“Pitting”... would this cause a grumbling noise?

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Re: “Pitting”... would this cause a grumbling noise?

Post by fiveftsix » Tue Aug 06, 2019 8:53 pm

I'm a little confused here l was under the impression this is a rebuilt box?
But here we see pitting on the main shaft
Why???
Is the input shaft worn where these rollers run?
Quite a common problem on a T84 jeep box
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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Wed Aug 07, 2019 1:55 am

Nope. Your not missing anything.

Correct. It was purchased as a rebuilt unit.

It was not my gear box to begin with, as I never had the correct 1/2 ton gear box in my WC-12

I purchased it as a rebuilt unit from one of the suppliers.

It was always “assumed” by me that they simply built this tranny up from a used transmission, cleaning it up, reusing the gears, shafts and all. But replaced all the bearing and seals, which was done and new replacement parts were used

Perhaps the main shaft and input shaft looked “ok” to them, or what they considered serviceable. Dont know.

It’s until I couldn’t deal with this grinding did I decide to tear into it and see what was wrong.

It’s always made this noise since day one of install

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Re: “Pitting”... would this cause a grumbling noise?

Post by artificer » Wed Aug 07, 2019 4:24 am

This really points out an important issue with all forums & expectations:

Full information & questioning is always needed!
Plus QUESTIONS ASKED properly answered & that is a rarity.

Mike W. is correctly always on about 'assume' as we all should be.

Geoff is on target 100% & indicates why we often end up with multiple pages of confusion.

When we hear of a rebuilt 'transmission' unit, this aspect, in most qualified folk's mind....trying to help, eliminates many things, including what actually appears later in this case.

A few recent pictures cleared up, identified spalling/flaking [bearing related] & pin pointed where this elusive noise was coming from.

These pic's help pin point where the 'growling/grumbling' [always bearing related] noise was really coming from.
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Re: “Pitting”... would this cause a grumbling noise?

Post by Joe Gopan » Wed Aug 07, 2019 5:58 am

The main Drive Bearing bearing should be suspect as particles from transmission wear may be imbedded in the Main Drive bearing or from a chipped tooth on the Main Drive gear. The Reverse Idler Shaft or Rev. Idler Bushing may be worn. Cleatance between shaft and Bushing should be less than 0.006", the cure is new Rev Idler shaft and gear. Main shaft ball bearing may also have imbedded chips inside.
Remember that this gearbox is 75 years old and some parts may not be reseable. I had a quantity of REOME rebuilt WC transmissions and they were assembled with used , but questionableserviceable parts. Suggest this be reassembled with original OEM gasket set if possible as there are different thickness gaskets to eastablish certain clearances.
Having the original manual is a must.

And those Caged Roller Bearings are inexpensive. There is a simple test for them. Grip either end and twist back and forth if there is any motion, it is time for new.
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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Wed Aug 07, 2019 6:34 am

I gotcha there Ben.

I’ve washed and then re-washed all parts in kerosene a few times now, removing anything else that may have been stuck in the bearings and crevices of the tranny case.

I did remove the reverse idler, and it it pretty tight on the shaft. Both appear to be good.
Full information & questioning is always needed!
Plus QUESTIONS ASKED properly answered & that is a rarity.
Absolutely right! What am I actually getting for my money? What’s new? What’s being re-used?

I know I didn’t ask those questions.
I guess for most owners of these trucks the growling was noted as being normal
And should expect it.

I just couldn’t live with it. Sorry!

Anyway.. I am ordering another NOS reverse idle shifter fork as well, because , after seeing the original bent one I had, wondering too if the used one I replaced it with was just marginally better.

Thanks for all the continued advice.

It’s nice having you really experienced guys here to get advice from.

I’m sure hoping this is it!!

I’ll do a follow up after I get and install new parts and put tranny back in truck
Last edited by wc56daveyboy on Wed Aug 07, 2019 2:27 pm, edited 1 time in total.


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Re: “Pitting”... would this cause a grumbling noise?

Post by W. Winget » Wed Aug 07, 2019 8:01 am

Gee, I thought this is why they put sawdust in the transmission cases before selling them...

If your planning on driving the ALCAN, i agree, swap it now.
If your planning on parades, low use every few weeks months, it may last another 75 years and be another future owners noise/growing concern when they get it. (assuming we cannot take them to the grave or smelt them ourselves willingly)
It's what makes you the owner / operator comfortable and happy, simple enough.
Don't like the growl...add money... instead of sawdust. :)
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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Wed Aug 07, 2019 9:57 am

I was almost there adding the sawdust!! :lol:

Still . Until I get the parts I just ordered and back in the tranny/truck, who knows the outcome.

I’ve done my best investigation and scrutiny of all the parts and it seems the most likely suspect..

But who knows :?

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Re: “Pitting”... would this cause a grumbling noise?

Post by Diesel Dave » Wed Aug 07, 2019 1:58 pm

You purchased as a rebuild from a supplier? What was their explanation?

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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Wed Aug 07, 2019 2:25 pm

I was given the option to “Send it back for a full refund”

I don’t have another to put in the truck should I have shipped it back.

I’ve got a lot invested already with time and fluids alone. Thought I would work with what I have and figure it out.

Seller Didn’t have an answer to my problem. I’ve spent considerable time and effort trying to diagnose this myself. In his defense, he has a lot of other customers to deal with. Doubt he remembers every detail of my Tranny

I’ve had a lot of advise, a lot of it good.

A lot of it was to replace certain parts, which I did, with no change.

Lots of parts were probably good to begin with, leaving a lot of us stumped and thinking other area of concern.

I guess if I looked closer at this nose piece earlier on, the first time I removed and dismantled it, would have saved me a lot of time and money.
Last edited by wc56daveyboy on Wed Aug 14, 2019 11:30 am, edited 2 times in total.

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Re: “Pitting”... would this cause a grumbling noise?

Post by fiveftsix » Wed Aug 07, 2019 8:41 pm

I'm a little late reading the follow ups.
But my impression now is the box was not rebuilt in the true sense of the word but revamped!!!
The instilation of new bearings in my view does not constitute a rebuilt box !!!
It is not just a case of renewing bearings but also shafts etc that run in those bearings and that would also include the case itself.!!!
One may as l would say get away with slightly pitted gears but certainly not bearing surfaces.
That main shaft should have been replaced together with the input shaft
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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Thu Aug 08, 2019 7:07 am

Tell me:

Another possible area that could cause this noise:
Would looseness between the main shaft splines and sliding gears cause “rattling” gears on the main shaft splines?

Perhaps causing a residual “chatter” or vibration as the truck runs in neutral?

Would loose spline to gear tolerance add to the noise in my video?

I was thinking perhaps so.

When I took out the 1-2 and 3-direct gears, they had a bit of play on the main shaft splines
The other Tranny I had lying around yielded very very tight gear to spline mating.

So I’m using them. They look better too

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Re: “Pitting”... would this cause a grumbling noise?

Post by W. Winget » Thu Aug 08, 2019 8:47 am

I think it comes down to the design of the gears themselves. Straight cut gears always have more clearance and less area to wipe against each other hence the whine and rattle/noise. Once cut as a spiral they quiet down well (later design) have less 'bang'/chatter as they interface at an angle VS flat contact tooth and
helical gears being the quietest (but I (personally) don't know how one could shift a helical gearbox).

(Side note: Watched a great Video from Chevy or such on YouTube about this, I Think it was about this one, but it may have been about cutting gears instead)
https://www.youtube.com/watch?v=JOLtS4VUcvQ

For it's time and design, a straight cut gearbox was desired for both reliability, ruggedness and frankly $$$ of manufacturing. I can't speak to the timeline for transmission design, but note the MB/GPW ended up with syncros in the 2nd and 3rd gears, likely as it had transitioned from a civilian car gearbox into mass production, the Dodge on the other hand came from a truck, and stayed a truck... until the M37 (and Power Wagon) production started adding a little luxury to the line, and redesign to address some of the "truck like" issues.
Once assembled, I would think to put in straight up Lucas Oil which like the old STP engine treatment, is thicker (not right, "higher degree of lubricity") and helps to keep oil on the teeth as they go around and clash against each other helping to quiet it down.

Either way, you will be the "Go To Guy!" for 1/2T transmissions after these experiences. :wink:
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Re: “Pitting”... would this cause a grumbling noise?

Post by Joe Gopan » Thu Aug 08, 2019 9:46 am

If your engine as an irratic idle, it can be the source of L-R Sliding Gear Rattle, Reverse Idler Gear Rattle. Out od adjustment PTO Clearance can also be a source.
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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Wed Aug 14, 2019 5:47 am

Checked all that too Ben. Erratic idle has been suggested as a potential noise source exactly as your stating here.

Well i got the replacement NOS parts in yesterday, that being both NOS main shaft and NOS input shaft. Hoping this is it. These look great.

Both sliding gears fit well with no slop on the splines.

I did want to share this excellent article I found on line. Though it is reference to a vintage tractor rebuild, the general design is similar to a lot of transmissions in so much as how they are built and designed to work.

the author takes a lot of time showing wear points and describing the effects of those wear issues.

http://www.ntractorclub.com/howtos/pdfs ... ission.pdf

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Re: “Pitting”... would this cause a grumbling noise?

Post by wc56daveyboy » Wed Aug 14, 2019 10:44 am

By George, I believe I've got it!

Yup. Noise is now gone.

In addition to the noise gone while running in neutral, the truck is just quieter all around.

Now that all said, I didn't take it on a long voyage yet..because it wasn't buttoned up 100%. but the truck was completely warmed up
and a short ride like I took would have by now made the transmission growl.

so I believe I have been successful.

what did I end up changing out?

1- Input shaft to a NOS unit
2- Main shaft to a NOS unit
3- the reverse idler shifter fork. WHY? because I thought i had a bent one.. well I did actually, at one tim so I wanted to take no chances that this, being bent, could allow the reverse gears to move forward and barely touch the rotating cluster gear set.


Amazes me that just that pitting (OR galling) on the main shaft and mating input shaft could cause such noises. Its like driving a different truck now.
I can only believe that this area of wear was the ultimate culprit here

to be fair, its possible that the use of the better 1st/2nd and 3rd/4th sliding gears added to this noise reduction.
perhaps Ill never 100% know or be sure..

My thanks to all who have participated in helping diagnose this issue.. I am grateful.

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