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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

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    Post Carb Clinic Additions… The final assembly was done under Hogfiddle’s watchful eye.
    I figure I should keep all of this together as this is the final piece of front brake rebuild for the XJ700n system. Like the front calipers, I purchased a used MC from eBay for the rebuild. Here you have the replacement unit with it’s guts out. There was a dry rotted dust boot and a circlip that you’ll have to muscle out… more on what that looks like (on the re install) down the thread. Nice and crusty!
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    After removal of the insides, I did my best to really buff the bore as much as possible, picked out the majority of the fluid level viewing window, taped up the openings and bead blasted it in a cabinet.
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    After the blasting, I got in there and picked out the remainder of the window. The yellowish clear ring was the window edge, then there was the metal plate with the slots and the o-ring that holds it all together. You have to clean the groove really well before install of the new window. Good time to do it now… use acetone.. there was “gummy” bits and window residue in there…
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    Next another wipe down with acetone… I think it’s always a good idea to use gloves. What is the sense in having your skin come in contact with chemicals anyway? Besides, the gloves keep you from transferring your oils back on to your prepped MC just prior to paint.
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    After Paint! The screws look bad… but we get new ones anyway!
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    Now for the good stuff… A complete MC rebuild kit from Len @ XJ4Ever! Get one. You won’t regret it.
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    You’ll have to cut down the tip of the applicator on the RTV tube. I nipped off the very tippy end of it first.
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    Then I whittled it down to a point. You want the thinnest “squeeze” of RTV possible. You’re about to attempt something difficult!
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    You’ll want to set yourself for as much accuracy as possible. That sight window groove is small. The RTV is sticky and hard to work with. You’re also working with a tiny circle glass window. You want to do your best to get it right the first time. If you get the RTV where it shouldn’t be… You’ll have to clean things up and start over. You want to keep your glass clear… and you just painted that shiny new MC… remember?



    Now put the RTV in… Not too much… but not too little either. That bead of RTV has an important job to do.
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    Once you put your RTV in, make sure your fingers are clean of any RTV (or perspiration, anxiety, cheese doodle dust, etc.) and send that window home.
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    After the glass was set, I put a second application of RTV on the outside. It’s REALLY hard to get that stuff smooth when you’re working in such a small area and in such small quantities. It’s a bit “lumpy” for my liking, but it is strong. Once done… Leave it a day or so to really set up permanently.
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    Now for the guts…
    Take your new spring and plunger gasket… assemble and slather on some of the included assembly grease.
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    Slide it into the bore. Set it in good.
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    Your piston will go in on top of that. Don't forget to grease that too.
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    Last edited: Jul 21, 2018
  2. Nuch

    Nuch Well-Known Member Premium Member

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    Now here’s the fun part…. Best case scenario, You should use a tool like this to set your cir clip.
    image16.png

    Unfortunately, I only had one of those $2 Multi tipped, Harbor Freight specials. Not only is it bad quality… Neither the straight nor the 90 degree tip will reach all the way into the bore necessary to set that clip. That is unless you modify! I had to grind down the straight tip back to the set pins to get more reachable length. Even then it was a while of muscling the clip into place to the point of ALMOST giving up and thinking about ordering the right tool for the job. Then… it happened… Snap! I couldn’t believe it. It went in! The next MC i rebuild will include the tool with the new parts in the order.
    image17.png


    Now sneak your dust boot on. Len’s full rebuild kit also comes with new screws for the top as well as the diaphragm for beneath your cover.
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    Fast forward to the carb clinic and install… Let’s remember why we’re here… The old rusty, crusty MC that believe it or not was still in service. The PO actually did put on stainless steel lines but the connections were getting rusty, they were not coated and they were definitely not the correct length.
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    And yes, that SAE bolt was going through the MC to hold the cover on.
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    So… Out with the old…
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    And in with the new… Including Len”s stainless steel braided brake lines.
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    Remember those rebuilt calipers from the beginning of the thread? Here’s one…
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    More Assembly… Before…
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    Getting there…
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    Beautiful fit…
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  3. Nuch

    Nuch Well-Known Member Premium Member

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    Then of course, once you put it all together, you have to fill and bleed the system. I feel like I’ve read 1001 horror stores about this taking days. Truth be told, once everything was assembled and fluid was put in, Saftie and I as well as some of the others spent a fair amount of time taking turns pumping the handle, holding, releasing at the bleeder valve, etc… Here and there a small bubble would emerge but at that pace, it was clearly going to take weeks to get a firm brake handle.

    Then...

    In steps Dave…
    image30.png
    He began doing something that I like to refer to as “The Hogfiddle Jiggle.” Ever so small agitations of the lever (like tiny, tiny squeezes). Man you had to see the bubbles rise from the weep hole in the bottom of the MC. I’m not joking, it took less than 5 minutes to get a firm lever. Amazing.


    Job done now. My new brakes did the carb clinic group ride as well as the run north in Lake George that weekend. Since home, no hiccups what so ever other than an annoying squeak which I’m hoping will dissipate at some point.
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    Much thanks to everyone who helped out including Saftie and The Crazy Gnat and of course Dave once again for his care and know-how and hosting the annual CNYCC each year.
     
    Last edited: Jul 20, 2018
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  4. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Excellent!
     
  5. hogfiddles

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

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    Awesome write-up, Nuch!
     
  6. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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  7. Nuch

    Nuch Well-Known Member Premium Member

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    Glad you liked it!
    Thank you!
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    Last edited: Jul 21, 2018
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  8. lostboy

    lostboy Active Member

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    Awesome pictures. It was like I was there .
     
  9. Nuch

    Nuch Well-Known Member Premium Member

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    It really was (and always is... 3 years running so far for me) a great time. I'm already looking forward to next year. Having a bunch of XJ'rs together for a day is really great. I make a "Me Weekend" out of it. Too bad it's only once a year!
     

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