Corn Head Grease

swat · Post by **swat** » Tue Mar 12, 2013 12:30 pm

Was finally able to get some corn head grease for my M38 axles. How do you get the old lubricant out. The new grease is in 14 oz cartridges. How much goes into each knuckle?

Post by **wesk** » Tue Mar 12, 2013 1:08 pm

This is why the knuckles are so often neglected. You must disassemble and clean the knuckles every 6000 miles and then hand pack and re-assemble. Do not install a zerk on the knuckle and try pumping that grease in or you will eventually overservice the knuckle and contaminate the axle/brakes.

swat · Post by **swat** » Tue Mar 12, 2013 3:19 pm

Thanks Wes, You've probably saved me a lot of trouble down the road. (No pun intended.)

skyjeep50 · Post by **skyjeep50** » Wed Mar 13, 2013 8:38 am

Just did my M38A1 front knuckles for the first time, should have checked them earlier. Found the usual rusty upper king pin bearings, worn bearings and races, wrong-sized bearing bolts, loose bearing pre-load and some rust in the knuckles themselves due to water infiltration from badly assembled knuckle seals. So now everything is right and tight, cleaned, de-rusted and repainted. How to fill? Military manuals call for #2 chassis grease for the knuckles which is sticky and will not "flow". If you are going to use #2 you will have to hand pack the knucles and bendix joints and then assemble. Civilian manuals for the early CJ's call for 0 (winter) or 1 (summer) weight lube which is semi-flowable. The king pin bearings need to be greased by hand before putting them in and checking pre-load, put some lube on the bendix joints and then fill the knuckle cavity level with the fill plug after assembly. The flowable lube should coat the bendix and knuckle/king pin bearings when the drive shaft spins.

Post by **wesk** » Wed Mar 13, 2013 8:58 am

You folks in southern climates are best off with the hand packed grease period. We folks up north have learned that #2 chassis grease is hard as rock at 0 degrees F and you can feel the initial cold weather rolling resistance. The 1950 thru 1955 military M series Willys manuals all refer to #2 chassis lube however if you start looking at the 60's and later civvy universal jeep manuals by Willys and Kaiser you see a reference change to a more fluid like gear oil. Of course these jeeps came with only Rzeppa and Spicer axle joints. The spicer joint must be disassembled to pack lube in it. In theory you can run the handpacked spicer joint in an empty hub with no problems. The top king pin bearing can only be lubed by hand packing and the grease filled knuckle does not keep this bearing lubed nor will the grease filled hub keep the lower bearing lubed. The real reason for filling the hub with #2 grease is to help keep the water out.

skyjeep50 · Post by **skyjeep50** » Wed Mar 13, 2013 2:02 pm

I tried heavy gear oil in my M38, it leaked even with new knuckle seals so I went back to grease.