XM757 frozen drive shaft

[cranetruck]

The drive shaft between the two rear axles is frozen solid. The avatar on the left here shows our efforts to remove it before the truck was towed home to Virginia last Fall.
I have tried heat, hammer blows, penetrants and today I hooked it up between a tree and the deuce to try to pull it apart (even used the crane on it last week).
It remains solid as a single piece of steel.

Question: How could the drive shaft end up like this? There is no sign of rust. It is not bent and the yokes are lined up.

This is not a critical item, all other drive shafts are in good condition and there are still three axles driving.

 

[maddawg308]

Am interested in hearing the answer as well - my driveshaft is locked up tight like this too, and it doesn't look in that bad a shape.

 

[mangus580]

Old dried up grease in tight quarters can act like glue... Although I would have thought heat would fix that.

 

[doghead]

I had a driveshaft of similar design that refused to come apart. I ended up heating it red hot and at the same time applied almost 5 tons of force in a press! Once it was apart it was apparent that the splined section was twisted slightly( and at a varying rate of twist)
The total degree of twist was not easily noticed visually while it was assembled.

 

[steelsoldiers]

If it is the solidified, dried-up grease that is keeping it together as Mike suggested, you could try taking it to an engine rebuild shop and have them hot-tank it for you. The combination of heat and solvent may do the trick.

 

[WillWagner]

Another thing, learned it here and it works, parifin wax...warm the slip with the splined part up and melt it into the splines, let it cool, couple of smacks with a hammer and it'll come out. I think that was from Wreckerman!

 

[pa.rich]

I doubt very much that dried grease as Mike said, would be this impossible to get apart. Sorry Mike. What Doghead said seems to make the most sense. Twisted spline.

 

[cranetruck]

Twisted spline makes the most sense, I'll cut it open tomorrow and let you know what it looks like.

 

[Recovry4x4]

For what it's worth, the stiff legs were frozen in place on the old M756A2 I had. I tried heating, pulling with the tractor, heating and pullling with the tractor and made no progress. Finally as I was about at my wits end, I thought of one more thing to try. I hooked the tractor back up to it with a chain, put as much tension as I could with the truck and locked it up with the tension on it. Got out the torch and heated the outside red then took a 4' spud bar and started hammering on the chain. The pull tension, heat and impact of the spud bar on the chain got it loose.

 

[timntrucks]

i had a froze rear shaft on a 1/2 ton ford that did the same thing, i spent many hours on it, and thats how i got it unstuck, a tree, comealong and a torch. the grease melted out along with somekind of coating that was on the splines. but afterward it worked fine.

 

[wreckerman893]

The parifin (wax) was not my original idea but it worked when I was getting the dolly wheel on my 105 trailer unfrozen. Try the following steps:

(1) Try evry other method known to man.

(2) Expend your entire stock of profanity several times over.

(3) Heat offending object and apply parifin all the while applying love taps with a BFH.

(4) Wait a day or so and repeat heat, BFH and parifin appication.

(5) Seek medical help when offending object falls on your foot when you least expect it to turn loose.

This method works for me all the time.

 

[doghead]

I'll cut it open tomorrow and let you know what it looks like

I've been wondering if you did, and if so what you found.

 

[cranetruck]

I put the drive shaft on the work bench and started to prep it for the operation when I got cold feet, just couldn't make myself cut it open...such a nice piece of hardware.

 

[pa.rich]

Well Dr. Brandstedt, I guess I will have to cross you off my list as a surgeon!

 

[doghead]

Have you considered giving it a hot oil bath?

 

[cranetruck]

Did that, cooked it for 12 hrs in hot (235°F) oil. Didn't help one bit. As you know it did work for the steering ball joints, but this is obviously not the same kind of problem.

 

[derby]

What about putting it in the freeze,then quickly apply outward pressure and alot of heat? sometimes the things that sound the straingest works.or what about the zerk on the end pump in some grease might push it apart? You might try two chains on each side so it will apply even pressure accross the joint.I don't know, kind of off the cuff.

 

[cranetruck]

The freezing part may be difficult unless I can find some dry ice...
Yeah, two chains on each end is a good idea to make a straight pull.
BTW, this frozen drive shaft is probably the reason I have a leak in one of the thru shaft seals where it was installed between the two rear axles. Must have caused a lot of stress.

 

[BFR]

If only you had a way to pick up heavy stuff

If it is an issue of twisted splines you could try....
Suspending a heavy load from one end of the shaft and impart rotational shock loads
(hit it [the load] with a hammer so that it tries to spin)

 

[Recovry4x4]

Before you chop it up Bjorn, send it to me. I'll gladly drip some sweat on it. Here's an Idea I had, using the chains similar to what you did could you suspend it from the crane and attach the other end to the pintle or a bed anchor and try to pull it apart with the crane?