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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078
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Discussion Starter #1
Background:
One of the theories behind tranny problems that occur in 404’s that get highway use is that the oil feed passageway that keeps the bushings lubricated gets blocked. Thusly this causes the shaft to overheat and swell. This means the tranny seizes and other awful things occur. This passageway is a hollowed path inside one of the shafts in the tranny.

Those who use a Mog more as it is designed (tractor) don’t seem to get this issue as much so maybe it’s a combination of things along with the above-described issue that causes the doccumented failure buttttttt…

Anyyyyway…. Now I hear there are "oil covers", or caps that can give one access to this shaft and its hollow passageway. Anyone know where these are? Any got pictures? Anyone got a diagram of where these are? Are they accessible in any way shape or form while the tranny is in the Mog? I would love to be able to keep this hollowed passageway cleaned out. Think that a tube could be inserted on occasion to vacuum out the thing? Would put some oil back into it if did this.

I doubt it would be easy but after reading about the caps my mind quickly jumped to tapping them, and installing an oil feed tube into the cap. Then pumping cooled oil in there to better feed the hollow shafts. I would think this would feeds the bushings better. Maybe use a very low-pressure pump since I believe these "hollow shafts" are originaly designed to be fed oil via a splash and catch action of some sort. Was thinking that with an oil cooler and an OIL FILTER SYSTEM this could be the ticket for 404's that see more than expected highway miles.
 

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Unimog_404.113_1970
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http://users.telenet.be/pcl/content/unimog/Gear_box_Mog.jpg

i see mostly ball bearings .. [?]
(posting image as a link .. quite large pic.)
 

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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078
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5,856 Posts
Discussion Starter #3
You know those yellow bushings that make us use GL4 and not GL5. Well those are the ones that are lubed via the passage ways that some say are prone to get clogged.
 

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Sharing info from the list

"I was checking out the tranny looking for these plates. I found two plates that may be what you are talking about. One is a 2 bolt plate on the rear drivers side about 3"L x 1.5"w (flat & thin)and the other is a plate you can see from underneath near the front drivers side beside the plate where the speedo cable connects (Thick and round cast looking). Any other plates look to me that they would require either tranny removal or bellhousing removal....

Thanks,.... Doug HALKETT"
 

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The plates are covering the front ends of the transmission shafts, I have only removed them on a stripped transmission so I dont remember how accessible they are in the truck. The one with the speedo gear is one of them. I will take a look and some pictures after work tonight and post them on mogtech.com

basically, you have pockets cast into the inside of the transmission case, these pockets collect gear oil and drain it into the cover plates which have passages that direct it into the hollow tranmission shafts.
By removing the cover plate you can access the end of the shaft and theoretically can rod it out. Bernardo mentioned that a unit he tore down was impacted with gear dust/sludge, and others have mentione similar things. I can see how an old used unit could get impacted, this would inhibit the already limited gravity oiling capability. Purely theoretical at this point, but seems reasonable? I have both a SAAR rebuild with a few thousand miles and a well-used trans. Myabe I will compare the two and see what comes out?"

Another poster backs this up and says ---> one is not accessible due to the bellhousing.
 

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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078
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5,856 Posts
Discussion Starter #6
By B.Westphal of the mail list "The (primary) shaft is not hollow, the main shaft is not hollow but the secondary shaft is total hollow (tapped at the rear end only) and the intermediate shaft is hollow to the middle (aprox) of it's length. Borings only open front the 'front' side.."
 

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404.s x VW-Lt
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I think when putting a oilpump and cooler in you have to watch out you dont drain the tranny. Its intend to give splash lubrication so i would try to hold that in. Maybe you can make above the oil level a side reservoir that fills with (extra) oil from were you pump oil trough a filter/cooler and with a nozzle back in the tranny. (aming nozzle(s) at those sticky shaft parts?)
 
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