Driveline noises to identify(pics/vids)

[Cancleaner]

Got a nice noise going on under the truck. Been searching around here for a bit trying to see if I can find post with similar issues. I may have found a few things to check out. I was just going to take it into the shop and see what they say, but I don't really know any trust worth shops around. Plus, maybe with everyone help I could save some coin.

91' burb 4x4 1/2ton, with 10bolt (has posi) on 35x12.5 tires, SC 350.

I hear whining / humming at deceleration and holding a steady cruise speed. Accelerating , nothing heard until over 45, but sounds like mud tires to pavement at that speed. ( I have AT's) So basically when Im driving, I try no to maintain a constant speed.

In my researching I was reading about drive line angles of the Tcase. I am not sure how much lift I have , but I would bet it's over 6". Did I read correctly that if this in fact the issue I can just simply drop the T case a bit? I had just notice it appears as if tranny fluid is dripping a tad just below the T case / U joint. Of the other descriptions , this sounds most like same symptoms. (but not exact)

Also, read about U joints. How do y'all know with out just replacing if this is it? Any "tests"? I grabbed on them and twisted feeling for any play at all, and they don't play . seems solid.

I sounds to me like the rear diff making all the noise , but after searching, it looks like could be some thing else giving me a false sense. I have a full time mechanic at my shop he seems to think (from my description) It may have something to do with the backlash. I had the diff cover off twice this week, both times didn't see anything crazy or broke.



A pic of my rig may or may not help , I can't think of anything else to add at this point. Sorry if I babbled, just wanted to provide as much info as I could offer.

Thanks fellas

 

[tRustyK5]

Is this a new noise? I'm kinda thinking you haven't driven this too much yet so you might not know...

It sounds like your U-joint angles could be off, and with your lift that is probable. Even if the U-joints are good you will still have a vibe/noise if the angles are wrong.

With the wheelbase you have you should be able to get the angles decent without going to a CV rear shaft, and without having to drop the T-case. You could drop the T-case as a diagnostic though. If with the T-case dropped things improve you can then focus in on U-joint angularity. An angle finder and some level ground will get you started. Your U-joints should be running at equal but opposite angles.

 

[Cancleaner]

Your U-joints should be running at equal but opposite angles.

That they are not. The pinion side points most towards the T case.

Tomorrow I'll grab the angle finder and post some pics.

I have had this truck about three weeks now, fixing this and that as I go. But that noise has been there the whole time. Just got a damn deal on the truck lol

 

[tRustyK5]

Under power that diff is going to try and rotate further up at the pinion. So steady throttle and accelerating should produce the noise/vibe. coast and decel should quiet things down...

You can fix that situation with some shims at the diff to tip the pinion down some.

 

[Fordum]

Ok, I'm going to throw a tentative vote for the rear end. Driveline angles usually are more of a rumble or a vibration than a whine.

Whines are usually gears or kids in the backseat.

But, the first thing to do is check the transfer case fluid level. Low fluid in there may be causing the bearings or gears to start to gall and wear.
If you have a leak, even a small one, you really have to stay on top of the fluid levels until you fix it.

It can sneak up on you and burn something up.

Otherwise, even though you have pulled it off before, pull the rear end cover off one more time.
Take your time, experiment with different angles, and try to get a couple of good pictures of the surface of the teeth of the ring gear. Both sides if you can.
Try it with and without a flash. Its tricky to take pictures of shiny things, but it can be done.
Post them here and let some of the rear end gurus look at them.

If you have a way to safely get both wheels off the ground, you can do a teeth pattern check.

Ask if you are not sure how. Basically, you paint some of the gears with something soft and messy and then rotate the drive shaft. That shows what parts of the gears are touching.

While you are under there, before you jack it up, Chock The Wheels, put the transmission in neutral.
Grab the yoke where it comes out of the rear end, and try to move it. Try up and down, side to side and in and out.
If you feel almost any movement at all, you may have found the problem.

Same goes for the driveshaft. With no load on it, try moving it from side to side and up and down watching for movement in the U-joints.

 

[drivelineman]

This reminds me of gear rattle - and its angle related . but let's see what the angles are first- Jess

 

[Cancleaner]

Very good info, exactly what I was looking for! Lots to look into. As zoom as I get home I'll lift it up and snap a few pics. Thank you all for you help, looking forward to finding the issue, more importantly learning something :-)

Maybe it'll be the axle, good excuse to go ahead with the 14 bolt.:-)


Thanks again

 

[Fordum]

If the gear pattern is off, caused by a bad bearing or being setup wrong, it will cause a whine and wear the teeth wrong in the short term.
Long term, it can cause a tooth to break.

If the wear is not bad enough to make the teeth too thin on the ends, you can set it back up correctly, and drive it.
You may still have a whine due to the improper wear, but if you don't mind it, its OK to drive.

But you have to get the setup correct first.

If its worn enough to whine, you can usually see it in the pictures.
I would consider doing a pattern check while you have the cover off.

 

[ryoken]

Whines are usually gears or kids in the backseat.

nice....

 

[Cancleaner]

ok boys, got some video,audio, and pics for ya

To start, I had a neighbor of mine who is a aircraft avionics mechanic for American airlines over today, we must have took 15 test drives trying to eliminate this noise. Even had him hanging out the back door while driving.

Don't know were to start, so lets start with the noise

Ok .....lemme figure out the short video thing real quick

 

[Z71paramedic]

ok boys, got some video,audio, and pics for ya

To start, I had a neighbor of mine who is a aircraft avionics mechanic for American airlines over today, we must have took 15 test drives trying to eliminate this noise. Even had him hanging out the back door while driving.

Don't know were to start, so lets start with the noise

no worky...

 

[Cancleaner]

Hang with me, figuring out how to do video



http://youtu.be/a-kzSP6rN_s

There we go.. Thats the best one I got !

 

[Cancleaner]

Okay, So we went around the block like 25 times, each time trying to eliminate one thing at a time. Anything that could sound like that.

Heat shield floppin around, nope, exhaust smackin the springs,nope, etc.. Checked all the fluids which were good.

So , we can't narrow down if it's rear or middle of the truck. even hanging out the door.

 

[Z71paramedic]

almost sounds like a broken stab-link or something kind of "tinny". Have you checked all the obvious stuff: license plates, the little piece of trim behind the rear bumper, shock bushings, spring bushings, etc?

 

[Cancleaner]

drive shaft angle, sorry, did have time in the day to break out the angle finder. Hope maybe some one can "eye ball it"

 

[Cancleaner]

almost sounds like a broken stab-link or something kind of "tinny". Have you checked all the obvious stuff: license plates, the little piece of trim behind the rear bumper, shock bushings, spring bushings, etc?

like 25 times we drove around, stop, smack stuff, strap stuff, brace stuff etc, for like 3 hours. I for the life of me don't know.. I never had a rear end or tranny issue so have NO idea what they souynd like.... to ME, That sounds like a tin vibrating on something.. How, why it decides to do it ONLY on decel and cruising..

 

[Z71paramedic]

like 25 times we drove around, stop, smack stuff, strap stuff, brace stuff etc, for like 3 hours. I for the life of me don't know.. I never had a rear end or tranny issue so have NO idea what they souynd like.... to ME, That sounds like a tin vibrating on something.. How, why it decides to do it ONLY on decel..

Normally a rear end noise would be more of a growl or clattering. That sounds much too "thin" to be a rear end IMO. Sorry I can't come up with more...

 

[Cancleaner]

40 bucks to who ever finds the damn noise!!!

 

[Fordum]

If it was that "ringing" sound, I'm not sure. There are still several things it could be. Almost sounded like something to do with the drive shaft, but sounded a little too high pitched for that.
If its that sound, take something and lightly tap on the drive shaft and see if that is what it sounds like.

That hollow shaft makes a really unique sound. Once you hear it, you will recognize it.
If thats the sound, and nothing is hitting it, then I would suspect a U-Joint. They can go bad with no obvious symptoms. Usually they get sloppy, but sometimes they actually get tighter.

One giveaway, look at the end of all the bearing caps. If you see one that has been turning in the joint, then its got a problem.

Warning, DO NOT let him tie himself or you up under the truck while you drive him around. Let stupid people like me do that when I was young and stupid.

Otherwise someone will wind up wound in a tight ball around the driveshaft like a guy I read about trying to find a problem with a big dumptruck.

Got cold chills when I read that, because it had not been too long since I did that with my Jeep......

Course, as fat as I was back then, I don't think that little 4 banger could wind me completely up around the shaft......

If you were closer, it would take me about 20 minutes to rig up a video camera on a pole with a microphone that you could stick under it from inside.

I would want to mount a small tube on the mic port to make it more directional.

Just aim it around under there until the sound got loudest in the headphones, and then look the way its pointing.

As I was writing this, it occured to me that the sound really sounded like slop in the rear end gears slamming back and forth.

Try chocking the wheels, putting it in neutral, engine off, and twist the drive shaft back and forth hard to see if you hear the noise .

 

[Cancleaner]

Normally a rear end noise would be more of a growl or clattering. That sounds much too "thin" to be a rear end IMO. Sorry I can't come up with more...

Can't say I wouldn't agree! Some times it is LOUD as hell.