Isabell Grand Tourer wrote:
No known replacement for GT, Here in Aus we can adapt rotors from Magna to sedan hub and use Magna calipers.
You can do a Google search and find someone who made reproductions of the original brake rotors. A reluctant offer of ~$1050 USD for a pair was mentioned.
You can buy iron and have them cut on a lathe, and it might cost $900+ for the parts and machine labor, and you will have spent at least the difference in the above option in the labor of doing the mechanical drawing and supervising the machinist.
The next problem will be the calipers, because there are no OEM rebuild kits or parts.
Several from Australia have mentioned modifying the original calipers to accept Jaguar(?) or some other brand of seals, having custom pistons made, and breaking the center guide pin out of the back of the caliper bodies.
The US Datsun Roadster expert who is the only one on the continent offering rebuild service for the Datsuns, which use the next size smaller of the same type caliper, says that if you break the pin out of the back of the caliper body, you should throw it away.
The brake hoses have a unique thread pattern on the chassis end, which has not been mass produced, so swapping in a different caliper is a problem, or involves either re piping the car or finding the only guy who had the brake hose fittings custom made. (Same Google search mentioned above).
Several from Australia suggested using Mitsubishi Sigma brake rotors and calipers. That car was not sold in the US. And much of the brake swap information appears to be based on drum-to-disk conversion, and the GT spindle and hub are not the same as the drum brake spindle and hub. The Magna mentioned in the quote is was not sold in the US, and the example cites the drum brake hub.
The Japanese say they just use hakosuka brakes. Another vehicle not sold in the US.
And, further investigation of the hakosuka brakes: The Nissan MK63 calipers cost well over $500 each and the only rebuild kits for the calipers are in Japan, and cost many hundreds of dollars.