Drivetrain Noise Diagnosis

[DirtDonk]

because it's not the bearings in the trans, unless it had 300K miles on it or ran without oil. as a rule the 435 does not have bearing problems.

I'm with bax on this, normally anyway...
You really should see the size of those main bearings. If you know anything about automotive bearings in general, seeing one of these can make you laugh out loud at how massive they are. And then taking a look at the first/reverse gear set's massive bulk inside the case is another reason to smile.
It makes you wonder how anyone can ever damage one of these things.

But the issue for me here this time is that we don't know anything about the transmission. For all we know it might actually have that 300,000 miles, or even 400,000 miles on it. Maybe even under hard use at a lumber mill driven by three generations of employees that didn't care about someone else's (especially a company) truck. Or run without oil!
And how was it taken care of in it's Bronco life? Beat on pretty good by the PO is very possible. And perhaps even why the Bronco was sold in the first place.
They are extremely strong, but not indestructible. Especially if someone neglected to keep the lubricant up to snuff.

So no, it's not out of the realm of possibility that your trans has some parts that are on the way out Amitchia. Anything is possible at this point.
Which takes me back to a previous question. I don't remember if it was discussed, but what lubricant is used in the transmission and transfer case, and how old are they, and what condition were they found to be in during the last oil change?
That might give a clue as to the condition inside the gearboxes.

Paul

 

[Amitchla]

because it's not the bearings in the trans, unless it had 300K miles on it or ran without oil. as a rule the 435 does not have bearing problems.

Neither of these are the case, so the bearings *should* be good.

Maybe this was already covered, but I went through a similar issue with mine and after trying everything, it ended up being my rear pinion angle was off. Looking at it it didn't even seem that bad, but when I excellerated or let of the gas and coasted it would do the same as yours. I placed a shim in the rear and it solved everything.

Interesting. Too steep of an angle, due to lifting, or the opposite? I recently lowered the rig (10.5" total to 8.5" total), so this might have something to do with it.

Well, even though it seems counter-intuitive, there is a slight change in the dynamics when you are running in front wheel drive. Maybe the load is just enough different that the noise changes. You did say that it did not go away completely, correct?

Don't discount what the mechanic is saying, even though it goes against our first thoughts. We have to assume that because they're there with the truck they might be able to determine something up close that we can't from afar.

Right. Yes - there still seems to be a minor amount of noise (very very slight, though) in FWD. I guess we'll see as I drive it home!

I'll report back.

 

[Amitchla]

I'm with bax on this, normally anyway...
You really should see the size of those main bearings. If you know anything about automotive bearings in general, seeing one of these can make you laugh out loud at how massive they are. And then taking a look at the first/reverse gear set's massive bulk inside the case is another reason to smile.
It makes you wonder how anyone can ever damage one of these things.

But the issue for me here this time is that we don't know anything about the transmission. For all we know it might actually have that 300,000 miles, or even 400,000 miles on it. Maybe even under hard use at a lumber mill driven by three generations of employees that didn't care about someone else's (especially a company) truck. Or run without oil!
And how was it taken care of in it's Bronco life? Beat on pretty good by the PO is very possible. And perhaps even why the Bronco was sold in the first place.
They are extremely strong, but not indestructible. Especially if someone neglected to keep the lubricant up to snuff.

So no, it's not out of the realm of possibility that your trans has some parts that are on the way out Amitchia. Anything is possible at this point.
Which takes me back to a previous question. I don't remember if it was discussed, but what lubricant is used in the transmission and transfer case, and how old are they, and what condition were they found to be in during the last oil change?
That might give a clue as to the condition inside the gearboxes.

Paul

Good points! I guess I don't actually know these answers, unfortunately, for certain.

I'll ask these questions to the mechanic when I see him shortly, and if he doesn't have those answers, i'll remove the floor panel and the top of the transmission to take a look inside as well.

I do know for a fact that there was plenty of oil in the transmission after this incident happened, and the oil that came out of the transmission and transfer case (on my finger, that is) was not overly darkened.

That being said - I don't know the weight of the oil in either. I asked him to change these on this go round - so I'll see what he used as well.

 

[Amitchla]

Ok - so - here are pictures and info from the mechanic.

When I asked more questions about the transmission, if the oil was bad, if the oil level was proper, etc, he pretty much just said that the "noise was coming from down here (points to where the transmission is located), and there's no noise coming from the rear end at all when it's coasting. If it was the rear end, it would always make noise."

Sure, I suppose. Anyway -

I drove the rig home in FWD. The only whines and noises I noticed were the whine from the straight cut ARB gears in the front diff that increased in pitch as speed increased (which I understand to be normal). There was also a *slight* rattle, I guess, with the clutch in or out with the transmission in neutral when decelerating/nearing a stop.

I've poked around and taken some pictures and videos that I'm attaching here.

1. It looks like I've got a wheel bearing out, right? I asked the mechanic to fix this 2 or 3 visits ago - so either it was not fixed, or it's gone bad again.
2. This leak confuses me. I saw this initially after buying the truck, and asked the mechanic about it. He said he went into the bell housing with a camera and saw no fluid leaking and nothing to be worried about. To me, this could mean problems with the front input shaft seal, and this could then damage the clutch/etc... right? I have no clutch issues, however.
3. General view of rear diff
4. "Play" in the driveshaft video - not sure if this is normal or not. Google Drive Link
5. Acceleration 2nd through 4th, then coasting stop in RWD. Google drive link
6. Acceleration 2nd through 4th, then coasting stop in FWD. Google drive link
7. Area between the U-joints on front of driveshaft - is this normal?
8. (NOT ADDED bc of glitch in posting) Acceleration 2nd through 4th, then coasting stop in 4WD with rear driveshaft removed - appears to be the same as FWD video. Does this prove that it's not the transmission/t-case, since there's no noise, or would this test be nullified because there isn't physical load on the RWD portion?

Please ignore the awkward video angle and messy floor. And, to answer your prior question - yes, the whole bed is bedlined. :-X

Happy times. Thanks again for all of the help on this.

 

[Amitchla]

Also-

9. Driveshaft angle in attached photo, as the truck currently sits.

 

[DirtDonk]

Even though it looks to be at a proper angle, the tell is the actual pinion angle as the rear u-joint and pinion shaft enter the driveshaft. Just out of your picture...

But if it's even remotely close, those traction bars should keep axle-wrap/pinion-climb to a minimum. Which also minimizes vibrations caused by angle change.
It won't change anything to do with bad, dry, or worn out u-joints, but it will subdue normal vibrations from acceleration and deceleration.

Just for giggles then, can you post up one more pic, this time showing more of the rear u-joint?

Thanks

Paul

 

[Amitchla]

I’m guessing the photo in the post just above that doesn’t show the angle properly either, correct?

The driveshaft is currently off the truck, for the 4WD/no driveshaft test I mentioned above. I’ll snap another photo with the driveshaft in place tomorrow.

Thank you for keeping up with this! It’s been very informative and helpful.

 

[DirtDonk]

Correct, not quite good enough.
But you're right that it does show, sort of like the later pic, that the angle appears to be pretty darn good. I just wanted to be sure.

But those pics also show that someone went to a LOT of trouble and expense to set up this Bronco. Overall it looks like they did an extremely sanitary job of putting it all together. Most new owners these days get the dregs of the experiments of the first-time flippers lack of experience with the previous owners lack of restoration experience and wiring prowess.
Yours on the other hand, looks like someone actually cared about it! Which makes sense if the PO built it to go wheeling with. After all, the last thing anyone wants to do is break down in the middle of Glamis on a 105° day while trying to decide whether to walk miles one way or the other, flag down a Metal Mulisha gang, or build an igloo and hope that someone stops by with a Saint Bernard dog and some whiskey or rum, or whatever they used to carry in that flask?

In other words, other than the things you're bound to have happen in any old, possibly hard used vehicle, it looks like you have a great starting point.

Paul

 

[DirtDonk]

And speaking of I Spy in those pics... It looks to me like the centering ball in the CV yoke is dry and full of grit. With the driveshaft off again, you might just consider cleaning that out somehow, then re-lubing it.
Might take some out of the box thinking, but anything to avoid pulling the CV yoke apart into it's component pieces would be good. It's not technically hard, but it's certainly awkward and daunting the first time.

I wonder what all that coloration on the bell housing is. Looks like oil is being flung out of the clutch fork boot. If that's what it is, that would be pretty unusual if it's also not dripping out the bottom weep hole of the housing.
Kind of curious just what's going on in there. Maybe check to make sure the weep hole is open.

If the hole was closed off to hid a rear main leak, oil could build up and get flung around and out the side hole. But that would also mean that your clutch is about to die an early and ugly death-by-oil.
Long shot maybe, but worth a quick check I'd say.

Maybe the coloration is just left over from some other work that was done.

Paul

 

[Amitchla]

But you're right that it does show, sort of like the later pic, that the angle appears to be pretty darn good. I just wanted to be sure.

New pics attached!

Yours on the other hand, looks like someone actually cared about it! Which makes sense if the PO built it to go wheeling with. After all, the last thing anyone wants to do is break down in the middle of Glamis on a 105° day while trying to decide whether to walk miles one way or the other, flag down a Metal Mulisha gang, or build an igloo and hope that someone stops by with a Saint Bernard dog and some whiskey or rum, or whatever they used to carry in that flask?

These scenarios are both hilarious and terrifying.

In other words, other than the things you're bound to have happen in any old, possibly hard used vehicle, it looks like you have a great starting point.

Thanks! That's what really impressed me with this truck. I felt like the build and drivetrain looked VERY well built - which is part of why i'm a bit frustrated with this situation. But - as you said - this is the life of a classic with an unknown past!

It looks to me like the centering ball in the CV yoke is dry and full of grit. With the driveshaft off again, you might just consider cleaning that out somehow, then re-lubing it.
Might take some out of the box thinking, but anything to avoid pulling the CV yoke apart into it's component pieces would be good. It's not technically hard, but it's certainly awkward and daunting the first time.

Hmm - I noticed that the (I assume) seal is moving around inside that area. Is that good/bad/normal?

I watched a video on how to disassemble this joint. It looked, I'm sure, easier on the video than it actually is. It looks like I could also purchase a complete unit as well, if necessary.

Would you suggest cleaning the exterior as best as possible, and attempting to pack in grease?

I wonder what all that coloration on the bell housing is. Looks like oil is being flung out of the clutch fork boot. If that's what it is, that would be pretty unusual if it's also not dripping out the bottom weep hole of the housing.
Kind of curious just what's going on in there. Maybe check to make sure the weep hole is open.

This is basically my train of thought - the grease would have to be slung up to that spot. Though, the clutch is functional (currently, at least). A friend had hypothesized it might be the front input shaft on the transmission that selectively leaks and slings oil. The weep hole is clean and not sealed.

Another realization from today - there's a missing zerk fitting on the forward-most u-joint. Could this contribute to the problem/s?

 

[DirtDonk]

which is part of why i'm a bit frustrated with this situation. But - as you said - this is the life of a classic with an unknown past!

And the guy did say right up front that it ate u-joints, right? Could be other driveline problems rearing up along with the u-joints.

Hmm - I noticed that the (I assume) seal is moving around inside that area. Is that good/bad/normal?

Sounds bad initially. Maybe wait for some others to confirm, but I think that seal (this is a "wiper" type seal around the polished ball, correct?) stays put and should not float around.

Just looking at the rusty end caps on the two "cardans" (the original name for what we call u-joints) makes it look to me like they've been in there for some time. The shaft itself looks almost new, but that's either because it's been painted in the meantime, or those u-joint caps are not very rust-resistant.

Would you suggest cleaning the exterior as best as possible, and attempting to pack in grease?

Yes to the cleaning. But no to the "packing" part if you meant like packing wheel bearings. There is a female Zerk fitting for doing that so you do not need to just slather grease in the workings.
Besides, it would all just fling up on the underside of the body the first time you drove it!
If that's what you meant.

Another realization from today - there's a missing zerk fitting on the forward-most u-joint. Could this contribute to the problem/s?[/QUOTE]

No, it's not missing. It's a female fitting, as opposed to the more common male fitting. Should be one on the centering ball too.
There are usually five different Zerk fittings on a typical double-cardan style driveshaft. Three for the u-joints, one for the centering ball and yoke, and one for the slip shaft.
I see a female fitting in the picture. Just needs a special adapter for the end of your grease gun that is a needle/pointy thingy designed to push grease into the cup, just as the end would normally grip the tip of the male fitting.

Speaking of the slip shaft... Yours does not look very "polished" like they would get under normal use. I wonder if the seal under that threaded cap is missing or deteriorated. Easy thing to check anyway.

And just to get this out of the way, you did just throw the shaft in for picture purposes. Correct?
Otherwise you might not get far with it not bolted in!%)
Haha! Had to mention it!

Paul

 

[bax]

Picture 1 guys. take a look what do you see?

 

[bax]

The slip yoke u joint is out of phase with the CV joint. That will set up a vibration that can shake the shit out of output shaft of the dana 20.

 

[DirtDonk]

Badda bing, badda boom...
Good catch! Yep Amitchia, get that sorted and see what else changes.

Do you see what bax is talking about?

Paul

 

[Amitchla]

Wow, good catch! What’s intriguing with this is that the truck didn’t immefiately start to do this after the diff was changed (which must be the time when it was misaligned by the mechanic).

The matching arrows are around 90-120deg off.

Now - the slip yoke will not slip off, of course. I may have to get creative on removing it.

I’ll report back on this when I correct it. THANK YOU!

 

[DirtDonk]

The slip might have the seal in there after all then. If so, it will bind up on the wider splined area (it's supposed to fit around the smooth shank part) so you may just have to get a little Conan on it rather than truly creative.
But a little of both can't hurt!

Paul

 

[DirtDonk]

Oh, and wouldn't that be nice if it gets rid of the noise!

Paul

 

[Amitchla]

Ok - I ended up taking it to a shop to get the yoke removed bc it was impossible for me.

I reinstalled the driveshaft and, unfortunately, the noise is still there.

At this point, I guess I'll rebuild the double cardan joint and replace the u-joints, then check the Dana 20, then go to the transmission.

The search continues...

 

[bax]

the cv joint is good to replace you will know thats not the problem when you are done.

 

[brewchief]

If you can find a local driveshaft shop they are sometimes cheaper than you might think for replacing the joints in the shaft, better yet they can verify balance on the shaft and correct if needed.

I agree with the others on it probably not being the transmission, I suppose if it had water in it at some point and rusted you might hurt the bearings but if it's always had some sort of oil like substance it's a pretty hard to hurt transmission.

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