Trouble with my rear

Now that I have your attention, looking for advice on diagnosing a possible rear differential failure. Could be a bearing or drive shaft U-Joint.

I am getting a rythmic knocking sound coming from the rear end. It matches the speed of the vehicle. Gets louder/rougher when on throttle/ under load. But persists while cruising or coasting. Feels like a bind and release. Sounds baaad.

I can recreate it in the driveway with the engine off, in neutral (manual trans), and rolling it back and forth. At those speeds it is very faint.

On jack stands all appears normal. Spinning the wheel is as expected, opposite side spins opposite direction. Do not feel anything strange.

Was driving home from work, parked it after driving <1mile. I just emptied the diff fluid and inspected. Only found a few pieces of very thin metal, no specs floating. Even fished around on the bottom of the housing, strained the fluid and inspected the pail. Then pulling the driveshaft to remove a variable; all new u joints within 3 years and <25k mi. Swapped front and rear diffs with ECGS rebuilds that had 4.56 gears installed just over 2 years ago, ~20K mi. Running the recommended Lucas Dino oil. Not sure of any other test that could be done before pulling the third member.

Ideas?

 

That looks fairly normal, those shavings are likely leftover machining bits.
You said you pulled the driveshaft, did you check all the U-Joints for play or binding since the problem started?

 

That's what I was thinking.
Plan on pulling the driveshaft tomorrow. They felt tight but need to flex them more when the driveshaft is off.

It's definitely a binding like feel. Tried to take a vid but the truck is too loud to capture the clunk. The clunk occurs slower than the driveshaft speed as far as a once per revolution occurrence.

 

You may want to inspect the transfer case fluid as well.

I would assume you checked them while you had it in the air but it's not a loose wheel is it?

https://www.youtube.com/watch?v=FCBk7JNGNS8

 

I'll check all fluids while under next time.
I did kick the wheels around. All felt tight.

The symptom lines up with a broken ring/pinion gear tooth. I'd think there would be more chunks floating around in the housing.
I've had a failed u-joint on this truck before. That felt much different. Also replaced the carrier bearing a couple years back. Still feels good, minimal slop.

I guess it could be an axle?
I did a hard pull the day before but felt no immediate affect. Drove to work the next morning, didn't notice anything. Left work to run errands, quickly realized there was an issue and headed home. It did not feel related to what gear I was in, but did change depending on load and throttle.

I'll check fluid levels, pull the driveshaft, feel out the u joints. Then put it in 4WD and roll it some. May end up pulling the diff out. At least it's not the front...

 

Broken leaf spring, maybe. I think you qualify to get the recall springs (I did)

 

Really odd symptoms for an axle if it has no metal/chunks in it.

 

Is it itching???

 

Is it lifted?

 

Dakar leaf pack installed several years ago.
Lifted front and back. But has not changed for years.
No recent work done.

 

Yes but both hands are on the wheel, unable to scratch. Looking for a hand…

 

Pull the diff and inspect.
In doing so, you can inspect each axle shaft as well as the driveshaft u-joints.
Should be able to pull each side out far enough not to worry about the drums.

 

I had a similar symptom this winter, on '09, kept climbing under truck and checking U-joints with a pry-bar. Even drove 100+ miles and immediately went in garage, feeling U-joints for one that is hot; no success. Convinced it is the diff, I pulled the driveshaft just to be sure, I was going down the right path. Turned out it was the U-joint nearest the carrier. Happened to be one I replaced several years ago (the other 2 are still original, and feel so good, I left them this time too).

Hope you find similar! way better than dealing with diff.

 

I really hope I don’t have to pull the diff. Don’t want to have my truck down and waiting for a replacement. I’ll keep moving that way and check the u joints with the driveshaft off. They feel tight when using the pry bar.

 

I really wish you good luck.

In hindsight, I think it makes sense; the way the carrier has that 1/4" play, if the U-joint near it gets at all stiff, it probably thrashes the driveshaft about that carrier play, exaggerating the problem (even though the U-joint has no slop yet), and produces the rhythmic vibration that I experienced. It had gotten to sounding so terrible at highway speeds, that when I still could not identify a bad joint; I was sure it needed diff work. Sooo happy that I was wrong about that. Hope you find similar.

 

Well, I'm pulling the diff. Driveshaft felt fine at all joints. Drove around in front wheel drive. Sounds is definitely coming from the rear differential.

The feeling and sound changed now that it is not under load. Reverse now sounds worse vs forward.
I'm not comfortable rebuilding such a critical component. If this would have failed on the last wheeling trip I would have had to abandon the truck in the Wyoming mountains.

Hope ECGS can expedite...

 

She dead.

Not sure what is more common, ring or pinion. Pinion gave up here. Guess I'm shopping tomorrow!

 

Ouch. Hopefully it’s just the pinion.

If it’s more than that, I’m selling mine.
https://www.tacomaworld.com/threads...ear-differential-and-housing-3rd-3-73.792350/

 

Ohhh, so sorry, thought for sure you would have had the same luck that I did.

Wishing you a speedy recovery.

 

ECGS is taking care of me. Shipping out this week.
Hurray 5 year warranty!