75 np203 mated to th350 - bad clunking

[AuroraGirl]

Is the fix for this the driveshaft or the axle shafts? Im still trying to understand how the full time setup works, but bare with me.

My dad parked his because of this, and i just figured out my 78 has a np203 and th350. the only difference is he is 3/4 ton, mine is 1/2. he really wants to be back on the road with it, and i want to help him. Can I see what the drive train looks like and what is the likely fix?

Both trucks dana 44 front, 6 and 8 lug respectively.

It appears mine had warn manual hubs put in at one point.

 

[75gmck25]

Is the clunking just going into out gear, or when driving? My K25 has a metallic clunk going into gear, but it doesn’t seem to hurt anything.

I recently had a very loud clicking noise while driving, and with a friend’s help determined it was the front driveshaft u-joints. There was also a broken centering ball in the CV Joint part of the driveshaft. One u-Joint was completely dry and falling apart, and the centering ball had completely worn through against the spring. I bought the 3 u- joints and centering ball from Rockauto, and it took about 2 hours to drop the shaft and replace them. The new u-joints are lifetime lubricated, so maybe they will hold up better. That front CV joint takes a beating with an unconverted NP-203 that is always driving the front axle.

Another thing that quieted down the noise for my truck was to replace cab bushings. The cab had settled and was making metal-to-metal contact with the top of the NP-203. Every little bit of drivetrain noise was being amplified by the cab body.

Bruce

 

[AuroraGirl]

Oh all good to know. 3 u joints and a CV. The CV is on the end of hte shaft on the 203-side of it all. And the clunking is directly proportional to driving and never really noticed issues shifting.

 

[75gmck25]

The CV joint has two standard U-joints, and the spring-loaded centering ball that keeps the two U-joints lined up with each other as the shaft spins and flexes. If the spring has failed or the ball seat has broken, the joint drops down a little, and kind of “pops” as it realigns itself while the shaft is turning. It seems like that may be your problem if you can hear the noise while slowly driving forward.

The third U-joint is the standard one on the other end of the front driveshaft.

Bruce

 

[AuroraGirl]

So I went and looked at his setup. The transfer case is a yoke to a yoke on the d44, it appears to be a d44 at least.

Is there a kit for this cv joint?
Or is there a good picture of what the shaft looks like?

I couldnt see his, its in storage atm and he had to go. he wants to retain the front as full time, which is fine. it never showed any adverse wear signs and it was kept maintained with oil.

Mine from my half ton might work? or at least it would have a similar design, i would think

 

[75gmck25]

I assume it’s the same as my ‘75 3/4 ton, and also the same on your 1/2 ton. I found a YouTube video that is pretty good. https://m.youtube.com/watch?v=KXn1nBkafNk


The one thing this guy left out is to lubricate the slip yoke grease fitting and make sure the driveshaft slides back and forth to let it adjust the length under load.

Bruce

https://m.youtube.com/watch?v=KXn1nBkafNk

 

[AuroraGirl]

I assume it’s the same as my ‘75 3/4 ton, and also the same on your 1/2 ton. I found a YouTube video that is pretty good.

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The one thing this guy left out is to lubricate the slip yoke grease fitting and make sure the driveshaft slides back and forth to let it adjust the length under load.

Bruce

Iirc, my dad's has a solid shaft. Which may have caused wear not being able to adjust? I'll have to see it for sure

 

[80BrownK10]

Oh all good to know. 3 u joints and a CV. The CV is on the end of hte shaft on the 203-side of it all. And the clunking is directly proportional to driving and never really noticed issues shifting.

I had a clunking and mine was only in 4wd. But that's the only time my front shaft turned with the 205 case. It was soft worn out collapsed trans mount letting the CV part of the front shaft contact the crossmember. New mints and it was fine.

 

[80BrownK10]

Iirc, my dad's has a solid shaft. Which may have caused wear not being able to adjust? I'll have to see it for sure

Something has to adjust? As the axle droops its distance increases from the T case. The shaft has to expand or collapse or else something will break.

 

[AuroraGirl]

Something has to adjust? As the axle droops its distance increases from the T case. The shaft has to expand or collapse or else something will break.

maybe i am mistaken by what he said, he may have not understood either

 

[Grit dog]

It’s not a solid front drive shaft. There IS a slip yoke on it.

 

[AuroraGirl]

I see what Im confused by now. My truck has a slip thing on the case while my parts frame has it on the driveshaft.

 

[AuroraGirl]

My bad again, I was misremembering front and rear
Front has slip, yes. How do i lube it? with what?

Rear is solid but slips in the np205, spare frame flange on np205, but the slip is on the driveshaft

EDIT: this is my truck, which i did confirm my dads was proper with slip

 

[75gmck25]

There is a grease fitting on the front driveshaft body. Use a grease gun to shoot chassis lube into it, and then manually slide it In and out until it moves smoothly (it will always be quite tight).

Bruce