Advice on brake bleeding?

Discussion in 'Old's Cool' started by svejkovat, Sep 29, 2012.

  1. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    1982 R65 has been in storage. Single disc in front w/Brembo caliper. Rode it a couple of times last year. Couple of times this year. That's about it.

    I know, don't yell.. I've neglected to replace the brake fluid in many years. When I brought it up out of the basement this year the level was fine but the lever was spongy. Got worse. Decided to flush with new fluid and bleed.

    Took off cap of reservoir, drained what was in, put in fresh, and started the bleed routine. Lever just got spongier. The harder I tried the less pressure I sensed and finally just offered no resistance whatsoever. I'm doing the bleed procedure correctly according to my experience in the past and a refresher look here..
    http://www.bmwmotorcycletech.info/brakes.htm

    Question then. Shouldn't the lever actuated piston/plunger develop pressure regardless of what may be amiss downstream? There is no fluid leakage evident downstream whatsoever. The tiny feeder hole at the base of the reservoir is visually unclogged and I can see the piston moving back and forth beneath it.

    Is this evidently (certainly?) a completely blown seal on that plunger? Or could it be something else? Reason I ask is that the plunger only has about five years on it since new replacement and has only seen about 12,000 miles of use (mostly highway at that). I'm hesitant to inspect it since that commonly abrades the seal lip yanking it out of an old corroded barrel. I'd rather not replace it unnecessarily.

    Thanks for any advice.
    #1
  2. baloneyskin daddy

    baloneyskin daddy bikaholic

    Joined:
    Oct 21, 2009
    Oddometer:
    2,177
    Location:
    southcentral PA.
    Take the banjo bolt out of the mastercylinder and plug the opening with your finger and with barely a pump of the lever you should feel enough pressure to easily push your finger away. If you can find a matching thread ,block the hole off and then pull the lever while cracking the bolt to bleed out any air and it should get stiff as a rock. If not the fluid is bypassing the plunger.Sort of like bench bleeding the master cyl.
    #2
  3. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    By banjo bolt are you referring to the bleed fitting? I've already loosened and tightened that while pumping the lever.... to no avail. Are you suggesting by removing it an plugging the hole that the bolt itself may be faulty? I don't see how that is possible.

    I will try your suggestion, but with no evident fluid leaks anywhere at the disc or caliper or hose, I'm already fully "blocked" at that banjo bolt when it's seated...no? If the seat of the bolt were faulty the fluid would have leaked out of it long ago.

    That's what I've been doing with the bleed screw/bolt per instructions. No fluid emerges and no pressure builds at the lever.

    Or are you referring to the the line-in? Mine is hard plumbed instead of swiveling banjo bolt. Don't know if that's common OEM but that's what I've got.
    [​IMG]



    [​IMG]
    #3
  4. mark1305

    mark1305 Old Enough To Know Better

    Joined:
    Feb 7, 2005
    Oddometer:
    6,124
    Location:
    Merritt Island, FL
    Not necessarilly. Air can hide in many parts of the system downstream from the M/C. The advice to plug the M/C outlet with either finger or bolt is sound, because if the piston seal has failed already you will have isolated the problem to the M/C.

    If the M/C passes the pressure test, and conventional bleeding just doesn't work, try to position the bike so that the entire brake line from the caliper up to the M/C is all uphill. pull the brake lever in halfway and tie it off that way. Leave it overnight, and with luck any air bubbles will float up and out through the reservoir. Yes it works, as long as the line can be made all uphill with no reverse downhill turns.
    #4
  5. baloneyskin daddy

    baloneyskin daddy bikaholic

    Joined:
    Oct 21, 2009
    Oddometer:
    2,177
    Location:
    southcentral PA.
    I said the master cyl ,you're down at the caliper. By disconnecting the line and plugging the outlet you can test the master cyl to see if it is bad. The banjo bolt is the bolt that is drilled to allow the fluid to pass through it to the caliper.
    #5
  6. mike in idaho

    mike in idaho Been here awhile

    Joined:
    Aug 14, 2011
    Oddometer:
    132
    There should be two holes there, the second one will be very small.
    #6
  7. anonny

    anonny What could go wrong?

    Joined:
    Mar 20, 2007
    Oddometer:
    5,776
    Location:
    Beautiful Revelstoke BC
    Get a BIG syringe with a hose that fits it and the bleeder screw, fill with brake fluid. Loosen bleed screw and push new fluid up from the bottom, tighten bleed screw..... done.
    #7
  8. Claytonroy

    Claytonroy Been here awhile

    Joined:
    Jan 25, 2006
    Oddometer:
    288
    Location:
    Oregon
    All good advice, but since it's a 30 year old motorcycle, the Brembo caliper is ready for a rebuild. Probably the M/C as well...and upgrade to a SS brake line if you haven't already.

    Why not? Two finger modulation is better than a four finger lever-to-the-grip fade :p3rry

    I believe there is a step by step article on refreshing the Brembo single puck commonly used on BMW's. Search the web and you'll find it.
    #8
  9. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    Any confirmation on this? There are two holes, but..... looking at my master cyl from this perspective,
    [​IMG]
    ... with the cup/reservoir removed, there is an approx 5/8 round hole where the cup and oring press into it.
    Looks (very roughly) like this.....
    [​IMG]

    At the bottom of the large hole are two approx 2 to 3 mm OD identically sized holes (going by memory). The left one leads to the master cylinder plunger, the one to its right is dead ended. Tried inspecting it with a dental pic. It is dead ended. Did I not inspect hard enough? (I'll run out the garage right now and look again)

    Found this on the net...

    Sound about right?
    #9
  10. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    What a damn drag. Went to Walgreens and the biggest syringe they had was 3cc. Sunday today so the orthopedic supply at the hospital is closed. Went to Meijer's (local equiv of Walmart) and got a "seasoning and marinade" injector for $4.50.

    Looked well built. Got it home and put a foot of poly tubing on the end of the steel needle and over the flare of my bleeder bolt. Opened the MC reservoir and siphoned off the contents.

    Dipped the bleeder bolt in the DOT4 and withdrew two full ounces of fluid. Inverted it and bled off the air while tapping the syringe.... ER style. So far so promising.

    As I walked over to the bike to start screwing the bolt into the caliper body the fu@ing syringe started melting before my eyes. The inside of the clear plastic first started turning frosty and then the seals on the needle and top just disintegrated spooging brake fluid all over my hands and floor. All in about 30 seconds! I couldn't even unscrew the top over a rag in the waste can as the black plastic top just started to crumble!!!! Wow.

    This shit is nastier than I thought. I was really hoping that I could switch over to silicone dot 5 while I was at this just for the sake of peace of mind since a little of this fluid inevitably ends up on the master cylinder body, caliper body, and even a little slung onto my powder coated snowflakes over time... no matter how diligent or careful I am since a bit of it eventually finds its way past seals, fittings, and hoses. But all the reading here and at other forums discouraged me from switching over.

    AAAAAARRRRRGGGGHHHH!!!!! Just wrapped it all in the rag and shoved it in the waste can.
    Don't bother with this type of syringe....
    [​IMG]
    "Grand Gourmet" or "Mr. Barbeque" brand. But they're probably all similarly made.
    Shame too since the plastic looks pretty robust, there are soft plastic seals/seats on the needle and top, double orings on the plunger, and the needle is a fairly heavy gauge chrome plated brass (i polished the face where it met the seal for a perfect fit and it was brass underneath).

    Too irritating to do more tonight. I'll have to check the hospital supply tomorrow.

    Sometimes I just miss wire spokes and drum brakes for god's sake.
    #10
  11. squish

    squish Out of the office.

    Joined:
    Dec 4, 2003
    Oddometer:
    6,505
    Location:
    Where the Ghetto meets the sea.
    Nope, not unless you want to put new seals in the whole system and a Dot five compatible master cylinder and lines.

    I suspect that your brake lines are going away from the inside out.

    I'd suggest rebuilding the master cylinder and caliper and replacing the brake lines, You might be able to find a new caliper which I found was going to be cheaper then rebuilding my calipers that needed new pistons
    Between the cost of parts and the labor (I figure my labor into working on my personal bikes, since it's what I do)
    It was cheaper to pay 108 bucks for a new caliper then 120 bucks for the seals, pins, pistons and new bleed fittings that my old caliper needed. Turned out that these were like the last few new ones floating around. I don't know if that's still the case but look around, you might find one cheaper.

    Also you can upgrade the caliper using some of the kits sold, or roll your own. If your master cylinder is shot, this might be a perfect time to modernize your brakes, it's amazing what modern caliper and master cylinders do to the feelings of brakes on these bikes.
    #11
  12. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    108 dollars for a new replacement caliper for this? Sound great.

    I'll have to look around. For the time being I'm going to give it one more try tomorrow with a different syringe and try to get a few more years out of what's here.

    Thanks for all the help here.
    #12
  13. victor441

    victor441 Long timer

    Joined:
    Jul 27, 2009
    Oddometer:
    1,071
    Location:
    Sonoma, Calif.
    sometimes a vacuum bleeder does the trick if you are having a hard time getting all the air out...this one is easy to find and not too expensive

    [​IMG]
    #13
  14. H96669

    H96669 A proud pragmatist.

    Joined:
    Nov 20, 2009
    Oddometer:
    4,750
    Location:
    Hiding off Hwy 6, B.C.
    Big Syringues at Wal-Mart, just around the fuel cans & accessories. Called a Mixmizer (?), used to mix small quantities of premix gas. About $5.00.
    #14
  15. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    I'll check out those walmart syringes. I like the idea of pressure feeding bottom up.

    Since some have weighed in here let me ask a question that I've not seen addressed in any of the comparisons or tutorials.

    I realize the bleeder screw is situated in the caliper body at the very top of the cavity, but there is also a couple of feet of hose leading upward to the master cylinder body. Everyone obsesses over getting all the bubbles out. Of the half dozen or so optional methods why wouldn't pressure feeding from the bottom (caliper bleeder screw) be by far the best one? Seems like the only one that pretty much guaranteed to purge bubbles as you fill/bleed.
    #15
  16. mark1305

    mark1305 Old Enough To Know Better

    Joined:
    Feb 7, 2005
    Oddometer:
    6,124
    Location:
    Merritt Island, FL
    Logically and theoretically pressure feeding from the bottom is the best method.

    The only real drawback is possibly overfilling the reservoir and spilling brake fluid all over painted parts.

    Have a helper watching the M/C reservoir to tell you when to stop pushing fluid. :deal
    #16
  17. mike in idaho

    mike in idaho Been here awhile

    Joined:
    Aug 14, 2011
    Oddometer:
    132
    When you finally get fed up with trying to bleed this thing, take it apart and clean out both holes in the bottom of the reservoir (there are TWO holes there, one is very small).
    #17
  18. Lomax

    Lomax Nanu-Nanu Adventurer

    Joined:
    Jul 15, 2004
    Oddometer:
    9,459
    Location:
    Westminster Colorado
    My bouts with Airhead brake bleeding. :lol3

    First, the syringe method and push fluid up from the slave cyl. Uh make sure you keep emptying the master cyl. :evil

    Another thing you can do for an initial bleeding is to take the slave cyl off, block it so the pads will not come out, hold it ABOVE the master cyl with the bleeder valve on top. Pump and bleed like normal. The idea is that the air will rise up and out the bleeder screw.

    What has actually worked for me is the vacume bleeder. It gets frustrating but works. The last one I did was on a dual disk front end. I just kept at it giving it a rest from time to time and after two days had great brakes. :lol3

    Marc
    #18
  19. svejkovat

    svejkovat Been here awhile

    Joined:
    Jun 23, 2009
    Oddometer:
    856
    Thank you mike in idaho. Too bad you weren't with me in the garage when I started this odyssey so that you could have applied your advice with a hammer... to my head.

    You mentioned two holes. I checked. Indeed, as I pointed out, with graphics, there was only one. You said the other was "tiny". I looked and probed again. Nope, just a blank recess in the right hand hole. I poked around with a pick. Nothing.

    So I kept on posting questions, scratching my head, and contemplating full rebuilds and expensive bleeding tools. I reread the hyper fas-tedium of these pages again...www.bmwmotorcycletech.info/brakes.htm

    Ok, ok. Just to satisfy your nagging I had another look. Nope, no "small" hole. Wait a sec. WTF? At the bottom of that 5mm recess is a hole approx 0.40mm small. 0.40 mm??? I never would have found it on second look If I hadn't been poking around with sewing needle this time. Well of COURSE it's clogged! For Christ's sake why wouldn't it be? And why WOULDN'T (he deserves this abuse of caps by the way) Mr. R Fleischer .esq have seen fit to mention this little tidbit EVEN ONCE in his exhausting anal-ysis of BMW brakes?
    http://www.bmwmotorcycletech.info/brakes.htm

    Thanks again mike in idaho. I chased out the hole with the finest wire I could find and up from the hole came a-bubblin' air. The brakes bled just fine after that via the conventional two handed method that's worked well in the past. All the components in this system are original (save the master plunger) so I'm just going to wait on a teardown/rebuild since it appears to be working like new right now.
    #19
  20. mark1305

    mark1305 Old Enough To Know Better

    Joined:
    Feb 7, 2005
    Oddometer:
    6,124
    Location:
    Merritt Island, FL
    Here's a tip for after the fact that helps with any tiny tiny clogged openings in carbs, brakes, whatever. Pick up a welding tip cleaning tool as used on oxy-acetylene torches. It has wire probes covering a huge range of very small diameters and they are designed so that if the tip of the wire probe fits in a hole, the rough part will clean out the hole without reaming it larger.

    Inexpensive and found at any welding supply shop.
    #20