Brake Components
Short answer: The brake-system valves explained:
- Metering valve — the round cylinder next to the master cylinder; holds back front-disc pressure so the rear drums make full contact first. All 1969–70 GM disc cars have it.
- Proportioning valve — a small square inline valve under the driver’s seat (on 1969 ‘birds, on the left subframe rail) in the rear-brake line; slightly reduces rear braking on nose-heavy cars. Not all 1969–70 GM cars had it (V8/AC cars did).
- Distribution block / warning-lamp switch — all 1967+ dual systems (including 4-wheel drum) have it; the two lines from the master become three out (one rear, one to each front wheel).
- Combination valve — from 1971, GM combined the distribution block, warning switch, metering, and proportioning valves into one unit (mounted on the frame, hard to see).
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Content last modified: June 13, 2026 at 10:06 am
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