Front Rotor Balance Weight

[britannic]

I had a problem with out of balance front wheels above 65mph. It was low priority until recently, now I'm doing more freeway driving. No amount of trips to the tire shop for balancing did the trick. So I decided to get in and check for other causes.

I found a special rotor balance weight in the vent of the left hand rotor (the lhs was where I reckoned the out of balance problem was), there wasn't one in the rhs rotor. I removed it and the problem went away.

I've never seen one of these weights before, has anyone else come across one and know why it was fitted?

[britannic]

Since this is an ex-Army and National Parks Service truck, I guess it would have had the rotors replaced by now (they have plenty of meat on them), since I estimate the mileage to be between 150,000-350,000 based on the odometer and timing chain wear (see my earlier posts on just how slack that chain was!).

[Dieselboy]

I noticed some weights on the inside of my original 8 lug 10 bolt rotors, but never drove on them since they were trashed by the time they came my way.

When I replaced them with after-market Wagner rotors, I saw there were no weights. No vibrations over the last four years and 30,000 miles.