Rear brake caliper contacting radius arm/watts link?

[KnifeySpoony]

 

I have a 420R with watts linkage and standard rear calipers. I noticed that there are witness marks on the forward watts link from the rear caliper on both sides. They appear to be relatively light scratches, not big gouges or dents, so it seems like the contact is light. Wondering if this is of any concern, or a case of TADTS.

[SM25T]

You can get a spacer to fit between the face of the DeDion ear and the hub carrier ... I used 5mm each side on mine.

[Richard Price]

How much static clearance do you have between the caliper and radius arm?

How worn are your brake pads? As the pads wear, the calipers move closer to the radius arms.

Are you running standard 1.5° dedion ears (the race 2° ears move the caliper closer to the radius arms).

[KnifeySpoony]

Ah... hadn't thought of that. I recently changed out the standard 1.5deg ear for a 2.0 ear. That would certainly account for it. I'd have to take out the damper to run the suspension through its travel to really assess static clearance. I know that there is a lot of side/side flex in the rear end under load. Given that it just seems to be grazing the watts arm, I guess it's safe to continue running like this, but I will consider a spacer under the dedion ear if need be. I trashed a set of wheel bearings disassembling the rear end to swap out the dedion ears, so I'm not super excited to go back again right away, as I'l probably have to replace them again. I'm in US and shipping from Caterham is $$$. 

[KnifeySpoony]

I checked and there's maybe 4mm of clearance between the caliper and watts arm at ride height. There a little bulge on the inside of the caliper that appears to be making contact. I've read that the Sierra calipers modified by Caterham to fit our application. I wonder if this is the interference that is corrected. That also makes me worry that it would be impossible to remove more metal from the caliper safely, otherwise wouldn't Caterham have removed more?