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Cronus577

Rebuilt NV4500 sticking in 5th

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Cronus577

Just put in a rebuilt NV4500 with a 1.375" input shaft, and fully splined output shaft. The guy who rebuilt it told me to use 50w full synthetic which I did, 1 gallon of Lucas 50w full synthetic was used. Drove it around town around 150 miles breaking in the new clutch, no issues, drove it this morning from Clovis NM to Lubbock Texas, it's a straight shot but some of the town the road runs through slows down to 30mph, no issues down shifting. There are also a few lights on this road that I had to stop at from 75, again no issues.

 

Driving back to Clovis about an hour into the drive I went to pull off to a gas station and get a drink and it did not want to come out of 5th. Shut the truck off, pushed in the clutch while trying to get it to come out. After a few minutes of this it finally releases like normal, seemed to just slide right out with no binding. Jumped on the highway and got up to 75, wondering if it was just a 1 time thing tried to pull it out of 5th and it slid right out. Coming up to a town and needing to slow down I tried to pull it out of 5th and it didn't want to release, this time just holding in the clutch and shifting like I was trying to go into 5th a little more and then pulling it into neutral seemed to do the trick. 5th gear doesn't seem any harder than any other gear to get into, all of the rest of the gears including reverse go in just fine. I'm no stranger to losing 5th gear, happened twice on my old transmission both times within 20 minutes of my 8 hour drive from San Antonio Texas to Clovis Nm. Does anybody know what the issue is or what could be causing the hang up? There were no indicators before this happened, no grinding or funny noises, no loud humming, just normal cruising and then stuck. Could this be a 5th gear nut? If so simple fix for me. But if it's anything else I could be in a bit of a pickle. I have a trip from Clovis to San Antonio coming up in the beginning of October so would like to have this sorted out before then

Edited by Cronus577

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Dieselfuture

Kinda hard telling, usually something binds up or linkage,  could be nut backed out and not enough movement for a fork to disengage, does shifter move at all or is it just stuck in one place. Also try pumping clutch pedal several times and then see if it comes out, maybe clutch not disengaging all the way.

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Cronus577

I tried pumping the clutch, while the truck is running in neutral with the clutch in I can get it into every gear including 5th and it'll come right out as well. I put it in 5th at a dead stop and slowly let out on the clutch and pushed the clutch back in and 5th gear out like it should, it only seemed to do it after I had been up to speed rolling in 5th for a while. 

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Dieselfuture

Could be in the shift tower if it's lose it won't travel fully. Next time you're on hwy try not using clutch and increase rpm and right before you let off try pulling shifter out of 5th, it should come out when speeds are matched. If this helps may be in shift tower.

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Cronus577
1 hour ago, Dieselfuture said:

Could be in the shift tower if it's lose it won't travel fully. Next time you're on hwy try not using clutch and increase rpm and right before you let off try pulling shifter out of 5th, it should come out when speeds are matched. If this helps may be in shift tower.

Got to use my new tool kit, it's a Pittsburgh, someone stole my Craftsman last weekend. Pulled the shift tower, everything was tight. Put it back on and ran through the gears and everything seems normal. Might pull it into the shop tomorrow and pop off the tail housing and see what's going on with the 5th gear nut. It would make sense to me that it was the nut because everything was fine for the first 300 miles or so. Then out of nowhere this happens. 

 

Just sucks that if it is the nut, on a fresh rebuild it want torqued correctly. Not to mention it's supposed to be a fully splined main shaft to prevent the issue

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Dieselfuture

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dripley

That is longest link I have ever seen to get to one simple thing. 

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Cronus577

Yeah but it might work if the main shaft is fully splined but I'll see. If it is I'll get one for it, if not then I'll have to use the same method I did on my last transmission, after using pipe wrenches as tight as I could get it. An impact hammer made sure it wasn't coming if, did about 30k miles that way and it didn't come back off. But that's IF it's even the nut. But since its able to go in and out with the truck on and the clutch in I'm assuming it has to be something with the lock nut. Since it's only locking in 5th after rotational force

Edited by Cronus577

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Cronus577

I went and adjusted the hydraulics so that the pedal has more throw to it, maybe this has something to do with it. Velair's HD hydraulics say the clutch should engage 2-3" off the floor which would put the clutch pedal nearly identical as the brake pedal which is where I had it but this seemed to to engage right around an 1½-2 inches off the ground or so. I'll try to measure it but I went off of an eyeball in my driveway. Also have my single disk clutch just taking up space if anybody wants it. Probably has 20k miles on it, thought my clutch went out and had a 2 days to get it fixed before an 8 hour drive to Texas so got this one from O'riley's, ended up just being a pilot bearing. 

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Edited by Cronus577

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Dieselfuture

What did builder of tranny has to say, it may be something simple. But I still think it has something to do with 5th gear in tail housing. Nut backed out or something with shift fork, or even synchro out of place. You got 2wd shouldn't take too long to get tail piece off and see.

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Cronus577
1 hour ago, Dieselfuture said:

What did builder of tranny has to say, it may be something simple. But I still think it has something to do with 5th gear in tail housing. Nut backed out or something with shift fork, or even synchro out of place. You got 2wd shouldn't take too long to get tail piece off and see.

"Common. It's not the nut, it's the shifter and shift gates in the top of the trans. They tend to "jump gates" not much we can do about that problem, it's a design flaw. But once you get it back out of gear. It should be normal again.. is it still messed up, or does it work fine now? Just go easy down shifting from 5th. Make sure you don't move the stick until the clutch is completely released
IF it continues to give you trouble, we'll swap tops. But no way of knowing if one is better than another
I had that problem with my old nv4500's in my big truck. No simple fixes to speak of. Some tops do it, some don't. No way to tell. They all look the same and all come from the same place. But I will send you a different one if it doesn't quit doing that. We have probably 40 of those tops."
At least he's confirming that there might be a problem, I adjusted the clutch last night and on my drive to work this morning it seemed to shift better and not take as long to get into gear, 5th came out smooth like it should. Seems to be an on/off problem, no real sign of knowing if it will stick or not.

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Dieselfuture

Well I'd say get a new top anyway, it's done it on a new built and can happen at any time, I would get a different top if he's sertain that's what it is. And the nut thing, if it's possible to put that collar on 2wd to make sure nut never backs off, wouldn't it make sense just to add that to the cost and do it to all just to be safe. I'm sure 100 bucks isn't going to matter much on that kind of build and a good way to make sure it never falls off. I wouldn't want to take tranny out over a 100 dollar part, I'd pay it up front. Gmo.

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Cronus577
2 minutes ago, Dieselfuture said:

Well I'd say get a new top anyway, it's done it on a new built and can happen at any time, I would get a different top if he's sertain that's what it is. And the nut thing, if it's possible to put that collar on 2wd to make sure nut never backs off, wouldn't it make sense just to add that to the cost and do it to all just to be safe. I'm sure 100 bucks isn't going to matter much on that kind of build and a good way to make sure it never falls off. I wouldn't want to take tranny out over a 100 dollar part, I'd pay it up front. Gmo.

I did notice a little bit of rust on the gate of 5th and reverse when I pulled the shifter tower, I bought the transmission while I was deployed so it sat in a garage for about 3 months before it got put it. I'm hoping that it could just be a little bit of rust causing the bind. It seemed smooth this morning but I'll continue to monitor it. I'm going to be going to his shop at the beginning of October to drop off my old transmission since I'll be in the area for a couple of weeks anyway. He knows about it so he's willing to work with me on it.

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Mopar1973Man


Most of the problem for the 5th gear nut is most people don't know the proper torque spec. Hammer and chisel is not proper torque spec. Also factory shaft is like 460 ft/lbs and upgraded shaft the nuts is torqued to 600 ft/lbs. (IIRC... )

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Cronus577
1 minute ago, Mopar1973Man said:


Most of the problem for the 5th gear nut is most people don't know the proper torque spec. Hammer and chisel is not proper torque spec. Also factory shaft is like 460 ft/lbs and upgraded shaft the nuts is torqued to 600 ft/lbs. (IIRC... )

So, do you recommend I take off the tail housing and check anyway? He's a reputable builder and a lot of people recommend him. I think this might be a case of I got the short stick. I'm probably going to go change the diff fluid today anyway so I could check, I just don't have the transmission fluid. Had to order the gallon of Lucas 50w Full Synthetic

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Mopar1973Man

First off verify my torque specs for the nut. Second off you'll have to buy the two special sockets for torquing that nut down which are not cheap. So for the whole 5th gear nut issue. my OEM transmission lasted 262k miles till I BROKE the mainshaft at the 3rd/4th syncro. I've never had a 5th gear nut issue and towed plenty of highway miles. 

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