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Need Advice…

1738 Views 72 Replies 10 Participants Last post by  mustangmarty1967, 
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I’m pulling a trailer with an old Mustang chassis on it on level ground about 55 mph in 5th gear. I started hearing a high pitched hum from the front of the truck and smelled a slight scent of something burning. I let up a bit. Then a sudden grinding sound for a second until I let up completely. Thought it might be the turbo blowing again. Put it into 4th and nursed it in to a Walmart parking lot. I pulled the BHAF and hose to check the turbo. It seems fine. Belt seems okay. It starts up fine and sounds fine. There is engine oil leaking from the where the engine and tranny bell housing come together. I’m wondering if the clutch is going out. Has this happened to anyone else? Any ideas what it could be? I really need to get this car moved today.
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Antonm
Unfortunately that's a common issue in the NV4500. General consensus is the only "real" (aka non band-aid) fix is a fully splined main shaft. But band-aids exist for a reason.
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Antonm
Give these guys a call.

Standard Transmission & Gear | Tremec - Borg Warner - New Venture - Getrag, Cummins, 4 speed transmission, 5 speed transmission, 6 speed transmission

We stock a complete line of manual transmissions, differentials and transfer case parts & rebuilt units. Dallas / Ft. Worth in-house R&R on all differentials, Transfer Cases and Manual Transmissions. We also remove and replace clutches and flywheels. Great Service & Prices on Standard...
standardtransmission.com standardtransmission.com

They're in Forth Worth Texas, but they have a really solid reputation for NV4500 work.
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Antonm
Oh, so you're going for the band-aid. I've heard that once the fifth gear gets pushed off once, the splines on the main shaft get a little worn/ loose during that process and those retainer nuts don't hold for long. Supposedly the retainer nuts work a lot better if you install one before fifth gear falls off (and the splines get worn/ loose) , but not so great after. Of course that's all rumor and hearsay obtained from the internet, so who knows if its actually true or not.
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Antonm
mustangmarty1967 said:
I wonder if I should order a new shaft then too? And if when I get in there, I find the shaft is good, return the shaft? Would I even be able to tell if it’s worn? How hard is that to change?
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A new main shaft requires a complete disassembly of the transmission, literally every part has to come off/ out of the case.

It can be done at home with a manual and some special tools, but most leave that job to the pros (like Standard Transmission and Gear I linked earlier).

I say throw the band-aid on and see how long it lasts. If the band-aid fails, then start looking at a complete rebuild, just MHO.
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Antonm
David Ivory said:
I have done extensive research on this. I own one. I have talked to many people that own them. There is no 100% permanent fix for this. It mostly comes down to the driver. As long as you don't turn up big power and tow heavy or lug it in 5th gear it most likely will be fine. If you do any of that it will eventually come off due to the inferior design of the splines. I have seen these go several hundred thousand miles without problem. Too much back-and-forth stress on the gear causes it to move on the shaft eventually loosening ANYTHING that tries to hold it.
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I too have done extensive research, and own two of them. A fully splined main shaft is the permanent fix. One of my NV4500 12 valves has the band-aid retainer nut (that I installed) and the other has a fully splined main shaft. I'll continue to run the retainer nut on the one that has it until that transmission either fails or needs to come out for another reason.
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Antonm
David Ivory said:
Excellent! What has your experience been with the fully splined main shaft? How many miles have you put on it? What loads did you put it through? What brand shaft is it? What type of retainer did you use on the fully splined shaft to hold the gear on?
I have seen 320K miles on the stock setup. I may go with your setup instead! Thanks!
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The one with a fully splined shaft I had re-built by Standard Transmission and gear out of Ft Worth TX (link to their website below). If your interested in going that route , take a look at their website or give them call. I have never heard of professional built transmission with a fully splined main shaft having the fifth gear fall off again. They have other issues (bearings, heat and lubrication) if you overwork them, but the fifth gear stays in place with fully splined main shaft.

Standard Transmission & Gear | Tremec - Borg Warner - New Venture - Getrag, Cummins, 4 speed transmission, 5 speed transmission, 6 speed transmission

We stock a complete line of manual transmissions, differentials and transfer case parts & rebuilt units. Dallas / Ft. Worth in-house R&R on all differentials, Transfer Cases and Manual Transmissions. We also remove and replace clutches and flywheels. Great Service & Prices on Standard...
standardtransmission.com standardtransmission.com
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Antonm
David Ivory said:
Excellent, thank you. How many miles on yours now?
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Mileage isn't the cause of failure, its load and torque applied. An nv4500 that has a stock engine in front of it, and that also isn't used to tow heavy in fifth gear, will last a lifetime in stock form. Put a brand new zero-mile stock nv4500 behind a high torque engine, then tow heavy in fifth gear, and it'll fail with a quickness.

If you don't use your truck in such a manner that it needs the upgrade (or have plans to use your truck in such a manner), then the upgrade is a waste of money.
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Antonm
I’m with GAmes on this one. He may be a grumpy old man, but he generally knows his stuff.
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Antonm
David you need to shut the hell up. You’re the idiot in this conversation and you don’t seem to realize that.

Going to name calling and putting words in other peoples mouths when you can’t win with logic is pretty dang pathetic.
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Antonm
David Ivory said:
NV4500 Transmission Problems | Find NV4500 5th Gear Fix Solutions Online at Torque King 4x4
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Wow, a business that’s sells parts says that their product is the best and thats it’s only product in existence that will fix your issue.

Wonder if any other parts retailers have thought of that marketing strategy???Seems like a solid way to sell parts to people.
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Antonm
David, you exemplify the things you kept calling GAmes, as such I’m out. Have a good life.
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Antonm
No gasket , just RTV ( at least on both the ones I’ve pulled apart anyway, including one freshly rebuilt by standard transmission and gear)
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