First off let me say this is on my 99F250 Sd 4x4. Secondly, I spent an hour reading some great info this am regarding greasing a unit bearing. This is...was, a Precision unit bearing with unknown miles. My truck has 145K on it and I'm getting ready to install #3 in the drivers side. Questions regarding the Hall sensor and grease compromising its ability seem moot as what I took apart was covered in thick tar like muck including the tip of the hall/ABS sensor. BTW the sensor came out easily with a wiggle and twist and the tip had a 1/8" of hard crap on it and the abs worked fine.
My reason for dissecting it was to see for myself if greasing one thru the ABS hole actually did any good. Some believe the bearings are sealed on both sides, not so on this one anyhow. Look closely at my pic and you'll see the tip of a small driver stuck thru the abs hole. Look deeper and you can see the bearing rollers as well. When the outer half is pressed in it leaves a void that in fact allows grease to get to the outer rollers of the inner and outer bearings. At this point the only concerns putting grease in the ABS hole would be grease compatibility with what's in there already and over greasing it. Yes, this can cause overheating and a short lived bearing life. I personally don't believe they need to be packed 100% full. Grease is nothing but oils in suspension by a media of differing products. IMO the heat created while driving will warm up the media and allow oils to be released lubing the bearings. I learned this in a pump and bearing school. In a nut shell.....



The American Society for Testing and Materials (ASTM) defines lubricating grease as: "A solid to semifluid product of dispersion of a thickening agent in liquid lubricant. Other ingredients imparting special properties may be included" (ASTM D 288, Standard Definitions of Terms Relating to Petroleum).
The link here is a great resource of that opinion. https://www.machinerylubrication.com.../grease-basics

 

Thank you for posting that. I used to grease mine through the abs years ago, I always wondered if it was actually getting to the bearings or just into a void to nowhere..