Brake Booster Circuit | FerrariChat

Brake Booster Circuit

Discussion in '365 GT4 2+2/400/412' started by SouthJersey400i, Mar 9, 2013.

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  1. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,679
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    Can someone explain how the brake booster vacuum circuit works? Here is what I know: There is a vacuum pump driven off the front of the motor. Hose goes to booster at a 'T'. Hose extends to intake circuit of driver's side bank of motor with a check valve in the line pointing to the motor (away from the booster).

    So what supplies the vacuum to the booster? The pump, the motor or whichever one wins?

    My check valve seems sticky, it takes a pretty good blow or suck to open it. I sprayed some light lube in it but it is still not opening easily in the flow direction. It appears this check valve is NLA at the usual houses. Does anyone know a generic replacement part? I might just try NAPA.

    My issue driving is that at idle I have no boost at all and have to stand on the brake pedal to keep from rolling. Otherwise, brakes are good.
    Ken
     
  2. jacques

    jacques Formula Junior

    May 23, 2006
    877
    Los Angeles/Florida
    Jegs .com has everything you need. JQ.
     
  3. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,679
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    I did a pretty through search of JEGS and came up empty handed. They had lots of check valves for fuel systems. The ones for brake boosters fit right into the booster which is not the function on our cars. Good site though.
    Ken
     
  4. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,679
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    I went to my favorite supplier for house and cars: McMaster-Carr. I ordered two parts. Catalog item 7933K35 looks he part in PVC but the crack pressure is too high. Catalog item 4610K17 looks like a winner and for $3.58 it is going to get a try. Crack pressure is negliglibe; it opens "by mouth". It is made of polyethylene which is resistant to fuel vapor and it is made for vacuum service.

    I'll give it a try this weekend.
    Ken
     
  5. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,679
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    Price of the selected part is $12.28, breaks the bank.
    Ken
     
  6. rustytractor

    rustytractor Formula 3

    Mar 25, 2012
    1,078
    London
    Full Name:
    Russell Schacter
    We could all club together and arrange a fund raiser if it helps.
     
  7. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,099
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #7 Rifledriver, Mar 12, 2013
    Last edited: Mar 12, 2013
    CS check valve. Cheap and fits the hose correctly. Under $10.00


    Fixing it right without hardware store parts can be cheaper and keep future buyers from thinking you were nickel and diming your car.


    Engine does not make enough manifold vacuum under all conditions for the brakes so it has a vacuum pump as well. Not really all that uncommon on diesels, multi carb and CIS cars.
     

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