Heavier u-joint on wreckers and tractors ?

[msgjd]

I did a quick search here and found nothing specific. . I ran across a post on the Facebook military wrecker site claiming the subject matter above to be true .. Apparently I am doing something right for the last 45 years as I have never busted a u-joint or jackshaft/short shaft/ stub shaft on any 6x6 regardless I have been working the 5-tons, sometimes quite heavily, for decades.. .. Have also not needed to replace any u-joints, they get greased (and other PM) every week they work.... But I have heard of a couple guys who broke theirs.

Without spending a lot of time cross-referencing dash-24P manuals, can anyone out there confirm there is a strength difference between a wrecker or tractor driveline, and a cargo ? If so, was there ever a MWO or general practice for BN Maint to replace one for the other? I am talking M39-series and M809-series only.

 

[Mullaney]

I did a quick search here and found nothing specific. . I ran across a post on the Facebook military wrecker site claiming the subject matter above to be true .. Apparently I am doing something right for the last 45 years as I have never busted a u-joint or jackshaft/short shaft/ stub shaft on any 6x6 regardless I have been working the 5-tons, sometimes quite heavily, for decades.. .. Have also not needed to replace any u-joints, they get greased (and other PM) every week they work.... But I have heard of a couple guys who broke theirs.

Without spending a lot of time cross-referencing dash-24P manuals, can anyone out there confirm there is a strength difference between a wrecker or tractor driveline, and a cargo ? If so, was there ever a MWO or general practice for BN Maint to replace one for the other? I am talking M39-series and M809-series only.

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Definitely would be nice to know for sure if there is a U-Joint upgrade .
Subscribed to this thread...

It is interesting.
Looking at the -24, the Cargo, Wrecker and Tractor are all in the same book.
A quick look by me didn't show different part numbers.

Wonder if the "Big 3" are driven a little more - and the "Cargo" is snatched around a little more?

 

[USAFSS-ColdWarrior]

Inquiring Mimes want to know.

I hope this is a bonus feature.

 

[98G]

I'm guessing not, for the following reasons-

1) I haven't observed a difference

2) the TM doesn't differentiate

3) The way the military thinks, if the wrecker and tractor needed a heavier one they'd simply spec the heavier one for all trucks in the series in the name of standardization.

Items 1 and 2 are actually a function of #3....

 

[msgjd]

I'm guessing not, for the following reasons-

1) I haven't observed a difference

2) the TM doesn't differentiate

3) The way the military thinks, if the wrecker and tractor needed a heavier one they'd simply spec the heavier one for all trucks in the series in the name of standardization.

Items 1 and 2 are actually a function of #3....

that is exactly my feeling about the matter .. thanks .. the Facebook post may have been right along the lines of the incorrect thinking that on 5-tons, the front axle only engages when truck is is 1st or reverse .. lol

 

[msgjd]

I stand corrected : Braved the rain-soaked ground and tall tick-laden hay to look at what's on the two mothballed M51A2's kept here .. They both have identical joints but are different than what I see on the 813, 817, and 818 that are working at this location presently, which have identical class 8 commercial style joints all the way around.. At present, all my other M809-series and M39-series stuff including the wrecker are 125 miles away at our other site and I'm not the one who PM's that bunch for me, have not been underneath them for over three years and don't recall what they have. Too much equip to deal with, and keeping memory intact is becoming a challenge.

Reached out to the fellow who initiated the claim and he provided pics and a very good presentation. It appears there are 5 different styles of joints & caps including the commercial "big rig" style I see on all the 809-series sitting here .. Am waiting on his permission to post presentation and pics here . As far as his dash-24P goes, he claims some of the parts numbers had already superseded to the heavier style joint , and part numbers may be the same but have an "A" designation for a different style joint, supposedly listed only for wreckers and tractors. Once again a subject is taking more time than what I have to spend

 

[msgjd]

a special thank you to Paul Mather for the 1st four pics and info .. Paul said the joint in pic #2 is the style prone to break, I can concur with that because I have a 8-ton civvy dump truck with that style (thin web) and it busted a cap and subsequently the differential yoke while backing up a steep driveway with a load . .. He also said the standard forged cap in pic #3 is the replacement found on cargo's etc., and the heavy-thick forged type in pic #4 is the one with the "A" suffix in the dash-24P for wreckers and tractors .. However, the commercial-style in the last pic is what is on my 813, 817, and at least one of the 818's . I have a long drive to make to check out my other M809's and M39's (and M62 wrecker)

 

[Mullaney]

a special thank you to Paul Mather for the 1st 4 pics and info

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Wow! It's amazing to see that many options all in one place!!
Extra very neat!!

 

[msgjd]

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Wow! It's amazing to see that many options all in one place!!
Extra very neat!!

makes me curious to get up to our other location and re-familiarize myself with what all the other trucks have , and if any had been upgraded prior the DRMO

 

[Mullaney]

makes me curious to get up to our other location and re-familiarize myself with what all the other trucks have , and if any had been upgraded prior the DRMO

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Agreed for sure. Having downloaded the pictures, I am hoping to slide under my M936 and look around. It's a 1984, so a diesel and auto transmission are in my setup. It will be interesting to see what might have been updated. There is exactly one MWO on this truck. A lot of things on it are "different from stock". Might have even been a "development" or "test bed" at some point in its life.

I will try to report back with a few pictures to add and compare. Weather permitting (back yard mechanic).

 

[msgjd]

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I am hoping to slide under my M936 and look around. It's a 1984, A lot of things on it are "different from stock". Might have even been a "development" or "test bed" at some point in its life.

somewhere months ago I saw pics of early trucks in your series that had some external features typically seen on the M809's . Or maybe it was the other way around ... short-term memory is going bye-bye

 

[Lonnie]

My M818 has the commercial flanged style.