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PB Brake BOOSTER ?
- Thread starter fonz
- Start date
Pete S.
Bronze Level Sponsor
Fonz, yes a properly working Girling brake booster does improve braking power and in my experience makes the car much more pleasant to operate. Unfortunately many boosters are poorly rebuild!
The typical stock routing of brake lines is the single line coming from the brake master running to the brake booster "in side" and then "out side" of the booster continues to the rest of the the braking system.
It is important to have the one way vacuum valve on the vacuum hose from the engine to the booster. And, make sure you use a 'vacuum' grade hose to supply the booster. A piece of fuel hose will not work as it will collapse and pinch the hose from engine vacuum.
When running a Girling booster, you'll also need to use Castrol DOT 4 brake fluid ONLY, per Girling spec. Flush the system and refill with fresh fluid annually as per the maintenance schedule from Rootes.
The typical stock routing of brake lines is the single line coming from the brake master running to the brake booster "in side" and then "out side" of the booster continues to the rest of the the braking system.
It is important to have the one way vacuum valve on the vacuum hose from the engine to the booster. And, make sure you use a 'vacuum' grade hose to supply the booster. A piece of fuel hose will not work as it will collapse and pinch the hose from engine vacuum.
When running a Girling booster, you'll also need to use Castrol DOT 4 brake fluid ONLY, per Girling spec. Flush the system and refill with fresh fluid annually as per the maintenance schedule from Rootes.
Barry
Diamond Level Sponsor
As long as the driver can comfortably exert enough pedal force to achieve maximum braking effort without a booster, then adding a remote vacuum operated brake booster will not increase braking effort. However, as Pete S noted, a booster can make the car much more pleasant to operate. Depending on the specific booster, the required pedal effort is typically reduced by about 50%.
Rebuilding a 50+ year old remote vacuum operated brake booster requires specific knowledge, equipment and parts and the results can still be "iffy." Originality is not an issue on a S-3 with a V8 engine, so I suggest that you purchase an operating booster; either a "good" used unit or a new aftermarket unit.
Note that something like 18" of vacuum at idle is needed for a vacuum operated brake booster to work properly. A "hot" camshaft with a lumpy idle may impress onlookers, but low idle vacuum is not a good combination with a vacuum operated brake booster.
Rebuilding a 50+ year old remote vacuum operated brake booster requires specific knowledge, equipment and parts and the results can still be "iffy." Originality is not an issue on a S-3 with a V8 engine, so I suggest that you purchase an operating booster; either a "good" used unit or a new aftermarket unit.
Note that something like 18" of vacuum at idle is needed for a vacuum operated brake booster to work properly. A "hot" camshaft with a lumpy idle may impress onlookers, but low idle vacuum is not a good combination with a vacuum operated brake booster.
Last edited:
Pete S.
Bronze Level Sponsor
Hello Barry. Yes, 18" of manifold vacuum is the minimum amount of vacuum needed to operate the Mk2A and Mk2B boosters per Girling. However, 20”Hg is the baseline vacuum for testing a brake booster per the Girling factory rebuild manual.
A properly rebuilt Girling is a perfectly good option. The trick obviously, is properly rebuilding it. Or having it properly rebuilt.
About 20 years ago I compiled a survey of people's experiences in rebuilding and having a brake company rebuild their servos. One company was by far the most highly regarded in my limited survey. PM me if you want the name.
A properly rebuilt Girling is a perfectly good option. The trick obviously, is properly rebuilding it. Or having it properly rebuilt.
About 20 years ago I compiled a survey of people's experiences in rebuilding and having a brake company rebuild their servos. One company was by far the most highly regarded in my limited survey. PM me if you want the name.