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Master cylinder rebuild question?

Speedpup ยท 2009-04-19 14:20

Trying to rebuild my master cylinder on my Lull 844. I have no clue how to get it apart further than the pictures. Any tips are appreciated before I mess it up! Thanks! [img=http://img514.imageshack.us/img514/8519/mastercylinderendviewane.th.jpg] [img=http://img518.imageshack.us/img518/8089/mastercylinderplungeren.th.jpg] [img=http://img294.imageshack.us/img294/7716/masterrebuild.th.jpg] [img=http://img2.imageshack.us/img2/6190/mastercylindersideview.th.jpg] [img=http://img2.imageshack.us/img2/8861/mastercylindercaps.th.jpg] [img=http://img2.imageshack.us/img2/3200/mastercylindertopviewop.th.jpg]

Replies12
  1. #1willie592009-04-19 16:31

    Did you have to remove a snap ring or some form of retainer on the end where the brake rod goes in?

  2. #2td25c2009-04-19 17:08

    Thats the first master cylinder I'v seen that has a threaded cap at the end of the cylinder housing.You might be able to gently drive the piston ,spring,Seals,out the threaded end.

  3. #3Speedpup2009-04-19 19:36

    retainer in the rebuild kit but I have not seen one yet:beatsme thanks!

  4. #4wrenchbender2009-04-19 19:50

    http://img2.imageshack.us/my.php?image=mastercylindersideview.jpg Looking at this pic you can see the piston assy will have to be pushed out the threaded end. I would use a large phillips head screw driver placed in the actuator rod seat and gently push the piston out.

  5. #5Speedpup2009-04-19 19:54

    not sure if anything here helps you guys help me. Many thanks :notworthy http://www.mico.com/products/images/34_docfile.pdf does page 14 look like mine? Lokking at the drawings with my limited knowledge I think you may be right on pushing out from the accuator side when the threaded end is removed. I'll try that tomorrow.

  6. #6wrenchbender2009-04-19 20:20

    That sure looks like the right one Speedpup.

  7. #7willie592009-04-19 21:08

    The pics look like a Mico straight bore master cylinder to me. If so, I believe it could come apart from either end. I don't think it's a dual stage master cyl, which has a stepped bore, because I don't see a relief valve under one of the fill caps. I'd do what wrenchbender recommended, place a phillips screwdriver in the rod end and stoke the piston in and out. It should pop apart.

  8. #8Muffler Bearing2009-04-20 00:02

    Can you even move the piston at all? If it's really seized in there it may be a lost cause.

  9. #9Speedpup2009-04-20 05:02

    It worked it just goes to the floor slowly then no brakes . I'll try to work on it tonight to see if it comes apart. I hope it rains early today.

  10. #10Speedpup2009-04-26 10:35

    Pushed it out from the rod end and rebuilt it. So it was a straight bore like you said ATCO. Nothing looked bad in the master. Bled it on the bench and installed it. Still no brakes I didn't really bleed the system yet as I can't do it alone but I think I have a problem more than bleeding. When I get someone to help me I'll know.

  11. #11willie592009-04-26 10:46

    Oh yeah, you can do it yourself, I do it all the time. You need a couple of feet of clear flexible vinyl tubing/hose, you can get it from stores like Home Depot. You need a size of tubing that will fit snug on the nipple of the bleeder screw. Open your bleed screw, stick the tubing on the nipple of the bleeder, then place the other end in a open 5 gal bucket with the end of the tubing submerged in a small amount of hyd oil (since your brakes use hyd oil). Now you just pump the brakes watching the air bubbles come through the clear tubing. When the fluid runs clear, no bubbles, close the bleeder.

  12. #12Speedpup2009-04-26 12:10

    Thanks but now I feel dumber than dumb. I do that on my race car and trucks all the time. Thanks for the refresher course. I think I can see the bleeder from the seat of the Lull. Hope I don't have to take the drive-line brakes apart it is a PITA job.