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m1078 to A1 driveshaft parts source

Oxyacetylene

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hmmm..... but wouldn't a 6x6 axle have the (for lack of better term) Offset differential Box rasiraising yoke above height of pumpkin? If so then this is not a 6x6 axle.
I was thinking that maybe rather than an offset box, the rearmost axle was angled upwards to help mate with the forward axle. Just a wild guess though.
 

Oxyacetylene

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Since I don't have a 6x6 I found a few pics online. Can I post pics from GP? Here's a few showing the rear most axle on a 6x6, and there is not much offset for it. Hard to tell but it appears to be angled up.
573923_6005_0_0002.jpg573923_6005_0_0003.jpg573923_6005_0_0004.jpg
 
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scottmandu

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A buddy of mine who has made hundreds of shafts for trucks at Fort Leonard Wood has this to say.

"These are 1610 series Spicer driveshafts. We have repaired bunches of them for the Army. They tend to be worn out at the splines.Your angles don't look too bad.

by the way, the 1610 series is rated at 720lb. ft. of continuous torque and 7100 lb. ft. Minimum Yield ( breaking) torque......... and we have seen them break."

Also the A1 trucks use the same rear axle/driveshaft up to 2008 model year.

A1's around 2008 started using the intermediate axle from the 6X6 and associated driveshaft.

The driveshaft problem was solved 100% fleet-wide back in the 90's. Stewart and Stevenson had to go to the field and replace bellhousings and driveshafts on 100% of delivered vehicles. A "D" was stamped on the VIN plate to denote that. (There is a thread here on that subject). The A1 came about because Cat came up with the C7 electronic engine, and S&S thought it would be way cool to use it.
The A1's started with the 3126 engine.
 
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profo

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I looked in the Tm's but not sure cause dont know if it sames as nsn 483-49-050-433 which was original from what I can tell, does anyone know the NSN for the updated 4" driveshaft on the m1078a1, I did notice on my data tag there is NO D stamped on it.

Thanks Marty
 
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coachgeo

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Believe the D only existed on A0 trucks for they needed an "upgrade" The rest; A1 and above, do not have a "D" cause they were built with the heavier components from the start.

when looking for parts in the past it appeared the A1 and upgraded A0 6x6's and 4x4's used the same driveshaft from Tcase end to axle.
 

profo

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So with that said was the transmission changed when the 3126 engines came out to the 3700sp cause i found some transmissions and transfers with less 500 miles on them I dont have truck yet and going crazy anticipating what transmission it is because I need a transfer housing to but If I can change the whole assembly thats what ill do. this truck is a m1078A1 with a 3126 engine.

Thanks Marty
 

profo

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Ill probably just change out the transfer because the transmission arent the same from what I can tell, all thou similar I think the wiring harness maybe different, but the transfers are the same, so ill probably have a very good take 3700 sp for sale! Just gota find a driveshaft now! All I found was old tm on nsn number for rear driveshaft does anyone know the current number cant find it anywhere!

Marty
 
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sjohn116

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It appears there are a few different options, and please correct me if I'm wrong:

1). have a custom CV driveshaft made for your LMTV, and it will reduce your likelihood of having a problem, but not too terribly much better off than stock configuration with a stock driveshaft in specs

2). clock the rear axle up 2-3 degrees,

3). replace the rear axle of your LMTV with the intermediate axle from an FMTV (fabricate new mounts, new driveshaft, lock the solenoid in the rear differential, and what to do with the spinning output yoke?)

4). 3rd member from FMTV intermediate axle into stock rear axle of your pre-2008 LMTV? I ask because BRYCE has high speed gears in the following options (complete front axle, complete intermediate axle, and intermediate axle 3rd members only).

5). combination of 1+2


In a different posting, largely guided by steve6x6x6x6x6x6x6x6x6x6, it was mentioned that the intermediate axle 3rd member commonly fails if left engaged in the 6x6 configuration; is that just too much fighting between the axles, or do the complicated nature of the intermediate axle reduce the robustness?
 

coachgeo

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....In a different posting, largely guided by steve6x6x6x6x6x6x6x6x6x6, it was mentioned that the intermediate axle 3rd member commonly fails if left engaged in the 6x6 configuration; is that just too much fighting between the axles, or do the complicated nature of the intermediate axle reduce the robustness?
In previous readings on the topic from various places saw it mentioned that designers of trucks with these type of rear axle setups went to an auto switch for locking the Power Divider instead of manual cause using that feature too often lead to early wear of the units. This seems to support the stance of too much fighting between axles may lead to wear. Makes since. It is like locking a truck into 4x4 when on dry pavement causes various bad things. Granted though.. more gears spinning.... more places for wear to occur course then again maybe this spreads the wear out over more surfaces with each wearing less instead of all of it in one place??? I'm no engineer
 

sjohn116

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Seems like the only long term options to rectify the driveshaft wear/imbalance causing issues with the transfer case. I called Carolina driveshaft in SC and they said there is no double cardan commercially available for the 1610 series. Nothing double cardan That big. In that case, a rzeppa (sp) ball and socket Cv joint is even less likely to exist in the market. Leaves the two options as:

1) constantly check slip joint play and replace driveshaft whenever it gets out of spec

2) replace rear axle with intermediate axle from FMTV, and provide air line to lock in diff full time.
 

scottmandu

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If your slip yoke is worn out then common sense would be to have it replaced, every slip yoke I've seen however the splines are coated with what appears to be teflon, and proper greasing of the slip yoke will ensure that it will last a very long time. It sounds to me like some people just like worrying about things.
 

coachgeo

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... called Carolina driveshaft in SC and they said there is no double cardan commercially available for the 1610 series. Nothing double cardan That big. In that case, a rzeppa (sp) ball and socket Cv joint is even less likely to exist in the market. ....
not sure how missed this comment before...... but this lack of commercial sized Double Cardan nor Rzeppa in combination with military brass desire to keep as few special made parts as possible ... might well be a big part of why they went with the High Pinion rear axle when they did that switch with the newer A1's.
 

JDR

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I have been looking all over for 2 weeks and can't find the answer. What is the part number for 1997 Stewart Stevenson M1078
 
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