Vacuum and the Knuckles
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Tuned
Joined: Apr 2004
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From: Aroostook County, Maine
Vacuum and the Knuckles
My e99 has long been switched over to fully manual hubs. The vac lines were pulled from the "tee" up near the canister (and plugged). As I am reassembling all the pieces/parts on a general front axle repair, I got to wondering about the channel cut through knuckle - that which delivered vacuum into the hub area to engage the hubs.
As I was cleaning things up I removed the fitting on the knuckle (which was not identifiable as a vac fitting) and put a plug in. Would there be an advantage to repurposing that to deliver grease instead?
Even though mine is the Lariat package, it never came with the front ABS I don't believe. The factory connectors are there behind the wheel well, but they are capped with something that looks factory to me. I can't tell if the unit bearing was original or not. The previous owner could not recall if he had them replaced (which would have been prior to 2014 and 157k miles), so I'm guessing they are prob original. So the option of greasing through the hub is not an option.
As I was cleaning things up I removed the fitting on the knuckle (which was not identifiable as a vac fitting) and put a plug in. Would there be an advantage to repurposing that to deliver grease instead?
Even though mine is the Lariat package, it never came with the front ABS I don't believe. The factory connectors are there behind the wheel well, but they are capped with something that looks factory to me. I can't tell if the unit bearing was original or not. The previous owner could not recall if he had them replaced (which would have been prior to 2014 and 157k miles), so I'm guessing they are prob original. So the option of greasing through the hub is not an option.
Laughing Gas
Joined: Mar 2021
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I thought about this before. Problem is the hole is so deep, and it exits right on the edge of the axle seal... if you used a long tube to deliver the grease on to the axle shaft it might migrate to the needle bearing and be useful. But you wouldn't know if it worked for sure unless you disassemble the hub and look at the needle bearing, and if you've done that you might as well just grease it by hand.
I just ran a 1/8 NPT tap through mine and used plugs to keep the dust out.
I just ran a 1/8 NPT tap through mine and used plugs to keep the dust out.
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Tuned
Joined: Apr 2004
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From: Aroostook County, Maine
As I think about it, it will boil down to the amount of pressure it will require to get the grease to make it's way to the needle bearing versus what the yellow O-ring/vacuum seal on stub shaft can resist. So yeah, you are probably right in that at the end of the day, it would be more effective to break everything down and get to the needle bearing directly.
FTE Chapter Leader
Joined: Jan 2005
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From: Henderson, NV
I have done exactly what @pvdiag is contemplating and put a grease nipple in the hole formerly used for vacuum. With sufficient grease pumped in, it will indeed grease the needle bearing. The needle bearing is the only bearing it will grease though because the main taper bearings sit on the outside of the tube the needle bearing sits inside of. Grease has to be pumped in through the ABS Sensor hole to reach the taper bearings. Packing that back cavity with grease is great protection against water intrusion WHEN (and I do mean when, not if) the knuckle seal fails though.
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As I think about it, it will boil down to the amount of pressure it will require to get the grease to make it's way to the needle bearing versus what the yellow O-ring/vacuum seal on stub shaft can resist. So yeah, you are probably right in that at the end of the day, it would be more effective to break everything down and get to the needle bearing directly.
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Tuned
Joined: Apr 2004
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From: Aroostook County, Maine
Butt-Head
Joined: Apr 2004
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From: Reed Point, MT
The only difference here is that there is relative motion between the hub and stub in 2 wheel drive (hubs unlocked) whereas the old fixed spindle design had relative motion only when the front axle shafts were turning.
I guess what I'm really getting at is would you rather have a non-selectable setup like a Durrrr-ge or a 4 wheel drive El Camino? I'm not a huge fan of unit hub bearings no matter what vehicle they come on but I sure do like the ease of replacement on a Ford given the choice. A 21mm socket and a pair of snap ring pliers. No big nut torqued to 200+ ft. lbs., no cotter pins, no air hammer to knock the Dodge hub out of the knuckle it's stuck in and no failures of a GM one every 6 minutes along with the IFS that can't support any weight without needing an alignment.
Oh, and a locking hub sticking out of the center just looks right....and manly. Dodge was good enough to us to offer a solid front axle just like Ford so at least there's that.
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Tuned
Joined: Apr 2004
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From: Aroostook County, Maine
To wit: last fall I did the whole grease/check front end heading into winter. The dust/vac seal looked good (from behind the hub). This spring - and 1000 miles later I noticed that the seal was having tech difficulties (I had only drove it locally <10 days in the winter, and then a single 900 mile trip). 900 miles back, maybe 100 miles local, and an eventful excursion into the NorthMaineWoods and there was nothing left of the needle bearing. The outer race was gone. In total I had <200 miles since fall with hubs and 4wd engaged. And I hardly had any 4x time the previous year because of electrical transfer case issues.
Having the ability to get some grease into the needles is better than doing a near full teardown to do so. I acknowledge it won't be the end all either.
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Laughing Gas
Joined: Mar 2021
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That needle bearing really needs to be a sealed bearing. It's rotating most of the truck's life and has no way to retain grease.
Iirc I think front hub assemblies on later super duty uses a sealed bearing in place of the needle bearing.
Iirc I think front hub assemblies on later super duty uses a sealed bearing in place of the needle bearing.
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