bend may install a new hub in my clutch disc for free if I buy the input shaft kit from them. I have no idea what they charge for an input shaft kit though...
 
I put a big shaft into my dodge 4500. With a big dual disk clutch from south bend.

There's shims for the input shaft. You need correct end play. Or preload. I can't remember which off the top of my head right now.

You want a litre over filled the case. Not just a little bit.
 
IIRC payed $600 for a south bend billet 1 3/8" input. About 6-7 years ago. But I was pushing around 1300ftlb of torque through it. So I wanted the assurance.
 
I think I overfilled by a pint. The main shaft has a spec of .002-.006 endplay. I remember being right in the middle at .004.

My motor is turned up, but its by no means crazy. I still have the stock injectors and lift pump on it. I do have a water-air intercooler, water/ methanol injection, the pump timing advanced, a Denny T stage 2 fuel pin, and the full fuel screw maxed out. I have never had it on a dyno but with the mods I've done I should be in the neighborhood of 275-300 HP and 600-650 TQ.

Do I need a bigger input shaft? This one only broke because the bearing seized

This bearing was obviously run dry, was the trans too low or do I have another oiling issue? The trans never leaked, and the t case isn't overfull. Why did it take 20,000 miles for this to happen?

Do the coolers make a significant difference? The oil being as dark as it was concerns me.
 
Ya buddy, it does sound like you have all your ducks in a row. I can't give you a reason for it. unless it was plain and simply a bad bearing.

I don't think the pto coolers are nessisary at all. I'm not saying they don't work. But I don't see the cost/value relationship adding up in my head. thats just my personal opinion though.
 
Not true.

It must be a synthetic. 75-90 GL-4 rating. That's it.

But most people don't understand what GL-4 means. That's the problem. The rating is for the benefit of the carbon fiber brass syncros not the bearings. Bearings are bearings. But you smoke the syncros right fast if it's not GL4 oil.
 
So do I need to be overfilling my NV4500? Mine is right at the fill plug level with the correct GL4 fluid.
 
All the official information says that only Castrol syntorq, the GM PN 12346190, and the mopar equivalent are approved by NVG for use with the nv4500. Mine only came with a notice saying that using any fluid other than the GM version would void the warranty. I'm not sure why anyone would take a chance on other oil.

But if the bearings are shot, then that may be another problem, unless bad oil caused the syncros to go bad and the syncro particulate contaminated the oil, which then caused a bearing failure. Sounds like the oil didn't look so good.
 
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