Drive (propeller) shaft slip joint grease

[kcjaz]

I know there are other threads on this which I have read. I also know that I am over thinking this but...

I greased my prop shaft in the beginning of May. I used almost all of a regular tube of grease (not mini tube) in the 6 zerk fittings. I'm pretty sure that the dealer was not greasing the prop shaft when the oil was being changed. The spiders seem fine and I know I over grease them but I just wanted to purge out all the old grease with the new grease.

I pumped what I thought was a lot of grease into the slip yoke but never got it to move like the FSM said. So today I dropped the rear propeller shaft just to see what was actually going on. There was grease but not very much. Nothing looked damaged and the splines were all all good and had a light coating of grease. I was expecting there to be some grease in the gap between the prop shaft and the slip yoke. When I pulled it apart there was no grease there which I think explained why I never got movement of the slip yoke but there has also never been grease there as the "capped" ends of both sides were clean see photos.

The only way I see that the slip joint can move is if there is grease in the space that pushes the two parts apart. If that is how it works why is there no grease in that space? Clearly I must be missing something.

 

[Sandroad]

Here’s a thread with some insights on that.

What happens when you over grease a slip yoke??

So I 'think' I made a big problem. So I am asking if anyone has insight on what happens when you over grease a slip yoke? 2013 LX570 I was performing a 90k maintenance my uncle's LX570 and I noticed the spider joints looked bone dry. So I hit it with some grease. No problem. Well when I went...

forum.ih8mud.com

 

[kcjaz]

Here’s a thread with some insights on that.

What happens when you over grease a slip yoke??

So I 'think' I made a big problem. So I am asking if anyone has insight on what happens when you over grease a slip yoke? 2013 LX570 I was performing a 90k maintenance my uncle's LX570 and I noticed the spider joints looked bone dry. So I hit it with some grease. No problem. Well when I went...

forum.ih8mud.com

Thanks. I've read that thread and actually replied to it. I probably should have just replied to that thread again but most of that thread is just debating on whether or not you can damage something from overfilling. I jut want to focus on a couple very specific technical questions regarding how, what should be a very simple thing (slip yoke) is intended to work. I don't want a debate here on what might theoretically damage something. I took my rear shaft apart just do I could really understand what was really going on inside it. So let me try this approach to separate fact from opinion, assumption, and question:

Fact: The FSM says to add grease to the slip joint zerk until the slip joint moves (both front and rear).

Assumption 1: for the slip joint to push apart due to grease being pumped into the zerk, hydraulic pressure would be required from the grease filling the "chamber" between the two ends of prop shaft.​

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Assumption 2: If assumption 1 is correct, then pumping grease until you see movement would "pack" the "chamber" which would prevent the slip yoke from compressing until the excess grease comes out the seal ring on the slip yoke.​

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Assumption 3: If you got some grease to ooze out of the seal, this would be messy but not bad by itself. (I understand the argument that a prop shaft that can not compress could damage the transfer)​

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Question 1: For the slip yoke to be able to move, it would seem that the truck would need to have the wheels of the ground or one end disconnected. I don't see how the prop shaft could extend with the truck on the ground with the prop shaft in place. Is this right?​

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Question 2: The pics in my original post seem to show that either my assumption 1 is wrong or my rear prop shaft was never greased per the FSM. Which? (note my 200 is a 2013 with 152K miles, and the slip yoke splines and seal all look fine.)​

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[CharlieS]

Regarding Question 1 - I think the idea is that the hydraulic pressure of the grease pressing on an enclosed space would permit the yoke to move, despite the force of the vehicle sitting on its wheels. My armchair assumption: there are tons of force being applied outward when that chamber is filled, and it only has one place to go - past the splines.

Those photos don't appear to me like much grease was pumped into them. Was the grease you used yellow?

 

[Sandroad]

I hope you matched marked everything so you won’t get vibrations. Almost all of a tube of grease is a LOT. Where did all that go?

Drive Shaft / Propeller Shaft Service - Detailed

The 80 series guys have had so many driveshaft issues with related Vibrations or Clunks that I believe can be easily avoided by proper drive shaft servicing. There is no reason the 200 Series should be any different and in my opinion, the Prop shafts are one of the most under serviced parts on...

forum.ih8mud.com

 

[kcjaz]

I hope you matched marked everything so you won’t get vibrations. Almost all of a tube of grease is a LOT. Where did all that go?

Drive Shaft / Propeller Shaft Service - Detailed

The 80 series guys have had so many driveshaft issues with related Vibrations or Clunks that I believe can be easily avoided by proper drive shaft servicing. There is no reason the 200 Series should be any different and in my opinion, the Prop shafts are one of the most under serviced parts on...

forum.ih8mud.com

yes I match marked it. There was a lot of grease wasted on the spiders and I also pumped some into garbage can purging the gun and to make sure the gun was actually pumping. Sometimes I can tell the gun is not actually pumping grease when I squeeze the handle. I'm not sure what the issue is with the gun in that regard. Anyway, I agree a lot of grease but it clearly wasn't in the slip yoke as it just wasn't full of grease like I expected.