Agree. The more I read the more I see about towing being the culprit. That said, I'm not going to get much sleep at night if I don't do something about it now even if I never plan on towing more than 1000 lb.tedlovesjeeps71 wrote:My understanding of it was that the main cause for the failure was when towing heavy loads while using cruise control. The constant on/off of the power caused the nut to become loose. The more it backed off the more the gear could "flex", creating the hourglass on both the gear and the shaft. Eventually there would be enough play that the nut backed off completely, falling into the TS housing. You'd "lose" 5th gear as a result and while 4 gears worked fine, the damage required a new mainshaft.
This may have been a dodge version specific issue... I know they each had some problems the other generally didn't.?
As far as fixes, I've seen everything from backyard welding the nut back on ( ) to new mainshafts with different locking nut designs. You may want to spend a while researching what Chevy guys have done to fix their issues. The NV has been out long enough to have some good field data and quality fixes. I still think it's a great transmission, just need the weak spots addressed.
Also, make sure you use a gasket for the tail housing. I used RTV on mine when I was trying to get it all together in Germany. It leaks. And that fluid isn't cheap. Haha!
These folks are really sharp with nv4500s. Spend a little while looking through their info and parts lists.BRUTUS wrote:Agree. The more I read the more I see about towing being the culprit. That said, I'm not going to get much sleep at night if I don't do something about it now even if I never plan on towing more than 1000 lb.tedlovesjeeps71 wrote:My understanding of it was that the main cause for the failure was when towing heavy loads while using cruise control. The constant on/off of the power caused the nut to become loose. The more it backed off the more the gear could "flex", creating the hourglass on both the gear and the shaft. Eventually there would be enough play that the nut backed off completely, falling into the TS housing. You'd "lose" 5th gear as a result and while 4 gears worked fine, the damage required a new mainshaft.
This may have been a dodge version specific issue... I know they each had some problems the other generally didn't.?
As far as fixes, I've seen everything from backyard welding the nut back on ( ) to new mainshafts with different locking nut designs. You may want to spend a while researching what Chevy guys have done to fix their issues. The NV has been out long enough to have some good field data and quality fixes. I still think it's a great transmission, just need the weak spots addressed.
Also, make sure you use a gasket for the tail housing. I used RTV on mine when I was trying to get it all together in Germany. It leaks. And that fluid isn't cheap. Haha!
Here are a couple links I read that shed a little light on the subject but still don't really provide an answer for a Chevy 4500.
http://www.pirate4x4.com/forum/dodge/99 ... d-fix.html
http://www.quad4x4.com/NV4500%205th%20G ... orque_King
It is a little disconcerting that there is basically no solution available other than the setscrew version or welding. I will definately take a closer look at that main shaft before buttoning it up again. I wonder if I just made a print of a 32 spline version and sent it to some machine shops for a quote as I like that as a solution but wonder why it doesn't already exist considering how long these have been available.
What kind of gasket did you use? Cut your own out of cork or rubber? Factory gasket? Mine did not have a gasket when I took it off. Thanks for pointing that out. I am going back to my local Chevy dealer to return the block heater wire, asking about the the spanner socket and I guess a tailhousing gasket.
I will definitely look into those. Thanks for the recommendation.Cheap Hobby wrote:For your power steering pump, look at the units used on the 2002 s10. The one on my wife's is mounted abdominal buried like yours. It has a long fill tube with a long metal dipstick. It looks like a shortened oil dip stick. The tube goes into the top of the resivor and appears to be locked in with a grommet.
I guess at this point I am seriously considering welding the gear to the main shaft after shimming the gear tight to the shaft. At this point I really have anything to lose since my alternative is to get a new mainshaft and gear anyways as Quad4x4 no longer makes/sells their "fix" for this shaft. They are pretty adamant that their latest fix is not to be used on any 4500 that has already been "fixed" once before as the gear will eat itself anyways. The bonus to this is that the spanner nut becomes basically irrelevant as far as keeping the mainshaft gear in place and therefore could be tacked at the 12, 3, 6 and 9 o'clock positions. Before I do this, I am going to call the place in Arvada CO (fifthgearfix.com) and see what they can tell me... worst case is I can load the tranny up and take it to them on a day off and see what they say as they are about an hour away from me.Pirate thread linked above post #23 wrote:This fix is a good idea but i think alot of people get stuck on stopping the nut from backing off and dont look into how mainshaft 5th gear fits on the shaft. If the gear does not fit tight on the shaft, it doesnt matter what contraption you put behind it, the mainshaft 5th gear will move around and eventually take out both countershaft and main shaft 5th gear teeth.
HEY! You knock that off! You know the rules; you can do smart things dumb and you can do dumb things smart. You can even do dumb things dumb if you want, but doing smart things smart raises expectations and that hurts everybody! Dial it back Davinci, before you start a Renaissance.BRUTUS wrote: I will have to put a groove in the spacer so that I can pull it if needed at a later date.
Now that's funny! I love raising the bar!REDONE wrote:HEY! You knock that off! You know the rules; you can do smart things dumb and you can do dumb things smart. You can even do dumb things dumb if you want, but doing smart things smart raises expectations and that hurts everybody! Dial it back Davinci, before you start a Renaissance.
Since the spanner nut is supposed to be installed with 400ft-lb of torque, I'm not really worried about gear compression or shaft flex as I am merely trying to replicate the original design perameters from the factory... just made more perminantely than it came from the factory.tedlovesjeeps71 wrote:That is an interesting idea....my only concern would maybe be gear compression/shaft flex. I'm no mechanical engineer but is there any chance the doughnut could cause issues? Kinda thinking like the reverse of the end play issue we get from a cam shaft???
REDONE wrote:Instead of a fancy machined spacer, how about the spring out of the business end of a weed whacker?
I really don't want to leave the "door open or even cracked open" that would allow the spanner nut to walk. Especially when you consider all the labor it would take to open everything back up to get at it... driveshafts, exhaust, pneumatic shifters, crossmembers, flangebolts, etc. I would rather "inspect" it when for example, I change out the clutch.tedlovesjeeps71 wrote:Or a spring from a front axle hub?
I'm not going to make it this year. I guess I should update those posts.Blake wrote:Hey what is the deal with the Rubicon run? Maybe next year?
I dont want to calculate the clamping force either!SJTD wrote:I dunno what the clamping force of 400 ft-lb is. Need to know the thread pitch and then have to do more figgering than I remember hoe to do but I'd bet it's more than the bearing in the TC can take.
So, a collar would keep the nut from backing off if it got loose but I don't think it's going to help much to keep it tight.