Got driveshafts balanced yet? Otherwise, it's like a grenade ready to go off at any time.

Reworked LMTV

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I have seen pictures of cracked bell housing, broken alternator brackets, cracked water pumps, and air compressors and gears damaged. In my case the interface of the compressor and power steering pump opened up due to a loose bolt. Those pesky driveshafts need balancing. It's not worth driving without having this done. The vibration is a real issue and can cause $1000's of dollars of damage. In fact, it should probably be the first thing a new FMTV/MTV owner should do.

FYI- I could not get my fuel primer to work. I had replaced it with a NOS one last year. Pushed on the button 100 times. Nada. I was expecting the typical broken valve spring. Nope. A very small amount of gunk from the fuel tank did not allow the valve to seal at the lip. Cotton swab on the gunk, and was back in action.
 

ramdough

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I had mine balanced, but my truck still vibrates. Guessing it is the old tires. The drive shaft balance was really, really cheap ($200). So I am still wondering what is the vibration from.


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Ronmar

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I had mine balanced, but my truck still vibrates. Guessing it is the old tires. The drive shaft balance was really, really cheap ($200). So I am still wondering what is the vibration from.


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There is an IOS app called “sonic tools“ that might allow you to identify a frequency at which your vibration is occurring, which might help you locate the source...
 

Reworked LMTV

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I had mine balanced, but my truck still vibrates. Guessing it is the old tires. The drive shaft balance was really, really cheap ($200). So I am still wondering what is the vibration from.


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I am assuming that there is no driveshaft phasing issue. I know that they are balanced. Phasing was incorrect on mine. Double check this. Are tires balanced?

For vibrations you have some options.
1. Steelman noise vibration system (around $200)
2. Put of lift and watch for movement
3. Picoscope with vibration sensor (I have the pico, but not the vibration sensor). I'm going to try the steelman sensors with the pico.

Look for a blue dot on the tires. This is a balancing mark.
 

Awesomeness

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I destroyed an engine because of the driveshafts being out of balance.

More info about the the issues, engineering reports, and fixes here in the doc in my signature. This should be one of the first thing any new FMTV owner does, because while it is only a small percentage it happens to, it's expensive when it does.
 

Plasa

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Gave mine also to balance now.
hinging test was 0,2mm, driveshaft companies said over 0,2mm the do no balancing, refurbished ones need to stay under 0,1mm.
At the same time I change the u-joints ank keep the old one for spare.
Next week I can tell more if there is a diffrence between 0,2mm and 0,1mm hinging.

Christian
 

ramdough

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I am assuming that there is no driveshaft phasing issue. I know that they are balanced. Phasing was incorrect on mine. Double check this. Are tires balanced?

For vibrations you have some options.
1. Steelman noise vibration system (around $200)
2. Put of lift and watch for movement
3. Picoscope with vibration sensor (I have the pico, but not the vibration sensor). I'm going to try the steelman sensors with the pico.

Look for a blue dot on the tires. This is a balancing mark.
I am almost certain the wheels are not balanced. I am thinking of trying the antifreeze trick. Then add weights opposite the CTIS valve if necessary.

I will check phasing. They came from the balancer and were installed by someone else, but I believe that would have been noticed by them.

The tires are the MVT’s.


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Awesomeness

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I will also usually get a shimmy until I've driven it a while. I assume this is the tires sitting a little, and getting out of round.
 

Plasa

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OK, got mine back from balancing:
before: Hinging test: 0.2mm, feelable if you move up/down shaft.
now: Hinging test: 0.08mm, you do not feel any movement if you move up/down driveshaft.
driving feeling: feels much better, I did not had vibrations before, but now its less noisy and now you feel/hear only tire unbalance / profile

BUT: don't forget to triple check your u-joints screws!!! I mount the drivetrain when I was tired, and discover after a halv mile test drive that I forgot to put 1 completely and the other was only hand tight (same bearing) :-( :-( :-( Nothing happen, except a restless night with pulse at 180!)

Christian
 

Awesomeness

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There has been a rash of posts on the Facebook page of people destroying stuff because of unbalanced driveshafts lately. One guy cracked his engine block, just like I did.
 

NDT

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There has been a rash of posts on the Facebook page of people destroying stuff because of unbalanced driveshafts lately. One guy cracked his engine block, just like I did.
Info about this vibration problem has been shared here on Steelsoldiers for over 4 years. Those dudes need to get off zuckerbergs dumbass website and get over here where the true knowledge resides.
 

Awesomeness

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Info about this vibration problem has been shared here on Steelsoldiers for over 4 years. Those dudes need to get off zuckerbergs dumbass website and get over here where the true knowledge resides.
Anytime I look at the Facebook group, I'm amazed by what is asked, and how poor the answers are. I'm surprised they can get the trucks running at all.
 

Reworked LMTV

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Info about this vibration problem has been shared here on Steelsoldiers for over 4 years. Those dudes need to get off zuckerbergs dumbass website and get over here where the true knowledge resides.
I refuse to use FB and RARELY Instagram, which they own.
 

coachgeo

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Folk on on Facebook LMTV MTV group are also perplexed on why recent rash of discussions on vibrations/drive shafts has come up. The past pdf's on the studies are even archived there yet some newbies are finding them on their own like it's some all new discovery. But honestly.. That happens occasionally on any format / form of discussion group
 

patracy

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Unfortunately newbies do come here and get chastised to read the TM's and use the search function, neither of which are helpful....
Which is not allowed.

On a side note about driveshafts. Something I learned from a old wise man who made a living working on driveshafts. When you've got things in place and there's just a little vibration you can't get rid of from it, drill a small hole and put about pint of ATF in it, then weld the hole back up. Kind of the same principle as the antifreeze in the tires.
 
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