Grease plug for steering knuckle (2 Viewers)

[atijerino]

I was wondering if by adding grease to the steering knuckle via the square plug on top of them gets any grease to the birfields. Is this grease moving between the birf housing and the steering knuckle? or are they separated by the ABS geared rings?
Also how much grease can you put thru that plug? I know that for the birfields the FSM states to fill it up to 3/4 of capacity, but it does not say anything about the steering knuckles.

Antonio

 

[OGBeno]

Lots of info. on this if you do a search under "birfield" "repack" "steering knuckles" "grease."

The consensus seems to be that by adding grease through the fill plug on the axle housing, you are getting grease into the housing, but not as much into the knuckle (or none at all really) which adds nothing to the effectiveness of the grease in the birfield itself.

When you search and come across different posts, you'll notice that there doesn't seem to be any hard data across many different birf. jobs, though people do seem to add as needed (IIRC, I think people put grease in with every oil change or roughly 3K-5K miles).

In terms of how much: Well, I put a small dipstick in to see how much grease was in there. I had packed it up to about 3/4ths full when I did the job originally in Sept. 2004. The dipstick came out with some considerable grease on it, so I did not put too much in--I think about a 1/3 of a tube of moly. But that was just my experience. I have heard of people putting in entire tubes...

Others will probably chime in on this one...

Best regards.
-onur
Akron, OH

 

[wb1948]

how can you tell if you packed the cavity 3/4s full?

 

[photogod]

I reciently used a full tube in both and another half in one and it was up to 3/4. Get a coat hanger and use the straight part to stick in the hole work it all the way to the bottom and remove. That will tell you the level of the grease.

 

[Rookie2]

As much as anything, you want to make sure not to overfill it. A full knuckle will comprimise the inner axle seal, and the next stop is a complete knuckle job (which if it's never been done, you may be ready for anyway). You're going to need to do some dip stick'n to get a feel for how much is in there.


Rookie2

 

[Beowulf]

Antonio,

As you can see from the attached diagram, it is unlikely that grease put into the fill plug on top of the knuckle housing will get into the inner birfield where it is needed.

-B-

 

[OGBeno]

Beo--

Thanks for posting that picture. I was meaning to get it the last time you posted it in the early Fall I believe, but I lost track of the thread.

This is a great picture that all newbies should see...

Thanks again.
-onur
Akron, OH

 

[Beowulf]

onur,

I can't take credit. I believe it was posted by Raven.

-B-

 

[OGBeno]

Thanks for the correction B...

Thanks Raven for the diagram of the Birf.

Bet.
-onur
Akron, OH

 

[AK igloo]

Very good pic. I have a better understanding of what I'm looking for and at! Just purchased 96 and was asked by someone on this forum if they were checked. I will be checking mine in the morning.

 

[Rookie2]

Even if everything else is sealed up and functioning properly, you're going to lose some grease through the felt wipers over time. I don't know that I agree with the thought that no grease is getting inside the birfield. At highway speeds, the wheel and axle are spinning upwards of 700 revolutions per minute. That's around 12 revolutions per second. The inside of the birf is shaped like a bowl. I think under these kind of centrifical forces, the grease in the birf is pushed outward along the inner birf walls, and if the knuckle housing is 3/4 full, and is surrounded by grease, that grease is pulled through the inner portion of the birf, creating in affect a circulation pattern. Now obviously this exchange is not completely fluid, but to an extent I think it's there.

Think about if you didn't add any grease over 140 to 150 k miles (which is what some would be doing if there was no fill plug, and you were Joe-Blow, don't know Jack Schitt about the need for knuckle repacks). I venture to say that knuckle housing is going to be pretty dry. And do you think the grease that's in the birf is just going to stay all tucked up in there??? Hell no... it's going to sling out into the knuckle. Then what-chew on-do? (insert broken birf. symbol here).


Rookie2

 

[Beowulf]

Where is the fill plug on the diagram? If it doesn't get grease to the birf why is it there?

The diagram is a 2-D cut-away. The fill plug is not shown but you can estimate where it would be by taking a look at where yours is and the perspective of the cut-away.

-B-

 

[elmariachi]

I don't know that I agree with the thought that no grease is getting inside the birfield. At highway speeds, the wheel and axle are spinning upwards of 700 revolutions per minute. That's around 12 revolutions per second. The inside of the birf is shaped like a bowl. I think under these kind of centrifical forces, the grease in the birf is pushed outward along the inner birf walls, and if the knuckle housing is 3/4 full, and is surrounded by grease, that grease is pulled through the inner portion of the birf, creating in affect a circulation pattern. Now obviously this exchange is not completely fluid, but to an extent I think it's there.
Rookie2

I think you are right, at road speed the birf is happily bathing in a pool of moly and some of it is inside the spherical ball cavity and some out in the knuckle housing. If the inner axle seal were left to itself for 100K miles, eventually all the moly would leak out and your knuckle would dry up. And you know what they say about dry knuckles.

Jim

 

[Rich]

Ok, 5K miles before somebody does a repack they need to fill the knuckles through the plug with some bright red or bright blue grease. Then, when the birfilelds are pulled 5K miles later you will see to what extent the grease migrates throughout the knuckle.

I'd think once warm the grease would migrate around quite a bit and end up flowing towards the bottom of the knuckle.

 

[Rookie2]

Ok, 5K miles before somebody does a repack they need to fill the knuckles through the plug with some bright red or bright blue grease. Then, when the birfilelds are pulled 5K miles later you will see to what extent the grease migrates throughout the knuckle.

Good idear. Maybe just take the usual moly and mix in some food coloring or some of that engine leak dye, before adding the grease into the Knuckle. Anybody got a birf job coming down the road, and up for the experiment?

 

[landtoy80]

I think adding grease in the fill hole is to keep the ball (the axle housing end) covered with grease so it doesn't rust.

You could add the dye, that you use to find oil leaks where you need a black light to see it and see if you can see the dye in grease.
You would need to test first by filling your wifes/moms food mixer with moly grease and add some of the dye and run the mixer to see if it can be seen in the grease.

 

[IdahoDoug]

I disagree with the characterization that the spinning birfield is causing any grease exchange from the birfield chamber to the knuckle chamber. Grease is specifically designed not to flow in order to keep it in a bearing even if it gets hot. Grease is intentionally too thick to flow as speculated.

This is one important reason why a regular birfield grease repack is important, and using a dipstick to establish the status of the birfield's lubrication status is folly. All it tells you is that someone recently pumped grease into the square fill hole and that this grease is fresh.

The grease in the knuckle is there to provide a waterproofing barrier and cooling for the birfield joint, lubrication for the trunion bearings, and protect the triple seal's edge integrity as it slides back and forth (and to keep the ball it runs on rust free as noted). It will also provide emergency lubrication for the birfield if it is failing and dramatically overheating. But there is no operational exchange or circulation of the grease from the birfield to the knuckle chamber.

The only way to freshen the grease in the birfield joint is to open it up and manually repack it.

DougM

 

[zipastro]

Once in place how much space is there between the birfield and the bell?

 

[perk]

"I disagree with the characterization that the spinning birfield is causing any grease exchange from the birfield chamber to the knuckle chamber. Grease is specifically designed not to flow in order to keep it in a bearing even if it gets hot. Grease is intentionally too thick to flow as speculated.

This is one important reason why a regular birfield grease repack is important, and using a dipstick to establish the status of the birfield's lubrication status is folly. All it tells you is that someone recently pumped grease into the square fill hole and that this grease is fresh.

The grease in the knuckle is there to provide a waterproofing barrier and cooling for the birfield joint, lubrication for the trunion bearings, and protect the triple seal's edge integrity as it slides back and forth (and to keep the ball it runs on rust free as noted). It will also provide emergency lubrication for the birfield if it is failing and dramatically overheating. But there is no operational exchange or circulation of the grease from the birfield to the knuckle chamber.

The only way to freshen the grease in the birfield joint is to open it up and manually repack it.

DougM"

Hope that worked out ok...still trying to figure out how to properly quote.

Doug,
What do you think the square plug is for?

 

[perk]

Wait...before you point out how stupid I am, I just noticed the quote button after each thread