This is the big draw back with the wilwood caliper, they have no dust seals, I am not sure if it is a legal issue or more of a wear out factor, without dust seals you will be replacing pistons way sooner than other calipers.
The caliper I am using is from the Brake up grade pack for the Australian Built GTO. Some companies have marketed them in Australia as upgrades for the Commodore. I bet they didn't disclose that they are actually illegal!!!!
Yes, definitely an after rego addition if using Wilwood. I know of a kit car manuafacturer that supplied Wilwood calipers as there upgrade and car were registered with these calipers
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When I was looking for brake bits DBA had some 4 piston Brembo calipers going real cheap, they were part of a brake upgrade kit that didn,t sell real well. I am not sure if they are lug mount or radial mount but they would fit a 330 x 28 rotor.
Phil