328 Brakes | FerrariChat
Buy

328 Brakes

Discussion in '308/328' started by guysimpson, Apr 29, 2009.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. guysimpson

    guysimpson Rookie

    May 6, 2006
    17
    Los Gatos, CA
    Full Name:
    Guy Simpson
    #1 guysimpson, Apr 29, 2009
    OK I know I'm approaching forbidden territory here - and I have spent the last hour searching the archives - but I could use some guidance on the brakes of my 1988 328GTS.

    At the end of thoroughly enjoyable track day at Thunderhill, I noticed the brake pedal had become significantly softer. The brakes worked fine, but the pedal travel was way too much.

    Back at home I decided I would use this as an opportunity to replace the flexible lines with Goodrich SS items. These were much more of a pain to fit than I expected, but eventually everything went back together nice and tightly. I completely flushed the brake system since the fluid was two years old. I used ATE Super Blue to replace of the Motul 600, so I could tell when all the old stuff was gone. Using the traditional (helper) bleeding method, the pedal firmed up nicely as I worked my way twice around the car.

    Starting up the car for a test drive today the pedal was no better than before I started this exercise. Clearly I must have some kind of servo/booster problem, but can anyone help me narrow this down?

    Thanks in advance.
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,105
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #2 Rifledriver, Apr 29, 2009
    Last edited: Apr 29, 2009
    I have never seen a failed brake booster make the pedal softer. Their failure mode causes a harder pedal.

    The brake pedal mushyness at the track event was probably boiling fluid and not anything to do with the hoses. Once it boils it will often never come back to a good pedal on it's own. 2 year old fluid is too old for track use. I personally consider any fluid more than 6 months old to be too old. In all the track events I have been affiliated with fluid less than 12 months old is required and brand new fluid is suggested.

    Bottom line is you still have air in the system. Without the assist available from the booster the pedal will always feel harder.
     
  3. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    2,198
    Seattle, Washington
    Full Name:
    Cliff
    #3 CliffBeer, Apr 29, 2009
    Are you sure you don't have a MC leak? The traditional approach (open bleeder, pedal down, close bleeder, etc.) often creates a leak with the MC as the piston seals are forced past the usual areas of throw into new territory which can have a corroded surface and destroy the seal (better to use a pressure bleeder in my experience).

    Like Brian said above, you might still have air in the system. A pressure bleed isn't that expensive and well worth the investment - just an idea.
     
  4. hardtop

    hardtop F1 World Champ

    Jan 31, 2002
    11,294
    Colorado
    Full Name:
    Dave
    #4 hardtop, Apr 30, 2009
    +1. Two year old brake fluid regardless of brand should never get near a track.

    Dave
     
  5. guysimpson

    guysimpson Rookie

    May 6, 2006
    17
    Los Gatos, CA
    Full Name:
    Guy Simpson
    #5 guysimpson, Apr 30, 2009
    Great feedback!

    Suitable chastened about the age of my brake fluid, I checked my guess against service records. Turns out it was flushed in May 2008 and the track day was January 2009, so no where near as bad as I thought. I have never had this kind of dramatic brake drop out on any other track car, but I was certainly pushing harder that the last time I took the 328 to the track.

    I will definitely try pressure bleeding next. I think I have an Eazi-Bleed kit somewhere in the garage, hopefully with the right adaptor. Any special advice on this procedure?

    I still puzzled by the improvement I felt in the brake pedal with the engine off, compared with almost no change when the booster is active. I've never come across this phenomenon before.

    Thanks again.
     
  6. FasterIsBetter

    FasterIsBetter F1 Veteran

    Jul 22, 2004
    5,855
    NoNJ/Jupiter FL
    Full Name:
    Steve W.
    #6 FasterIsBetter, Apr 30, 2009
    Two other things to look at. First, did you check the wear on the pads. If they are seriously worn down, that can cause the brakes to go mushy on some cars. Also, if the rotors are warped at all, they can cause "knock back" where the rotors literaly knock the pads back, pushing the pistons back into the calipers. So when you hit the brakes, they feel mushy at first, but firm up when you tap the brakes a couple of times.

    As for pads, I like the Porterfield R4S pads. I used them on the 308 on the track and loved the performance. Also run great on the street. When the 328 is due for pads, will definitely get a set of those Porterfields.
     
  7. guysimpson

    guysimpson Rookie

    May 6, 2006
    17
    Los Gatos, CA
    Full Name:
    Guy Simpson
    #7 guysimpson, Apr 30, 2009
    I was expecting to replace the pads, but they still had plenty of material left. The rotors also seem fine although I'll put a runout dial on them when I take the wheels off for the pressure bleeding.
     
  8. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    2,198
    Seattle, Washington
    Full Name:
    Cliff
    #8 CliffBeer, May 1, 2009
    Guy, what you're experiencing there (harder pedal with the car turned off) is simply the normal effect of the booster - when the car is off there's no "boost" helping you so the pedal is quite stiff. With the car running the pedal should still come up hard (the booster won't compress the fluid!) at a point not too far down the travel but you have some air or some other problem so the booster is helping you move the pedal farther down it's travel.
     
  9. guysimpson

    guysimpson Rookie

    May 6, 2006
    17
    Los Gatos, CA
    Full Name:
    Guy Simpson
    #9 guysimpson, May 2, 2009
    Last edited: May 2, 2009
    Just finished pressure bleeding the brakes and it feels better, although not as firm as I'd like. Pedal travel is much less, but it still feels spongy as it starts to bite. A full road test will have to wait until the weather clears up here in the Santa Cruz Mountains. If I'm still not happy, I guess the next project will be to rebuild the master cylinder.

    Thanks again for all the great advice.
     
  10. MarkCollins

    MarkCollins F1 Rookie
    Owner

    Jul 2, 2002
    3,202
    South England
    Full Name:
    Mark Collins
    #10 MarkCollins, May 2, 2009
    Guy

    If it appears to be bled OK but you still have a pedal that feels a bit soft I would consider that the pads maybe glazed. take them out and rough up the surface then take the car out and bed them in, it may take 50 to 100 miles to get back to where it feels good again
     

Share This Page