re: rack on a tube axle
I think I understand what you are doing. If you are just using the grease to lube the D shaft, that's one thing, but if you want to use the tube it siding into as a reservoir, that's another thing. Have you ever heard about using grease to remove a crankshaft pilot bearing? First you put grease in the bearing and then using a shaft the same size as the hole in the bearing, hit it with a hammer and the bearing pops right out. The reason this works is because the grease is not compressible. I'm thinking you would find the same thing happening here. If you are just lubing the shaft and the tube, then drill a small hole in the tube to vent the trapped air, otherwise you'll end up pushing the grease out when the shaft compress'.Hope this helps.