EZ lube spindle and bearing repack question
My TT axles have the EZ lube spindles with the grease fitting on the end. It's time for me to repack the bearings. Is it safe to hand pump new grease through the fitting while slowly turning the whe...
Forum Discussion
wnjj wrote:Oh the grease WILL be pressurized. There IS resistance to the grease movement as it goes thru the system. If you have ever hand packed bearings, you will have experienced this pressure. You gotta force the grease into the bearing, it doesn't just fall into them willingly. With the EZ lube your are effectively packing two bearings at once. So twice the resistance. and then there is the added resistance of the grease flowing thru the passage ways and the hub.. This resistance will hardly be felt by someone using a grease gun developing 3500 to 10,000 PSI. But it CAN easily over power the seal. That is why Dexter cautions about pumping SLOWLY.... Of course they do not mention how many SLOW PUMPS it will take for a complete grease change. (231 to 392 per hub MINIMUM) That will take a long time and use a LOT of grease.Huntindog wrote:
Some grease gun facts:
Grease guns develop pressure in the grease, that is what causes it to move. No pressure = no grease movement. Grease guns are capable of 10,000 PSI!!! In fact the lowest one I can find develops 3500 PSI!! With a grease seal able to hold back only 10 PSI, there is an obvious mismatch. It is easy to see how a grease seal can be overpowered by a grease gun pressurizing the grease.
And on a related note, I saw ratings from 33 to 56 strokes per oz. of grease! So if a hub takes 1/2 a tube of grease (7 oz) to fill it, that could mean 231 to 392 pumps for ONE hub!!
Grease does take pressure to move and grease guns can make lots of pressure, however the pressure in the system is limited to the lowest exit point. If moving the grease through the bearings to the open air surrounding the fitting takes a lower pressure than the rear seal can hold it works just fine. How much pressure the grease gun can generate is irrelevant in an open system.
The only thing you are correct about is that the opening to the outside of the spindle adds little to no resistance.
