5th gear nut fix NV4500

yjay

yjay

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Jun 21, 2014
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I have searched quite a bit on this and find a lot of different opinions. My trans is coming out Tuesday for a new Southbend, and I was thinking it would be a good time to fix this. I know the full spline shaft is ideal, but I got a ton of money going out right now, so what is the preferred fix while using the stock shaft? Or wait till it comes off if ever and fix then?
Thanks.
 
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Any fear of breaking the shaft after this? Pre heat/post heat required? Fully weld or stitch?
 
I didn't pre or post and I put 4 small welds on. That was 2 years ago and it's still on the road.
 
Welding the nut is just asking for a busted shaft.

The end all to the 5th gear failure. This nut splines to the main shaft and locks the nut in place.
 

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From my study work I found that oversize tire tend to increase the chances of 5th gear nut failure. when you go around asking all the people that have had 5th gear nut issues all had 285 or larger tires. Like myself I've never seen a issue with ithe 5th gear nut and dropped my 265 to 235 years ago. Also cleared 231k miles and still rolling and hauling heavy trailers and towing in 5th gear.

http://i60.tinypic.com/2py9ge9.jpg

As for fixing I would rather use MaxTorq's device which will secure the nut in place. Welding is not a good option.
 
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No personal experience with either, but welding has been done WAY too many times to say it's not a good option.

My old 12v has 100k with 265s and 180k with 285s and it's still holding on just fine, I wouldn't say tires cause it.
 
displacedtexan said:
No personal experience with either, but welding has been done WAY too many times to say it's not a good option.

My old 12v has 100k with 265s and 180k with 285s and it's still holding on just fine, I wouldn't say tires cause it.
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I think you are both on the same page but in different words. Lugging in 5th is what typically causes it to back off. I think larger tires lead to lugging more often with somebody who isn't aware of what it may cause.

That and a 16 year old dikhead who just gutted their AFC and wants to stare at their stack leads to it backing off.
 
zfaylor said:
I think you are both on the same page but in different words. Lugging in 5th is what typically causes it to back off. I think larger tires lead to lugging more often with somebody who isn't aware of what it may cause.

That and a 16 year old dikhead who just gutted their AFC and wants to stare at their stack leads to it backing off.
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True...
 
Well I ordered the collar this morning. Seems like the best option if keeping the stock shaft. $145 shipped. We shall see. Truck has 215k so maybe it never would have come off. Original clutch too believe it or not.
 
Ive had two trans that had a collar like that in them. Both had the tabs break off and nit still backed off. Weld it or buy the updated shaft and be done with it seeings that piece cost just as much as the shaft.
 
bradley59dzl said:
Ive had two trans that had a collar like that in them. Both had the tabs break off and nit still backed off. Weld it or buy the updated shaft and be done with it seeings that piece cost just as much as the shaft.
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This exact one from fifthgearrepair.com? This one is chromoly and they say they've had no failures with this design when I talked to them. They said a tiny percentage of the first design models failed, but not these ones. I realize that I was talking to the people who are selling them so take that for what it's worth.
 
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I just recently just put my trans together n I bought it brand new nv built with all the upgrades but I runnin a dual disk so I got the upgraded 1 3/8 input shaft so I had to tear it half way down to reshim it n the fifth gear nut they used was junk so I replaced it with one I had layin around the shop from quad 4x4 that has a strew that pulls it together n has worked good in other trans. And I'm running 35s. When I change the oil n filter on the trans I'm gonna buy the new set of Dan has at quad it's a three washer kit with the same nut I'm using now. U get that n the full spline main shaft for 325-350 I do believe.
 
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