D27 Knuckle Stud Project

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In case anyone wants to know why closed knuckle axles aren't used much anymore...here is a rebuild thread for my D27 front axle that I broke the knuckle off of - well really, it stripped out the mounting bolts that hold the wheel hub and spindle to the knuckle, and thus keeps the axle shaft in the axle housing. Anyway, I am not just doing a straight repair of this, but hopefully an upgrade that will not something similar again....Instead of the bolts that hold it all together going from the outside-in, and threading into holes in the cast iron knuckle (those are the weak spot), the new set-up with bolt from the inside out, and will be nutted off on the the outside. Using appropriate grade hardware, this should be much stronger than relying on weak cast iron threads that are even weaker after 50+ years of corrosion and wear. But, bolting from the 'inside-out' is not trivial due to clearance issues of the knuckle spheres and axle u-joint...so use of button head bolts and removal of the knuckle to aid in a bit of grinding in select spots should do the trick....hopefully....

Example here is from the passenger side (this side did not break - yet...) - first thing is to remove the knuckle....as the FSM says: requires removal of the hub and brake drum assembly, wheel bearings, axle shaft, spindle, steering tie rod, and steering knuckle.

After removal of the wheel hub (and locking hub/drive flange etc), the heads of the 6 bolts to be replaced can be seen holding the brake backing plate on....
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_180025854.jpg

FWIW, I have 11" bendix brakes here, but its the same for OEM 10" or 9" etc. Removal of these bolts allows removal of the backing plate and then the spindle:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_180808999.jpg

With the spindle removed, the outer surface of the knuckle is exposed....the bolts thread into the knuckle, and its these threads that are weak and can fail.
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_192802040.jpg

To remove the knuckle, a bit more work is needed...the axle shaft can be pulled out and set aside:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_192925569.jpg
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_192929126.jpg

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And then the steering TRE needs to be disconnected:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_193629805.jpg

Next, removal of the felt seal and retainer plates from the backside of the knuckle:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_194253435.jpg

And lastly, removal of the lower and upper kingpin bearing caps:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_195352605.jpg

The upper bearing will probably have shims....and the kingpin bearings fall out easily (especially the bottom one):
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_200026729-1.jpg

I went ahead and cleaned up the knuckle a bit and chased all the threads:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_203748840-1.jpg

Here is the inside of the knuckle....the button head will sit against the inside of this knuckle...the inside surface where the button head will sit needs to be spot faced to make it flat and smooth:
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_204336066-1.jpg

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Here are the driver side kingpin bearings, caps and races....these 'posts' essentially are the vertical axis that the spindle/wheel rotate around....the oiling set-up is nothing more than splash and sling - mostly from the axle shaft spinning through the 'pool' of oil/grease inside the knuckle. Of course, when in 2wd (and hubs unlocked), that means no oil slinging. Originally, these jeeps didn't come with locking hubs - they would have come with permanent drive flanges, when meant the front axle shafts turned when the wheels turned, and that helped keep things lubricated, but wore out parts faster, used up some mpg, and with manual steering on paved roads, was a bit of a hassle. Even with modern open knuckle ball joint set-ups, its probably good idea to lock your hubs in every once in a while to keep things lubricated.
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_223157058.jpg
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_223236413.jpg
https://www.beamingpix.com/images/2021/08/19/PXL_20210819_223310674.jpg

it all looks fine to me (sorry last pics wasn't that great)....but I am always tempted to replace at least the bearings and races. These bearings don't see much rpm- and only rotate as much as you can turn the wheels, but they do see a lot of side loading and binding, and have a tendency to damage the race surface, especially when oiling is limited (some similar axle set-ups on IH scouts used bushings - possibly only with power steering as the friction might increase too much for manual steering).

Anyway...Replacing the bearings and race isn't needed...but I ordered a complete set of 4 (2 per axle) since we are this far in, and anything to keep the steering as good as can be (which is just above scary bad). Next up will be figuring out how to machine the inside of the knuckle where the button head sits....then it will be test fitting to see if any of the button heads will have clearance issues (often 2 of the 6 need some additional work)....

[Jim]

I'm not envisioning the full setup, but...

...could these roller bearings be packed with grease - and if things were fortunate, add a grease fitting to each bearing???

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In theory, I guess a fitting could be added though the bearing cap and drill a grease passageway down through the post to the bearing area. Grease fittings and passageway can create areas of weakness...in an already weak area prone to breaking. The OEM design certainly isn't great by today's standards, but if the proper lubrication is used, and frequent maintenance checks are done per the factory specs, they are fine...just don't use too heavy of a grease and keep the knuckle lubrication full (has a tendency to leak out) and they work. Just gotta keep up with them.

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Unfortunately I ordered the wrong size spot facing tool...so now everything is on hold until I can get the right tool.

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Okay...so with the help of some jeepers, making a little bit of progress...I was really struggling with the spot facing aspect of this project, and getting the right tool has been an issue. A friend from CA sent me a set of knuckles with the buttonheads already installed (they came off his D25/27 front axle that he replaced with a D30 (open knuckle) after irreparable damage had occurred else where. So that has really helped keep my progress moving forward on the cj so it will be ready for Moab in a few weeks. But I am also working on a 2nd set of knuckles that is getting the full spot facing treatment now that I have the right tool and possibly know what I am doing (eh, probably not) so I can finish the same project on the 58. So far, no highly desired 2 hole knuckles have been destroyed in this process...

Doing a bit of test fitting for clearance with the buttonheads against the axle housing sphere - its the 3 and 9 oclock heads that hit the sphere. Working on the right side, here is 3 oclock:
https://www.beamingpix.com/images/2021/09/06/PXL_20210904_200221103.jpg

and 9 oclock:
https://www.beamingpix.com/images/2021/09/06/PXL_20210904_200208938.jpg

And here is the axle mounted stop screw still in its original location:
https://www.beamingpix.com/images/2021/09/06/PXL_20210904_201941485.jpg

That stop screw has quite a big gap between it and the knuckle, although some of that space will be taken up by the felt seal/plate and mostly the hex head that hold the felt top plates on. But I decided to make a bit more clearance...it may not really have been necessary. But I ground the buttonheads down a bit. From the backside of the knuckle, the one on the left is 3 oclock in its finished state, and the one on the right is 9 oclock and only partially finished. Its hard to test if the 9oclock one is okay as there is no stop screw on the backside - the only proper way to test would be to jack up the entire front, re-connect the steering linkage and turn the steering wheel to see what hits first, the 9 oclock head, or the stop screw on the opposite side wheel. Anyway, I just kind of eyeballed it - it reality, all this tedious fit testing and re-testing probably doesn't truly affect the turning radius much.
https://www.beamingpix.com/images/2021/09/06/PXL_20210906_152711590.jpg

and also ground some notches in the sphere:
https://www.beamingpix.com/images/2021/09/06/PXL_20210906_161242334.jpg

With all that done, the fit looks good....the knuckle now with seals installed contacts the stop screw still in its original location.
https://www.beamingpix.com/images/2021/09/06/PXL_20210906_182302046.jpg

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With all that done, new kingpin bearing and races went in packed with grease:
https://www.beamingpix.com/images/2021/09/06/PXL_20210906_162807774.jpg

And the knuckle in its final state - I actually had some trouble getting the knuckle seal to fit - seemed like it wouldn't stay in place and I had to sort of keep working it into place as it was clamped down by the seal plates and crushed felt....I tried to add a bit of RTV to the outer edge of the seal that contacts the outer knuckle, and basically it just made a mess. The inner lip that slides over the sphere gets a bit of grease...I also added a bit of thread sealant to the bearing cap bolts and torqued to spec.
https://www.beamingpix.com/images/2021/09/06/PXL_20210906_182326143.jpg

Think everything is now ready to slide the axle shaft back in - the axle ujoint seems perfect so leaving it alone. Spindle will slide on, and then brake backing plate and tighten down nuts on the newly installed buttonhead bolts/studs.

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Once the spindle and backing plate are on, everything is held in place by nuts that go onto the studs from the outside - so no longer relying on bolts threaded into relatively thin and weak cast iron from the outside in. Even if the buttonheads strip out (red loctite used) when trying to remove the nuts - highly unlikely but possible - the kingpin bearing caps and backsike knuckle seal plates can be removed and the entire knuckle assembly with spindle and backing plate will slide off the axle housing.
https://www.beamingpix.com/images/2021/09/06/PXL_20210906_193819455.jpg

And with everything back together, ready to roll:
https://www.beamingpix.com/images/2021/09/08/PXL_20210908_155742899.jpg

Although all the pics are of the passenger side, I did the driver side as well (which was actually the side that tore apart). Finish up some body work on the rear corner this week and she'll be ready to go again. And that means back to work on the 58....

[Tom]

Yay! Big project.