Kingpin and front wheel bearings

[Deadguy]

What is the correct grease to pack these with?
Also, I am going to replace my Kingpin bearings. Is it a good idea to replace the wheel bearings while I'm at it? And if so, will I need new cups, or just the bearings?

[RimfireJim]

Kingpin bearings get the same lube as the steering knuckles (CV joints), as they are in the same housing. Original lube instructions for the M38 and M38A1 call for "Grease, automotive and artillery", i.e. NLGI No. 2 chassis grease, for all temperatures. I found this reference http://www.novak-adapt.com/knowledge/steering_knuckle_repair.htm that said to use No. 1 for summer and No. 0 for winter. Do a search on here and on the web in general on steering knuckle lubrication and you will find a lot of discussion on the topic regarding optimum viscosity. We decided to go with John Deere Golf and Turf Cutting Unit Grease, a NLGI No. 0 product, because the jeep will be spending a lot of time in cold Idaho winters. According to our local JD dealer, this is the same as their Corn Head grease, just labeled for different user markets.

Wheel bearings get regular ol' NLGI No. 2 chassis and wheel bearing grease, unless you put on those disc brakes you have, in which case you need wheel bearing grease rated for the higher temps of disc brake rotors.

You'll need to replace whatever is worn. You won't know until you disassemble, clean, and inspect. No point in replacing perfectly usable bearings. We wound up replacing every single bearing cup and cone in both axle assemblies by the time we were done with that process. That added a fair chunk of change to the project that we weren't anticipating! Probably could have gotten some more use out of a few of them, but it was a case of "while we're in here with it all torn apart . . ." Good thing doctors don't (usually?) use that philosophy!
_________________
Jim M.
1952 M38 son-father project
Discovering more worn out parts, one assembly at a time

[Deadguy]

Are the wheel bearings really going to be affected by dis brakes? I understand they are on the front axles, but the rotors dissipate heat better than drums, and the wheel bearings are a fair distance away. Ill get the number 1 grease, in Texas the heat is way more of a concern than the cold. I may as well get new wheel bearings. The originals are probably 59 years old, and while I have the whole thing apart...

[madmike]

Age has nothing to do with it. Look to see if the bearings are showing discoloring or if the race is pitted or discolered. Slight tinge of copper is okay but if you see heat damage or hot spots then replace. Change the seals though because the rubber or leather is probably dried out.

Disc brakes run hotter because the all discs drag slightly against the rotor even when no braking is applied. Thus the need for higher temp grease.

[cmpman]

The military has replaced the old GAA with a more modern synthetic version. It has a far greater temperature operating range, and repels water far better than the old GAA, which seemed to mix with the water to form an oxidant.

My experience with the modern synthetic is that I would never go back to the old stuff again.

[wesk]

Keep in mind while toying with all the new stuff that the military is no longer using these old Dana 25's and Dana 44's. Their new GAA is designed for their modern vehicles. Just like engine oils have matured into oils that are no longer meant for use in old flat tappet engines many of the other lubricants have advanced into that category as well. Before using any modern lubricant in an antique check with the lubricant manufacturer and see what their recommendations are.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php