knuckle;is all that moly grease really needed?? (2 Viewers)

[CreeperSleeper]

That's why I always add a little gear oil in the Winter...

 

[crushers]

if you go to Napa and ask for a birfield they roll their eyes, if you go and ask for a CV rebuild kit they come out with a birf...

interesting, though if i asked at my local motor factors or even toyota dealer for a "birf", i would be greeted with;

 

[smcruisin]

First of all, how does one overfill with grease in the knuckle? It is not sealed container. Overfilling means you somehow squeeze more that can be filled. Thats only possible in sealed containers. Any extra amount of grease you put in will simply come out from knuckle. I just dont see how that can be overfilled.

I can not see how you would overfill through the fill hole. So adding to the top of the hole sounds for me like a good idea.

If you over fill the knuckle, you put too much pressure on the inner axle seal. This will lead to a premature seal failure. I did this the first time I rebuilt a nuckle. Trust me when I say it can happen.

RedTacoma,
It was pointed out to me by my cruiser-guru cousin that the opening in the top of your knuckle is suspiciously similar in size to the nozzle of most grease-guns. It's really satisfying to wedge the tip of your grease-gun tightly into the hole, and pump away happily on your grease gun. If you've got a pneumatic gun at a shop, even better! Hey, we've all been taught that greasing our trucks is good preventative maintenance...

However, now you have created a 'sealed' container (or at least have created a 'potential sealed container' if you're overzealous). The only places for grease to go is through/around the felt wiper, or past your inner axle seal. If the inner axle seal gets torn/stretched due to this forced-entry grease, gear-oil leaks back into your knuckles. This has a solvent-like effect, and flushes the grease out of your knuckles.



In regards to hand packing grease into a birfield as opposed to 'topping-up' the knuckle, the argument of the grease getting runny and filling up the inner cavity of the birfield does sound plausible. I just keep thinking of an air pocket that hydrolocks (pneumatolock... is that even a work???) any grease from getting in to where it needs to be.

I agree that for 'regular-maintenance-interval' purposes, the 'top-up' method would work fine, but for rebuild/yearly-intervals/deep watercrossing weekends, I'd feel pretty strongly about packing the birfield full by hand. I realize it's rotation characteristics are different than wheel bearings, but I don't think anyone here would skimp on thoroughly packing a wheel-bearing (regardless if it was a shop overhaul or a trail-side repair). The ball bearings INSIDE the birfield need the grease. Everything else the grease does is secondary in priority.

I'd rather know that my birfield bearings had grease where they need it to be rather that hoping that the mixing/churning action would eventually distribute the birfield grease.


That reminds me... it's probably time to do that leaky knuckle felt wiper seal rebuild/birfield repack I've been putting off...

 

[Rogorn]

Rovers have a birfield design where the knuckles call for gear lube as opposed to moly grease.

The guy at the local dealership they assigned to PM my LC while it was under warranty and extended must have been a former Rover mechanic.

Once I started the PM and repair work myself and investigating why the front wheels were dripping, I discovered "he" had been filling with gear oil instead of grease...

That was back when I used to allow them to work on my truck, before I repeatedly learned how bad that idea had been.

 

[Rogorn]

My son(8) and I just finished watching several "Bush Mechanic" DVDs
DougM

Pray tell, Where did you find them? Those DVDs sound most entertaining.
Or, are there better titles?

I just searched my Blockbuster on the web, the local library, and Amazon. No luck using a title of "Bush Mechanic".

My son and I used to watch the Junkyard Wars on one of the cable channels. They were entertaining as well.

Thanks.

 

[mainemike]

Interesting discussion. My birfs were repacked 30k miles ago, everything is good with no seepage at the axle. Changing the front diff oil I saw grease contamination. I refilled with M1 gear oil and replaced the breather with a vacuum hose/fuel filter set-up. This should alleviate the suction of grease past the inner axle seal into the diff fluid.

But I'm wondering if I should add some grease to birf fill plug to replace what I saw in the diff oil? Or is the contamination amount not enough to worry about? It sounds like adding some wouldn't hurt. I have M1 in my grease gun, but that isn't moly based, and it sounds like M1 grease wouldn't be the best choice here.

I wasn't aware of the concept of adding grease thru the filler plug as part of PM, but now it seems I should add some moly grease to each birf to be safe. Not 'pack it full' but simply add some...



Rogorn: Bush Mechanics here:

Bush Mechanics!

DVDs here:

Bush Mechanics - The Series - ABC Shop - The Home of Australian Content

 

[Natty]

I think the only way to ensure the knuckle housing has the right amount of grease is to take it apart and do it by hand, the filler plug should be only for emergency top up. With the spindle off and the freshly packed birf-axle in, if you slide the axle side to side there is just enough room to slide your fingers in behind the birf to pack in the grease and ensure there is no air pocket. Do this to both sides, then pack around the front of the birf, yet leave space and room before installing the spindle to the housing - this what is meant by 3/4 full... too much grease is tempting but will destroy the seals.

 

[Natty]

this to me is THE WORST of all vehicle preventative maintainance / repairs to do... You gotta do it yourself 'cause shops charge HUGE to do it. To me you need a good solvent wash station with electric pump - or at least it would really help to. I just did mine, started on a Friday evening, finished on Saturday night... however 3/4 of the process is simply cleaning parts. It is a disgusting job, but to me one of the most satisfying. Its such a good feeling installing the tires and pumping up the brakes again ( I compressed mine with C clamps to get them back on so I didnt have to bleed the brakes ) once your done.

 

[fj40z]

I know there are pictures of this on 80's tech already but I thought I would post up a couple on this thread. Right after I bought my 80 the driver side birf started clicking, I had to continue driving it for a couple of weeks until I got the rebuild done. I searched here on mud and read about a grease needle that will fit through the fill hole, so I picked one up and filled both knuckles about 2/3's full to prevent any further damage until the rebuild. I checked the knuckles with a makeshift dipstick and the knuckles were almost totally dry. After greasing the clicking almost totally went away, only barely noticeable at full lock with the windows down. About 2 weeks later we tore it all down for the rebuild and I was amazed how much grease had found its way into the birf. I picked up the needle from Northern Tool for 12 bucks. Well worth it for fill ups in between rebuilds.

 

[chapel gate]

"however 3/4 of the process is simply cleaning parts."

agreed. scooping grease out by hand, wiping, soaking in diesel, brushing, spraying with degreaser, wiping....

a bloody nightmare IMO!

 

[Natty]

How would you know if the knuckle is 3/4 full if you fill it from the fill plug? Behind the birf could be completely packed and in front could be void... if you dip something in that hole and pull it out there is no way that would be an accurate way of checking its contents, unless the grease if of course mixed with gear oil and its gotta come apart anyways... there is no way of accurately knowing how much and what quality of grease is in there unless its taken apart. Pump grease in there if you want, it might do more harm than good ie overfilling or neglecting needed attention ( rebuild )

 

[fj40z]

I just filled my knuckles up through the fill plug about an hour ago. I rebuilt the front end about 8,000 miles ago. When I pulled the plug I checked the depth today with a zip tie it had about an inch to an inch and a half on the end of it. No gear oil had seeped in so the seals are holding up. I cut the tapered end off of the grease needle to allow for more volume of grease per pump. I put 1 tube of grease per side and it still left more than enough room to prevent any damage from over filling. There is no doubt that its isnt better to take it down and pack it by hand, but it only takes about thirty minutes and about 6 dollars to do this in between repacks so why not do it.

 

[RedTacoma]

How would you know if the knuckle is 3/4 full if you fill it from the fill plug? Behind the birf could be completely packed and in front could be void... if you dip something in that hole and pull it out there is no way that would be an accurate way of checking its contents, unless the grease if of course mixed with gear oil and its gotta come apart anyways... there is no way of accurately knowing how much and what quality of grease is in there unless its taken apart. Pump grease in there if you want, it might do more harm than good ie overfilling or neglecting needed attention ( rebuild )

What is the mileage between your repacks and how much grease you have left there when you open them up again.?
I drop at least a tube per side every 1000-2000 miles. My knuckles are constantly covered by grease but anything inside is looking shiny like new. Also since I use Mobil it is always red fresh looking.
If I went more then 5000K between the checks I would probably have dry knuckles.

 

[IdahoDoug]

I'm with FJ40Z. I just do a rudimentary check with a makeshift dipstick to get a gross feel of how much low they are. Then I generally pump an entire tube in. Ditto the other side.

There are outward signs the knuckle needs more grease - such as the sweep seal is wet on the bottom and dry up high indicating the seal is not encountering any grease to drag across the spherical tip of the axle housing. For that I'd put a half tube in. It's all kind of a feel thing once you've got a couple knuckle teardown and repacks under your belt.

While we're on this, someone could make money fitting a threaded plug into that square plug's hole that had a grease nipple on the other end. I hate messing around with that square plug and the filty grit that settles around the opening. Much rather wipe off a zirk fitting and pump away....

DougM

 

[WarDamnEagle]

Also since I use Mobil it is always red fresh looking.

I'm pretty sure that Mobil 1 red isn't moly fortified. (At least not the Mobil 1 red that I use to pack wheel bearings.)

 

[scottm]

While we're on this, someone could make money fitting a threaded plug into that square plug's hole that had a grease nipple on the other end. I hate messing around with that square plug and the filty grit that settles around the opening. Much rather wipe off a zirk fitting and pump away....

Would that be a problem with the aformentioned pressurizing of the birf cavity and possibly pushing grease into the axle? Perhaps you could add a vent, maybe a small screw hole? Perhaps venting the birfs would be a good thing, but adds complexity to what I consider a fairly clean design.

 

[Tools R Us]

What is the mileage between your repacks and how much grease you have left there when you open them up again.?
I drop at least a tube per side every 1000-2000 miles. My knuckles are constantly covered by grease but anything inside is looking shiny like new. Also since I use Mobil it is always red fresh looking.
If I went more then 5000K between the checks I would probably have dry knuckles.

Mobil 1 gives up it's oil relatively easy, quickly, even just sitting in the can, it's also relatively thin. This is good in a sealed compartment like wheel bearings, but in the knuckle it will weep out quickly. I tried it in u-joints, was replenishing it constantly, in these cases you want a thicker, tackier grease. Moly is very beneficial, it's extreme pressure lubricating and stick to surfaces characteristics will help to extend the birf life, in this application I wouldn't run a grease without it.

 

[Tools R Us]

... With the spindle off and the freshly packed birf-axle in, if you slide the axle side to side there is just enough room to slide your fingers in behind the birf to pack in the grease and ensure there is no air pocket. Do this to both sides, then pack around the front of the birf, yet leave space and room before installing the spindle to the housing - this what is meant by 3/4 full... too much grease is tempting but will destroy the seals.

It really doesn't matter where the extra grease is placed in the cavity. The action of the birf spinning and steering turning will redistribute it anyway.

 

[RedTacoma]

Mobil 1 gives up it's oil relatively easy, quickly, even just sitting in the can, it's also relatively thin. This is good in a sealed compartment like wheel bearings, but in the knuckle it will weep out quickly. I tried it in u-joints, was replenishing it constantly, in these cases you want a thicker, tackier grease. Moly is very beneficial, it's extreme pressure lubricating and stick to surfaces characteristics will help to extend the birf life, in this application I wouldn't run a grease without it.

So far has been working for me but I was dumping so much into knuckles.
I am Thinking to try the Valvoline Synth.

As long as it has the same water resistance characteristics (or better) that Mobil has.

 

[IdahoDoug]

If you are in a place where you take your Cruiser in water regularly there also is a type of grease made to resist washing out for boat trailer wheel bearings. I don't know if there is one that specs correctly for the birfields, but I use this stuff and it is amazing in water and amazingly tacky. Call any marine supply store and they'll have it.

DougM