Brake Proportioning Valve? I've keep hearing people recommending swapping out the brake proportioning valve when doing a drum to disc conversion. I recently spoke to a guy who recently did a rear disc swap on his 95 celica and he claims that toyota told him both the rear disc and drum models had the same parts no. for BMC and proportioning valve. One of the reason I downloaded a Toyota EPC (Electronic Parts Catalogue) were to check that fact and sure enough it checks out. And not only that, the 93-97 corolla also has that same parts no. for the valve as well as the 88-92 models.. I've been told that when using a gauge to check brake pressure on a disc brake ae92 corolla vs. drum brake model the pressure on the drum models were significantly higher... Am I missing something here?