Rear Hub Grease Cap

[dschwartz1957]

I am replacing the rear wheel bearings in my 1968 Mini Traveller (yeah, it is an MK2) and have two questions about the rear hub grease cap.

1) On my car, the grease caps have a tiny hole in the center, which surprised me since grease can leak out. The reproduction grease caps available on Mini Spares do not have a hole in the center.

http://www.minispares.com/product/Classic/ATB4098.aspx

The old grease caps are in decent condition, and can be reused. However, I wonder if they should replaced with new caps that don't have the hole? To use a software term, is the hole "a feature or a bug?"

2) When I removed the old grease cap I found it was half full of grease. The bearings had plenty of grease, and it appeared a previous owner had simply filled the cap with extra grease. Should the cap be filled with grease before installing it on the hub?

Thank you,

David Schwartz
Framingham, Massachusetts

[olddave]

Hole or no hole. The 'pinhole' releases the excess air when refitting the cap, so a good idea. Also some grease in the cap does no harm.

[Spider]

For a normal road car, a breather hole is a good idea. I'd run the caps you have.

[Peter Laidler]

Yes, pinhole. Some grease will migrate due to centrifuge but those clever bearing manufacturers have thought about that too.

[dschwartz1957]

Many thanks. I was already inclined to use the old (possibly original) grease caps.

[Tim]

There shouldn't really be that much grease in there that it would leak out the hole. It's not like a boat trailer where the caps are completely filled with grease and pressurised.

Tim

[Herbert850]

The hole is to let a bit of air in & out as the hubs heat up & cool down in use. They were found to be unnecessary so were deleted on later caps.