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Discussion Starter · #1 ·
Am new here - hoping you folks might help me out. Have '95 Rodeo, 4WD, 250K miles. Believe everything's stock (I bought her used 6 years ago). Recently have had vibration from rear on taking off - not terrible but not overlookable either, seems like from rear. Few weeks ago, going up prolonged grades on freeway,loud deep-sounding vibration from rear, at around 60 MPH and ~3000 RPM. But, haven't been able to reproduce it which would make me happy except who knows when it might return. Recent work that might shed light? -rebuilt transmission installed 10K miles ago, just replaced the rear u-joint and rear spring end bushing and uppper control arm bushings. Mechanic advised, given she's not worth much, and money is tight, to just drive her until she dies ... or the drive shaft falls off. Or, he thinks he can replace the drive shaft for maybe $2K. So a question - realistic odds on drive shaft falling off ?!? The doggies and I go out to the boonies a lot - they take a dim view on getting stranded. And, am not mechanically handy ... in San Diego, any tips on good local mechanics? Much appreciate any help.
 

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If the vehicle is stock height then it sounds like a carrier bearing. Looks like this

Get under there with a light and inspect for dry rot or missing pieces then try and manually move the shaft up and down. If it flops around easily then you have found your problem.
 

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Discussion Starter · #3 ·
OK, I found the carrier bearing - pic was very helpful - and to my eye it looked OK - maybe the rubber gaskety thing was a bit dry but still had give. I could rotate the shaft just with my hands but it didn't seem loose and wouldn't go up/down. Now, this was with her sitting on the ground - do I need to break out the jack and lift her up for this test ?? Not sure where/how to look for dry rot or missing pieces?
 

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Discussion Starter · #4 ·
Extra info .... I saw that I had the rear carrier bearing replaced approx 45K miles, and 2 yrs ago. In fact, believe I remember the mechanic showing me all the flop in the driveshaft when she was up on the lift. Vibration is a recent development, last month or so ...
 

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The rubber ring you see in the pic is a bellow it is not solid and it is designed to let the shaft move in and out of the transmission as the suspension moves. Its job is to also stabilize the shaft. If you can move the shaft up, down, left or right then its shot. It should be quite secure. If there are any cracks or missing chunks its shot. It costs about $50

The other thing is that you said you replaced the U Joints. Did you take the center of the shaft apart at all?
 

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Discussion Starter · #6 ·
Hmmm ... then if I'm understanding you right, then the carrier bearing may be OK, because for sure I could only rotate the drive shaft slightly, in other words clockwise/counterclockwise - I couldn't move it any other way.

Re the u-joint, looked over the shop's bill and it just says they replaced the one rear u-joint. I did not know there's more than one u-joint. :( I don't see a labor charge for working on the shaft, but then maybe it's included in the labor for the joint. But if they only replaced that one u-joint, I'm thinking they wouldn't have had any reason to mickey with the shaft center?
 

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Well there is the possibility they un bolted the center of the shaft and removed the center splined yolk but to replace just the rear joint that is un likely. Your next step is to check that all the joints are phased correctly and the angles are correct.
 

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Being that you said this happened when you were driving on a long uphill grade, which means you were under power, and at high speed 60 mph then whatever it is is at its infancy. being that it only happened under power it is most likely something to do with the driveshaft. This is a good thing as other possibilities are more difficult and sometimes more expensive to fix.

Has it only happened that one time? if so then you may need to wait until the problem worsens a bit so you can reproduce it and find the problem. Not being able to reproduce the problem means you wont even know if it is fixed. This kind of issue is not a game stopper. your drive shaft is far from falling off at this point. The issue will get much worse before it falls off. They changed the rear U-Joint, there is still at least 2 more joints on the rear shaft. Altho the front one rarely goes bad becuase there is little angle involved it is poossbile. If you cant find any play in the shaft (not the differential) and you cannot reproduce it then you probably wont be able to do much, unless you like spending money not knowing if it will fix anything, until you can reproduce the problem.

Based on what you have already said, I would wait until you can at least reproduce the problem or it worsens before worriing about it.
 

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Discussion Starter · #9 ·
Hmmm (in response to betterthanyou reply) ... am rapidly getting out of my depth here. Don't have much in the way of tools, let alone auto-related ... Guess I'm just an automotive lightweight, although I very much appreciate the guidance ...

And to phoenix ... thanks also for your input ... I can see your point that if it's not happening reliably, won't be able to tell if it's fixed if I throw money at it ...

So I guess at this point, am thinking to just keep an eye on things, treat her gently, and try to nurse her along. Am looking at heading out desertward next few days - so will be tackling same grades that produced noise before and will see how she does ...
 
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