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Another bad U-joint????

7

78 GMC Jimmy

1/2 ton status
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Jan 30, 2024
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Location
Seattle, WA
So I had my rear u-joint overheat and splode a while back. It overheated and then the damn thing flew apart and the driveshaft dented the shit out of the underside of the floor. There was evidence that it had happened prior to that, with a previous owner. I replaced it. Maybe a few hundred miles later, I hear a rotational squeaking noise when backing up. I went under the rig, and the U-join is HOT and there are blue spots on it from heat. The whole front half of the driveshaft is hot.

What gives?

Bad angle?

Check these pics out:


https://seattle.craigslist.org/sno/wan/d/stanwood-wanted-k5-blazer-rear-drive/7757909061.html
 
Which brand of u joint?
Who installed it?

Are we 100% positive there is no damage to the driveshaft causing the joint to fail?
 
Unknown brand, it was old and used - but in good condition. I inspected and re-greased it. I installed it as well.

I have replaced plenty of U-joints in the past, and never had an issue.
 
78 GMC Jimmy said:
Unknown brand, it was old and used - but in good condition. I inspected and re-greased it. I installed it as well.

I have replaced plenty of U-joints in the past, and never had an issue.
Click to expand...
Maybe the PO bent the ears on that shaft?
 
I know the end you’re talking about is the transfer case, but the smashed ear at the pinion is no good. No matter what you need a new driveshaft. Typically there is a three joint style driveshaft in there.
 
Bent77 said:
I know the end you’re talking about is the transfer case, but the smashed ear at the pinion is no good. No matter what you need a new driveshaft. Typically there is a three joint style driveshaft in there.
Click to expand...


In an ideal world, a new drive shaft would be great. But I don't want to go that route. Yes, the diff end is messed up and the center is dented, and the other end is burning up U-joints, but if I can solve the U-joint issue then I am good to go. What could I try in order to fix the U-joint issue? Angle is not the issue, is that correct? So what else could I try?
 
Are your angles out of phase ?
What are the angles for each joint ?
 
Might just be too much angle for that short of shaft.

And as said earlier you DEFINITELY need the yoke at the axle end of that shaft replaced - immediately.
 
Out of phase?

How would one remedy that problem?

I might be able to get LeVar Burton to use his phaser on it?
 
If the pictures where taken without the driveshaft moving it is out of phase, as mentioned above. Should have vibrating like a sob.
 
Wes Harden said:
If the pictures where taken without the driveshaft moving it is out of phase, as mentioned above. Should have vibrating like a sob.
Click to expand...
You should even hear/feel a good bit of chattering because of this issue.
And that is causing the excessive heat in that joint.

But let it be said one more time - that lower yoke must be replaced - soon.
If it goes and slings the backend of the shaft while at speed you could break a bunch of parts that cost way more than a driveshaft.

We’re just trying to help and warn you about how serious this could become.
 
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