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Brake/servo issue on 328

Discussion in 'Technical Q&A' started by gts328uk, Feb 24, 2004.

  1. gts328uk

    gts328uk Karting

    Nov 26, 2003
    122
    Yorkshire, UK
    Full Name:
    Mark
    I have noticed recently that when I start her from cold after a few days lay up in the garage the brake peddle is rock hard (very little retardation) as I come off the drive but by the time I press the peddle again, say in 100 yds its perfect. I took her out yesterday and the same thing happened again except this time it carried on for at least 5 or 6 stomps on the peddle with very little retardation. The 7th time I hit peddle expecting no bite it was perfect with the resultant lock up of the fronts.

    The car is an 87 328 with no ABS.

    I have had this before on rally cars and it is usually associated with either a faulty servo or servo vacuum pipe. What I cannot understand here is why it only happens on initial start from cold. On all other occasions its perfect. Any ideas before I call the dealer.

    I have posted this also on the technical section of the forum.

    Thanks

    Mark
     
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  3. DGS

    DGS Four Time F1 World Champ
    Rossa Subscribed

    May 27, 2003
    44,416
    MidTN
    Full Name:
    DGS
    Have you checked the "check valve" in the servo vacuum feed?

    (It's mounted on the vac line near the manifold plenum, in the engine bay, on this side of the pond. Far as I can tell from the parts catalog, it's the same on the RHD versions.)

    If the check valve is leaking, you'd be losing all your servo vacuum during shutdown.
     
  4. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,388
    USA
    I had similar symptons a couple years ago, the "check valve" mentioned by DGS, was replaced and all was well.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    21,168
    Texas
    Full Name:
    Steve Magnusson
    Same here -- bad check valve (but I think the problem isn't leaking, it's the internal shuttle of the valve sticking on its seat so no vacuum is developed inside the booster chamber until you eventually jar it loose). Very unpleasant in a 2-ton TR lumbering around a tight parking lot/driveway.
     

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