RM European Auto Parts
Results 1 to 12 of 12

Thread: Save or Toss - Brake piston diagnosis

  1. #1
    Join Date
    Mar 2006
    Location
    NJ
    Posts
    339
    My Cars
    1998 328is, 2006 330ci ZHP

    Save or Toss - Brake piston diagnosis

    Hi all,

    I'm working on my front suspension overhaul and just popped the pistons of my front calipers to inspect them after 220K miles in service. I've been told pitting / rust on the piston is bad, but I don't know how much rust would dictate I throw them out and get new calipers (since the pistons don't seem to be available separately).

    Attached is a pic of one of the pistons. The other has similar scarring. So what say you? Save or toss?
    Attached Images Attached Images

  2. #2
    Join Date
    Jun 2002
    Location
    Aberdeen, NC (yes, again)
    Posts
    23,673
    My Cars
    E39M5, E500 4WD
    Toss.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  3. #3
    Join Date
    Mar 2006
    Location
    NJ
    Posts
    339
    My Cars
    1998 328is, 2006 330ci ZHP
    Thanks Chris. I was hoping you'd reply.

  4. #4
    Join Date
    Nov 2010
    Location
    Houston, TX
    Posts
    2,630
    My Cars
    2003 BMW 540iA
    Get some rebuilt calipers, you can get them for under $50-100 a piece after core charge. www.rockauto.com is pretty good, however your local auto parts store might be cheaper overall since you wont have to pay to ship them back.

    Looks like the dust boots went bad on them, allowing the piston area past the fluid seal to rust out.

  5. #5
    Join Date
    Mar 2006
    Location
    NJ
    Posts
    339
    My Cars
    1998 328is, 2006 330ci ZHP
    Quote Originally Posted by ElleShooTiger View Post
    Get some rebuilt calipers, you can get them for under $50-100 a piece after core charge. www.rockauto.com is pretty good, however your local auto parts store might be cheaper overall since you wont have to pay to ship them back.

    Looks like the dust boots went bad on them, allowing the piston area past the fluid seal to rust out.
    I'm leery of cheap rebuilts because I can't guarantee the quality of the parts they use.

    The only options I see that I like are either BMW new ($285ea my cost) or ATE OEM (new) from Turner ($225ea). I'm leaning toward the ATE parts at the moment though my dealer has been able to give me some pretty amazing deals lately because sales are down and they seem to be looking for business.

    As for the piston damage, the boots looked intact, but I didn't do a really close inspection of them. It's entirely possible they were compromised.

    By the way, does anyone know if it is safe (from a clearances perspective) to powdercoat the caliper brackets? My concern is that too much (or any) paint on the surface where the ears of the pads ride might cause them to bind. Just curious if anyone has done that before.

  6. #6
    Join Date
    Dec 2004
    Location
    Huntsville, AL
    Posts
    25,923
    My Cars
    87 325is
    As Chris said, those pistons are done for. They make pretty decent paper weights.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  7. #7
    Join Date
    Mar 2006
    Location
    NJ
    Posts
    339
    My Cars
    1998 328is, 2006 330ci ZHP
    Quote Originally Posted by thejlevie View Post
    As Chris said, those pistons are done for. They make pretty decent paper weights.
    Thanks Jim. Good to hear from the heavy hitters around here.

  8. #8
    Join Date
    Jun 2002
    Location
    Aberdeen, NC (yes, again)
    Posts
    23,673
    My Cars
    E39M5, E500 4WD
    I agree with new calipers, rather than a local, questionable rebuild.

    I doubt you'd have any problems with a powdercoat, but you're right to question it. A few years ago, I routinely had to grind the paint off the ends of Akebono brake pads to make them fit correctly (they seem to have fixed that issue since) But that leads to your solution, too: if the pads are tight after powdercoating the brackets, a light filing should fix the issue. In fact, why not consider just sanding the powdercoat off of the contact areas when you're done, leaving a nice clean shiny metal surface for your antiseize?

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  9. #9
    Join Date
    Mar 2006
    Location
    NJ
    Posts
    339
    My Cars
    1998 328is, 2006 330ci ZHP
    Quote Originally Posted by bmwdirtracer View Post
    I doubt you'd have any problems with a powdercoat, but you're right to question it. A few years ago, I routinely had to grind the paint off the ends of Akebono brake pads to make them fit correctly (they seem to have fixed that issue since) But that leads to your solution, too: if the pads are tight after powdercoating the brackets, a light filing should fix the issue. In fact, why not consider just sanding the powdercoat off of the contact areas when you're done, leaving a nice clean shiny metal surface for your antiseize?
    I think I can have the powdercoater sandblast the entire part and then mask off the contact areas. Not sure yet...have to talk to him. Worst case is he just paints the whole thing and I do what you suggest and sand off the contact areas. Thanks for the tip.

  10. #10
    Join Date
    Jun 2008
    Location
    Nashville, TN
    Posts
    1,460
    My Cars
    '95 M3,'04 ZHP, 01 330Ci
    Bimmerworld sells stainless steel piston and rebuild kits. It's all direct fitment and far less expensive than a "new" caliper.

  11. #11
    Join Date
    Mar 2006
    Location
    NJ
    Posts
    339
    My Cars
    1998 328is, 2006 330ci ZHP
    Quote Originally Posted by 284Shooter View Post
    Bimmerworld sells stainless steel piston and rebuild kits. It's all direct fitment and far less expensive than a "new" caliper.
    You got my hopes up there for a second but the bimmerworld site appears to show these are for M3's or E30 non M only. Rats.

  12. #12
    Join Date
    Dec 2003
    Location
    Maryland
    Posts
    1,141
    My Cars
    Avus e30(sold), '95 Avus
    I replaced a caliper a few weeks ago on an e36 M. Rebuilt from Turner $50 +core
    Level 1 Certified BMW Technician

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •