1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

1985(86) XJ700 Caliper Rebuild

Discussion in 'XJ DIY How-To Instructions' started by Nuch, Jan 30, 2018.

  1. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Initially, I thought I’d get through the process and I’d post my entire rebuild from beginning to end. Then I thought it’s better that I post in stages and consider the thoughts of the good folks here as I go… Especially since I have never done this before and honestly don’t know what I’m doing! Today is the teardown and clean up of my newly acquired eBay XJ700 front calipers. I was going to just rebuild the ones I have on the bike now, but then I can’t ride while this gets done.

    Here we have our suspects. Relatively clean on the outside… they came packed nicely, though they were rolling around in their own fluids… Both for 12 bucks (plus shipping)! How can you beat that?

    01_front_brakes_xj700.jpg 02_front_brakes_xj700.jpg



    After pulling the pins and pads I used compressed air to get things moving… The 700 has a two piston caliper, so the air will inevitably push one and not the other. When the two pistons come together, you’re done.
    03_front_brakes_xj700.jpg



    Grab a 14mm wrench and remove the two bolts holding the two halves of the caliper together.
    04_front_brakes_xj700.jpg
     
  2. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    When you take the two halves apart, the piston that did most of the moving should come out pretty easy… Mine took nearly no effort…
    05_front_brakes_xj700.jpg



    Now you have to deal with the other half. The two halves of the caliper share the brake fluid through two fluid transfer ports. For the second half of the caliper, you’ll have to plug up one side (I used a punch) and force air into the other side. YOU NEED TO COVER THAT PISTON when you do this. If you don’t, you’ll get really familiar with that piston really fast! The rag I used is not there in the picture so you see what is going on. Give it a good shot of air. The pop of the piston out of the bore was more satisfying than a champagne cork on new years eve! Again… keep it covered when you do this… 06_front_brakes_xj700.jpg



    Look at all that good stuff that was floating around in your brake fluid!
    07_front_brakes_xj700.jpg



    Drain off your fluid and pull the dust seals…
    08_front_brakes_xj700.jpg
     
  3. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Then pull your pressure seals…
    09_front_brakes_xj700.jpg



    Here you can see your fluid transfer ports… make sure you clean these as well… Pull the rubber fluid transfer port seals off too… you’ll want to replace them… At this point I gave the calipers a good scrubbing with brake cleaner, then rinse with water, then more brake cleaner, then more water, etc...
    10_front_brakes_xj700.jpg



    Now it’s bath time… I used good concentrated dish liquid and soaked all of my parts in it with hot water… I was amazed at how it really did cut though the brake dust grime that the heavier chemicals didn’t get! Scrub thoroughly and rinse!
    11_front_brakes_xj700.jpg



    Clean and ready for rebuild. Keep in mind, you'll have to do two of these for the XJ700. Len @ XJ4EVER (top right hand corner of every page if you don't know who I'm talking about) has already confirmed that the new seals are on their way, along with my much needed master cylinder rebuild kit…
    12_front_brakes_xj700.jpg

    Let me know what you think I should be looking out for as I put these things back together. I’ll update the thread with pics when I get it done…

    Thanks!
     
    Last edited: Jan 30, 2018
    Maxim-X and chacal like this.
  4. Tim morris

    Tim morris Member Premium Member

    Messages:
    109
    Likes Received:
    15
    Trophy Points:
    18
    Location:
    Hopatcong NJ 07843
    Great post
     
  5. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Ordered on and Shipped from Atlanta, GA on Jan 30th. Received in NY on Feb 1st. That's the definition of fast. Thank You Len.

    Now, any advice on the application of grease and reinstall/assembly? I feel like this is one of those "not too much/not too little" amount of grease situations to minimize the chance of the grease and brake fluid mixing.

    Thoughts from those who have trampled this path before?

    13_front_brakes_xj700.jpg
     
  6. Eddie Swedlund

    Eddie Swedlund New Member

    Messages:
    6
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin
    Great post! I'm about to go through the same process. I look forward to any experienced users comments on grease and re-assembly.
     
  7. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

    Messages:
    7,696
    Likes Received:
    1,047
    Trophy Points:
    113
    Location:
    At My Computer
    That is correct........you want a thin smear on anything, minimize build-up, it really won't contaminate the brake fluid, it's designed to be used with it.
     
  8. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Any when you say anything, do you mean everything? All three (dust, pressure and fluid transfer) get the grease?
    Also, Seems like the bolts holding the two halves together will "bottom out" when tightened. Is this the case or is there a torque spec?
    I'm assuming that I should use thread lock as well?
     
  9. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

    Messages:
    7,696
    Likes Received:
    1,047
    Trophy Points:
    113
    Location:
    At My Computer
    Yes. It doesn't hurt to put a little bit on the slider pins, too.

    They won't, and we've never seen a torque spec either, but you remember how hard they were to break loose? That's how hard you'll need to tighten them, too! Semi-permanent (purple) thread-lock won't hurt, but should not be necessary.
     
  10. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Good point... Indeed I had to put them in an open vice to give me the leverage needed to break 'em loose.
     
  11. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    I now have more to share...

    Now that we’re “zestfully clean" and rebuild parts are in house, let’s put things back together…
    After a thorough clean up, I gave the pistons one last buff and polish with Mother’s Mag and wheel polish. They shined up real nice!
    14_front_brakes_xj700.jpg


    Snip the grease packet and squeeze a small amount on your favorite finger!
    15_front_brakes_xj700.jpg


    Give the pressure seal (the thicker of the two provided) a thin coat of the grease and send it home into the larger of the two grooves in the piston bore.
    16_front_brakes_xj700.jpg


    Then do the same for the dust seal! It goes in the thinner groove.
    17_front_brakes_xj700.jpg
     
    Last edited: Feb 10, 2018
  12. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Your fresh seals should look something like this in their new home…
    18_front_brakes_xj700.jpg


    Now it’s time to send your piston home. With even pressure on either side, she should slide right in. Be careful not to scratch it on the edges of the bore.
    19_front_brakes_xj700.jpg


    Now do the same with the other half of your caliper…. once that is done, it is time to address your fluid transfer seals.

    Give your fluid transfer seal a thin slather of grease like you did the others. You’ll notice that there is a recess on one half of the caliper, but not the other. Seat the seal in the recessed groove. There are two so you’ll have to do both…
    20_front_brakes_xj700.jpg


    On the other half of your caliper, you’ll notice the matching surface is flat. I gave that spot where the two come together a touch of grease as well.
    21_front_brakes_xj700.jpg
     
  13. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Now sandwich them together and put some Removable Loctight on the threads of the bolts. Don’t use the HARD STUFF! the blue Loctight should suffice.
    22_front_brakes_xj700.jpg


    When both of your bolts are put into place “finger tight” you’ll notice that there is still a gap between your halves. That’s because the transfer seals are there…
    23_front_brakes_xj700.jpg


    I used an open vice with a rag in it to give me the leverage needed to wrench down on the two bolts. I went back and forth from one bolt to the other until the transfer seals begged for mercy.
    24_front_brakes_xj700.jpg


    When she’s good and tight the gap should be gone and the residual grease should be satisfyingly squeezed out!
    25_front_brakes_xj700.jpg
     
    Last edited: Feb 10, 2018
  14. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Now… do it all over again because you have two front calipers!

    Well that’s it for now. Here are the rebuilt specimens. I’m working on the Master cylinder right now and have documented things in pictures so far. I’ll be adding it to this thread as well. The plan is to assemble the entire front brake system at Hogfiddles’ Central New York Carb Clinic this June… complete with new Stainless Steel braided lines. I’ll update the string as more happens…
    26_front_brakes_xj700.jpg
     
    Alexandru, Maxim-X and chacal like this.
  15. Maxim-X

    Maxim-X Well-Known Member Premium Member

    Messages:
    1,686
    Likes Received:
    69
    Trophy Points:
    48
    Location:
    London Ontario Canada
    This an excellent thread, meticulously written and photographed.
     
  16. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    Thank you @Maxim-X. I'm learning as I go with the help of those here. If anyone should see a problem with what I've said (procedure/steps/sequence, etc.) please let us know here. I thought about what I would have wanted to see BEFORE I started the job... then took those pictures. Much thanks to @hogfiddles and @chacal for their support on and off the forum.

    I'm done rebuilding the master cylinder now. I'm thinking I'll post that sequence here in this thread as well. In June after the carb clinic, I'll have the entire front brake system assembled and back on the bike... That will close this chapter!
     
  17. hogfiddles

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

    Messages:
    11,901
    Likes Received:
    3,481
    Trophy Points:
    113
    Location:
    near utica, new york
    Looking real good!!
     
  18. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    8,286
    Likes Received:
    2,084
    Trophy Points:
    113
    Location:
    Great North Woods
    when your done with the brake system maybe len will consider it for a pdf on his how to's
     
  19. Nuch

    Nuch Well-Known Member Premium Member

    Messages:
    565
    Likes Received:
    365
    Trophy Points:
    63
    Location:
    Suffolk County, NY
    I'd be happy to format it as a PDF if he feels that it is worthy!
     
  20. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

    Messages:
    7,696
    Likes Received:
    1,047
    Trophy Points:
    113
    Location:
    At My Computer
    Would be happy to!
     

Share This Page