DC shaft slip yoke keeps taking grease

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Joined
Oct 8, 2024
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Location
NC
I have a LX450 w/ Tatton DC shafts front/rear. They were installed by a POs shop and have about 4k miles on them.

I wanted to grease them and am running into an issue with the slip yoke. The U-joints were pretty straightforward, but the slip yoke just won't stop taking grease. I've pumped probably 30ish times into the rear and 20ish to the front, no grease comes out of the seal and it doesn't seem to be pressurizing internally. The shaft doesn't extend while pumping either. I tried removing the zerk fitting to see if it was pressurized, again it wasn't. I drove around and compressed the suspension a fair number of times, but no grease came out of the zerk hole even after driving around and getting a bunch of suspension movement.

I'm aware of the risks of the shaft being overfilled and the damage it can do to the transfer case, so I'm hesitant to drive until I sort this out.

Has anyone experienced this before? I'm concerned they were installed dry or with insufficient grease, but I'm not clear how much to keep pumping in, as my understanding is it should only take 1-2 pumps.

Thanks!
 
Can you post up a photo of the driveshaft slip yolk(s)?
Are you sure the grease is coming out of the gun and how much grease comes out with each pump, or how many pumps per ounce?
 
The slip yolk in oem shafts have a freeze plug in the end of the outer slip joint section.
Might be the inner part?

Can't remember. I blew one out. Think it was the inner section and grease spilled out at the uni joint end.
 
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Can you post up a photo of the driveshaft slip yolk(s)?
Are you sure the grease is coming out of the gun and how much grease comes out with each pump, or how many pumps per ounce?
Grease gun says .7oz/40 pumps. It is working, I used the same grease & gun for the U-joints and they flushed old grease out fine. I get the same feedback at the gun that I do when it was on the U-joints.

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i wouldnt keep greasing the slip yoks, you shouldnt be seeing grease come out to the joint after greasing it,. when i greased my drive shafts i would usually just go with 3-4 pumps for the slip yolk.

Agreed, that's why I stopped, but my thought process with continuing after 3-4 was that eventually I could remove the zerk fitting to release whatever excess is in there, yet that never happened. It didn't seem to move or pressurize the shaft at all, either.

The slip yolk in oem shafts have a freeze plug in the end of the outer slip joint section.
Might be the inner part?

Can't remember. I blew one out. Think it was the inner section and grease spilled out at the uni joint end.

These aren't OEM, they are Tatton, AFAIK they don't have a plug.
 
If you keep pumping grease in there, you’re going to blow a head gasket. 🥴
 
I remove the drivelines for maintenance. This allows me to clean the splines and apply an appropriate amount of grease evenly over the internal and external splines. The center flush grease fitting of the DC joint is also much easier to lube positively.

It looks like that shaft pictured could be longer based on the amount of splines exposed.
 
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I ended up going for another drive with the zerk fitting removed and it seemed to get some of it out of there, but I'm not confident it removed enough.

I will probably end up pulling it like mentioned above and at least fully compress it to make sure it's free/clear. I tried this earlier but couldn't get the flange bolts loose, so we'll see if I can get an impact on it to free them up.

In retrospect, I wish I had removed the zerk fitting before doing this to see how much was in there. I stuck a zip tie in to sample what was in there and I suspect there wasn't any grease there to begin with based on what came out.

I may end up replacing these anyway, I've heard too many reports of premature failure.
 
I removed the flange from the diff and cycled the shaft with the zerk open, a ton of grease came out. I guess that's expected when I do something stupid

I removed most of it by compressing the shaft, then removing the yoke and wiping the end of the shaft off. Doing this a few time seemed to help get excess out more than just pressing it through the open zerk fitting. I then manually greased it and it slides really smoothly.

So I guess the lesson is don't buy into the idea that opening the zerk fitting will release excess pressure, just spend the time to remove it and slide it properly. I saw this advice a lot and figured it'd be sufficient, but it wasn't. I'll probably just do the above going forward and pull the whole thing every oil change to grease it rather than depending on the zerk fitting.
 
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