U joint rear rumble vibe issue

[toddball]

The rear u joint came loose this weekend on my 85. Looked like a inner clip came loose at the axle yoke strap pair. Only had 30k miles on driveshaft with rebalance and neapco heavy duty u joints.

I replaced both u joints with some spicer red box on the rear driveshaft but there still is the same rumble. Everything looked good when I put it back together. There was no binding with the new u joints and axle yoke end play was fine. It starts at 10 mph when accelerating but not when coasting.
Any ideas?

 

[shady]

Slip joint shaft?
Could it be out of phase...?

 

[toddball]

Slip joint shaft?
Could it be out of phase...?

Yeah, slip joint. Np208 to 10 bolt rear. I marked everything so it was put back together the same way.

 

[shady]

I've seen where there was wear on the little tabs that kee the Ujoint centered in the yoke, allowing it to sit farther to one side than the other. ...
Only other thing 'I' can think of.
Hopefully someone else has an idea.

 

[toddball]

Another thing is in reverse it's smooth accelerating but then rumbles on coast.

 

[toddball]

Yeah, slip joint. Np208 to 10 bolt rear. I marked everything so it was put back together the same way.

Actually a slip "yoke" It's the stock style driveshaft.

 

[Joel Wilson]

sounds like there is some flex somewhere or the driveshaft angle is a bit out of tolerance. Is the slip yoke nice and tight as in no play or slop? I believe Wes Harden just went through the driveshaft angle thing.

 

[toddball]

sounds like there is some flex somewhere or the driveshaft angle is a bit out of tolerance. Is the slip yoke nice and tight as in no play or slop? I believe Wes Harden just went through the driveshaft angle thing.

I've been running this angle for 100k+ miles it's been about as smooth as you could get without a sye. This rumble just happened and it feels like something is going to break. Seems like the u joint failure is a symptom of something else wrong. There is a tiny amount of play (up and down) at the slip yoke (like few thousands of inch) but isn't that normal, what is the spec on this? The t-case rebuilt 20k miles ago. Pull diff cover? I don't know where else to look.

 

[toddball]

Well chunk of metal in diff is not good. Pinon teeth.

 

[shady]

Thems some big chunks

 

[toddball]

150k miles on these 4.10s. Royal purple changed every 2 yrs

 

[Joel Wilson]

Sorry man. Sounds like you did everything right. Royal Purple isn't cheap. On the plus side, since you have to reset the gears, perfect time to add a locker.

 

[Clark75K5]

Yikes - sorry to see that!

 

[Blue85]

Look on the bright side. It didn't lock up on the highway, you got it torn down in a convenient location (I assume) and now you know what's wrong.

Why did it happen? Hard to say. Factory defect in the gears? Could a roller bearing have gone for a swim in the oil? Anything violent happen to it lately?

 

[toddball]

Yeah could be worse. I was on the freeway going 75 mph when the noise started. I knew right away to pull over and check it out. Decided to tow it home when I saw the loose u joint. No major issues or wheeling lately.

Is the u joint coming apart a symptom of the pinion gear teeth breaking or the other way around?

 

[Joel Wilson]

Yeah could be worse. I was on the freeway going 75 mph when the noise started. I knew right away to pull over and check it out. Decided to tow it home when I saw the loose u joint. No major issues or wheeling lately.

Is the u joint coming apart a symptom of the pinion gear teeth breaking or the other way around?

I would be curious about that one. I had a pretty bad vibration above 65mph and it made me nervous as hell going to VA appts. Changed tires and it was pretty much gone which is kinda strange given the amount of weight I had to add just to get the tires balanced. Still, very glad you got home safe but sorry you broke something after spending good quality money on it trying to keep it going.

 

[Bent77]

Yeah could be worse. I was on the freeway going 75 mph when the noise started. I knew right away to pull over and check it out. Decided to tow it home when I saw the loose u joint. No major issues or wheeling lately.

Is the u joint coming apart a symptom of the pinion gear teeth breaking or the other way around?

U joint isn’t related to the axle going poof

was that a 10 bolt ?

 

[toddball]

Yes, stock 10 bolt 28 spline

 

[shady]

Maybe the axle going poof jarred the joint enough to get outta whack....

 

[Bent77]

150k out of a stock 10b is normal life expectancy