4wd front end noise?

[Brimow525]

70 K20, 4:10 gears. Dana 44 front end, np 205 transfer, th350 tranny rebuilt.

Replaced front end drive shaft u joints, all front end bearings except pinions and carriers, drive shaft u joints replaced (to the wheels)

Now I have no noise in 2wd, no noise when I lock the hubs, but I have noise when in 4wd high above 8-10 mph. I plow with the truck so thats why I know the speed. Is a kinda grumbling noise. I can't place it. Its only when in 4wd. I was thinking pinion bearings but I get no noise if hubs are locked but not in 4wd. Any thoughts?

[chevyfarmer]

Might want to check front drive shaft a little closer. What condition is the spline in? Also, the t case end of shaft has a bearing in between the two u joints, (since it is monday i can't recall the name ) center bearing? i had to replace it on a blazer i had before, good luck

[Brimow525]

When you say the spline are you refering to the area where there is a grease fitting and the drive shaft slides back and forth on? If you are, that is loose. Like I can shimmy the driveshaft around while its on the truck. I thought it was a little odd but I'd never owned a vehicle this old before and wasn't sure if that was normal. I have thought about the bearing on the transfer case. When I took the drive shaft out to replace the u joints, it didn't have any play or leakage so I thought it was OK. From what I'm told NP205's are very reliable and almost bullet proof.

[chevyfarmer]

Yes on the spline, where it slides in and out near the grease fitting. It should not have very much play in it at all so this may be the problem.

As for the other end, I am referring to the bearing between the two u joints. My blazer was a 1/2 ton but I would think the drive shafts would be similar. Between the 2 u joints on the transfer case end of the front drive shaft there is a bearing, something like center bearing, or centering yolk bearing, come on some buddy help me out I am struggling here

[Brimow525]

There is alot of play in the front drive shaft then. If I compare to what you say.

I know the "bearing" in question. Its kinda spring loaded. When I replaced the u joints, that bearing was dry as a bone. I put new needles in it and greased the heck out of it. I hope that'll do the trick.

[Mudder]

Ttt

[JIMs70GMC]

something like center bearing, or centering yolk bearing, come on some buddy help me out I am struggling here

It's the centering yoke, replaced mine when I did the u-joints. For spicer it's about $55.

Does it make noise when going faster? Are you in 4hi or 4lo? Could it be just the gears?

[Brimow525]

4hi is when it make the noise. It makes the noise after about 8-10 mph and up, the faster I go, the louder it gets. I have only put it in 4lo once just to see if it worked. i changed the fluid in it when I did the u joints. I just can't understand why no noise even when the hubs are locked but in 2wd at 50 mph (testing purposes ONLY). But as soon as I put it in 4hi the noise starts. I'm not sure if its the gears or not. I never heard the noise the last couple of plowings I did with the truck, but now I do hear it and I just don't want to make stuff worse if its just an easy fix like a bearing or something.

[Brimow525]

OK, an update. I put the truck in 4hi and it made the noise. (in a parking lot) Ran out of room so I put it in reverse and .....no noise! went foward..noise...reverse no noise. So since I haven't used 4lo since I bought it..fiqured ..why not? Couldn't get it out of 4hi...tranny in N, R D, P. wouldn't come out. Finnally in reverse with tap of the gas and it comes out to 2 hi. Shift to 4lo and go.....no noise. reverse...no noise....foward..no noise. WTF? So obviously its something to do with the 4hi gears. And not being able to take it out of 4hi very easily either is a problem. I was literally pushing the shifter with my leg. ( not really, but I was damn ready to)


Any takers on what I should plan to do?

BTW, should the transfer case have ATF or gear oil. I was told gear oil and put in synthetic.

[wanted]

I had a problem with shifter linkage. It would bind and sometimes not fully engage and sometimes would get stuck.

[Brimow525]

TTT, still wondering how easy it is to either fix or rebuild. If it is easy to rebuilt, about how long, minus taking it out of the truck and reinstalling, would , or should a rebuild take?

[4x4Poet]

You, sir, are trying to solve all your problems at once. You need to eliminate proven problems before moving on to potential causes. Obviously, you should have started with the front driveshaft. Pull that sucka and have a driveshaft shop check it. They will tell you what it needs. They will check the spline engagement, the crosses, and the CV. Once you have the diagnosis, you can ask what work, if any, you can do yourself. For instance, if only the spline is bad, you could remove the constant velocity joint and u-joints yourself to save a few bucks labor. If the driveshaft spline/yokes will be replaced, and none of the u-joint crosses are new, you should definitely install new ones in the new driveshaft. Senseless to run old crosses in a new driveshaft. I recommend using spicer crosses.

While the front driveshaft is out, check the play of the front output shaft. Move the yoke up and down. Should be nearly no such movment. Grab both the front & rear output yokes and check for rotational play. Should be little play. If you think the play is significant but aren't sure, you could have a trustworthy tranny shop or 4x4 shop check it for you while the front driveshaft is still out.

Also, while the front DS is out, lock the hubs and check for rotational play at the pinion. Should be little play. See how much the pinion yoke moves up and down. Should be nearly no play.

Once you have a new, or otherwise serviceable and balanced front driveshaft installed, reanalyze your problem, if any. Keep eliminating any found problems before guessing at others. Usually saves money that way.

[Brimow525]

I see what you are saying poet, but in previous posts I stated that the front u joints where just replaced. I did however fail to mention that when I changed the front u joints, that I had the transfer case out to check it over. (the noise was present before I did this) Plus I had broken the stud that holds the 4wd shifter on. So its that tuff to get it out of 4hi. Lemme tell ya, that was no fun to drill out, esp. when I broke an easy out in the hole!!! I no longer believe that the noise is in the drive shaft or the front axle. I do think there is a little more play in the front drive shaft spline then necessary(sp?) but I do not think it is the source of my noise. BTW all joints and outer bearings and seals have been replaced on the front and rear axle. I am pretty sure that it is in the transfer case itself. With it being SOOO hard to disengage 4hi, I'm pretty sure that its a bearing or something. I just have never taken a case apart and have no idea how it works or what parts do what.

[Brimow525]

Hey chevy farmer... is that an Eaton rear in your picture? Is so, wheres a good place to get rear drums for a full floater srw? Thats what I have. I couldn't find any, but the closes I got was a 73 dana 60 full floater. But I had to have the outer lip machined down 1" to fit on my backing plate. But the drums are almost at their limit of turning so I'd really like to find a newer set. Now that I looked again, no its not. Sorry.

[tnblazerk5]

for complete teardown and rebuild on a np205 go here
http://bulldogs-house.com/Projects/np205/

[4x4Poet]

OK, you're on it better than you initially posted, exactly. Happens to gearheads who get their hands dirty more often than their fingers touch a keyboard. Cool. I'd still refurbish that front driveshaft since you have to replace the splined slipjoint anyway. Or, at least have a driveshaft shop verify the DS is ok. Then you'll know for sure that you've eliminated every possibility before a final symptom check and tearing into the xfer case. Hope it works out well for you.

BTW, my local bearing sales store stocks NP205 master rebuild kits (seals, bearings, snaprings, etc) for $125. I've found they were $150 elsewhere. Maybe your local bearing sales can beat out the best price elsewhere, too. And the NP205 is easy to rebuild. It better be. I'll be tearing into my K10's NP205 shortly.