Couple of quick NV4500 questions

[Tpull123]

Well bought my second transmission now for this truck since the first one (which was supposed to be rebuilt) wouldn't shift into 3rd gear. Luckily this 2nd one was actually rebuilt and I was able to test drive it before it came out and have the paper work for it.....

Well the transmission swap was going good until I went to slide the slip yoke in only to find that it stopped after 2" or so......... Looked up in side and here the spring from the seal somehow came out and was jammed into the extension housing bushing. Just my luck, so thought I would take the tail housing off the old trans and put it on, but that bushing showed some signs of gauling. So here are my two questions:

1. How critical is that extension housing bushing on the 2wd trans and could it be a cause of vibration? I had a nasty sounding vibration somewhere in the driveline and trying to track it down (granite I am also chasing down the idea of it being a driveshaft angle~10 deg, transfercase, or driveshaft balance issue as well). Since I have a divorced case, it is only supporting a 6" stubby driveshaft.

2. After inspecting my original trans, all the internals are in great condition based on visual inspection, had the upgraded 5th gear nut and all. Is it possible that someone could have put the 3rd gear syncro in backwards during rebuild?? I have roughly 1100-1200 each in both of these trans and would like to recoupe some of my money if thats all that is wrong with it.

 

[Tpull123]

Well the new transmission was test last night, shifted much better into 3rd!! But I still have the vibration. Put the back tires up on Jack stands and ran it through the gears, still have the vibration in 4th + 5th. Then unhooked the front and rear driveshaft and you could still feel the vibration, just not as bad. Another thin I noticed is the temperature of the tailshaft where that bushing is was considerably warmer than the rest of the trans.

I am starting to wonder it that short shaft (6" long to the transfercase) is not so straight, causing the vibration in the Extension housing/tailshaft. I am not even sure a place could check a shaft that short.

Either way the vibration is speed dependent and not load dependent.

 

[Tpull123]

Here is a quick picture of the setup if that helps anyone provide some suggestions. The angles on the short shaft are less than 2 deg.

 

[bradford4020]

Unhook the small shaft and see if you still have the vibration.

 

[Tpull123]

I can try that tonight, requires pulling the transfercase back out and disassembling the yoke joint there and sliding the slip yoke back in. Hopefully the slip yoke stays put in the back of the trans.

My other idea is to lower one side of the transfercase to see if its an angle alignment issue.

 

[Tpull123]

Has anyone replaced the Extension housing bushing on their own? Just wondering how tight they are in there and if it could be done at home. Or rough cost to take just the housing and bushing to a shop and have them pull it out and press the new one in.

I am all for trying it myself, but if its a losing battle then so be it. This is now my only truck and desperation is sitting in to get this thing on the road.

 

[gunracer1]

you know the drive shaft has to have some off set right? and it need to be the same offset at the front and the rear u joint of that little jack shaft. if either end is in line it will vibrate.

 

[gunracer1]

i dont want to sound like a azz but i am trying to word this so you know what i am saying. it looks like the t case is layed back a bit in stead of being in the same plane as the transmission. just trying to help but i still think i am not wording it correctly.

 

[Tpull123]

Well the transfercase has about 1-2 deg of slope yes, but I didnt think that would be enough to cause any issues.

i have been trying to chase it down by adding weights to the short shaft in 90 deg positions and running it up. Didn't seem to affect the noise and or vibration. So then I tried dropping the transfercase down3/4" on one side to change the intermediate shaft angle a little bit and still nothing. Then took the transfercase and shaft off all together and tried it with just the transmission. Obviously the last case was the quiestest, but seem like there was still some a slight booming vibration, could just be my motor mounts being a little stiffer than normal.

So think I decided to just replace the bushing in the extension housing and run it......first failure should expose the problem or at least give me a reason to try a different trans / case setup..

 

[Tpull123]

Just for fun, I may try to leave the 2 front bolts in the transfercase and jack up the rear to see if remove the 1-2 deg angle that it has is causing the issue.

 

[burnin oil]

Looks like the transfer case is cocked forward on the passanger side. Like gunracer1 was saying the joint angle have to be the same or you will get a vibration. If you really want to nuke it got to roadranger.com and download the driveline angle installation guide. That is one invaluable tool for setting up drivelines. Covers every configuration you can think off. 1 or 2 transmissions, 4x4, single, 2 piece, and multiple shaft drivelines.

 

[Tpull123]

@ burnin Oil, Very good reference information. Looks like they recommend highly that there be some offset, and that they be with in 1/2 deg operating angle of each other.

Guess my set up si probably not offset enough, and guessing not with in 1/2 deg since my tools probably aren't that accurate. Guessing I will be modifying my transfercase mount for the 4th time........:doh:

 

[burnin oil]

Glad ya liked it. Try and get about 1 1/2-2* offset with both joints acting at the same joint angle. If the angle is zero the caps will freeze and start vibrating. I used that refrence when I installed my aux transmission. I wish every manufacturer was like Eaton!

 

[Tpull123]

Well pressed a brand new extension housing bushing in, and was disappointed to see how much slop / play it still had. I measured 2 yokes, so I know its not that. Anyway, assembled it and took it for a small test drive and thought it was much much better, to the point that it was actually usable. Well today I drove it to work and got it on the highway and the vibration was still there (~60mph) !!

So it seems I just pushed the speed at at which it happens. The short driveshaft angle is now set up almost perfect to Eaton's recommendations 2.5 deg slop roughly, with about ~1.5 deg angle on each end, opposite operating angles of course. The only other thing I can think to do is take the slip yoke and short shaft assembly to get it balanced, its the only piece of the puzzle left.

Question: I have never personally dealt with any shaft balancing before. How short can they do typically, and do they want just the shaft, or the shaft and slipyoke assembly? My shaft is ~6" from hole center to hole center........its basically as short as I could go.