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Maxim X Can't get Caliper Pistons to go back

Discussion in 'XJ Technical Chat' started by ryancdossey, Oct 7, 2012.

  1. ryancdossey

    ryancdossey Member

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    I have the pads out and it pretty clean but now I can't get the caliper pistons to go back in to where I can fit the new pads in. I've tried by hand and with a c clamp no luck... what gives? How do I do this?



    Also on the rear brake... Got a center stand to work. Tire off the ground... But I can't get the axle bolt to come off. Its on the left hand of the bike right through the center of the wheel. I tried penetrating oil even soaked it over night. From my manual looks like it should unscrew and come right off. Am I doing this wrong?
     
  2. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Caliper... Sounds like your caliper O-ring needs to be replaced.

    Axle ... Make sure your pinchbolt is still tight on the right side of the swing arm. You can not remove the nutif that is loose. Also make sure that the castle nut cotter pin is out. Once the nut it off, then you loosen the pinchbolt and work the axle out on the right side of the arm.
     
  3. tskaz

    tskaz Active Member

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    Caliper - also make sure you use fresh clean brake fluid to lube the piston after installing a new seal, and tap it into place evenly. Doesn't take much to get it off center and get it stuck.
     
  4. ryancdossey

    ryancdossey Member

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    I have no clue how to do that.... They were working fine before I took them off just squeaky pads. Is it possible I just don't know how to push them back in?

    any pdf as to how one goes about replacing the seal?
     
  5. maximike

    maximike Member

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    I don't think he had the piston all the way out. I think he just changed pads, so now needs to push the piston back to get a little more clearance, right?

    It's possible that your pressure relief hole in the master cylinder is clogged, if that were the case the piston might not want to be pushed back. There's a tiny hole in the bottom of the master, take a look at that.

    Axle- Like the man said, make sure the cotter pin is out of the castellated nut that holds on the axle. Now, keeping the pinch bolts tight is the right way, but I had a thought on a wrong way to do it.

    If you look at the axle, you'll notice that the right hand side has a hole cross-wise through it. This is to place something like a screw-driver through and hold it still while you tighten or loosen the nut on the other side. You could *loosen* the pinch bolts on both sides, make sure the cotter pin is out of the nut on the left side, and spin the axle from the right side with a screw-driver through that hole in the axle until the nut drops off the other side. Attempt at your own risk :p
     
  6. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    But they weren't "working fine."

    You had "squeaky pads" because the caliper piston(s) were hanging up, causing the brake to drag.

    The seals are simply square-section rubber rings that sit in channels in the caliper bores. To replace them, you DISASSEMBLE the caliper; thoroughly CLEAN the channels they sit in, and install new ones. THEN you re-install the pistons that you've carefully cleaned, polished, and inspected for pitting.

    Just changing the pads won't fix squeaky brakes. You need to do the whole job.
     
  7. ryancdossey

    ryancdossey Member

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    My brakes were squeaking because the pads were too worn. I believe I thought it was just a simple swap of the pads.
     
  8. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    There is more to 30 year old brakes than just changing the pads.
     
  9. ryancdossey

    ryancdossey Member

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    Bummed :( was hoping for this not to set me out for long.... Is there a thread on that? Or a pdf write up?
     
  10. maximike

    maximike Member

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    There's lots of threads. I would suggest that squeaking brakes is neither here nor there, you can get rid of squeaks with some disc brake quiet on the back of the pads. But fitz is right, when I took my caliper apart there were seals MISSING. So rebuilding (by which we mean pulling the piston out, examining it for scoring, replacing seals and cleaning channels seals sit in and lubing and cleaning the sliding pins the caliper rides on) is in order.

    I didn't mention it before because you were just talking about pads and I don't get into what you *should* do as a general rule, just what you actually ARE doing. But having said that, you should, for your safety, do the COMPLETE brake job, including lines, that bigfitz is talking about. Here I go, proselytizing, I said I wouldn't do that;)
     
  11. ryancdossey

    ryancdossey Member

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    Its alright guys I just decided to do the whole damn thing and do it right. Even though I want to ride and its been a pain.... Anything different on the maxim x brakes as opposed to normal?
     
  12. ryancdossey

    ryancdossey Member

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    can someone post a link for caliper rebuild and brake line replacement?

    Do i just unbolt the lines from the calipers and let them drip out in a bottle? Then undo the other ones and do the same? Let the mc drain all out. Put new ones on and put new fluid in?


    How do I separate the caliper?
     
  13. maximike

    maximike Member

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    The problem is that these bikes use a lot of different brakes. There's no one write-up, but it's fairly straight forward, but not necessarily easy.

    I don't know anything about "X" bikes. Just like you said for lines, you might want to put new "crush washers" in as well, the copper ones where the banjo bolts attach.

    Enter "brake caliper" in the forum search box and "bigfitz52" under author. I think you'll find some info on general re-building of calipers.

    Edit: here's one thread with some pics of seal channels and piston: http://xjbikes.com/Forums/viewtopic/t=3 ... liper.html
     
  14. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    This is why I've never done one. I only own two of the myriad of different styles of XJ calipers out there; but the principles are the same.
     
  15. ryancdossey

    ryancdossey Member

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    Okay guys so.... I unbolted the brake lines from the calipers, then the center connection, then the master cylinder. Let them drip out. Master cylinder is empty all the OLD lines are now removed.

    I have my calipers they are still together... I see two bolts do I take those out to get the caliper open and just start cleaning? I've read that the pistons need to be forced out some how? If I just undo them completely shouldn't they just slide out? The master cylinder and the other "ports" are covered in bags to prevent dust or moisture from getting in. The bike is in an insulated garage.
     
  16. maximike

    maximike Member

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    I think you are referring to the sliding pins that the caliper travels on when you say "piston" The actual piston won't just slide out, I wish. The piston is the thing that the fluid pushes out that pushes the brake pad out, and against the rotor. To get that out, and do the all-important cleaning of the seal channels, the recommended technique is a grease gun. Or compressed air, be careful. The sliding pins just need a little cleaning up, maybe some honing, and lubing. But they don't come off, per se, you just pull the travelling part of the caliper off, clean the bores of that, while you're at it.

    Edit: see if this works, photobucket from phone, two calipers, one disassembled, [​IMG]
     
  17. ColoradoDan

    ColoradoDan Active Member

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    I don't have the maxim x, so just one caliper. But I just did the same to mine. Several threads going for the last two weeks about it, some just for fun.

    I took the whole caliper to a local shop that does the bike repairs I'm too much of a p***y to do, and he air-popped the piston pro bono.

    Got the seal kit from this guy: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0494401537. He might have other sets - for max x.
     
  18. ryancdossey

    ryancdossey Member

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    So does your have just one of the bigger circle things inside of it? The part that the oil presses agains the other piece that presses the pads? Mine has two of the large circles on each side... Someone give me the right term here lol...

    [​IMG]

    Got mine good and clean. A whole can of brake clean, a shop rag, and a tooth brush later.

    Thats a shot of one of them. So it looks like I have the hole where the brake line went to and then some other nozzle? no clue what that one does....Do I remove those two bolts to open it up?
     
  19. ColoradoDan

    ColoradoDan Active Member

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    Yep, just one piston to push the pads tight. Someone will definitely chime in soon about the two sides on yours.

    LOL, "some other nozzle" is the bleed nipple, and its fun to say it as often as needed. That's what squirts out the excess fluid and air when bleeding the system. I cut my teeth with hydraulics on 70s corollas, slumming my way thru college in the 90s, which is why this was easy for me. Pay off for being a starving student.

    Its easier than it appears.
     
  20. Maxim-X

    Maxim-X Well-Known Member

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    Go and take a look here for names and descriptions.
    http://www.cheapcycleparts.com/model_ye ... ke-caliper
    Use the + - buttons in the top left corner of the page to zoom in/out then hold down your cursor to move the picture around, when you see what you want scroll down through the parts list and get the name and description.
    Hope this helps.
     
  21. ryancdossey

    ryancdossey Member

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    Any advice on how to take this apart? thanks Dan for the clarification!
     
  22. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    You remove the bolts holding the two sides together.

    Those "round things" that push against the pads are the pistons.

    They sit in bores in the caliper; and there are round rubber rings in the caliper holes that they slide in and that seal out dirt and keep the brake fluid in.

    Those round rubber rings (that you can't see yet) are known as "caliper seals." They were supposed to be replaced after two years.

    What happens over time is that crud builds up in the channels those seals sit in, and they start to bind the pistons. This accelerates their wear (remember they're almost thirty years old) plus keeps the piston(s) from moving freely.

    What will happen if you only change the pads is that the calipers will continue to bind up, causing brake drag that will eventually overheat the brakes and warp your rotors which gets VERY expensive.

    Plus that thirty-year old thing. Which is why we're telling you to fully rebuild the calipers.

    Start by taking them apart and removing the pistons.

    None of this is overly complicated, or all that difficult. What it IS, is a lot of careful work and quite frankly, a pain in the butt. And you haven't even started trying to BLEED them yet. (Another reason to only want to do this once.)

    We will make a mechanic out of you yet.
     
  23. ryancdossey

    ryancdossey Member

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    I appreciate your patience with me and my thick head hahah. I have decided to do as you said and fully rebuild them AND replace my brake lines.

    Hence why they are off. So after I take them apart will the pistons just fall out?
     
  24. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Dude, really? How many threads are there on here about "removing stuck caliper pistons?"

    Do a little research here (use Google to search the forum rather than the site search engine) they are not likely to "fall out." They are likely to put up a fight; don't gouge them all up in removal attempts.

    Compressed air will often work; really stuck pistons require the "grease gun method."

    I highly recommend you do some reading, and get the pistons loose or out before you split the calipers. You have what are known as "dual piston" calipers, that will help your research.

    A lot of the discussion on this site is in regard to simple, single-piston calipers so be careful and understand the difference.

    Again, the basic principles (rubber rings in grooves that need to be dentally clean) are the same.
     
  25. ryancdossey

    ryancdossey Member

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    Sorry completely new to this. And every thing I have come across seems to be for single piston calipers. I'll dig around some more.
     
  26. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    No worries. A couple of folks have done piston removal tips for dual-piston calipers, and just recently.
     
  27. ryancdossey

    ryancdossey Member

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    So for dual calipers am I right in that I keep them together and hook up a grease gun to the brake hole. Or is it the bleeder nipple I use? And that should push both of them out enough to where I can safely remove them by pulling?

    Is there a way I bolt the grease gun in or do I simply just hold it in place?


    Forgive my ignorance I have never used one. From what i've seen it looks like a caulk gun?
     
  28. maximike

    maximike Member

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    Nah, just holding it won't work, you are dealing with lots of pressure to force out pistons. What you need is a fitting to attach gun to the bleed nipple, I believe. Or air if you choose. Some folks even use the master cylinder, but you have your lines off. Don't know how your dual piston set-up would complicate that.

    And you'll have to make sure other holes are blocked. Most calipers you can put the bolts that were holding the caliper on the bike into the hole the line attaches to, so you can seal it. Again, ymmv, because I only know about single piston.
     
  29. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The stock bleed nipple is shaped like a zerk fitting; my grease gun engages just like it would a grease fitting.

    I don't think the dual piston caliper would be different in that respect. I've only done single-piston Yammie calipers too.

    Yes, the type of grease gun we're referring to looks like a caulking gun; they have a little spring-snap arrangement in the tip to "engage" grease fittings. My apologies, I always assume everybody has experience with basic auto-shop stuff like that too.
     
  30. ryancdossey

    ryancdossey Member

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    Ill see what I can do :)

    And no apologies needed. This is my first project so I'm just getting my feet wet. Ill go get a grease gun tonight.
     
  31. bensalf

    bensalf Well-Known Member

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    i have just posted a thread on removing stuck pistons on dual piston calipers
    ----------------------------------------
    removing stuck caliper pistons
    ----------------------------------------
    its at the bottom of the "xj chat" page at present "oct 6th 2012"
    sorry , havent figured the link thing yet
    stu
     
  32. maximike

    maximike Member

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    To post a link, all you have to do is copy and paste. Go to your thread, go up to the address bar in the browser, copy the url, then paste it in this thread, or anywhere. That's it :)
     
  33. bensalf

    bensalf Well-Known Member

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  34. ryancdossey

    ryancdossey Member

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    Looks simple enough... Why do I need the tire valve? I don't have one...


    And I ran to an autozone to look at grease guns and ask about what I needed it for. Guy was a tool... And they always seem to be. I walked out didn't buy anything. Ill drive an extra 15 min to go to a shop where they'll actually help me.
     
  35. ryancdossey

    ryancdossey Member

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    How does pushing them in help get them out?
     
  36. maximike

    maximike Member

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    I'm not sure I followed that write up exactly either. But, it makes sense that you hold one piston to get the other out. I had assumed you split the caliper apart first, but I guess that wouldn't work. I don't think you actually, "push them in" to get them out, but if you don't clamp one in place, then they'll just push out into each other, right? Then there isn't room to pull them out. You gotta hold one, extract the other, somehow block off hole of the one you just got out, and extract the one you just held. Whew! The phrase P.I.T.A. comes to mind.

    Edit: okay, re-read it. The shraeder valve is if you use air, of course. He is attaching his modified valve where the brake lines attach, not at the bleed screw. You are using grease at the bleed nipple. Same idea, but you *block off* the hole he stuck the valve into. (He blocked off bleed nipple, by closing it, lol)
     
  37. ryancdossey

    ryancdossey Member

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    Is there anyway to hook one up without fabricating a nozzle? I don't have the capabilities to do that. How would you clamp one in place? So did he use the c-clamps/ steel to hold one and the air to force the other? Than how did he block that hole to get the other one out?

    Contemplating just having a shop pull the pistons out for me. Idk that I can do it.
     
  38. Polock

    Polock Well-Known Member

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    if you use grease, how will you get it out of the passageway that connects the 2 halves of the caliper ?
     
  39. ColoradoDan

    ColoradoDan Active Member

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    Hey ryan, I don't wanna take the wind out of your dude-sails, or ruin your Do-It-Yourself experience, but you could do what I did:

    Go to a local bike repair shop (I used the one that helped me out when I bought the bike) and ask them super nicely to do it, then buy something or give them a six pack.

    They'll get a little ego boost, but you'll to the actual caliper rebuild much quicker. I tried using the master cylinder method, but mine was too locked for that, and after reading the instructions on the grease method, I went for a drive in my cage of shame over to "Rolf's" and begged for mercy.
     
  40. bensalf

    bensalf Well-Known Member

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    ----------------------------------------------------------------------------------
    Is there anyway to hook one up without fabricating a nozzle? I don't have the capabilities to do that. How would you clamp one in place? So did he use the c-clamps/ steel to hold one and the air to force the other? Than how did he block that hole to get the other one out?
    ---------------------------------------------------------------------------------
    ok, i'll try to elaborate/ simplyfy the way i did it.
    (fabricate a nozzle) its just an old tyre valve, go round to your local tyre centre, they throw them away, they will be all over the floor, or they throw them in a bin, just ask for one , then shave the end down with a sharp knife, till its got just enough rubber on , for you to screw it into the brake line , banjo bolt hole.
    like this
    [​IMG]

    then screw it into the caliper
    [​IMG]

    at this stage you can couple up to an air line and see if one of the pistons will push out, cover all caliper with a towel and blow a piston out, it took 70psi to push one of mine out. but the valve held ok

    now you should have a caliper with one piston out and the other stuck in,
    heres where you use the bit of old steel and inner tube
    there are used to block off the "open" piston pot, the "one youve just got out
    "
    so seal the open pot with the bit of rubber and place the steel plate over it, then clamp it in place with a wrench or thick bit of wood on the outside of the caliper
    thus..
    [​IMG]
    then apply the air line again to the valve , and the other piston should pop out
    simples :lol:
     
  41. bensalf

    bensalf Well-Known Member

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    ------------------------------------------------------------------------------------


    if you use grease, how will you get it out of the passageway that connects the 2 halves of the caliper

    -----------------------------------------------------------------------------------

    blast an aerosol ,maintenance spray, or wd40 through the pasageways , from inside the bottom of the piston pot,
    then blast carb or brake cleaner through,
    then blow with air line, or an aerosol air duster
    [​IMG]

    stu.
     
  42. Maxim-X

    Maxim-X Well-Known Member

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    ^^^^ great idea.
     
  43. ryancdossey

    ryancdossey Member

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    Thank you very much for the advice. What I found the easiest to do.... We broke the caliper apart into two. Used an air gun into the main line hole on the one while holding the two small holes on the sides shut. Popped right out. On the other side we simply went in the bleed nipple side and held the two holes shut by hand again. Popped right out.


    Just in case anyone else runs into this.
     
  44. ryancdossey

    ryancdossey Member

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    Okay So my rebuild kits are on the way from Chacal looking ahead.... How do I bleed the system without any bleed screws or special tools just the "gravity" method? Also I am doing stainless lines. I've noticed the bolts have holes in them is there anyway special I need to hook them back up or just bolt it back up?
     
  45. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Use NEW "crush" washers, one on each side of each hose union.

    Your calipers have bleed screws; "speed bleeders" are useless on an empty system.
     
  46. hbwb

    hbwb Member

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    I used compressed air on my GPz and stuck the air gun nozzle into the line hole. To get a good seal I wrapped electrical tape around the nozzle end. They were stuck good but when I shot the air to them they popped right out. After the first one I learned to point the piston down to the floor so they would not go flying across the shop with the seals also shooting out.

    Just saying there are all sorts of ways to do something and sometimes if you just look a thing over and think about it for awhile you may get ideas. There is also something to be said from getting ideas and knowledge from people who have been there. This site is full of people like that who are willing to help.
     
  47. hbwb

    hbwb Member

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    Pretty much what we did on a radian. We held the cross passage holes down against a block of wood and shot air in behind the pistons to pop them. We had to use the seals that connect the holes to keep air from leaking out.
    By doing it like this the wood would catch the piston before it got all the way out, but it was easy to pull out from there.
     
  48. ryancdossey

    ryancdossey Member

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    Alright so someone give me layman's terms for bleeding my brakes. I am going from a completely dry system. New lines, pads, and rebuild calipers. I bolt them all back up... Then what?
     
  49. maximike

    maximike Member

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    Okay, so, if everything is together, first thing: put brake fluid in the master cylinder. Then put a clear tube on the end of the bleed nipple. I forget if you have one or two calipers. If two, then start on the one farthest from the master cylinder. Run the clear tube into a container with a little brake fluid already in it. Now MAKE SURE the reservoir(the box on the master cylinder) never runs dry as you do this, or else more air gets in. Now, a partner helps, but isn't mandatory. You pump the lever with the bleed valve open until fluid comes out into the clear tube. Basically you keep doing this until only fluid, no air, comes out. You have to do some pumping until you get resistance with the valve closed, usually, after the initial adding of fluid.

    Repeat both sides. My best advice is once you add fluid to master and have fluid coming out both bleed nipples. Close them, tie the brake lever back, and leave it overnight. Air should escape out the master.
     
  50. MiGhost

    MiGhost Well-Known Member

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    Lets back up a second here.
    You are rebuilding the calipers, and replacing the hoses.
    What are you doing about those 30 yr old, outdated, rubber parts that are still in that Master Cylinder?

    Your brakes will only be as good as the weakest part.
    At the moment. That is the MC.

    And while you are at it. Make sure that you clean out the juction block where the hose from the master cylinder splits into the two hoses to the brake calipers

    Do it all at once, and live to tell the tale. Do it seperately, and do it again. IF your lucky enough to get the chance!!


    Now on to the bleeding
    There are several methods for bleeding the brakes. From pump, and bleed. To using a vacuum pump. And even the syringe method. The basics boil down to making sure the system is completely filled with brake fluid, and all the air is removed.

    Pump, and Bleed:
    Pumping the brake lever, and releasing the bleeder screw to force the brake fluid through the system.

    Using this method. You will pump the lever several times to build pressure in the system. Then while holding the lever to maintain presure on the system. You release the bleeder screw to allow the air to escape. The hard part of this method is making absoute certain that the master cylinder is functioning properly. The first few times of pumping, and bleeding will not result in much action until the fluid is moving through the master cylinder properly.

    A variation on this method involves holding a finger over the hole that the hose attaches to. Then use the finger as the bleeder valve. Releasing the pressure on the finger to allow the air to escape. This method allows the system to be bled as you assemble all the parts.

    Vacuum Pump:
    Using a manual pump attached to the bleeder screw to pull the brake fluid through the system

    Using this method involes attaching an external pump like a mityvac to the opened bleeder screw. Then the pumping action aplies suction to the system to pull the brake fluid through the system.

    Syringe:
    Using a syringe to force brake fluid backward through the system.

    This method involves using a syringe to force brake fluid through the removed bleeder screw hole to force the air through the system from the calipers to the master cylinder.

    All methods will result in the same end result. With the system being full of fluid. Each has its good, and bad points. Everything but the pump, and bleed will require the system to be finished off with the pump, and Bleed method to remove the last bit of air.

    Ghost
     

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