Drivetrain Clunking Sound?

[f2502011]

I have a clunking sound that seems to be coming from the rear. It will do it if I am in a forward gear and the rear seems to be under load such as if I had just stopped and then let off the brakes it will clunk and I can feel it. If I press/pump the brakes and then let off real quickly while stopped, it will make the clunking sound. Also if I accelerate hard from a stop it will also do it and clunks. It also seems to do it while making the 1-2 shift at low speed which results in a slightly hard shift. Any ideas on what might be the problem?

 

[blazinchuck]

have you grabbed the rear drive shafts and checked for play? check ujoints. also might not hurt to pull the rear drums off and check the shoes...i have seem ppl install the shoes backwards and it would make a clunking sound. and lastly...pulling the 3rd member to check inside carrier

 

[broncobilly72]

You might want to check the ubolts that hold the axel to the springs. Broncos are famous for the axel rolling on hard stops thn clunking when rolling again.

 

[f2502011]

Thanks for the tips I will check it out.

 

[rwill]

I twisted the rear U =joint out yesterday with the same issue, part of the problem yoke was "loose"at the pioion .

 

[JayT]

I've also had a lug break and the rest back off, and the noise came from wheel rocking back and forth when breaking/accel... (which elongates the holes, and requires a new wheel, of course)

 

[f2502011]

I crawled under it. There is noticeable slack in the slip yoke and not sure if it's supposed to be that way but the front one does not move like the rear one does. Was also very dry of grease so I greased it, but it didn't make any difference in the sound.

I looked on the local Autozone website and they sell U-Joints but no slip yokes. Any idea where I can get a slip yoke and what part exactly that I need to get if that turns out to be the issue?

I will check the other things mentioned today.

 

[f2502011]

I think the issue may be the slip yoke. There is noticeable play in it. I can put the truck in park, rotate the wheels forward to where the transmission will stop it and the yoke will move up and down, in and out noticeably on the end of the shaft. I can also feel the same sound in the wheel that I hear and feel when driving it. The truck is stock height, but appears that it may have had some rear drive-train issues in the past because it has a sticker for a repair shop affixed to the rear drive-shaft itself. With that said I'm not sure if it has it's original drive-shaft, yoke, u-joint parts or what it has and how to tell. They look stock style to me but I don't know.

Anyone have any tips on what I should do to fix the issue and where to get the parts? I have little experience with drive-shaft, yoke, u-joint issues.

 

[broncoslim]

Try these guys for the slip yoke. oliverscustomdriveshafts.com Ask for Dave or Andrew

 

[Apogee]

Since you said you have little experience with driveshafts, the slip yoke is basically a non-serviceable part in a driveshaft, meaning that it is welded into the assembly. Replacing the slip yoke means rebuilding the driveshaft, something that you should probably allow a reputable driveshaft shop do for you. Post up where you're located and you may get some recommendations for local shops.

By the time you price rebuilding your old shaft, especially if it needs more than just the slip yoke, you may be better off buying a complete new assembly.

 

[f2502011]

DFW area TX.

 

[f2502011]

Thought I would post up the solution to this problem if anyone else has the issue. I replaced the U-Joint which was bad, put it back together, lubed everything well with chassis grease and still had the clunk. I did an internet search and found Motorcraft PTFE XG-8 teflon lubricant mentioned on Toyota and Ford sights as a possible solution. I bought some from the local Ford dealer for $8, took it back apart and cleaned off all the old grease, lubed it back up with XG-8 and it solved the problem. No more clunk.