Return of the Rear Axle Clackity Sound

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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Re: Return of the Rear Axle Clackity Sound

Post by warbirdphotog » Sun Jun 06, 2021 12:50 am

Okay, and now that I've replied to everyone... now on to the latest update!

Opening up the Differential - So, last weekend I finally opened up the differential and took a look inside. I drained the oil and inspected everything mentioned in this thread so far. I'll go through them all one by one...
  1. Cover - I checked the cover for any signs of something striking it, rubbing on it, etc. The good news, like most axles, the inside of the cover and the inside of the differential have been 'stained' with the oil for so many years that it's turned that darker color. Because of that, it makes it very easy to see if something is rubbing/striking as it will look more silver. The cover showed no signs of anything hitting, and the outside edge of the ring doesn't show any signs of scraping.
  2. Ring - As mentioned, no signs of scraping on the outside. I took very detailed photos of the ring during install, so I compared it now with my photos of it then, nothing seems to have changed.
  3. Carrier Ring Bolts/Lock Straps - I checked the bolts holding the ring to the carrier and the lock straps. No signs of them rubbing/striking the differential housing in any way. I can't see how it could be moved enough to strike as the carrier is in there nice and snug and there's at least a quarter of an inch or more of space between the bolts and the housing. But regardless, nothing looked scraped on the housing walls.
  4. Pinion - As with the ring gear, I used photos I had from install and inspected it. Could not find anything out of the ordinary.
  5. Spider Gears - Checked all four of the gears, no sign of wear.
  6. Axle shafts - Pulled out the axle shafts, no sign of abnormal wear on the ends interfacing with the spider gears.
  7. Carrier - Didn't see anything out of the ordinary with the carrier itself.
Metal Shavings - I did find some fine metal shavings in the rear axle oil. Not nearly as much as the first GPW rear axle, this time it was minor and I've driven the Jeep well over 20 miles since we set this axle. I've been told by several people I sent photos to that it looks like normal wear from a newly set ring and pinion as they find their best place.

Axle Wedges - As mentioned a few pages back in this thread, some people were saying they felt the angle of the differential when I decelerate is moving downwards too much, possibly causing the pinion to move from stress. So, I went out and got a set of axle wedges to give it a try. At this point, I'm willing to try whatever. It was a process getting those in there. I used 4-degree wedges (about .4 of an inch). After installation and everything tightened down, I took the Jeep for a spin. The sound didn't change at all. Sigh.

Drums - Another item that I wanted to try, just to check a box off, was my drums since they have moved over from the original axle. The drums are replacement GPW ones I got from a friend after the drums that came with the first GPW axle were so far out of spec that you'd need to use thicker pads. So I got a set of GPW replacements for the rear axle that were well within spec. As you might recall, to make sure with these replacements, I recently took them in and had them resurfaced with no change in the sound. So, I grabbed one of the original out-of-spec drums and decided to install one of them (with different bearings/races) on the axle one at a time. This way, I'd still have 3 wheels that would brake. Tried the out-of-spec drum on both sides, no change. It was a long shot, but gotta check everything off. So the good set is back on the Jeep.

New Yoke - Another item mentioned was that possibly my yoke is worn out since that is another item that's traveled from the first axle to the second axle. It's been a bit of a pain finding a good yoke. All the repro yokes you can get online are modern versions that look nothing like the WW2 ones, and at about $45+, I'm not going to spend that much just to test a yoke that I won't use. So, a week ago I won a good condition yoke on eBay (take-off). Sadly, it's been a week and the seller hasn't shipped it yet. I'm hopeful it will ship soon after I sent him a message yesterday asking for a status update. Once I get that, I'll swap yokes (and check the pinion pre-load again).

So, that's where I am now. Pretty much back to square one. I did take the Jeep for a drive to the Planes of Fame Air Museum at Chino Airport, CA (I'm a photographer/social media creator for the museum) yesterday and she ran just fine, though it was VERY hard to tune out that clackity sound the entire 30-minute drive there and back. I was hyper-aware of any weird sounds, vibrations, etc worried that something was going to go wrong. But thankfully, nothing did.

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Last edited by warbirdphotog on Tue Jun 08, 2021 4:55 pm, edited 1 time in total.
Britt
1944 Ford GPW #208102 undergoing restoration!
Follow the progress: http://www.facebook.com/1944gpw or on the Blog: https://1944gpw.warbirdphotos.us


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Re: Return of the Rear Axle Clackity Sound

Post by YLG80 » Sun Jun 06, 2021 1:21 am

Waooh, what a beautiful photo ! Thanks for sharing a picture of these two legends.
If I'm correct, that particular Mitchell "Pacific Princess" was used in the movie "Pearl Harbor", isn't it?

It's too bad that you didn't find anything when opening the rear axle.
I guess that the only solution to locate exactly the source of the issue will be to use a stethoscope.
Yves
Ford GPW 1943 - Louisville - DoD 12-7-43
serial 164794

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Re: Return of the Rear Axle Clackity Sound

Post by Wolfman » Sun Jun 06, 2021 6:08 am

Have to appreciate fine art !
Good looking jeep too !!
Sure be interesting to see what this noise is when you find the source.
Off the wall thoughts.
What did you put in one of the tool boxes before this started ??
Maybe a shock hanging up ??
Starting to think it is going to be something weird like this.
Mike Wolford
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Re: Return of the Rear Axle Clackity Sound

Post by harve » Sun Jun 06, 2021 10:33 am

Pull the oil pan down asap , sounds like something in the bottom end. I wouldn’t drive it anymore. Rod bearings or crankshaft end play isn’t Kosher . :roll:

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Re: Return of the Rear Axle Clackity Sound

Post by parker007 » Sun Jun 06, 2021 10:57 am

Wow what a undertaking to find the problem .Im wondering if it could be transfer case. have you pulled the cover? and inspected.

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Re: Return of the Rear Axle Clackity Sound

Post by warbirdphotog » Sun Jun 06, 2021 3:08 pm

YLG80 wrote:
Sun Jun 06, 2021 1:21 am
Waooh, what a beautiful photo ! Thanks for sharing a picture of these two legends.
If I'm correct, that particular Mitchell "Pacific Princess" was used in the movie "Pearl Harbor", isn't it?
Correct, that is the North American B-25J Mitchell 'Pacific Princess', and she was one of the B-25s used in the Pearl Harbor (2001) movie. An interesting fun fact, that B-25 Mitchell was built the same month and year as my Jeep! June 1944.
YLG80 wrote:
Sun Jun 06, 2021 1:21 am
It's too bad that you didn't find anything when opening the rear axle. I guess that the only solution to locate exactly the source of the issue will be to use a stethoscope.
I'll see what I can do tomorrow, but problems going to be trying to hang out the Jeep and listen for it. Gotta hang out enough to get the probe to touch the rear axle.
Wolfman wrote:
Sun Jun 06, 2021 6:08 am
Have to appreciate fine art ! Good looking jeep too !! Sure be interesting to see what this noise is when you find the source. Off the wall thoughts. What did you put in one of the tool boxes before this started ?? Maybe a shock hanging up ?? Starting to think it is going to be something weird like this.
Thanks! As far as the tool boxes, it's too repetitive to be something in there, and it has a mechanical 'clackity' to it. But, I did shift things around in the toolbox just in case a few times. All that's in there is my spare tool kit (in the canvas tool kit bag) and a small dust clearer. The other side has spare headlight covers.
Don't think it's the shocks, I tested them when I had them off, they work really well considering they are original GPW Gabriels. I wish it was something as simple as that!!
harve wrote:
Sun Jun 06, 2021 10:33 am
Pull the oil pan down asap , sounds like something in the bottom end. I wouldn’t drive it anymore. Rod bearings or crankshaft end play isn’t Kosher . :roll:
It is not engine-related. We have proven this through this thread and the previous one. This is 100% rear axle related. Yes, the valves on my Jeep are noisy, but there's nothing wrong with the engine.
parker007 wrote:
Sun Jun 06, 2021 10:57 am
Wow what a undertaking to find the problem .Im wondering if it could be transfer case. have you pulled the cover? and inspected.
When the first rear axle had the issue, after the initial checks and tests we thought it was the transfer case and/or the transmission. So I took several weeks and did an extensive detailed rebuild and restoration of both the T-84 and D-18. I got it as perfect as perfect could be... no change in the sound. That ruled out the two of them :-/
Britt
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Follow the progress: http://www.facebook.com/1944gpw or on the Blog: https://1944gpw.warbirdphotos.us

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Re: Return of the Rear Axle Clackity Sound

Post by Wolfman » Mon Jun 07, 2021 6:27 am

Using a stethoscope to listen to the rear differential on a moving jeep would be a real circus act.
Neighbors will think you have lost it ! :lol:
Don't get hurt !!
???
May not be proper to ask, but, How old are you ???
I could see me pulling this off when I was 18, but now days, Forget it !!
When I brought this up, I was thinking more of a jeep on jack stands. Good Ones !
Mike Wolford
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AOPA ( 50 yrs)
EAA ( 49 yrs)
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Re: Return of the Rear Axle Clackity Sound

Post by GPW1263 » Mon Jun 07, 2021 7:10 am

One solution would be to buy a Gama Goat. You can't hear ANYTHING over the roar of that Detroit Diesel (especially with ear pro) and when you finally have had enough and you get back to the jeep, you'll be deaf as a post. Then, all will be well. :lol:

By the way, I'm thinking you have a fouled up clutch disc.

Cheers,
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Re: Return of the Rear Axle Clackity Sound

Post by JAB » Mon Jun 07, 2021 8:41 am

Maybe it's time to start a guessing pool. Everybody throws in a dollar and posts their guess and when the cause is determined the winner takes all. Lol!
-Jeff

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Re: Return of the Rear Axle Clackity Sound

Post by parker007 » Mon Jun 07, 2021 9:26 am

The more i listen to i think it possible rubbing like a muffler to body? or transfer case to underbody.

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Re: Return of the Rear Axle Clackity Sound

Post by Wolfman » Mon Jun 07, 2021 10:48 am

I suggested a loose muffler baffle way back, Parker.
I won a set of hood blocks a few years ago on a "Who can guess the problem first" contest, a "G" member ran, Jeff.
A guy drove his jeep up to a stop sign & stopped. When he tried to move, nothing. Everything seemed to be working but the jeep wouldn't move.
I won't keep you in suspense.
The cotter pin on the nut on the rear of the transmission main shaft was left out.
The nut came loose and fell off, shortly followed by the transfercase drive gear and there he set.
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Re: Return of the Rear Axle Clackity Sound

Post by warbirdphotog » Mon Jun 07, 2021 11:16 pm

Wolfman wrote:
Mon Jun 07, 2021 6:27 am
Using a stethoscope to listen to the rear differential on a moving jeep would be a real circus act. I could see me pulling this off when I was 18, but now days, Forget it !! When I brought this up, I was thinking more of a jeep on jack stands. Good Ones !
Yeah, it's going to be a fruitless act I'm sure, but I could at least place it on the rims/wheels and see if one side sounds louder than the other. What I need is some brave person to be strapped into a creeper under the Jeep as I slowly drive it! Ha ha.
GPW1263 wrote:
Mon Jun 07, 2021 7:10 am
By the way, I'm thinking you have a fouled up clutch disc.
Sound isn't coming from anywhere near the clutch. I had the GoPro set right next to the bell housing in multiple angles, no sound. You can only hear the sound from the GoPros when it's on/over/near the rear axle. I also had the flywheel resurfaced, and a brand new clutch disc. Remember, things were just fine BEFORE replacing the CJ axles with the GPW ones. Nothing was changed with the clutch between doing that.
JAB wrote:
Mon Jun 07, 2021 8:41 am
Maybe it's time to start a guessing pool. Everybody throws in a dollar and posts their guess and when the cause is determined the winner takes all. Lol!
Except at this point, I'm pretty sure we've exhausted most of the guesses! Ha ha.
parker007 wrote:
Mon Jun 07, 2021 9:26 am
The more i listen to i think it possible rubbing like a muffler to body? or transfer case to underbody.
This was checked earlier on, the muffler is not touching the body at all, and there was no change with the muffler between the removal of the CJ axles and the addition of the GPW ones to explain the dramatic change. Transfer case is the same way, and it's verified that it's not touching. When the CJ axles were on the Jeep, this sound was not there (and I drove over 400 miles like that). It was only when I swapped the axles that the noise started.
Britt
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Follow the progress: http://www.facebook.com/1944gpw or on the Blog: https://1944gpw.warbirdphotos.us

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Re: Return of the Rear Axle Clackity Sound

Post by W. Winget » Tue Jun 08, 2021 5:56 am

I think you mentioned you had a guy that knew what he was doing set up the rear gear and pinion.
Not hitting on them, they installed it and it works, tooth pattern would tell more...

Is there a slight possibility that the ring, or the pinion gear are possibly cut incorrectly?
often surplus NOS can become clouded with surplus parts that were factory rejects from production checks for one or more reasons and get picked up by purchasers that should be scrapping them VS selling them off as NOS correct parts.

If there were one degree cut difference, or one 'tooth' that had an incorrect cut, maybe the back side of the tooth...it may be the cause of the noise.
Somewhere two years ago I had a loose NOS Ford marked ring I would have sent you, but I think it was sold at the Aberdeen show.
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Re: Return of the Rear Axle Clackity Sound

Post by Michael O. » Tue Jun 08, 2021 7:45 am

Were the ring gear and pinion a matching “set”?
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Re: Return of the Rear Axle Clackity Sound

Post by warbirdphotog » Tue Jun 08, 2021 4:53 pm

W. Winget wrote:
Tue Jun 08, 2021 5:56 am
I think you mentioned you had a guy that knew what he was doing set up the rear gear and pinion.
Not hitting on them, they installed it and it works, tooth pattern would tell more...
Here's the thing, if he were to be doing this incorrectly, then I doubt the front axle would be working. But, it's totally fine. And he'd just done two other ring and pinions in an MB Jeep just a week before my second rear GPW. They have no issues with their axles. So I have no reason to believe he did anything wrong, as the front axle would be wrong as well. And, on top of that, maybe I could say he got the first one wrong (still I don't believe that, but for argument's sake), but we both did the second rear axle and I can tell you that we put it together by the book. I don't think you'll find a better-built axle out there. Minus the sound, of course.
W. Winget wrote:
Tue Jun 08, 2021 5:56 am
Is there a slight possibility that the ring, or the pinion gear are possibly cut incorrectly?
often surplus NOS can become clouded with surplus parts that were factory rejects from production checks for one or more reasons and get picked up by purchasers that should be scrapping them VS selling them off as NOS correct parts.
That was our thought on the first GPW rear axle. It was a NOS set I got from Mullens on eBay. They were a matching pair, but we think there was something slightly off with them. However, the second GPW axle has a totally different set (which was already in the axle, so we know they work as they had been used in that axle) with a totally different carrier. The fact the sound is the same between both axles with no change tells me that's not the issue, sadly. But that was one of the first thoughts we had!
Michael O. wrote:
Tue Jun 08, 2021 7:45 am
Were the ring gear and pinion a matching “set”?
Yes, all the ring and pinions I've used are matching sets. The front GPW axle had a really good ring and pinion, so I just reused them. Remember, the first GPW rear axle had a spider gear explosion which ruined the carrier, ring, and pinion. So I got another GPW carrier, and then a NOS GPW ring and pinion set (all matching numbers). When I switched to the second GPW rear axle, I used the matching ring and pinion pair that was already in that axle since they were in good enough condition to use with the carrier. So, that's two different ring and pinions for two different rear axles that both have the same sound.
Britt
1944 Ford GPW #208102 undergoing restoration!
Follow the progress: http://www.facebook.com/1944gpw or on the Blog: https://1944gpw.warbirdphotos.us


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