2000 mile road trip in an FMTV

[Suprman]

I believe he removed the center axle to rear axle driveshaft. And the tcase to center axle driveshaft was freewheeling without mode being on.

 

[NDT]

So is there something special about the divider gizmo on the intermediate 6x6 axle that allows it to have a differential between the two rear axles?

YES!!!! Inter (between) Axle Differential. All modern 18 wheelers have it and a pneumatic lockout on the dash to control it. MTV has it but engagement is automatic.

 

[simp5782]

Not strange at all, that is the interaxle differential, Wes is not familiar with those 'cause his old school 5 ton doesn't have one.

I was more concerned with the fact that with the truck in neutral. The rear drive shaft removed. And the air brakes released the truck drove itself up hill almost 6 inches before he stopped it with the brakes. My driveway slopes down to the street and it tried to go up hill in neutral.

What puzzled me was that. I am used to an interlock axle switch on a truck just used to them having the switch.

Replaced the rear drive shaft joints. Spicer 279Xs. Got the shaft splined right. Refilled the diff with synthetic fluid to keep the temp down. Went and fueled up. Drove it. Its got 2 tires out of balance pretty bad is his worst vibration. I am thinking the wheels have issues since this is an on going issue with this truck. Same as before replacing the tires from XMLs to MVTs. Which tells me someone pur the wheels back in the same drive place they were before if its the same vibration. Everything else is fairly tight on the driveline.

It did puke out 4 gallons of gear pil so it was overfilled.
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[TNriverjet]

Are you guys able to isolate which two tires are out of balance? I swapped drivers side front and rear on that side thinking that was the one giving an issue. Maybe try the same on the passenger side.

I’ve sent Recce01 a personal message on the rear driveline issues. I was not aware there was such an issue and plan to help with costs incurred today. Most important thing is to get home on the road enjoying the truck on his trek westward!

 

[Awesomeness]

YES!!!! Inter (between) Axle Differential. All modern 18 wheelers have it and a pneumatic lockout on the dash to control it. MTV has it but engagement is automatic.

Thanks, I wasn't sure which of the three axles it was "inter".

 

[simp5782]

Are you guys able to isolate which two tires are out of balance? I swapped drivers side front and rear on that side thinking that was the one giving an issue. Maybe try the same on the passenger side.

I’ve sent Recce01 a personal message on the rear driveline issues. I was not aware there was such an issue and plan to help with costs incurred today. Most important thing is to get home on the road enjoying the truck on his trek westward!

Left rear rear and the passengers front tandem.

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[Recce01]

I appreciate all you guys chiming in to help us figure this out. Glad I didn’t smash simp5782 when the truck rolled uphill!!! We had the wheels chocked on the downhill side, that was a moment.....

simp5782 was a lifesaver today. He really helped me with my confidence to carry on. He dives under these trucks like they are cute little jeeps and makes stuff happen. He mentioned what repairs were made, what he didn’t mention was his taking most of his day and into the night to help get me going again. He drove 30 miles to come and meet me to make sure the issues I had were ok to drive on, then we caravaned back to his spot to commence work. Then he drove an additional 40 or so miles to 3 different spots to get the supplies we needed. If you ever get a chance, ride in his truck and watch in awe as that 16 speed tranny does work, it is awesome. To top it off, he wouldn’t accept any $$$ from me for doing the job. I happily bought a wheel and tire from him and donated some $$$.$ to the Steel Soldiers rescue fund. If he wouldn’t take it from me, maybe he would use it to fund his next SS rescue mission.... awesome guy!! THANKS MAN!!!

where I stand now, I have done a total of 269 miles as of right now. The tire balance situation is hindering the efficiency of this operation, so I stopped at TA at MM 263 where their wheel balance machine was broken, they recommended Loves at MM233, I am here now where the tech came out, took one look at the truck and said “ oh h e l l no” lol. So, I need to find a spot that can balance these tires for me to get my efficiency level where it needs to be. The truck can do 50 to 55 comfortably at times, but most of the time I am stuck at about 45. That’s a hard speed to do for so many miles. Does anyone know of a place along I 40 that Can and will balance these size tires? My next best bet is MM161 where there is another TA according to the first TA guy and th Loves hater. Thoughts?

Thanks again for all of your help working through this endeavor. I couldn’t do it without you all! I am sorry if I dont respond to each of you individually, hopefully I’ll have more time once I get a handle these issues. Thank you so much!!

before I forget, intermediary axle temps are down to 180, thanks to suprman and simp recommending the synthetic gear oil. Little more expensive, but 40 degrees less!!

 

[coachgeo]

....before I forget, intermediary axle temps are down to 180, thanks to suprman and simp recommending the synthetic gear oil. Little more expensive, but 40 degrees less!!. ...

Did you do Synthetic in just the one axle with the Power Divider Box (Intermediate axle)? Did you hear from anyone if the Intermediate Axle typically will have higher temps than the others?

 

[tennmogger]

Please remember you are driving an empty 5ton truck with tires aired up to handle maximum load. IMHO you will never get those tires to run smooth even after high cost of balancing. The issue is probably out-of-round tires, not specifically balance. They are all out of balance, CTIS and all.

If you unplug the CTIS and drop tire pressures it will smooth out. The rears have low load and I personally would drop pressure significantly until a little bulge shows. Same with fronts. You might end up with 25 psi in the rears. Just check tire heat when you stop.

As for all the other work done, have you really found anything wrong? The intermediate axle splitter might be pressure actuated clutch-type like the transmission drop box uses, and will warm up. There's a big difference in how a 5 ton MTV operates compared to the old trucks.

 

[NDT]

I think trying to get the 395s balanced is a hopeless endeavor especially over the thanksgiving weekend. Army never did, Stewart & Stevenson never did either.

 

[CARMAN]

Not trying to being an a$$. But pick up a load. It will probably ride like a dream. Just like most big trucks.

 

[big block 88]

Balancing a tire of that size is nearly impossible... the goodyear at2 and mtv are made inherently unbalanced so they will harmonically balance at speed im not sure about other manufacturers tires though

You are wasteing time and money on trying to get them balanced. I would recommend getting/finding/buying something that weighs a couple tons to put over the rear axle and it will calm her right down.

 

[Recce01]

Did you do Synthetic in just the one axle with the Power Divider Box (Intermediate axle)? Did you hear from anyone if the Intermediate Axle typically will have higher temps than the others?

i did just do the intermediate axle, and I did not hear from anyone what theirs runs at yet. I am pleased to see a temp drop anyway!

 

[Suprman]

The 4x4 trucks have a much more compliant suspension. You don't have to have weight in the bed for them to ride ok. The 6x6, especially the the tractor, do better with a bit of weight in the back. I have had a few 1083s and they all rode ok on the highway to 55mph without significant vibration. I would put my best 2 wheels on the front and the worst ones on the middle axle. One of the biggest causes of highway vibrations is front mis alignment. You can use string to measure the distance between the front of the front tires and the rear of the front tires with them set straight. It should be equal. If you don't track straight on the highway that's another indication you are slightly off in the front.

 

[Recce01]

Please remember you are driving an empty 5ton truck with tires aired up to handle maximum load. IMHO you will never get those tires to run smooth even after high cost of balancing. The issue is probably out-of-round tires, not specifically balance. They are all out of balance, CTIS and all.

If you unplug the CTIS and drop tire pressures it will smooth out. The rears have low load and I personally would drop pressure significantly until a little bulge shows. Same with fronts. You might end up with 25 psi in the rears. Just check tire heat when you stop.

As for all the other work done, have you really found anything wrong? The intermediate axle splitter might be pressure actuated clutch-type like the transmission drop box uses, and will warm up. There's a big difference in how a 5 ton MTV operates compared to the old trucks.

Thanks for the advice, pretty sure I came to the same conclusion last night... RE balancing.

I am am going to try the air down trick this morning, but that makes me nervous with aged tires, that was a serious nono for us to do with old rally tires.

The only actual problems were the u joints out of phase on the rear-most driveline (detrimental?), the tires out of round? And maybe the center axle temp, but not knowing much (if anything) about these trucks, I am relying on the experts who suggested airing on the side of caution. I am doing the best I can man, this is a learning experience for me, as I plan to do a lot of miles in the future. Have I mentioned the seats really suck?

Thank you!

 

[Recce01]

I think trying to get the 395s balanced is a hopeless endeavor especially over the thanksgiving weekend. Army never did, Stewart & Stevenson never did either.

I will try to air down a bit this AM, then I will swap out the 2 tires most suspect, I have 2spares with wheels on board. Thank you!

 

[Recce01]

Not trying to being an a$$. But pick up a load. It will probably ride like a dream. Just like most big trucks.

being it’s my first voyage, and probably the first trip of this length for this truck, I’d hate to be stuck somewhere with someone else’s goods on the back, though in the future (pre-RV build), I’d be happy to do it!

 

[Recce01]

Balancing a tire of that size is nearly impossible... the goodyear at2 and mtv are made inherently unbalanced so they will harmonically balance at speed im not sure about other manufacturers tires though

You are wasteing time and money on trying to get them balanced. I would recommend getting/finding/buying something that weighs a couple tons to put over the rear axle and it will calm her right down.

thank you big block 88!

 

[Recce01]

The 4x4 trucks have a much more compliant suspension. You don't have to have weight in the bed for them to ride ok. The 6x6, especially the the tractor, do better with a bit of weight in the back. I have had a few 1083s and they all rode ok on the highway to 55mph without significant vibration. I would put my best 2 wheels on the front and the worst ones on the middle axle. One of the biggest causes of highway vibrations is front mis alignment. You can use string to measure the distance between the front of the front tires and the rear of the front tires with them set straight. It should be equal. If you don't track straight on the highway that's another indication you are slightly off in the front.

I am going to get on the road this morning, find a valve core remover and a tape measure. Thanks for your help Suprman, and thanks for the advice yesterday.

oh, and Happy Thanksgiving all!

 

[CARMAN]

Just meant some weight. Not a paid load. Pick up something nice for the wife.