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M1078 LMTV planetary hub setup

simp5782

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I have seen so much stupid things done on trucks by military 'mechanics', they clearly don't sometimes know what they are doing.
I believe most things are done or left in a screwed up manner the way they are is that they have their problem child trucks just like any mechanic has a problem child car. They screw things up on them or leave like an unphased driveline or a wireloom that will rub a hole in it and cause the truck to mess up and redline it and after so many of them they will move the truck out of the unit to surplus or a reserve unit and give them something else to replace it.
 

Floridianson

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If you think it might be a problem I can take it out and have the local drive line shop spin it?

O boy get to use my virgin Tiger tool that has never been used and in the tool box for 10 years.

PS just spoke wit the drive line shop. He said put it in phase and drive it and if it is not correct I should feel it. Pull one side and 180 turn and test drive again. Hope that works if not I will have them spin it up.
We a kinda walking on top of Steve's nice thread if we could move it or start one if this train of thought goes farther.
 

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Floridianson

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Thanks again to Kodyman got a chance today to correct the out of phase front drive shaft. Guess I got lucky no vibrations so going with balance is good and noise is gone. Maybe someone flat towed it with just removing the rear axle shafts and for the front just the front part of the drive line and left the yoke on the Trans. Then someone put it back together wrong.
 
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snowtrac nome

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I have seen so much stupid things done on trucks by military 'mechanics', they clearly don't sometimes know what they are doing.
try being an army mechanic telling this to an airforce mechanic, we almost had a throw down in the maintenance facility, when I told them it was obvious to me they knew nothing about s cam brakes.
 

Pointman0853

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One of the most difficult things on my gear swap, was chasing our all the bits of RTV from the planetaries and hub innards. I guess Bubba thinks, "If a little is good,
..."

Pointman
 

Awesomeness

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One of the most difficult things on my gear swap, was chasing our all the bits of RTV from the planetaries and hub innards.
Not having seen the inside of the hubs in detail, what was difficult about cleaning them out? Are there lots of little crevices for it to get into?
 

Floridianson

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Not having seen the inside of the hubs in detail, what was difficult about cleaning them out? Are there lots of little crevices for it to get into?
No trouble really. Mine had a ton of silicone in the bolt holes that hold on the outer hub cover. Just sprayed brake clean in the bolt holes and use air to clean them out. Just funny as to how much sealer some people think it takes to seal. I used High Tack spray adhesive and just sprayed on the outer hub and no leaks so far.
Nice thing about the high tack it cleans off with some spray brake cleaner if I have to service it again.
 
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Awesomlmtv

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I am ready to get gear lash adjustment going in my LMTV. Using Steve6x6x6's method and a cut open hub cover, what should the lash between bevel gears be if I have it shimmed correctly?
 

Floridianson

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Would be interesting to try it your way then check same hub with Steve's way. It really is not any trouble Steve's way once you have done one or six.:cool:
 

Awesomlmtv

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I like the direct gear lash measurement of Steve's method, it would seem that is the more accurate way. That being said, I wish we had better guidance on the lash setting. .010-.020 is a lot of tolerance for something that is supposed to be precise.

Has anyone been skilled enough to get an LMTV to sound smooth and quiet (whirring noise aside, relatively) at 55mph?

Would it help to put in Royal Purple Maxgear 75w-140 Synthetic (with protection for yellow metals)? Is there a heavier option?

Here is the noise it makes at 50-57mph (closer to 60, speedometer reads low according to GPS). It sounds so much less severe on video than in the truck. Listen for the low frequency growling sounds. When the hubs are warmer, the vibration happens at lower speeds.
 
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m-35tom

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you know it is very easy to calibrate speedo, right? as for the gears, remember the helical cut gears in M-35 trans? they usually have .014" lash. so for the bevel gears to have average of .015 sounds about as expected. the hub and hub covers are precision machined and all the same so it follows that all you need to do is have the correct distance from the parting line (face of hub) to the face of the wheel bearing nut with shims installed. you need to take the hub cover off and the spider assy out to clean all the crap sealant that joe army put on it so just take it apart one time, measure, apply correct shims, put it back together. and when cleaning it remove the o rings, clean it so that the end plates slide right off and on. put o rings back on and do NOT put any sealer on them! they are o rings for a reason. to seal. only put a very thin film of sealant on one side of the mating surfaces. very thin!! put it together clean and it will not leak. I make a straight edge with a dial indicator mounted on it. made a standard to calibrate it. so when resting on hub surface and indicating shims, when they are right it reads zero. otherwise it tells you how much to take out or to put in. fool proof. well I did it so almost fool proof.
 

coachgeo

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..... the hub and hub covers are precision machined and all the same so it follows that all you need to do is have the correct distance from the parting line (face of hub) to the face of the wheel bearing nut with shims installed...
This is how my machinist friend saw it too.. Aka... Measuring from machined part surfaces would be most accurate. Steve6x6x6 may well have got his measurements after setting it up via TM method (same as above realistically ) , but then bolting on a cut hub to determine amount movement with gauge what is the the equivalent numbers via feeler gauge. Still it is an indirect measurement.

Word is though Steve is an excellent axle guy who knows his shiat so likely his method works fine.

Update> Edited to better describe measurement method of Steve's
 
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Awesomeness

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I like the direct gear lash measurement of Steve's method, it would seem that is the more accurate way. That being said, I wish we had better guidance on the lash setting. .010-.020 is a lot of tolerance for something that is supposed to be precise.

Has anyone been skilled enough to get an LMTV to sound smooth and quiet (whirring noise aside, relatively) at 55mph?

Would it help to put in Royal Purple Maxgear 75w-140 Synthetic (with protection for yellow metals)? Is there a heavier option?

Here is the noise it makes at 50-57mph (closer to 60, speedometer reads low according to GPS). It sounds so much less severe on video than in the truck. Listen for the low frequency growling sounds. When the hubs are warmer, the vibration happens at lower speeds.
I listened to your video a couple times, and I'm not sure if I can hear the gear whine or not. With all the other noises these trucks make (e.g. engine, turbo, fan, tires, etc.), it's hard enough in person unless the gears are really howling loudly.

When I first got my truck, I read in the manual that there was supposed to be 11-13oz of 75W oil in the hub, got a little cup, and opened the drain plug. About 36oz of very thin oil (motor oil?) came out. It didn't wine before that, but I just wanted to change the fluids. I put back in the Royal Purple gear oil, and it works well.

I've taken my hubs apart and put them back several times, and have not had issues with whine. If the engineers wrote in the TM that 0.010-0.020" is appropriate, I would want a really good reason to just decide that was too sloppy. If you are careful, it shouldn't be too hard to set up well, and even easier with some of the tools available (e.g. cut hubs). Many of these hubs were set up very poorly by the military, so it may be easier to fix the problem than you think... the bar isn't that high to start with.
 

Floridianson

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Steve6x6x6 may well have got his measurements after setting it up via TM method (same as above realistically ) , but then bolting on a cut hub to determine with feeler gauge what is the the equivalent numbers via feeler gauge.

No feeler gage as you can not get one between the two gears. You rock the 6 o'clock gear with your fingers and watch movement or gage movement. I will admit I do not run my 1088 at 55 mph more like 45. All I made sure of is my hubs are not running hot and I feel that when I did the cut hub way they are close to what they should be. Also all I used the truck for was a yard dog and now I take it to the local mud pit and just have fun with it.
 
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Floridianson

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I am ready to get gear lash adjustment going in my LMTV. Using Steve6x6x6's method and a cut open hub cover, what should the lash between bevel gears be if I have it shimmed correctly?
Think I see your problem. Tan dash / truck, OD colored speedometer.:driver:
Run your hubs and see if it changes or you find them too loose / tight. Remember Steve said a minimum of 10 /20. Bet it could be .030 and still be fine. We just do not want them running too hot.
 
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Kbarnes0

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Even though it will be good to run through all of them. I would put it in the air and run it. Might be good to see what area its coming from. Then you can listen to the diffs also.

If you don't have a stethoscope with a pointer for hearing the internals, you can use a long screwdriver to your ear with fair results.
 
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