Driveshaft greasing questions (1 Viewer)

[Igotmearedone]

Like most things I do with my 40, I had no idea what I was doing and was just greasing up the zerks underneath. I was pumping away in the driveshaft (without the car jacked up, another thing I didn't know to do) and after 10 or so pumps I got a sudden burst of grease straight out of a seal, probably most of what i put in. Of course only afterwards I started looking this up further. My questions: Did I just completely mess up my driveshaft? Do I need to remove it and rebuild it? Why does the car need to be jacked for this procedure? For the future, is moly grease ok for the driveshaft and u-joints, this seems debated? Thanks in advance

 

[JohnnyC]

Everything is debateable

Mess it up ... not at all

Yes most times you will get grease pushing out... you should see how much comes out when you use power lol

Ideally it goes in and you see the seal swell on tre’s ... drive shafts it kinda oozes out

If you see water come out after you pump it that’s not to good... go a bit more till it’s clean... hit it again next day after driving it

If you see rust come out same as above and .. hit it next day ... and another day

If it’s clunking... it vibrating badly... then replace it

U jack it up in order to turn the shaft to align it to position the zert to fill it

I usually do not jack it up.. just roll it forward or back to get the the zert

 

[1911]

I watch the u-joints carefully as I pump the grease gun, and stop as soon as I see grease seep from the u-joint. If you do it regularly (I do mine every oil change) they will need very little additional grease. If you keep grease in them, there won't be room for water to get in. But the u-joints work pretty hard and have a fair amount of stress on them, especially with a suspension lift that increases the working angles on them, so you need to keep the grease topped off.

You want be careful not to completely fill the drive shaft slip joint though. There is a zerk there, and it will take a lot of grease if you keep pumping - but if you do, it will fill the tube completely and hydraulically lock it so that it can't compress as the suspension flexes, which will put a lot of stress on your differential pinion gear, which obviously you not want. The slip joint just needs a little bit of grease to lube it so it slides; I do maybe one pump every other oil change on those.

 

[Igotmearedone]

Thanks for the replies. How do I make sure it’s not hydrolocked? I saw it expand quite a bit, then had the sudden extrusion of grease. I imagine I wouldn’t be able to compress it by hand either way or should I be able to if it’s not hydrolocked?

 

[GA Architect]

Thanks for the replies. How do I make sure it’s not hydrolocked? I saw it expand quite a bit, then had the sudden extrusion of grease. I imagine I wouldn’t be able to compress it by hand either way or should I be able to if it’s not hydrolocked?

FWIW - You can remove the zerk fitting and let some of the pressure off.

 

[GRM]

Remove the zerk and fully compress the driveshaft.

I like to pull the driveshaft and goop up the splines with marine grease and a brush, then reassemble.

This is because I’ve had far more driveshaft failures due to seizing from corrosion than wear.

 

[Igotmearedone]

Thanks. I was able to expel quite a bit, just from jacking it up with the zerk removed. I tried to put a bit back in but everything I put in comes straight back out of the seal that's marked by the arrow, across from the zerk. Is that still OK? I expected it to retain 1-2 pumps at least after removing so much.

 

[1911]

That's the U-joint, not the slip joint. You want to fill the u-joints all the way until grease seeps out.

The slip joint is on the drive shaft itself. There is a grease zerk on the outside; rotate the drive shaft until you see it.

 

[Igotmearedone]

Isn't my grease gun going into the driveshaft zerk in that photo? I guess you can't see the zerk from that angle, but I wanted to show how the grease comes straight out of the U-joint right next to it when I fill the driveshaft

 

[jim land]

It is the cap that pop out. , it look like a freeze plug, it is in the yoke as on your pic , if you put too much grease, it pop out as the suspension compress the slip joint

 

[jim land]

Clean the area and use a pry bar to push it back in. , and dont over grease it the next time

 

[Igotmearedone]

Oh I see. Yeah, it's definitely the plug at the end that's popped halfway open. I jammed it back in, but it seems delicate now. I'm afraid to put any more grease in there anymore, so we'll see what happens.

 

[1911]

Isn't my grease gun going into the driveshaft zerk in that photo? I guess you can't see the zerk from that angle, but I wanted to show how the grease comes straight out of the U-joint right next to it when I fill the driveshaft

OK, I didn't even see the grease gun tube in the photo, my eye was drawn to the red arrow. Yes, in that photo the grease gun looks like it is attached to the slip joint zerk.

I would do what @jim land said. As has been previously said, you can also remove the slip joint zerk and that will let some excess grease out and relieve some pressure.

 

[65swb45]

A halfway unseated freeze plug is not a good thing. Either seat it properly or remove it. The fact that it popped indicates that at some previous point there was a excess of grease in there. At that point the freeze plug did what it needed to do.

I am personally in the same camp as @GRM about using heavier grease that is applied by hand, not from a grease gun. It does not squeeze out from the splines as easily; I.e. it lasts longer.

I used to own an early Suburban with a 454 that could pass anything but a gas station : The splines on the output shaft of the transmission were worn, and I didn’t have the money or the inclination to replace it. I hand packed that slipyoke once a year, and all was good.