Potomac-Greg

It could just be that the cap does not pop in firmly enough. But is there anything else that could be causing it to pop out?

It only comes out after track use, suggesting that the heating of the hub expands it enough to allow the cap to work loose. I can't imagine that any positive pressure could be developing.

Thoughts? Should I just whack the cap a bit out of round so it gets a better bite on the lip?

Bri Bro

This should fix the problem unless you have water in your hub grease. Cheap, $20.
http://www.paragon-products.com/prod...7.405.692c.htm

KuHL 951

In tried a search with no luck. Someone posted this exact problem about 18 months ago. I would just flare the flange a bit and see if it keeps doing it.

schwank

Drill it and add safety wire?

931guru

Too much grease in the hub. It expands and hydraulics the cap off.

Potomac-Greg

It doesn't go anywhere (the cap is bigger than the hole in the center of the wheel). It DID cost me a center cap though! If anyone finds a center cap at NJMP/Thunderbolt, it's mine!!!

schwank

Doh. I run no center caps.

Chipster

Had the same problem - a friend recommended that I drill a very small hole in the center of the cap (as his race shop did on his car). Works great.

knfeparty

One of mine does this too. Ditto on the heat causes the grease to expand and pop it off. Sometimes air gets caught in it and it makes an awesome farting sound.

You can definitely just flange it out some (hammer I guess) and it should stay better or just be careful about how and how much grease you put in.

Definitely don't run center caps on track!

M758

You don't need center caps on the wheels, but do need to run grease caps on the hubs. You don't want to get crap in grease as it will take the bearings out.

Lemming

I use metal duct tape to keep them on.

schwank

That's what I meant Joe! I certainly run the grease caps...