I'm doing a disc brake conversion on my '74 Scamp and I now need the booster/ master cylinder. Hw can I check a JY booster while I am at the JY? Do I need a vacuum pump and vac meter or is there a rule of thumb method to get me results? Thanks. BTW a new/reconditioned one is about $150 and a JY is between $45 and $65.

Thanks again.

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Sweet Emotion