Flat towing Humvee with 40,000 lb military tow bar

[Mogman]

This probably has no association with flat towing a HMMWV, but I remember decades ago that I was told that you should never flat tow an automobile or truck with an automatic transmission if the transmission didn't have a rear oil pump. If you towed a vehicle without a rear oil pump, the spinning driveshaft didn't provide lubrication for the rear bearings in the transmission and the transmission would fail, regardless of whether the transmission was in neutral. I was told that if a rear oil pump wasn't present that the drive shaft had to be removed prior to towing, regardless of the distance towed. I don't know HMMWVs and don't know if they have a rear oil pump in the transmission or not.

If you have the trans in park then that is not an issue as the rear transmission shaft is not turning,

 

[HUMMER H1]

I can only speak from experience and don’t care what TM says,

Transmission in neutral, transfer case in neutral,

I towed humvees and H1 behind other vehicles,
and will keep doing the same if I need to again.

 

[Ls3rx7]

Might be a stupid question but how do you lock the steering to keep it from turning the wheels

 

[Coug]

Might be a stupid question but how do you lock the steering to keep it from turning the wheels

For towing you don't. The wheels will follow the path of least resistance, which is just following the tow vehicle. That is why a good quality tow bar hooked up properly is important, as it doesn't just pull the vehicle forward, it also forces it sideways when turning.

 

[HUMMER H1]

The centrifugal force will keep towed vehicle wheels in line with towing vehicle,

 

[Mogman]

I can only speak from experience and don’t care what TM says,

Transmission in neutral, transfer case in neutral,

I towed humvees and H1 behind other vehicles,
and will keep doing the same if I need to again.

You definitely do not want the transmission shaft turning as that will damage the transmission, this is why it is recommended to tow with TC neutral trans park.
Having said that the trans shaft is not too likely to turn with the TC in neutral but I would not risk it.

This would also insure the TC was in fact in neutral, if not the trans being in neutral could give you a false indication and the TC could still be in gear which would be a disaster.

 

[Davetheplumber]

I read in the military literature to disconnect the shafts if your going over 30mph... I have put many T-cases in N and towed chevys all over the place... Is there something different in the M1151A1 TCase? I'm with you... it just doesn't make sense but everyone is saying to disconnect. I want to pull mine on my road trips behind my pusher RV. I don't know what to think

Sorry.. I posted incorrectly to your response

 

[Davetheplumber]

So after talking with some people at our local base... The general idea, true or not, is as follows...
The manuals are to be written for ALL HMMWVs so the guys in the field did the same towing procedures across the board and this procedure included pulling the shafts on the old 3 speeds because the TRANS does not have a Park position.
If the TCASE is in Neutral and decides to engage or someone didn't get it all the way in N then you would be going down the road destroying the TRANS.
The newer trucks of course, like mine, have a Park positions making it very obvious if the TCASE happen to kick in gear.
Let me know if there is holes in this theory. Thanks guys

 

[98G]

So after talking with some people at our local base... The general idea, true or not, is as follows...
The manuals are to be written for ALL HMMWVs so the guys in the field did the same towing procedures across the board and this procedure included pulling the shafts on the old 3 speeds because the TRANS does not have a Park position.
If the TCASE is in Neutral and decides to engage or someone didn't get it all the way in N then you would be going down the road destroying the TRANS.
The newer trucks of course, like mine, have a Park positions making it very obvious if the TCASE happen to kick in gear.
Let me know if there is holes in this theory. Thanks guys

If my 3spd w/o park goes into gear while being towed , it destroys the transmission slowly and gradually.


If your 4spd with park goes into gear while being towed, it destroys the transmission immediately and catastrophically.

I don't see this as an improvement. What am I missing?

 

[Davetheplumber]

If my 3spd w/o park goes into gear while being towed , it destroys the transmission slowly and gradually.


If your 4spd with park goes into gear while being towed, it destroys the transmission immediately and catastrophically.

I don't see this as an improvement. What am I missing?

The tCase is in N... it would only damage the parking pawl if the Tcase for whatever reason went into gear. Still a drivable rig. The 3speed will burn up and be inoperable all together.

 

[Mogman]

If my 3spd w/o park goes into gear while being towed , it destroys the transmission slowly and gradually.


If your 4spd with park goes into gear while being towed, it destroys the transmission immediately and catastrophically.

I don't see this as an improvement. What am I missing?

It might not even damage the parking pawl if only a short while, they tend to "ratchet" when given enough force.
If the 4 speed was in neutral and the T case went into gear it would not take long the destroy the transmission, the rear shaft and its planetary gears/clutches would be running without lubrication so that would not be "slowly and gradually" none of the rotating mass in an automatic run in oil so there would not even be any "splash" lubrication.
Long story short if you run ether transmission with the T case in gear you are going to have serious issues, park or no park.

 

[98G]

It might not even damage the parking pawl if only a short while, they tend to "ratchet" when given enough force.
If the 4 speed was in neutral and the T case went into gear it would not take long the destroy the transmission, the rear shaft and its planetary gears/clutches would be running without lubrication so that would not be "slowly and gradually" none of the rotating mass in an automatic run in oil so there would not even be any "splash" lubrication.
Long story short if you run ether transmission with the T case in gear you are going to have serious issues, park or no park.

Speculate for me. How long would it take at 40mph?

 

[Mogman]

Speculate for me. How long would it take at 40mph?

I really can't say, but we are talking about flat towing not dragging it down the road with a tow strap.

 

[Davetheplumber]

It might not even damage the parking pawl if only a short while, they tend to "ratchet" when given enough force.
If the 4 speed was in neutral and the T case went into gear it would not take long the destroy the transmission, the rear shaft and its planetary gears/clutches would be running without lubrication so that would not be "slowly and gradually" none of the rotating mass in an automatic run in oil so there would not even be any "splash" lubrication.
Long story short if you run ether transmission with the T case in gear you are going to have serious issues, park or no park.

You always flat tow with the trans in Park. NOT N

 

[Davetheplumber]

It might not even damage the parking pawl if only a short while, they tend to "ratchet" when given enough force.
If the 4 speed was in neutral and the T case went into gear it would not take long the destroy the transmission, the rear shaft and its planetary gears/clutches would be running without lubrication so that would not be "slowly and gradually" none of the rotating mass in an automatic run in oil so there would not even be any "splash" lubrication.
Long story short if you run ether transmission with the T case in gear you are going to have serious issues, park or no park.

I have rebuilt a 4L60 that had ratchetted the pawl and it was for about 10 secs... it looked pretty bad when I got it out. Had to replace the sun shell also.

 

[biscuitwhistler37]

Personally, for a thousand mile haul, I'd use a flatbed trailer. That's a lot of miles to be paranoid that a t case might somehow accidentally engage, or have the trans slip into gear, or whatever else Murphy can throw at you. If that wasn't an option, I'd follow the procedure in the TM, even if it isn't "necessary", because Murphy really likes me and I do all I can to stay away from him.

Hope it goes well for you.

 

[biscuitwhistler37]

I have rebuilt a 4L60 that had ratchetted the pawl and it was for about 10 secs... it looked pretty bad when I got it out. Had to replace the sun shell also.

Oh man...... It wasn't out of a 9C1 Caprice was it? I tried to use park to stop once, for about 10sec, before hitting my brother's truck and actually stopping.....

 

[98G]

I really can't say, but we are talking about flat towing not dragging it down the road with a tow strap.

O

I really can't say, but we are talking about flat towing not dragging it down the road with a tow strap.

I've done both in recent memory.

 

[thompsoncustom]

Renting a trailer seems like the easier, quicker, safer option.

 

[Valley Rock]

I really just don't want tow the triple axle Farm trailer that far as storing it for a week is really a pain.

It's been 3 months I think the old farm trailer would have had it done by meow, do you still not have this thing moved ?

Put it on a trailer or your next post will be needing help on the side of the road, take at least two spare trailer tires with you .