Rear brake compensating valve leaking

Discussion in 'Mech Tech' started by Skyelectrix, Jul 11, 2019.

  1. Okey dokey all sorted and usual you clever lot on here have saved my butt again! Stripped the valve down and it was full of horrid black gunk. Unfortunately the gasket was in a few pieces so cut a new one from thin gasket paper. With a smear of sealant it was back together. I left it overnight before refilling the brake fluid and it seems to be leak far!
    So once again I’m in debt for the great advice and one step nearer to actually getting away soon so hats off to you clever lot!!


    garethpuk, nicktuft, mgbman and 7 others like this.
  2. Ok this is embarassing. I've taken mine apart and can't remember how it goes back together! I've got an ali washer about the size of a penny and a rubber bit about the same size with a hole in the middle and I don't know where those two bits go. Anyone got an exploded diagram of how they go back together please?
    Razzyh likes this.
  3. :rolleyes:
    Mark Darby likes this.
  4. [​IMG]
    Think ur on about the rubber band seal goes in the ridge and the washer I think goes on end of spring

    @pkrboo has some great pics

    Sent from my iPhone using Tapatalk
    Mark Darby, pkrboo and snotty like this.
  5. Clean it up outside in the sun :)
    Skyelectrix likes this.
  6. Thanks for the pic. Looks like the rubber bit is in on the left hand half over the shaft of the smaller slidey piston bit (no it's OK I knew where the o ring went). So does my washer go between the spring and the larger piston slidey bit that's under it, in your pic? Or does it go between the spring and the rubber in the opposite half? (Hope that makes sense)

    @pkrboo - Matt if you've got a diagram, please would you send it to me?
  7. pm me your mobile and I'll WhatsApp over the pictures I have
    Mark Darby likes this.
  8. Does the cross section help? It looks like the washer goes between the spring and the secondary piston (the larger slidey bit)
    Brake compensator valve.jpg
    Last edited: Jul 25, 2019
    mcswiggs and Mark Darby like this.
  9. Mine is the later type and looks a bit different to that one, I assume the principal is the same though. Thank you. Neither Bentley or Haynes were any help.
    77 Westy likes this.
  10. If you look at mine stripped down the washer goes between the spring and the smaller piston, or between 2 & 3 in @77 Westy diagram
    Mark Darby likes this.
  11. I’ve never had one apart and I don’t really know what the spring does but doesn’t the washer give the spring something to push against? The shoulder is smaller on the secondary piston side compared to the primary piston.

    What does the washer do if it’s on the primary piston side?
  12. I called "2" the bigger piston as I went by diameter, so we agree I think.
    Skyelectrix and 77 Westy like this.
  13. Now I’ve had a look at @Skyelectrix pic I think he’s calling the secondary piston the smaller piston, even though it’s larger diameter. The cross section drawing is correct and we’re in agreement – probably.
    Skyelectrix and Mark Darby like this.
  14. Yep 2 is the shorter piston I guess but fatter!
  15. I finally realised where this pesky rubber bit goes
    It looks like it'll fit in here
    It fits! It was nothing to do with the plungers after all - doh! It goes under the ball bearing :)
    77 Westy, Skyelectrix and snotty like this.
  16. That’s the valve seal (#8 on the drawing); I thought you were talking about the washer between the pistons earlier.:)
    Mark Darby likes this.

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