Driveshaft/Axle issues?

[Corvette1974]

Hello. Long story short, my deuce has been having drivetrain issues. First it started with finding metal in the rear axle (still haven't messed with this yet)

Second, the driveshaft vaporized as I was going down the highway. Took the parking brake with it. Put a new unit in and it works fine, but now I am having two issues. How critical is it to get the U joint to purge when greasing? I cannot get it to at all. Pumped like a whole tube through each fitting with driving in between. I even pulled the two u joint cap bolts and it didn't make any difference. Any tips without destroying my driveshaft/ujoints?

The major problem is that the front most rear axle seems to have a lot of play in the input yoke. Drivetrain makes no sounds while driving. But I was thinking that maybe this caused the original driveshaft explosion. It has play in the side to side motion about a 16th of an inch at least. More than the other axles. No major leaking. It does make a nice metal thudding sound when moving it around by hand. Is this acceptable or do I have issues?

Will

 

[73m819]

DO you "THINK" the metal in the rear just sorta might have something to do with this issue ?????????????????????????????????????

 

[Corvette1974]

DO you "THINK" the metal in the rear just sorta might have something to do with this issue ?????????????????????????????????????

Different Axle! That is the rearmost rear that had the metal in it. Everything seems tight with that one. The frontmost rear axle is the one with the excess play...

 

[scboolitcaster]

Seems like any number of bad things might happen if that rear axle were to stop turning at speed. Who's to say which thing connected to it (or connected to something connected to it) would vaporize?

 

[Corvette1974]

Seems like any number of bad things might happen if that rear axle were to stop turning at speed. Who's to say which thing connected to it (or connected to something connected to it) would vaporize?

Very true, however, the only play is just that side to side. Gears seem fine. Meaning it is the only real problem with the axle I think. My truck definitely isn't the only one that has had this problem I don't believe that for one second. I've heard that the upper pinion bearings are common to wear out. Can I replace them simply with new bearings

 

[sandcobra164]

I have never noticed pinion shaft play on my Deuce while I had it. It is a very basic axle design if you research top loader axles. I would tear it down and replace the input bearing and seal if I could move it that far in any direction. It can probably roll many miles as is without issue but will need some attention at some point in the future. As to trying to grease the joints. They do not take too much grease before you can push the new grease out of a cap seal. The problem you run into is getting a good fit and seal on the grease fitting and actually putting grease in the joint.

 

[Corvette1974]

I have never noticed pinion shaft play on my Deuce while I had it. It is a very basic axle design if you research top loader axles. I would tear it down and replace the input bearing and seal if I could move it that far in any direction. It can probably roll many miles as is without issue but will need some attention at some point in the future. As to trying to grease the joints. They do not take too much grease before you can push the new grease out of a cap seal. The problem you run into is getting a good fit and seal on the grease fitting and actually putting grease in the joint.

Totally agree on the simplicity of the axle. I just wasn't sure if a bearing/race swap was a feasible idea without a complete overhaul. Like I said, if I didn't actually feel this slop today, you would never know there are no sounds or any other sign. I will order the bearings and see what lays in store... It is strange that it doesn't leak more than it does though. There is no leakage from that pinion even with the slop. I think this truck has just lived a hard life before me, so I'll be playing catch up like this for years haha The front front axle has slight slop, and the rear rear axle has none. Only the rear front has this large amount. One of these days when I rebuild the axles seal/brake wise I will be installing the locking hubs too so thatll help with axle wear.

The grease is 100% going in to the u joint (meaning it isn't just escaping at the zerk) It just is not purging from certain seals. I'll shoot the grease in until it comes out of the others but one will still not purge. You can see slight "dampness" from the unpurging seal that seems to indicate that there is at least some grease there that is getting spread out by driving the vehicle. I talked to my buddy who does big trucks and he said they should purge, but that it isn't the end of the world if it doesn't completely.

 

[rustystud]

Take your 'U'-joint apart and see if anything is plugging the holes. You can run a wire through it to check.
As far as the Pinion shaft being loose, try and torque the nut and see it has any movement. If it's tight then you have bearing issues.

 

[73m819]

If the number 3 axle is bad, it could cause vibration ALL though the REARS/DRIVELINE, the seal issue could be caused by this, seals/bearing DO NOT get loose on there own, THERE IS A CAUSE, fixing things is only a TEMP fix TILL the cause is found.

 

[Corvette1974]

Take your 'U'-joint apart and see if anything is plugging the holes. You can run a wire through it to check.
As far as the Pinion shaft being loose, try and torque the nut and see it has any movement. If it's tight then you have bearing issues.

Any hints on pulling the cap style u joints? It seems pretty seized into the yoke...

I'll pull the shaft and check the yoke nut. How tight is tight? IIRC the TM says 300-600 ft lbs...

 

[Corvette1974]

If the number 3 axle is bad, it could cause vibration ALL though the REARS/DRIVELINE, the seal issue could be caused by this, seals/bearing DO NOT get loose on there own, THERE IS A CAUSE, fixing things is only a TEMP fix TILL the cause is found.

Well I totally agree with that, however, I know you are not supposed to trust the dash but my dash says 70k miles - that is a ton for a deuce compared to most others if that is true. Knowing that the upper pinion bearings can be problematic in general, I wouldn't be surprised if the bearings were just plain worn out. The first axle is taking more load than the rest so it wouldn't be out of the question. I'm going to check the axles out for play. Regardless, the front axle needs new bearings...

 

[Corvette1974]

Drove it again today. Everything is good as usual (no bad noises or vibrations) so I will replace those bearings and see what happens...

 

[dmetalmiki]

If you are pumping (grease in), and nothing is coming out of the U joint, the gun is not pumping. IT WILL come out IF it (the grease) is going in. I have guns that pump through some nipples, but do not on others, although they 'feel' like they are. The air grease gun DOES shoot the same grease through these stubborn grease points, no problem.

 

[Corvette1974]

If you are pumping (grease in), and nothing is coming out of the U joint, the gun is not pumping. IT WILL come out IF it (the grease) is going in. I have guns that pump through some nipples, but do not on others, although they 'feel' like they are. The air grease gun DOES shoot the same grease through these stubborn grease points, no problem.

I am using an air grease gun. It is definitely pumping grease into the zerk and into the u joint, as it is very clearly purging from 3 out of 4 seals. Not just coming out of the zerk. I am the manager of a farm so I definitely know what you mean when you say it "feels" like it goes it. In this case, it is definitely going in. Like I said, it does seem there is evidence of slight grease purging from the one seal that doesn't purge while greasing - there is some grease dampness from that seal just from driving.

 

[M543A2]

I do not find it unusual for a joint to exhibit the situation you describe. When I have one do it I believe the cause is that there has to be a perfect balance of the seal integrity between all of the yoke cups to cause the grease to come out from all of them at the same time. The one not showing grease will have its seal making a tighter seal on the yoke than the others. I do not remember having a problem with those that did that. I believe this is because when the shaft is spinning at high RPM the grease in the cross is thrown into the reluctant cup as needed by centrifugal force. It is also held in the cup by the same force. If you are still concerned you can take it apart and check it. I think you will find grease in the reluctant cup. If you do, do not worry about it, go ahead and run it. If it looks dry, then you need to find the cause.
Regards Martin

 

[Corvette1974]

I do not find it unusual for a joint to exhibit the situation you describe. When I have one do it I believe the cause is that there has to be a perfect balance of the seal integrity between all of the yoke cups to cause the grease to come out from all of them at the same time. The one not showing grease will have its seal making a tighter seal on the yoke than the others. I do not remember having a problem with those that did that. I believe this is because when the shaft is spinning at high RPM the grease in the cross is thrown into the reluctant cup as needed by centrifugal force. It is also held in the cup by the same force. If you are still concerned you can take it apart and check it. I think you will find grease in the reluctant cup. If you do, do not worry about it, go ahead and run it. If it looks dry, then you need to find the cause.
Regards Martin

Cool insight into the u joint physics. I had suspected that differences with seals could be the cause of this. I will say, at my farm, I have never worried about not purging all four seals, and have never had a single u joint failure. The equipment does get very frequent greasing, but in comparison, so do all of my vehicles in relation to the maintenance interval specified. Also modern grease is far superior to old stuff...

I have also taken it for a drive and felt the u joints - they were all basically dead cold/temperatures were all consistent for each cross. That is also some positive feedback in support of the fact that the grease levels are fine.


I *am* definitely doing my axle pinion bearings. The job isn't very hard from what I have been told. Next step is pulling the driveshafts and checking for wear in the rear/rear axle.

Will