Rear hub bearing

[vee eight]

Hi All,
Has anybody had a problem with the metal cap that goes into the hole in the rear hub where you grease the rear wheel bearing. Last year I noticed it was missing and replaced it with a new one. It fitted in quite tightly but I have just come to grease the bearings and it is missing again. Any ideas?
Is there any pressure build up that is pushing it out or any other reasons?
This is a series1 4.2.

Thanks Phil

[christopher storey]

Phil : you have identified the problem .If too much grease is pumped in there is insufficient airspace left and when it heats up it blows the cap off. I always drill a small ( 1.5 or 2 mm ) hole in the cap which helps to reduce the chance of this happening . I believe the original caps had such a hole, but modern replacements often do not

[Simonpfhc]

I recently ordered a pair from SNG and they arrived with holes in ;-)

Cheers.

[vee eight]

Thanks Christopher & Simon.
Mine did not have a hole in the top and that must be why they have been ejected from the hub.
Going to order some new ones and get out my 2 mm drill if the do not have a hole in the top.

Cheers Phil