Spring inside rotor vanes - what is it for?

[tshort]

Doing a rotor replacement on my ‘88 911. At 62xxx miles I believe I’m replacing the original rotors (I’m not first owner).

I noticed an odd looking wire spring inside the rotor vanes, straddling one of the vanes. There are two of these about 30 degrees apart. My new rotors (Zimmermans, same style) don’t have this spring thing. The brake hardware kits don’t show them - just pad pins and spring clips. Except for one on eBay I found, which does show the spring.

Anyone know what this is for? Should I pull them off the old rotors and put them on the new ones?

Thanks for any tips.

[Marc Bixen]

Those are brake wire retainer / cross pin retaining springs for a 944. Not for any 911.

[tshort]

Originally Posted by Marc Bixen

Those are brake wire retainer / cross pin retaining springs for a 944. Not for any 911.

OK - well maybe I've got the wrong part number. Regardless, there is something inside the rotor vanes on my original rotors.

Here are a couple pics of what I'm seeing, both from the inside view and the outside view of the rotor vanes.

[bkreigsr]

I always thought those were for rotational balance.
YMMV
Bill K

[dannobee]

Balance weights.

[Marc Bixen]

Yes, Balance weights, on most modern rotors they just machine material off to balance them, but that was the old method of balancing a rotor.

[tshort]

Great. Makes sense. Thanks!