It looks like you have the dust cap for EZ-Lube hubs on your Scamp
. There is a rubber plug in the end that is removable for injecting grease into the end of the spindle. The grease comes out at the inside wheel bearing. I have EZ-Lube spindles on my Flexiride axle
with the same cap.
I recently found a source of hub caps that fit these 4-lug early Scamp
wheels and it kind of shocked me that they are made for one of the oldest aftermarket automotive companies around.
The center cap for Cragar smoothy wheels fits perfectly. I put mine on over the EZ-Lube cap. They seem to clear the EZ-Lube cap although they didn't seat against the rim all the way around. The hub caps have been on for several thousands miles.
Today I repacked the bearings and put standard dust caps on instead of the EZ-Lub cap so I could get a little more clearance for the hub caps. I haven't put the Cragar hub cap on yet. I will probably tow the trailer for at least 50 miles and recheck the lug nut torque before I put them on.
I bought my Cragar center caps from Summit Racing. It was on the Jeg's web site that I found correct pictures of the caps with the critical dimension. The Cragar part number for these is 29113. Here are links to both web sites:
Cragar 29113 Cragar Wheel Center Caps
The picture of the cap on the Summit web page is not the correct one. The picture on the Jegs web site is the correct one.
I've be wanting to post pictures of them on my wheels. If I get a chance in the next day or two I will. Otherwise, I will be off camping and will do it at a later date.